PUBLIC HEALTH ASSESSMENT
US DOE MOUND FACILITY
[a/k/a MOUND PLANT (USDOE)]
MIAMISBURG, MONTGOMERY COUNTY, OHIO
PUBLIC COMMENTS ON THE MOUND PLANT PUBLIC HEALTH ASSESSMENT AND ATSDR'S RESPONSES
ATSDR received comments on the Mound Plant Public Health Assessment, Public Comment Release version (December 2, 1996), from approximately a dozen parties--individuals, organizations, and agencies. We thank all of those who took the time to comment. The comments we received reflect a strong and sincere interest from people in the Miamisburg community. However, several sets of comments came to us from outside the Miamisburg community. This appendix includes a listing of the public comments we received and our responses to them.
The comments we received covered many topics. Recommendations included asking us to move material around in the document, delete words, add enormous amounts of support documentation (some of which we did), conduct additional research, and reconsider our conclusions: some people wanted us to soften them and some wanted us to strengthen them. One commenter recommended that the public reject the assessment out of hand. In the opinion of ATSDR health assessors, many of the comments and questions we received were very good ones.
In many different ways, there were two major concerns that were expressed repeatedly throughout the comments and questions that people sent us. First: Are the data adequate to support the conclusions that we reached? And second: How much contamination in the environment, or exposure to the contamination, is enough to call it a health hazard? Both questions underlie the public health calls that we make.
Our brief response to the first question is that we have adequate data to address plutonium and tritium in the environment from Mound, but not sufficient data to address historic releases of nonradioactive substances. Since we released the Public Comment Release version of the Mound public health assessment we reviewed our plutonium calculations again and acquired and reviewed additional tritium data, and we have not changed our earlier conclusions. In response to comments, to clarify our position, we have defined "current" in this public health assessment as beginning January 1, 1987, and we define "historic" as prior to that date.
For polonium-210, we apparently have not reviewed all the available data, and the data we have seen are not adequate to reach a conclusion. (This is also the position we held in the Public Comment Release public health assessment.) As requested by several parties, we are exploring the feasibility of reviewing Mound's 1950s laboratory notebooks for additional polonium environmental data. The notebooks will have to be surveyed for radioactive contamination prior to our having access to them.
A partial answer to the second question--how much of a substance is a health hazard?--is that it depends on the situation. ATSDR does not maintain a set of values for substances that define what is and what is not a health hazard. We have health-based comparison values for some chemicals that we use to initially screen environmental data. However; exceeding screening values does not mean a substance is a health hazard. For each situation, we consider what exposure assumptions are appropriate and what is known about the toxicity of the substance. We explore the answer to this question in greater depth in our responses to specific comments.
Related to the question of hazard, several commenters specifically noted that with radioactive materials, there can be no safe level of exposure and any contamination consisting of radioactive materials in the environment poses a public health hazard. In our opinion, this is not true. We recognize that people who assign risks to radioactive materials usually assume there exists some incremental risk from exposure to radioactive materials no matter how small the quantity of radioactive material in the environment (i.e., an assumption of the no-threshold models), and they calculate incremental risks by linearly extrapolating risks from higher radiation doses. This approach is a conservative one that is used by regulatory agencies to provide adequate protection for workers and the general public from potential radiation hazards. But this assumption is not necessarily an accurate description of the true risks from exposures to low levels of radiation. Unfortunately, we cannot measure those risks directly using currently available scientific methods (e.g., epidemiology and toxicity testing). Furthermore, considerable mounting evidence from the fields of genetics and cancer research, as well as numerous epidemiological studies refute the linear, no-threshold risk models for exposures to low levels of radiation. Rather than assuming that any quantity of radionuclides in the environment will cause adverse health effects, we consider both existing radionuclide-specific toxicological data and the ongoing recommendations of radiation advisory bodies (e.g., the International Commission on Radiological Protection [ICRP] and the National Council on Radiation Protection and Measurements [NCRP]). We believe that this is the most sound scientific approach.
Finally; at ATSDR, we bring to bear the collective education and experience of public health scientists, health physicists, toxicologists, epidemiologists, environmental health scientists, physicians, and others, to the assessment process. In this environment, we work to keep current on scientific and social issues, and discuss, both internally and externally, different approaches to the assessment process. Where previously noted, for this public health assessment we went outside ATSDR to obtain additional expertise--primarily, the Boston University School of Public Health and the US EPA National Air and Radiation Environmental Laboratory. And, as described in greater detail in this appendix, this document was peer reviewed (outside ATSDR) prior to the Public Comment Release. After the Public Comment document was released, ATSDR had it peer reviewed a second time. Nevertheless, we recognize that not all people will interpret the same information the same way we did, and we respect others who may have opinions different from ours.
We address the comments we received in the following section. Please note that we are using the term "Concern" to refer to those questions and statements we collected earlier, and presented in the main part of this document and in the Public Comment Release document; and we are using the term "Comment" for those questions and statements we received in writing in response to the Public Comment Release document, which we are presenting in this appendix. This distinction may be useful because, in this appendix we refer to both.
Page number references in this appendix indicate where text occurs in this document--not to the pages where the text occurred in earlier versions of this report. However, some comments refer to text in the previous (Public Comment Release) version that has been changed or deleted in this version. In those cases, the page references indicate the locations in this document where the text has been changed or deleted.
ATSDR responses are provided after each comment or group of comments. Comments from multiple sources are numbered separately, even when one response is provided. Multiple paragraphs following a single number represent a single party's comments.
We have added a bibliography to this version of the Mound Plant public health assessment.
In addition to the references we included in the Public Comment Release public health assessment, the polonium-210 data came from the documents listed in the bibliography that we have added.
The report needs maps. Where are the contaminated wells located. Where are other private wells that have not been examined for contamination located? Similarly, municipal well #2, which is between Bud's trailer park and Mound isn't mentioned.
We limited our description of the site because this type of information can be found in other documents. We also chose not to include maps and data that can be found in other documents. Please see the bibliography we added. Usually--but not always in the older documents--sampling methods and strategies are discussed with the data. For our sampling program with the EPA NAREL (Appendix E), we developed and released a Work Plan that described our sampling strategy [1].
There are many Mound documents that contain environmental data that predate the RI/FS process. We reviewed data in hundreds of documents. The references we included in the Public Comment Release version of the public health assessment were included to support or reference statements we made in the text. They were never intended to represent an exhaustive bibliography of materials we reviewed. The bibliography that we have added provides a more complete listing of documents which we reviewed for the public health assessment.
We considered both recent and historical data when we evaluated Mound's releases during their most active years. We note that 1990s environmental data can provide useful information about past activities.
In regard to missing data. Should further attempts to locate missing data be made?
Pages 1-2. In the cases where data is said to be missing, should recommendations be made to review additional data, if it is collected later.
Page 2. Is there any need to do any type of follow-up based on the known, historical releases of polonium-210?
Page C-4. P1utonium-238 in water: 2nd Paragraph: No data available on plutonium-238 in Great Miami River before 1967. My question is: The government knows exactly what nuclear materials are capable of doing to the population around nuclear weapons plants and I have my suspicions as to what has happened to missing and incomplete data. It's all just another coverup of just how crooked the American government can be. Look at everything else the government has hidden from the American public. Too many openings in the Mound's paperwork and too much incomplete data has caused many citizens to stand up and ask questions.
Page 17. What worries me is that you do not have complete data to be absolutely positive about polonium-210 in the 1950's. Incomplete data requires guesstimations which are not the burden of proof. It bothers me that so much data is either incomplete or missing. I question if it was conveniently misplaced or destroyed. It appears as if the government has been playing Russian roulette with people who live around nuclear weapons facilities. So much distrust has come about through secrets of human body experiments and other findings that cause the common folk to disbelieve what the government says and to question their ideas, theories and capabilities.
We did not review Mound data in original laboratory notebooks; we reviewed data in summary reports. It is likely that some of the data that we called "incomplete" in the Public Comment Release, such as those for polonium releases to the environment in the 1950s, are available in laboratory notebooks. Other "missing" data, such as those for releases of nonradioactive substances to the Miami-Erie Canal and the Great Miami River, were probably data that we would like to have but for which samples were never collected. In other words, they are not really missing. We took these possibilities into consideration when we evaluated the data in the summary reports. Measurements of environmental concentrations of hazardous materials are never "complete" enough that we can be "absolutely positive" about exposures, i.e., what people truly breathed, drank, ate, or otherwise came in contact with. We did not examine all of Mound's data. We are presently examining the feasibility of reviewing Mound's original laboratory notebooks. Should this occur and we find sufficient evidence to change our conclusions, we will issue a health consultation or a Site Review and Update (SRU) for the Mound Plant. We will also review additional information that is brought to our attention. Statements to this effect are presented in the introduction, "The ATSDR Public Health Assessment: A Note of Explanation."
We agree that there appears to be reporting discrepancies in the documents reporting 1960 data. For example, in one report (first quarter data), average concentrations were apparently incorrectly calculated using the number of sampling locations rather than the number of samples; these were corrected in later publications. ATSDR scientists agree that this is confusing, and probably misleading, but we do not think the discrepancies make any difference in the final analysis because the differences among these published values are small and they do not affect the average radiation doses that people could have received to any appreciable extent.
We concluded we have insufficient data to make a health call for some contaminants. For other contaminants, we believe the data support our conclusions. We disagree with this commenter concerning the interpretation or the relative importance of the data deficiencies.
There is no basis for the assertion that good quality controls were absent from data collected before the late 1970s. The Mound Laboratory always employed quality controls. It is instructive to note that Mound scientists (and DOE scientists at other sites) developed procedures for detecting and analyzing radionuclides. Radiation protection programs for employees were part of the Dayton project operations in the 1940s before the research was consolidated at the Mound Laboratory. Environmental monitoring programs for radionuclides were initially an extension of the technologies (particularly, urinalysis methods) developed to monitor workers. Should we disregard all data collected anywhere before the late 1970s because quality controls were not as they are today? We recommend that people look closely at the sample collecting and analytical techniques that were the standard of the day. We do not believe that Mound's historic data should be dismissed readily.
We begin by noting that the maximum long-lived alpha concentration in air that could be attributed to plutonium-238, in the data that we reviewed, is 1.413 E-12 µCi/mL, recorded during the fourth quarter of 1961 at the junction of Route 201 and Chambersburg Road. The average for this location during this quarter (n=4) is 3.638 E-13 µCi/mL. This is somewhat higher than the alpha concentrations measured in air during 1960.
The air and water standards in effect for the Atomic Energy Commission in the early 1960s, published in the National Bureau of Standards Handbook 69, were recommendations of the National Committee on Radiation Protection (later, the National Council on Radiation Protection and Measurements, NCRP). These recommendations were based on the available medical and scientific information describing the effects of external radiation to the human body and to specific organs and the effects of radionuclides in the body. The air concentrations were conservatively chosen to express permissible concentrations of radionuclides in air that workers could be exposed to for 24 hours a day, 7 days a week, for a year. The NCRP recommended that standards for the general public be set at one tenth (0.1) those set for workers, "primarily for the purpose of keeping the average dose to the whole population as low as possible, and not because of the likelihood of specific injury to the individual." The NCRP calculated the permissible concentrations of radionuclides in air and water based on an annual radiation dose of 5 rem to workers, and an annual radiation dose of one tenth that, or 500 mrem, to the general population. NCRP considered that exposures to radionuclides from facility operations in concentrations greater than the Maximum Permissible Concentrations were acceptable as long as the annual dose from all exposures did not exceed 5 rem (500 mrem to the public). Two of the reported maximum gross alpha readings in air that could be attributed to plutonium (in 1961 and 1966) would have resulted in radiation doses greater than 500 mrem to people who breathed that air for 24 hours a day for a year. However, none of the average concentrations of alpha-emitters in air in any year would result in radiation doses of 500 mrem to anyone who would breathe the air 24 hours a day for a year.
In 1993, the NCRP adopted the current standard of 100 mrem per year for exposures to the general public. (The ICRP adopted the same standard in 1990.) NCRP (and others) revised their exposure recommendations from 500 mrem to 100 mrem to limit exposures to "as low as reasonably achievable" (the ALARA principle) because the facilities utilizing radioactive materials were able, by the 1990s, to achieve the 100 mrem dose standard for the general public through control technologies they had developed. No adverse health effects had been observed at 500 mrem.
Due to grossly insufficient temporal and spatial coverage of environmental monitoring data in connection with the non-uniform pattern of releases from Mound, a proper dose reconstruction cannot be based on environmental monitoring data alone. An in-depth analysis of the plutonium-238 release data on which ATSDR relied upon in its dose calculations on page C-2 showed that the underlying raw data does not allow a reliable reconstruction of the magnitude and the distribution of airborne radioactive releases from the Mound facility. In addition to the inconsistencies found, the stack monitoring data is unreliable because of the lack of isokinetic sampling.
We would certainly like to see data for 1960 as good as we could obtain today; however, we do not believe the sampling conducted in 1960 is completely invalid because it doesn't meet today's standards. Even if we are missing some data, the data we have are numerous enough and consistent enough that they would require large deviations to move the average concentrations very far. None of our ways of looking at the data (e.g., air concentrations, release quantities, CAP88 modeling, soil concentrations) indicate that there are large inconsistencies in the data.
We agree.
We have not seen any evidence that this is true. We believe the commenter might be interpreting the 1962 Mound internal memorandum from H.E. Meyer described above. We disagree that the memorandum indicates monitoring was done only "on low release time". More likely, monitoring was done during "high release time", and their environmental monitoring was biased toward measuring stacks releases (though not open-burning releases) in the environment.
One page 1, the ATSDR report contains the following claims: That releases of plutonium-238 to the environment from the Mound facility did not pose a public health hazard and that sufficient data is available to make that determination, and that the data on polonium-210 is insufficient to evaluate fully whether polonium-210 releases from Mound ever posed a public health hazard, but that the existing polonium-210 data does not indicate levels of concern.
As a major source for its determination, the ATSDR references the environmental monitoring reports. The monitoring system in place around Mound had serious deficiencies as explained in greater detail in the enclosed affidavit in the court case which is submitted as part of this comment. [ATSDR note: We are not including the affidavit here.]
Monitoring was done on a discontinuous basis. While samples were taken over a large area up to a distance of 40 miles, the cumulative offsite air monitoring duration constitutes a very small proportion of a year, ranging from a low of 0.25% (22 hours) in 1959 to a maximum of 3.6% (314 hours) in 1950. In essence, most of the time, no offsite radiological monitoring was conducted at all.
The elemental and isotopic composition of the samples was not determined prior to 1966. In other words, the monitoring data do not indicate whether the measured alpha activity came from polonium-210, plutonium isotopes, other long-lived alpha emitters, or from some mixture of alpha emitters.
That Mound scientists did not monitor continuously is not critical for this public health assessment. What was important was that they measured concentrations of released materials that were representative of the concentrations that people could have breathed. Mound scientists were interested in gauging the safety of their operations and the impact of their operations on the environment. It would have been easy to measure only background radiation. We note that the most frequent measurement of alpha radiation in air above background during the 1950s was zero. Measuring low levels of radiation above background was a scientific and technical challenge. We have seen no evidence suggesting Mound employees avoided tracking emissions in the predominate wind direction.
We assumed all the alpha activity measured in the environment before 1960 was from polonium-210 and all the alpha activity measured from 1960 through 1966 was plutonium-238. These are conservative assumptions based on production activities at the Mound Laboratory and they maximize the estimated detriment to the community.
In summary, the ATSDR report ignored important evidence which is in contradiction to its findings regarding to the nature of the radioactivity releases from Mound and subsequent exposures in the environment. There is sufficient evidence that exposures from polonium-210 and plutonium-238 were in excess of historical or current dose limits.
We agree there is evidence that polonium-210 and plutonium-238 concentrations in air exceeded regulatory limits or dose limits in place at the time they were measured in several instances. However, exposures that exceed regulatory limits or recommended dose limits are not necessarily a health hazard.
Mound scientists reported in many of their documents in the early 1960s that alpha radiation detected in the environment was very low and the isotopes of polonium and plutonium were not distinguishable from each other or from the natural background. This is because the alpha energies of polonium and plutonium are very similar to one another, as well as to the alpha energies of other naturally-occurring alpha emitters such as uranium, thorium, and radon. The field equipment in use at Mound during this period could not separate the energy signals sufficiently to identify these various radionuclides at these low levels. The assertion that polonium and plutonium are indistinguishable from background is not the same thing as stating that these radioisotopes are part of the natural background or that radiation from them is a part of the background radiation. This is a measurement problem. When Mound's measuring capabilities improved and their instruments were capable of separating the signals from the various alpha-emitting radionuclides, Mound scientists began reporting concentrations of polonium-210 and plutonium-238 separately in their environmental reports (beginning with 1967 data). Prior to 1967, Mound's reports clearly state that the alpha energies measured could be a result of either polonium or plutonium from the Mound Laboratory. They also present the maximum concentration of each isotope that would have been present if 100 percent of the alpha radiation measured were from only that isotope (either polonium or plutonium). What we found with the 1967 data (and later) was that the peak concentrations of alpha-emitting radionuclides measured in air were decreasing. To be conservative, ATSDR scientists assumed that 100 percent of the gross alpha readings reported by the Mound Laboratory in the 1950s in air are attributable to polonium and 100 percent of the gross alpha readings reported in the 1960s (before 1967) are attributable to plutonium. These assumptions are consistent with Mound's primary production efforts during each decade, respectively, and maximize the potential hazard to the public.
We do not think it is worthwhile modeling a plume based on one data point collected 24 miles from the site. Our report states that polonium-210 may occur naturally (page B-2); however, it is not possible to distinguish between man-made and naturally-occurring polonium-210 when measured in the environment. Mound scientists measured alpha radiation in air, and their measurements could have included alpha radiation from other radionuclides naturally present in the environment. Mound reports describe this measurement as simply "polonium". To be conservative, we assume the alpha measurement is all polonium-210 from the Mound facility; some or most of it could have come from other sources. It is also not necessarily true that the air near the Mound facility would have had a higher concentration of polonium than that measured at Fairhaven, particularly if the polonium was emitted from a tall stack at Mound. We did not have other data to compare the Fairhaven datum to; the Fairhaven datum was reported as the highest value measured during the quarter (3rd quarter, 1958). We did not average the two readings together and state that there was no problem. We pointed out that one measurement is not representative of what people would be expected to breathe. This is partly why we concluded that exposures to polonium represent an indeterminate pathway.
The commenter describes two analyses which we are not including here. The first is a comparison between measured soil plutonium concentrations and predicted soil concentrations using the CAP88PC dispersion model. The analysis was performed on soil data collected from 1970 through 1973 at 56 locations (102 data points). The commenter presents the result--that plutonium concentrations measured in soil exceeded those predicted by the model at 55 of the 56 locations (measured to predicted ratio range, 0.5-441). However, we are not told the average amount that the concentrations in soil exceed those predicted by the model nor what dispersion parameters were used to run CAP88PC. We expect some discrepancies between measured concentrations and model-predicted concentrations. The second analysis is a comparison between Mound's reported releases (through the mid-1970s) and a least-squares calculation of the soils inventory of plutonium-238 based on the 1970-1973 data. The commenter does not state the assumptions that underlie the least-squares analysis or provide data, but states that this analysis results in a soil inventory approximately 14 times the inventory reported by Mound. However, because of the limited amount of measured data, the commenter states the plutonium-238 inventory estimate "must be viewed as approximate." We did not analyze the 1970s soil data. Our contention that the soil data are consistent with the amounts of plutonium released is based on considerably more sampling data collected at 252 surface and subsurface locations in 1994 [2]. However, if we assume the commenter is correct and our method underestimates airborne releases by a factor of 14, and therefore, we multiply our highest calculated dose from releases of plutonium (Table I, page C-2) by 14, the resulting dose (about 160 mrem in 1960 for plutonium and tritium combined) does not indicate that releases of plutonium from Mound posed a health hazard.
The CAP88-PC program will under-predict the projected doses for short-term, high-level releases of radionuclides because the program employs the full annual (weighted) distribution of meteorological conditions to project radionuclide concentrations in air. However, over a short-term release, the wind direction is not expected to vary as much as it will over the full year and a person who is in an air pathway is more likely to remain there over a short period of time. (Although, on average, fewer people will be in the path of a short-term air release because the plume will not have had time to disperse.) Therefore, a person could be exposed to a higher concentration of radionuclides than the program would predict for a chronic release (i.e., for the same quantity of contaminant released over a longer period of time).
Nevertheless, we are able to modify the meteorological parameters of the CAP88-PC program to model a short-term, straight-line plume (one that doesn't vary over geographic sectors) and produce dose estimates for people who are in the pathway of the plume. These dose calculations are valid.
At the time we released the Public Comment Mound Plant Public Health Assessment, we had not taken into account the short-term nature of the 1989 tritium release. Therefore, we have since recalculated the estimated dose to a person who would have been in the pathway of the large tritium release on November 18, 1989. We substituted the revised dose (65 mrem per year) in Table I in Appendix C for the previous number which incorrectly represented the total tritium releases for 1989 as averaged over the whole year. The revised tritium dose does not change any of our conclusions.
If we would assume that most of the 1960 air release of Pu-238 occurred in a few hours in one day, CAP88-PC would have under-predicted the plutonium dose at the maximum off-site dose location by a factor of about 24. This would have resulted in a committed effective dose of 252 mrem to someone who would have breathed the most highly concentrated air at that location. Breathing this air would not have presented a public health hazard. We emphasize that we do not have evidence that the 1960 plutonium releases all occurred over a short time period. We include this information because the highest annual air plutonium release occurred in 1960. Whether the Mound air releases of radionuclides occurred as high quantities over short periods or low quantities over long periods, we are able to model them using CAP88-PC. In either case, the results do not show that these releases posed a health hazard.
CAP88-PC and its predecessors, AIRDOS-EPA, RADRISK, and DARTAB, have been used by EPA since the 1970s for a wide variety of environmental assessment and regulatory applications. The code has been validated and benchmarked. CAP88-PC employs a Gaussian plume model for air dispersion, terrestrial transport models, and dose coefficients that are similar to those listed in EPA Federal Guidance Reports 11 and 12, which are based on ICRP26 and ICRP30. The terrestrial transport models are based on NRC Regulatory Guide 1.109. Both the Gaussian plume model and the terrestrial transport models are widely applied throughout the nuclear community.
An article entitled "A Review of Validation Studies for the Gaussian Plume Atmospheric Dispersion Model", by Miller and Hively, provides an evaluation of the Gaussian plume model for various applications and lists 107 references regarding its validity and application to various air dispersion computational problems [3]. This article is an excellent resource for further information on the Gaussian plume model.
Personnel at the Idaho National Engineering Laboratory (INEL(1)) compared committed effective doses calculated using CAP88 and GENII. The GENII code meets the ASME NQA-1 Basic and Supplementary Requirements for Design Control which include requirements for verification and validation of computer codes. According to the authors, GENII has undergone rigorous testing. CAP88 does not meet all of the quality assurance requirements now specified by the ASME for computer software because the origins of the code date back to the 1970s, before the quality assurance requirements were developed. The purpose for this study was "benchmarking," i.e., comparing the results obtained from CAP88 with the results of a rigorously tested code. The authors determined that the values of the test statistic designed to compare the results from both programs were within the limits for acceptance for all 42 comparisons. The authors state, "The variety of radionuclides released from INEL facilities, coupled with the wide range of receptor distances, provided a rigorous suite of benchmark tests." And; "Based on the benchmark tests, increased confidence in the results obtained using CAP88 was gained." A noteworthy aspect of this paper is the large number of references which discuss the atmospheric dispersion model, the food chain transport model, and the terrestrial transport models used in both CAP88 and GENII [4].
Numerous papers have compared the predicted results from CAP88 with measured results. In some of them, the ratio of the concentrations has been greater than 1 and in others, less than 1. Ali A. Simpkins and David M. Hamby compared calculated annual-average tritium concentrations in air at several off-site locations near the DOE Savannah River Site where annual-average measured tritium concentrations were available using three computer codes, AXAIRQ, MAXIGASP, and CAP88. The comparisons were for the ten-year period from 1985 through 1994. The annual averaged ratios of predicted-to-measured tritium oxide air concentrations were 1.89±0.56, 1.70±0.48, and 1.40±0.39, for AXAIRQ, MAXIGASP, and CAP88, respectively. In the conclusions section of this paper, the authors state, "Various dose assessment computer programs used at SRS for long-term air concentration estimates over-predict off-site tritium oxide concentrations by a factor of 1.4 to 2.0. Since annual average concentrations are typically predicted within a factor of two to four using Gaussian plume models, these results show exceptional agreement. Each of the computer models follows appropriate regulatory guidance, and any attempt to change currently acceptable methodology would require extensive site-specific studies and significant technical justification [5, 6]."
In other instances, the comparison of computer-generated air concentrations and measured concentrations has shown that CAP88 under-predicts doses. Jack Faucett Associates looked at six data sets from five facilities in an effort to correlate air concentrations of various air pollutants calculated using AIRDOS-EPA to measured values [7]. Considering all the data sets together, without adjustment, the predictions are 12 percent low overall when compared to environmental values. One data set in this study was Mound environmental measurements for tritium from 1981. The arithmetic mean of the ratio of measured to predicted tritium concentrations were 3.3±2.1 (1).
In summary, we believe there is ample information in the literature quoted and referenced above to conclude that the CAP88-PC code is applicable and has been properly validated for use in predicting annual-average doses for facilities with airborne releases of radionuclides.
Based on the foregoing, reference to the air sampling data for the 1949-1971 period is likely to underestimate actual concentrations because it is more likely than not that periods of high concentration were missed by the short-term air monitoring program; and it is likely that specific locations experiencing large concentrations as a result of large short-term releases would not be measured due to the geographical sparseness of the sampling points.
Mound's airborne radioactive releases likely involved discontinuous events, but the data (except for the 1989 tritium release) do not show that the annual releases occurred in just a few short episodes. We agree that the sampling methodology could have missed the highest concentrations of radionuclides in air. However, contrary to demonstrating a bias for low air concentrations, the survey method was apparently biased toward sampling in the downwind direction or in an adjacent sector, which could have resulted in average measurements higher than the true average air concentrations.
Probably none of the air data reflect what people actually breathed. Even if we had continuous air monitors set up in the 1960s, as we do today, the air monitors do not monitor the air everywhere; and winds change direction and people move around. What we look for in the data is consistency between Mound's production activities, their institutional controls, their reported air releases, and the concentrations of radionuclides measured in the environment. As a screening tool and to be conservative, we usually calculate doses based on maximum exposures and the maximum concentrations we find among the data. While it may be true that the published plutonium data do not reflect true average air concentrations, we have no evidence for this assertion.
We agree that the available health outcome data and epidemiological data are of limited use. We did not base our conclusions strictly on historic environmental monitoring data, however. We also considered program activities, spills and releases, worker data, and the historic significance, when appropriate, of current environmental concentrations of radionuclides.
The conclusion was based on information in the appendices and in the references provided. Please refer to the bibliography that we have added which includes most of the documents we reviewed for this public health assessment.
We did not dismiss a possible health hazard; we specified that we do not know whether polonium-210 and nonradioactive materials in the environment ever were a public health hazard. We agree, we do not know what the missing and incomplete data contain; however, a health survey will not reveal whether environmental contamination caused health problems in the community.
We agree that our indeterminate pathways (exposures to polonium-210 and nonradioactive materials) allow for further investigation.
Page 1. Could have been; inconclusive historical data; insufficient data; missing documentation.
D-2--Last Paragraph-- "YOUR BEST GUESS" For a company that has so many brilliant and educated people, you sure do a lot of guessing! We don't want an educated guess: We want the total and complete, precise and most accurate answers. WITHOUT ACCURATE DATA YOU DON'T HAVE ACCURATE ANSWERS! ! ! !
"Best guess" is a technical expression that means we have considered different ways to find an answer and we have chosen the one we think is best. It is an educated guess. There are no "total and complete, precise and most accurate answers." There is no foolproof way to know that the data we have is accurate. All of our calculating, modeling, and evaluating is "guesstimation" at some level or another. We cannot give you 100% certainty.
Mound scientists estimated the total amount of tritium released; also, continuous air (environmental) monitoring stations were in operation on site and off site at the time of the release. The monitors at two locations showed elevated concentrations of tritium. Plumes are not homogeneous. We expect there were areas of the plume that had higher concentrations than other areas.
We didn't ask for a complete source listing of radionuclides because it isn't necessary to have it to evaluate off-site contamination. Most of the materials that would be listed would not have ever left the site as environmental releases.
We are always looking for more health information and we are considering looking further at historic data in laboratory notebooks.
We agree. The stacks were designed to disperse air releases. However; Mound's deposition studies show that the highest concentration of alpha-emitters from the site are within a 1-mile radius of the site.
We are not sure what statements about background levels the commenter refers to. The background samples we took (ATSDR/NAREL sampling, Appendix E) were collected at Lebanon, Germantown, Farmersville, and Columbus, Ohio.
We expect gravel to be naturally radioactive; most rocks are. In particular, igneous rock (such as granite), will contain significant levels of uranium, radium, and thorium. Limestone rocks will contain lower levels of radioactivity than granite.
The report referred to is a draft report that was never made final. We did not review this report prior to releasing the Public Comment Release version of the Mound Plant public health assessment. Since then, we obtained a copy and reviewed it. The report is an audit of environmental monitoring practices at the Mound Plant. It was intended to be critical to identify problem areas and recommend improvements. Mound officials responded to the audit items and it appears that many of them were unfounded. We are not aware if the commenter has seen the responses of Mound officials. We believe the audit items do not support a conclusion that Mound's environmental data from this period are understated or otherwise inaccurate.
Environmental monitoring programs are not designed to measure off-site exposures. They are designed to measure off-site contamination. This is why environmental data is rarely ever sufficient to serve as a surrogate for doses when conducting an epidemiological (health) study. We disagree that the data upon which we drew our conclusions were defective or unreliable.
We agree that complete records should be kept.
There are no "100% proofs". We cannot turn back the clock and sample people's blood or urine, which would provide the best measure of exposures to environmental contamination. We have to use the information that we have available--usually, environmental sampling data (such as concentrations of contaminants in the air and water)--to estimate people's exposures. Scientists and health officials use various methods to interpret environmental data, but none of these methods provides 100% proof that people were actually exposed and received the doses we calculate.
ATSDR scientists think that the liquid effluents from the Mound facility might have contained, at times in the past, concentrations of substances, both radioactive and nonradioactive, that could be harmful if swallowed. One example that we described was releases of polonium-210 to the Great Miami River in the 1950s. We have determined that we are not able to evaluate this pathway because we do not know the identities or concentrations of all the contaminants that passed through the outfalls, or when. We are not likely to come up with meaningful results by presuming the identity and quantities of contaminants in the effluents at these outfalls. For this reason, we concluded that exposures to the historic releases of polonium-210 and nonradioactive substances to the surface water are indeterminate pathways.
In recent years, the concentrations of toxic substances in Mound's liquid effluent streams are better characterized than in the 1950s and 1960s. We evaluated the liquid effluent data published in Mound's environmental monitoring reports and did not find anything since the early 1980s that we considered was a public health hazard (see Appendix A).
ATSDR evaluated mercury contamination in the East Fork Poplar Creek at the DOE Oak Ridge Reservation in Tennessee. This is the only other instance where we looked at a major effluent stream from a DOE site going into an open stream in a city park. The ATSDR health consultation on the East Fork Poplar Creek is available to anyone upon request.
Air, soil, and water samples were collected in the Miamisburg Community Park and in the Miami-Erie Canal and Overflow Creek in conjunction with several programs over the years. These included the Miami-Erie Canal plutonium spill investigation (1974), the park water slide construction (1984), the remedial investigation reports (Operable Units 4 and 9, 1992), the special canal sampling report (1993), and data from samples that ATSDR/NAREL and the Ohio EPA collected (1994, 1995). We reviewed data from each of these and concluded that radionuclides in the canal and Overflow Creek are not a problem.
Concern 16 asks whether several adverse health outcomes could have resulted from drinking well water for 12 years (beginning sometime in the 1970s) from Bud's Mobile Home Court. We have sufficient data to state that radioactive contaminants in the water cannot account for the health outcomes listed. However, the wells were not tested for all the possible chemicals that might have affected peoples health.
We do not know where this resident (referred to in Concern 17) lives. We do not know if the private well at this home was contaminated, nor if this well was tested.
The answer to Concern 18 states that the VOCs in the public drinking water do not come from Mound because public drinking water for Miamisburg is drawn from an aquifer west and west-northwest of Mound. However, the answer to Concern 19 states that Mound has contaminated the Buried Valley Aquifer with tritium and VOCs.
Municipal water treatment plants may employ different methods, including aeration, to remove VOCs. We do not know whether the Miamisburg water treatment plant employs any methods--or has any reason to employ any method--to remove VOCs. We do not know whether VOCs from sources other than Mound are going into the municipal water supply. It was not the purpose of this public health assessment to investigate all possible sources of contamination in the community. The aquifer flows south-southwest; therefore, contamination in the aquifer (including VOCs) from the Mound site is not going toward the municipal wells--it is going away from them.
We have data for other wells in the area west and southwest of Mound (e.g., data in Mound's environmental monitoring reports, Mound's Residential, Municipal, and Industrial Well Investigation). The data do not show that plutonium or VOCs pose a health hazard in these wells. Residents would be prudent to have their well water tested because they live in a city where there may be other sources of contamination. (See also our response to Concern 20.)
The aquifer flows south-southwest. Huber Heights is north of Dayton, northeast of Mound, and far enough from the Mound Plant that we would not expect any impact from the Mound Plant to their water supply.
The resident (Concern 47) indicated that the health department is already aware of the problems with the well. We would have referred the resident to the local health department (the Combined Health District of Montgomery County), because they are the appropriate agency to investigate well water problems.
There is no clearly-stated, specific discussion of how site contaminants were moving off-site, especially with regard to groundwater. There is no clear description of how Pu-238 and tritium got from Mound: 1) into the city water system; 2) into private wells in unincorporated residential areas southwest of the Mound plant; and 3) into the well(s) servicing Bud's Trailer Park.
The Mound Laboratory discharged waste water directly to the Great Miami River via an underground pipe and to the Miami-Erie Canal. Waste water containing tritium was released directly to the Canal, though quantities were greatly reduced in 1970 when newer control measures were adopted. Waste water containing plutonium was released primarily to the Great Miami River. However, plutonium washed into the Miami-Erie Canal in 1969 after a pipe broke and a rainstorm washed the spill off site. Water in the Miami-Erie Canal and the Great Miami River charge the underlying Buried Valley Aquifer. Water discharged from the Mound facility to the Miami-Erie Canal will percolate into the groundwater and migrate west southwest with the aquifer water. Miamisburg Well #2 is near the Outfall 002, where Mound discharged water to the Canal, though it is unclear to us when this well was used to supply water to the city.
Today the Miamisburg municipal well field is upstream from the Mound Plant and on the west side of the Great Miami River. Pumping on the aquifer at that location is likely to pull river water into the municipal water processing stream (upstream of Mound) because of the proximity of the well field to the river. Radioactivity found in municipal water may be naturally occurring, or a result of airborne fallout (or rainout), or from a source upstream from Mound in the river or aquifer.
A) Well #2 is directly west from the Mound facility, 250 feet west of the Mound property line, in the general vicinity of the former Miami-Erie Canal and the 1969 Pu-238 spill. We are still trying to see if we can get well logs for this and the #3 well from the water plant engineer, but have been unable to contact him as of 1/28/97. Well #2 was used as a city production well through the 50's and 60's and up to 1978 when it was disconnected from the water system allegedly because of high chloride content of the well water. This well, for the past 15 years, has been owned and operated by E&G Mound, evidently as an interceptor/extraction well.
B) Well #3 is located in Miamisburg Community Park, 500 feet northwest of the Main Hill area at Mound, and evidently was never or rarely used by Miamisburg as a production well. Up until this year, its major function was to provide water to fill the pool at the park. As the pool is no longer being used, Well #3 is no longer in service.
C) The Riverview Avenue well field (wells #8, 9, 10, 11) on the west side of the Great Miami River and 1250 feet northwest of the Mound plant, dates from the 50's and 60's. It currently is the sole source of the city's drinking water supply. The city's Water Treatment Plant began operations in 1978. Before that, the city's water supply was essentially untreated, raw water.
ATSDR scientists met with the Superintendent of the Water and Waste Operations of the City of Miamisburg in February 1996 and obtained the same information presented above. We were not provided written documentation of well construction or usage. We think it is unlikely that Well #2 was used as a production well for the city through 1978 because Mound employees began using the well in 1976 to pilot-test pumping on the aquifer to reduce tritium concentrations [8]. We think the city abandoned Well #2 in the late 1960s, although we have been unable to determine when this occurred.
The use of the statistical modeling to obtain a correlation between the private well H-3 concentrations (predicted) and the measured canal water is justified. However, the uncertainty associated with the model predictions are great. There are only 4 data points in the 1970s when both canal and well water H-3 measurements were taken within the same year. If the relationship between the canal and well water is real, then in all cases the private well water concentrations would be greater than the canal H-3 water concentrations in a similar fashion as the empirical data. The statistical model over-predicts the private well water H-3 concentrations during some years in the 1960s and, more importantly, under predicts the maximum H-3 levels in well water for years around 1961, 1963 and 1968 (Fig. 1, page D-19).
The measured tritium concentrations in private wells in Bud's Trailer Court are greater than the measured canal tritium concentrations for the four years 1975-1978. Initially, we calculated the ratio of these concentrations for each of these years, and calculated the average ratio (about 1.8, well water concentration to canal water concentration). Then we multiplied the average ratio times the canal concentrations going back through 1960, which, of course, will show that the well concentrations were always higher than the canal concentrations. Kenneth Pohl, a statistician with the EPA NAREL, pointed out to us that this relationship would not necessarily always hold. The data for the years 1975-1978 show a decline in the tritium quantities released from the Mound Laboratory, as evidenced by the tritium release data and the canal tritium concentrations. Although the releases of tritium were higher during the years 1960-1974 than in later years, the fluctuations during that period were great also. Therefore, we must consider the effect of transit time on the concentrations of tritium from its introduction to the canals until it first impacts the drinking water in the private wells. We talked to Mound hydrogeologists about the transit time (particle velocity) between the canals and the wells and were told that it is approximately 150-200 feet per year(2). This means that tritium introduced into the canals does not appear instantaneously at the wells in Bud's Trailer Court. Our model shows that the concentrations of tritium in the wells depend not only on the tritium released during the same year, but also, partly, on the amounts released in the previous two years. Our model agrees fairly well with the particle velocity reported by Mound hydrogeologists. In the years when the greatest amounts of tritium were released to water (1961, 1969), the tritium from those releases was "seen" at the wells in 1961, 1962, and 1963, and 1969, 1970, and 1971, respectively. This accounts for the higher levels of tritium in wells, relative to the canals, during the years 1975-1978, when quantities of tritium releases were falling (i.e., the well water "included" tritium released in previous years in higher concentrations). The model was designed to "fit" the actual measured well data, which it does quite nicely (oval data plotted on Figure 1, page D-19). The figure indicates the well tritium concentrations were sometimes higher, and sometimes lower, than the canal tritium concentrations in the early 1960s; it does not show that the model over-predicts or under-predicts the tritium concentrations at the wells. ATSDR scientists think that the annual ratios of well tritium concentrations to canal tritium concentrations did not remain constant over time and that the statistical model we employed accounts for the fluctuation in tritium quantities released. We agree that the uncertainties associated with this type of extrapolation are large.
This analysis is questioned due to the pumping of Well #2 in order to dilute off-site tritium concentrations beginning in 1976. The effect of this diluting well upon the analyses performed by ATSDR is not discussed, nor is the diluting effect mentioned. Perhaps what is being seen is the effect of dilution. If so, then the continued operation of the remedy is necessary to prevent future contamination reaching the wells. These assumptions and their affect on the outcome, i.e , concentrations in private wells needs to be clarified, before these values can be accepted.
Pumping on the aquifer at Miamisburg Well #2 beginning in 1976 could have affected tritium levels disproportionately in the aquifer beneath Bud's Trailer Court relative to the canal. If the tritium concentrations reaching the private wells were reduced (because of pumping) more than those in the canal, the model we described in Appendix D would have under-predicted the well tritium concentrations in those years (earlier) when pumping did not occur. To address this concern, we requested additional data from DOE. We received data describing measurements of tritium in the on-site production wells, Bud's Trailer Court wells, and the Miamisburg municipal water supply for the years 1971 through 1974 [9].
The Mound production wells are approximately the same distance from Well #2 as the private wells in Bud's Trailer Court, and they likely would have been affected similarly by any pumping at Well #2. On-site production well water sampling began in 1971. The data show that (1) in the years before Mound began pumping on Miamisburg Well #2, tritium levels in Bud's Trailer Court are nearly the same as those in Mound's production well #1 (later designated #0071), and (2) our model over-predicted tritium levels in Bud's Trailer Court in the years 1971-1974 by approximately a factor of 2. These data suggest that the model we derived from the data in Appendix D provides a conservative, upper-bound to the tritium concentrations that appeared in the wells in Bud's Trailer Court in the 1960s.
Continued pumping on the aquifer to reduce off-site tritium levels is unnecessary because tritium concentrations in the 1990s are less than 10% of those in the mid-1970s.
We concluded that neither the wells in Bud's Trailer Court nor Miamisburg Well #2 were contaminated with tritium at levels of health concern. We based our conclusion for the wells in Bud's Trailer Court on our model estimates of tritium concentrations in those wells, as described in Appendix D. We thought that tritium levels in Miamisburg Well #2 would not have been significantly higher than those in Bud's Trailer Court because of the proximity of Well #2 to Bud's Trailer Court wells. Our analysis shows that if tritium concentrations in Miamisburg Well #2 were as high as those in the Miami-Erie Canal (the primary source of tritium in the aquifer), they still would not be higher than the highest calculated tritium concentrations in Bud's Trailer Court, and they would not be a public health hazard.
Additional data that we reviewed after releasing the Public Comment Public Health Assessment support this conclusion. The additional data include measurements of Miamisburg municipal water during a portion (1971-1974) of the critical period (1960-1974). Municipal tritium levels were consistently much lower (50% to 90%) than those in Bud's Trailer Court. These data suggest Miamisburg Well #2 was not a municipal water source, or, at least not the only municipal water source, during any part of the 1970s. Although we were unsuccessful at establishing when Miamisburg Well #2 was used for city drinking water, we are confident that tritium from the Mound facility was never at levels of health concern in public or private water supplies near the Mound facility.
The three wells in Bud's Trailer Court plus the nearby well at Jim's Chicken Shack (designated J-1 in the environmental monitoring reports) are the only off-site wells for which we have tritium data for the period 1975-1978. We do not have data from Miamisburg Well #2 during this period, probably because it was not being used as a municipal water source and presumably because Miamisburg's water was sampled at the tap. We also do not have data for tritium releases to the water prior to 1967. The trend backward in time from 1969 to 1967 is decreasing, not increasing. Projects and production activities at the Mound Laboratory would not lead us to believe that people would have been exposed to higher levels of tritium before 1960.
People were exposed to the radioisotope (tritium). We did not state that people were not at risk. We did not calculate risks; we calculated doses. When we state that tritium was not at levels of health concern or that tritium did not pose a public health hazard, we mean that those risks were either zero or they were very small. We do not think a well survey is warranted since we did not determine that the levels of tritium posed a health hazard. We did not look at data from this period for other private wells because we are unaware that any exists.
We see no reason why any of the wells that were established in the late 1970s and provided "credible groundwater monitoring" should not be used for "overall site monitoring". We do not know what timeframe the commenter is referring to in the statement about the conceptual models of the aquifer. The hydrogeology and the Buried Valley Aquifer are very well understood locally. Please see the several volumes of the Operable Unit 1 Remedial Investigation reports and the Operable Unit 9 Hydrogeological Investigation report on the Buried Valley Aquifer that were released by DOE in 1994.
We have multiple criteria for determining what constitutes a public health hazard. We maintain a database of chemical comparison values, which we use to screen environmental data. ATSDR's comparison values are included in the ATSDR database, HAZDAT, which is available to the public on ATSDR's web page (http://www.atsdr.cdc.gov/). However, data that exceed our screening values do not automatically represent a public health hazard. We also consider the relative accessibility of the contamination, which populations may be exposed, the magnitude of the exposure, and the toxicity of the contaminants. Our public health calls are weight-of-evidence decisions. Regulatory agencies maintain precise standards; however, we are not a regulatory agency.
We do not define dose levels that we consider would be a public health hazard in all situations, nor do we use dose levels as a sole criterion to evaluate an environmental hazard.
The commenter does not state in what way we misrepresent ICRP dose limits. We have had health physicists, public health experts, and occupational medical professionals help write and review this public health assessment. None of them has made this observation.
We have added radiation terms to the glossary at the end of this document. We used definitions provided by the Health Physics Society from their Internet home page, http://www2.hps.org/hps/.
It is true we did not show all of our calculations, but we did reference the values that we used. Our calculations in Appendix E are based on the following formula:
concentration x consumption rate x dose conversion factors = dose
Concentrations come from environmental data (e.g., pCi/L). We used dose conversion factors from ICRP 67 and 68 (as stated). Consumption rates depend on the exposure scenario: e.g., how long we are exposed; whether we are eating, drinking, or breathing; and whether we are children or adults. We presented our assumptions (consumption rates) in Appendix E for those calculations. Conversion factors were necessary to convert the results to millirem (mrem). These dose calculations are standard and can be found in any health physics text.
Pages D-12 through D-14 contain a discussion of the toxicology of tritium in the context of tritium levels in water. With respect to abnormal development of the central nervous system, ATSDR quotes the "lowest tritium (or low-level gamma radiation of x-rays) dose capable of causing adverse health effects in the order of 3 rad". With respect to cancer ATSDR claims that "the lowest tritium dose associated with cancer effects in humans may be approximately 10 rem received by an unborn child".
Finally, in the context of environmental sampling activities by ATSDR and NAREL, the ATSDR report suggest on page E-2:
"For a reference dose that is protective of the public health (i.e. a dose that will not result in adverse health effects), all the radiation dose estimates included in this appendix may be compared to a standard the International Commission on Radiological Protection (ICRP) recommends." [The ICRP limit is 100 mrem/yr from sources other than medical and those occurring naturally in the environment - up to 500 mrem/yr if 5 year average does not exceed 100 mrem/yr.]
It should be noted that the ICRP reports do not contain a claim that doses below the limit for the general public would not result in adverse health effects. The 1990 Recommendations of the ICRP (ICRP Publication 60) states that "it must be presumed that even small radiation doses may produce some deleterious health effects" (p 35) and "stochastic effects cannot be completely avoided because no threshold can be invoked for them" (p.25).
ICRP further defines its philosophy of setting individual dose limits as follows: "It is the Commission's intention to choose values of dose limits so that any continued exposure just above the dose limits would result in additional risks from the defined practices that could be reasonably be described as 'unacceptable' in normal circumstances. Thus the definition and choice of dose limits involve social judgements. These judgements are difficult, partly because the dose limit has to be set at a defined value and there is no discontinuity in the scale of acceptability. For agents like ionizing radiation for which no threshold can be assumed in the dose-response relationship for some of the consequences of exposure, this difficulty is inescapable and the choice of limits cannot be based on health considerations alone." (p 30f )
In summary, the ATSDR report fails to properly define "exposure levels which may not result in adverse health effects"; the definitions used in various sections of the report are clearly inconsistent when compared with each other. If the ICRP dose limit would also be used to evaluate the polonium exposures referred to on page B-2, they would be determined to be above "a level that is protective of the public health" using the ATSDR rationale documented on page E-2. ATSDR furthermore misrepresents the ICRP definition of its dose limits by asserting that doses below such limits are associated with no adverse health effects even though the ICRP finds that no threshold can be invoked for stochastic effects such as cancer.
You need to explicitly state how data is interpreted for dose-response assessment and human health evaluation. State assumptions. Then give opinions as to what levels of radionuclides emitted in the air or water would be a public health concern for the Mound facility. Just saying that there is no health concern or that we do not know because exposure data is incomplete seems like an easy way out of a difficult subject. Interpretation of data and assumptions is policy and risk management and must be separated from science (raw data).
We use the ICRP 60 recommended annual dose limit of 100 mrem above background to members of the public as a screening value. Adverse health effects from radiation have not been seen below 500 mrem, which is the dose limit ICRP recommended prior to adopting the 100 mrem dose limit. ICRP sets dose limits to limit exposures and to be safe. Exceeding dose limits does not mean adverse health effects will occur. Dose limits are set as low as technologically achievable because we do not know exactly how radiation causes cancer. Because the technology improved, ICRP lowered their recommended dose limits. At low levels of radiation (such as those we find in the environment), ICRP extrapolated risks derived from data at high levels of radiation (such as those found in the laboratory). The extrapolated risks may not be real. Because none of the doses we calculated in Appendix E exceeded 100 mrem, we provided the 100 mrem dose (dose limit recommended by the ICRP) as a comparison value, i.e., a measure to compare our estimated doses to.
In other places in the public health assessment, we calculated doses for exposures to polonium-210 or plutonium-238 that exceeded 100 mrem. When our calculations result in doses above 100 mrem, we look to see what toxicological evidence there is for harm at those higher dose levels and consider what are realistic exposure scenarios.
When we assume an exposure scenario, we typically choose either an extreme ("worst-case") exposure situation--for example, breathing the air with the highest measured or estimated concentration of contaminants for a year--or, a more reasonable exposure--e.g., a 30 kg child breathing the air with an average concentration for a year. (A 30 kg child may be 6 to 10 years old and may be either sex.)
In the case of air exposure to the highest measured concentration of polonium-210, the 0.01 µCi polonium per kg of body weight is a LOAEL (lowest observed adverse effect level) observed in mice. We did not extrapolate the mouse data for different sized populations or assume additional safety factors before applying the result to humans. We know that low levels of toxic substances that do not produce adverse health effects in small populations (e.g., mice in laboratories) may result in detectable adverse health effects in larger or different populations (e.g., humans) exposed to the same dose.
We do not know the probability that the environmental exposures to polonium were higher than the data suggest. We have stated this in different ways on page B-2. This is the primary reason we concluded that this pathway is indeterminate.
Yes, we agree on all these points. Toxicologists set screening values lower than the NOAELs and LOAELs (no observed- and lowest observed adverse health effects levels) to be safe. However, we are evaluating exposures that have already taken place, and are not trying to set safe levels of exposure. We considered the mouse study along with a large amount of other accumulated data on the effects of radiation. While we acknowledge that we do not have large safety factors (e.g., 1,000) for some of our data, we also consider that our exposure assumptions are very conservative.
The 100 mrem dose is one comparison value that we use. In Appendix E, that was all we needed to compare our calculated doses to because they were all below 100 mrem. In other cases (when an effective dose exceeds 100 mrem) we take into consideration other information.
The 10 mrem dose limit adopted by the EPA in the National Emission Standards for Hazardous Air Pollutants (NESHAPS) applies to air releases only. The 100 mrem dose above background (ICRP 60 recommendation) for the public is for all pathways of exposure, internal and external.
The ICRP does not recommend that Table C-6 (ICRP 60) be used to calculate risks to the general public. Table C-6 presents the detriment at various annual radiation doses on the basis of a multiplicative projection model. This table is presented in ICRP 60, Annex C, as a comparison to the additive projection model which predicts constant excess induced cancers throughout life. Annex B describes the pros and cons of using a strictly additive or multiplicative projection model. In the main body of the report, the Commission describes the modified model (not strictly additive or multiplicative) which they use and why. In the main body of the report, the Commission reports the nominal probability of fatal cancers for the whole population as 5.00 E-2/Sv (5.00 E-5/100 mrem) and the aggregated detriment (non-fatal cancers) as 5.92 E-2/Sv (5.92 E-5/100 mrem). The Commission's opinion, stated on page 45 of ICRP 60, is as follows:
"The consequences of continued additional exposure giving annual effective doses in the range from 1 mSv (100 mrem) to 5 mSv (500 mrem) are presented in Annex C. They provide no easy basis for a judgement, but do suggest a value of the annual dose limit not much above 1 mSv (100 mrem). On the other hand, the data in Figure C-6 of Annex C show that, even at a continued exposure of 5 mSv/y (500 mrem/y), the change in age specific mortality rate is very small. Excluding the very variable exposures to radon, the annual effective dose from natural sources is about 1 mSv (100 mrem), with values at high altitudes above sea level and in some geological areas of at least twice this. On the basis of all these considerations, the Commission recommends an annual limit on effective dose of 1 mSv (100 mrem)."
We agree that if we ask the public which of two risk numbers they would find more acceptable, they will always choose the smaller of the two.
Concerning BEIR V and HEAST: BEIR V does not state what their risk numbers are based on. The EPA Health Effects Assessment Summary Tables (HEAST) are derived from health effects data and dose and risk models from a number of national and international scientific advisory commissions and organizations, including the NCRP, ICRP, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the National Academy of Science (NAS, which publishes the BEIR reports). In HEAST, the EPA bases low dose, low dose rate cancer mortality and morbidity risks for the public using 509.1 E-4/Gy (5.1 E-5/100 mrad) and 760.6 E-4/Gy (7.6 E-5/100 mrad), respectively. These numbers are essentially equivalent to those reported by the NCRP and ICRP.
If ATSDR were discussing a chemical like lead where the possibility of health effects is thought solely to be a deterministic function of dose (meaning that there is a threshold dose below which health effects are not expected to occur, and above which the severity of the effects increases) then such a statement may be justified. However, the prevailing scientific view of radiation is that--in addition to certain deterministic effects--exposure to radiation also imposes so-called stochastic effects. These are severe effects (namely cancer and genetic effects) for which virtually any level of exposure involves a risk for inducing these health outcomes. In these instances risk is a function of dose and is assumed to be essentially linear--that is, the risk is assumed to be proportional to dose at all levels of exposure.
To quote directly from the National Council on Radiation Protection and Measurements: "The induction of stochastic effects (cancers and genetic effects) is considered to be the principal effect that may occur following exposure to low doses of ionizing radiation."
Thus, given the prevailing scientific view of radiation, the releases of these radionuclides from Mound does indeed pose a health hazard. It is the magnitude of the hazard that is open to question, not the reality of the hazard. And, regrettably, ATSDR has done little to analyze the actual risk to the public caused by these releases.
We do not agree that low levels of radioactive materials in the environment necessarily pose a public health hazard. And, we do not agree that the linear, no-threshold theory of adverse health effects from exposures to radiation is the "prevailing scientific view of radiation."
The linear, no-threshold theory is the predominant model used to extrapolate risk to low doses for the purposes of radiation protection and risk assessment. Risk assessors have to model these risks because we do not have the scientific tools to measure them directly. Since the risks to low radiation doses cannot be measured, the model cannot be validated. The radiation protection and scientific communities currently are discussing the significance and relevance of the linear, no-threshold model. We refer readers to issues of the Health Physics Society Newsletter from mid-1995 through 1996 and the March 1997 issue of the Belle Newsletter for examples of the ongoing discussion in the scientific community.
From a historical perspective, the linear, no-threshold model was developed to explain a particular set of radiation experiments on fruit flies. After World War II, interest in the model expanded because of its simplicity and its representation of an upper risk level. Over time it has gained widespread use in spite of the lack of strong scientific evidence, especially at doses near those associated with environmental exposures.
The national Health Physics Society, in a position paper published in March 1996 stated "In accordance with current knowledge of radiation health risks, the Health Physics Society recommends against quantitative estimation of health risk below an individual dose of 5 rem in one year or a lifetime dose of 10 rem in addition to background radiation. Risk estimation in this dose range should be strictly qualitative accentuating a range of hypothetical health outcomes with an emphasis on the likely possibility of zero adverse health effects. The current philosophy of radiation protection is based on the assumption that any radiation dose, no matter how small, may result in human health effects, such as cancer and hereditary genetic damage. There is substantial and convincing scientific evidence for health risks at high dose. Below 10 rem (which includes occupational and environmental exposures), risks of health effects are either too small to be observed or are non-existent [10]."
In September 1997, an international group of radiation experts participated in a conference titled, "Creating a Strategy for Science-Based National Policy: Addressing Conflicting Scientific Views on the Health Risks of Low-Level Ionizing Radiation", co-sponsored by the Council of Scientific Society Presidents (CSSP) and the Johnson Foundation. One outcome of this meeting was an agreement that a radiation dose below 10 rems can be considered safe for an adult. While evidence exists which indicates that children are more susceptible to radiation (even down to levels as low as 1 rem), the conclusion of no cancer increase below 10 rems is based on a robust database for adults [11].
This, again, is total nonsense. ATSDR assumes that people living near Mound were exposed to the radioactive materials--including hundreds of thousands of curies of tritium--released from the plant. With radiation, exposure implies some risk of stochastic health effects. So they do have evidence that exposures were sufficient to cause adverse health effects.
Page 24. Concern 8. There is simply no basis to conclude that off site contamination at Mound is "not enough to cause anyone health problems." As discussed earlier, there were/are certainly off-site doses from Mound releases, doses which increased the risks of cancer and genetic damage to those exposed. In this sense, radiation from Mound was/is certainly sufficient to cause health problems--even if detecting those health problems is either very difficult or impossible.
Page 25. Concern 15. This is just a bogus answer. If there were measurable levels of plutonium and/or tritium in the canal, then it is possible that exposure to this water was enough to cause health effects in those exposed to the water. Period.
If you assume the dose-response curve is linear with no threshold, there is a non-zero risk with any amount of exposure. We do not make this assumption.
No one in Miamisburg was exposed to "hundreds of thousands of curies" of tritium, as this commenter implies.
You conclude that this was never a public health hazard. It does not take a rocket scientist to determine that releases at these levels have and did affect people. And furthermore, I honestly believe that a health study will prove it.
We agree that 364,685 curies of tritium released in one year is a lot of tritium. However, tritium is the least radiotoxic isotope of all known radioactive materials. We do not agree that people were affected or that a health study could prove it.
Our discussion of Bud's Trailer Court well water in 1975 is the subject of Appendix D. We agree that the tritium concentrations in the wells in Bud's Trailer Court likely exceeded the current drinking water standard (20,000 pCi/L) for all of the 1960s and most of the 1970s. (See Table II, page D-4.) And we agree that the well tritium concentrations exceeded the proposed tritium drinking water standard (60,900 pCi/L) for many of the same years. The highest value reported for tritium in the private wells in Bud's Trailer Court is 89,900 pCi/L in 1975. However, we do not agree that the tritium in the private wells posed a health hazard to the residents who used the wells for their primary water source (for drinking, cooking, bathing, and washing, etc.) Our interpretation of the well tritium concentrations is based on our estimated radiation doses to people using the well water and the range of tritium doses shown in the scientific and medical literature that are necessary to cause harm.
Maximum Contaminant Levels (MCLs) are maximum permissible levels of contaminants in water which are delivered to any user of a public water system. They are regulatory values established by the Environmental Protection Agency [40CFR141]. ATSDR scientists think MCLs for most substances are protective of the public's health under most exposure conditions. We often compare environmental data to MCLs because MCLs are widely used by regulatory agencies and therefore, they are recognized benchmarks. However, we do not use MCLs--or any regulatory standards--as sole indicators of a public health hazard. We consider that exceeding some MCLs in drinking water may not pose a health hazard, and that exposure and toxicological information should be considered for each exposure pathway. In the Mound Plant public health assessment we have addressed situations, such as those for tritium, where the MCL is exceeded. Our evaluation of the worst-case exposures indicates to us that the concentrations do not pose a public health hazard.
The MCL for tritium (20,000 pCi/L) is protective of the public's health; however, neither 75,000 pCi/L nor 89,900 pCi/L will cause anyone to become ill. When the EPA set the MCL for tritium, they calculated the value (20,000 pCi/L) based on a committed effective dose of 4 mrem. In July 1991, the EPA proposed raising the MCL to 60,900 pCi/L based on the same dose, 4 mrem, using newer dosimetry models.
We would consider that a public health hazard exists for tritium in drinking water that would result in an effective dose of 1 rem. If we accept that 60,900 pCi/L of tritium in water (the proposed EPA drinking water standard) will result in an annual effective dose of 4 mrem (per EPA calculations), then a concentration that will result in 1 rem will be 250 times the 60,900 pCi/L, or approximately 15 million pCi/L.
The Mound Laboratory did not use tritium in large quantities until the late 1950s and early 1960s; therefore, we do not think people could have been exposed to higher doses than those we calculated.
The levels of naturally occurring tritium in the environment will depend on how old the water is; very old groundwater will have very low or undetectable levels of tritium whereas moisture in the air will have easily measurable levels. Tritium concentrations in drinking water in five cities in Ohio, including Cincinnati and Columbus, range from 100 to 400 pCi/L. The data are 1993 U.S. EPA survey data.
A given amount of tritium oxide is 10,000 to 25,000 times more hazardous than the same activity of elemental tritium, because tritium oxide is absorbed into the body at 10,000 to 25,000 times the rate as elemental tritium. Once tritium is in the body it will behave the same, regardless of which form it was in in the environment.
We determined dose rates from tritium using a specific activity model. The model predicts an equilibrium state between air, water, food, and body tissues for a specific location. We assumed that tritium transfers into the body mainly with water, and that the maximally exposed individual permanently resided 24 hours a day where the tritium concentrations were highest. This provides a very conservative, upper bound to the dose that anyone could have received. (For example, we did not consider dilution of tritium through ingestion of water or food from a location where the tritium concentrations were smaller.) There are more accurate methods for calculating doses when actual concentrations of tritium in air, water, and food are known, but we don't have this information, and the methods are not warranted in this case.
We looked at studies where the effects of radiation are most similar to those of tritium because we did not find any studies of the effects of tritium in humans. Low energy gamma or x-ray external irradiation is similar to tritium in two regards: (1) Tritium distributes quite uniformly throughout the body and doesn't concentrate in target organs, like whole body gamma or x-ray external irradiation, and (2) at the cellular level, where energy reacts with molecules in the cells, the relative biological effectiveness (RBE) for both tritium and numerous gamma and x-ray emissions is about the same. Although tritium is contained in the body for some period of time and most gamma radiation and x-rays pass directly through the body, what appears to be most important at low radiation levels is the total radiation dose absorbed. Therefore, we think that comparing the effects of tritium to those from low-energy gamma radiation and x-rays is valid.
Why don't they calculate the total dosage from all sources from the various kinds of radiation. Also why don't they calculate the dosage to someone with a radon contaminated basement, or having other additional exposure routes.
The National Council on Radiation Protection and Measurements (NCRP) estimated that the total average annual effective radiation dose to people in the U.S. from all natural and artificial sources is 360 mrem per year [12]. However, this is an estimated average and it can vary widely for individuals. We don't calculate people's total radiation doses from all sources of radiation because we don't have the information to do so and it is outside the scope of the public health assessment to try to collect the information. People's naturally occurring radiation doses depend on many factors including eating habits, smoking habits, methods of travel, and location. Background radiation levels, particularly radon levels, vary widely from one place to another--even between two houses next door to one another on the same street. Household radon levels depend on the rock and soil types beneath the house, building materials used to construct the house, and the degree of insulation and the permeability of air through the house. We considered household radiation exposures only where we could identify possible pathways whereby measured environmental contamination could be brought indoors, such as in well water or on garden vegetables. We note, however, that the radiation standards recommended by the NCRP and the ICRP refer to levels above background levels.
Similarly, we did not estimate what people's exposures are to various hazardous (nonradioactive) household products--because we don't have the information to do so and it is outside the scope of the public health assessment to try to collect the information.
We considered multiple exposure routes when we had concurrent data and the data indicated multiple exposure routes contributed to the total radiation dose that a person could receive. See, for example pages C-2 and E-26.
We agree that usually, as this commenter states, we expect health data can provide an indication of environmental exposures only in the most severe instances of contamination. Therefore, we rely on other information, primarily environmental data, to tell us whether there have been exposures and how serious they are. When environmental data do not indicate that exposures have occurred at levels of health concern, we may look at health outcome data to see if the data show unusual health outcomes or unusual prevalence or incidence of health outcomes. And we may review health outcome data because there is an expressed community request to look at them.
Releases from other facilities in the area are expected to be confounders for exposures to plutonium, polonium, and tritium, because the same health effects that we would expect from exposures to these radionuclides may be caused by other chemicals.
We attempted to find information that would lead us to believe people were exposed to releases from the Mound Plant in quantities that could cause them to become ill, and we were unsuccessful. We disagree that we did not attempt to "assemble the information."
The data that ATSDR gathered for the health assessment were sufficient enough to conclude that a health study in the general population is not warranted; therefore, we have no recommendations to do one. If we cannot assign doses to people, our feasibility analysis is complete. It doesn't matter whether we can satisfy other feasibility criteria for conducting a health study. Without doses, a health study is not feasible.
We also stated that we have no recommendation for health studies among the workers at the Mound Plant. This is not because we cannot assign doses to workers. This public health assessment did not consider exposures to workers. Worker health studies are the purview of the National Institutes of Occupational Safety and Health.
For example, as measured in (whole body) effective doses, natural radiation is responsible for much higher radiation doses than those caused by releases from DOE's Hanford facility. And yet, because Hanford released a radioactive chemical (iodine-131) that is virtually unknown in nature and which results in very specific health effects (thyroid cancer and other thyroidal diseases) it is plausible that these effects can be detected among those exposed to Hanford emissions.
Iodine-131 causes very unique health effects, but this is not true for most other radionuclides. Natural levels of radiation may pose a risk for cancer or genetic effects, but we cannot measure those risks because we cannot distinguish between cancers and genetic effects caused by background radiation and those caused by other factors. On the other hand, there may not be any risks of cancer or genetic effects from naturally occurring radiation. In areas of the world where naturally occurring radioactivity is very high we do not see elevated levels of cancer or birth defects [12]. In fact, decreased cancer death rates and increased longevity have been observed in populations in the U.S., China, India, Austria, and the United Kingdom exposed to high natural background radiation [13].
We do not intend to be derogatory. We stated that people have likely been exposed to radioactive contamination from the Mound Plant because some contamination went off site. Often health officials want to know, first: Have people been exposed to hazardous materials? And second: Are these materials in the environment at concentrations that pose a health hazard? We do not think that all exposures to toxic substances will cause harm. The conclusions that we reached in the Mound Plant public health assessment are meant to include sensitive subpopulations--the very young, the elderly, and those with compromised immune systems.
Although you may have a very weak immune system, that does not mean you have no defenses. We note that the term "immune system" usually refers to an integrated network of specific organs, cells, and specialized macromolecules (antibodies) whose function is to distinguish between foreign matter and "self", and to detoxify or eliminate the foreign matter. On a more basic level, the human body maintains a myriad of cellular and DNA repair mechanisms. These defenses (anti-oxidants, cell cycle feedback, DNA repair enzymes, apoptosis) operate in our bodies constantly and are responsible for maintaining our natural homeostasis. Ionizing radiation creates free radicals and free radical oxygen species in the body which are highly reactive and are thought to be responsible for the cellular and molecular damage that leads to cancer. However, genetic mutations occur naturally with a very high frequency. Additionally, the human body is subjected to the formation of free radicals and free radical oxygen species merely from being in sunlight and breathing air. Without cellular and DNA repair mechanisms, apart from the immune system, we would not be alive.
We cannot. If you have a very weak immune system, you may experience adverse health effects from many substances that would not be considered toxic to a healthy individual.
We agree that we cannot state precisely the minimum amount of any one contaminant that would be harmful to any particular person, because each person's body is different. There will always be a range as to what a minimum toxic dose will be in a population.
We cannot tell anyone that contamination has not harmed him or her. We do not know for certain how much of a substance anyone has inhaled or ingested or how that substance has affected him or her. But the available data can provide a good upper bound on the quantity of a substance that people were exposed to. And we use conservative assumptions to estimate their doses. In our opinion, based on the available data and scientific information, no one would have been harmed by drinking water in Miamisburg.
We can never be sure that airborne plutonium did not cause adverse health effects, but the data we reviewed do not support that contention.
"Current" begins when the Mound Laboratory corrected its sewage waste treatment facility problems in the mid-1980s. We define "current" beginning January 1, 1987. We are confident that the Mound Plant has posed no apparent public health hazard for at least 11 years. Apart from the waste treatment facility problems, the Mound facility has posed no apparent public health hazard for at least 21 years.
Page 48. The first sentence states that the "Mound Plant poses no apparent public health hazard to off-site populations". However, under conclusion 1, ATSDR states that the site does "not pose a current public health hazard". Which is it?
ATSDR uses the conclusion category, no apparent public health hazard, for sites where human exposure to contaminants in the environmental is occurring or has occurred in the past, but the contaminants do not pose a health hazard. No apparent public health hazard is our overall conclusion category for the site. The Conclusion 1 statement (that the site does not pose a current public health hazard) is literally correct. However, under ATSDR's guidance criteria for conclusion categories, no public health hazard is reserved for sites where there is no evidence of current or past human exposure to contaminated media. We do not mean to imply that exposures to releases from the Mound Plant have not occurred. Therefore, we have added the word "apparent" in Conclusion 1 and combined the first two statements in the Conclusions section in this version of the public health assessment. We have also corrected the statement at the end of the section titled, "Nonradioactive Hazardous Substances: Vicinity Soils."
Also, the site may pose no apparent public health hazard now, but what about in the past. It is not clear what your conclusions are concerning past exposure.
ATSDR concluded that we could not determine whether polonium-210 or nonradioactive contaminants were a public health hazard in the past (i.e., those pathways are indeterminate). However, we think the data are sufficient to conclude that radioactive substances in the environment, other than polonium-210, including plutonium and tritium, were no apparent public health hazard.
Comment acknowledged. We use both terms in writing. They are the same thing.
We disagree.
Also, why are age groupings included in the table if the purpose of inclusion is not discussed? [I] believe that you may be making references to sensitive populations, but this is never stated.
The demographics maps and tables describe the population distribution near the Mound Plant by census category. They are included for general information purposes and do not imply exposure. We have not attempted to assign risks to any part of this community because we have not determined that anyone received high enough doses to cause health problems.
The primary ATSDR investigators who visited the Mound Plant and contributed to the public health assessment are William H. Taylor and Carol A. Connell. Other ATSDR staff who visited the site are: Burt J. Cooper, Jeffrey A. Kellam, Andrew R. Dudley, L. French Bell, John H. Mann, and Emilio Gonzalez. Other ATSDR employees visited Miamisburg for meetings, but did not visit the site. Ohio Department of Health staff accompanied ATSDR staff on our initial site visit in May 1992. Employees with the Boston University School of Public Health and the EPA National Air and Radiation Environmental Laboratory also accompanied us during various visits to Miamisburg.
This public health assessment does not contain a formal pathways section. Please see the Environmental Contamination and Evaluation section beginning on page 12 and Concern 5 in the Community Health Concerns section, instead. Pathways analysis is also covered in some detail in the appendices. We identified only one completed exposure pathway to hazardous materials at levels of health concern: sewage wastes released to the Great Miami River in the early 1980s. We estimate 3,000 ±2,000 people could have been exposed.
We did not check area landfills.
This public health assessment does not address on-site exposures. On-site contamination is being addressed by DOE, and the U.S. and Ohio EPAs under site investigations and clean-up programs. Areas by roads and railroads have been included in environmental sampling programs.
Comment acknowledged.
Coal burning utility plants release radionuclides into the environment from stack emissions and from coal ash piles. Many parameters affect the relative distribution of radionuclides from coal plants, including the original content of radionuclides in the coal and the efficiency of the plant operations and emissions controls. Mound scientists conducted a study of the contributions to the public's radiation dose from a coal-burning electrical plant in Iowa in the late 1970s. The plant burned western U.S. coal. The only significant contribution to the public's radiation dose came from eating food grown in the immediate vicinity of the ash piles. The source of the radioactivity was thought to come from the resuspension and dispersion of coal ash. The estimated dose (25 mrem) was an approximate, order-of-magnitude estimation [14]. This dose is approximately the same dose as the total of all worst-case scenarios we estimated from the highest exposures to all pathways we considered from our sampling program with NAREL (Appendix E). We would need more information than we currently have to estimate what populations would be most affected and what are the radiation doses to them from the current or historical coal-burning plants in Miamisburg. We expect the radiation dose to some people, which comes from substances released from the local electric plant, could be significant compared with the contribution from the Mound Plant. However, we did not see evidence in Mound's or our environmental data that any facility, apart from Mound, is distributing radioactive materials non-uniformly in the environment in the Miamisburg area. Nevertheless, the coal ash piles are clearly visible in the EG&G Overflight Survey maps of surface gamma radiation collected in the vicinity of the Mound Plant [15].
Environmental compliance information can be obtained by contacting the Ohio Environmental Protection Agency.
The Mound Plant uses, and has always used, nonradioactive materials. We considered both water and air pathways. We reviewed nonradioactive air emissions data from the Mound Plant which led us to compare these to background air data. Our investigation suggests to us that there are likely more important constituents of the air that residents breathe than emissions from the site. Because our primary purpose in doing a public health assessment is to prevent exposures to pollution present in the environment that may result in adverse human health effects and diminished quality of life, we deemed the information valuable.
"[O]ther soils in the vicinity" refers to non-residential soils; i.e., municipal, industrial, and agricultural soils.
We would put it with "Historic Mound Releases That Did Not Pose A Health Problem."
Yes.
No. The ATSDR health consultation (September 29, 1993) is available to anyone upon request.
The legacy of plutonium in the Miami-Erie Canal--including the details concerning remediation activities--is documented elsewhere. Please refer to the Operable Unit 4, Miami-Erie Canal removal action design and responsiveness summary documents for more information.
We do not have evidence that people were exposed to tritium from the 1989 air release and we do not have evidence that people were not exposed to tritium from the 1989 air release. As we stated, air monitoring data do not show greater tritium air concentrations in 1989 than in 1988 or 1987. However; we think it is feasible that people could have been exposed to the tritium released in 1989. Therefore, we answered, "possibly." We welcome anyone to provide us with additional, relevant factual information.
Giardia lamblia can go undetected in the body for many months and the asymptomatic carrier rate is high. Clinical illness generally occurs 1 to 4 weeks after exposure to Giardia lamblia cysts. For a young child, illness may occur within days. The symptoms of Giardiasis are not different from those listed on page 16 if the organism goes undetected in the body for a long period of time. A person who has the parasite continues to be infectious.
Thank you.
Misclassification on death certificates is a problem that is well recognized by health officials but it is not as great a problem as it once was. The U.S. Standard Death Certificate, prepared by the National Center for Health Statistics (one of the centers of the CDC) includes fields for up to 2 underlying health conditions contributing to death, and other significant conditions that existed that are not an immediate cause of death. Some items on death certificates vary by states.
This is very misleading. Given the scale of the tritium releases, one can rest assured that people living downwind of the plant (or drinking the contaminated well water caused by the canal discharges) were exposed to tritium. It is also a safe assumption--given the magnitude of the releases, the half-life of the tritium and what we know about its cycling in the environment--that even people living upwind and not drinking the water were also exposed to tritium to some degree.
We agree that this statement may be confusing. Exposures probably occurred off site, and people living downwind or downstream would have been exposed to the highest concentrations. Using conservative assumptions, however, we determined that tritium from Mound was not a health hazard to anyone in the community.
Scientists are beginning to study the possible relationship between Gulf War illness and Chronic Fatigue Syndrome (CFS). Clinically, they are almost indistinguishable from one another, although health officials have not yet agreed upon the causes of either. Researchers at the Centers for Disease Control and Prevention (CDC) have noted that fatiguing illness closely resembling CFS is 4 to 16 times more common among Gulf War veterans than among nondeployed troops [16].
CDC's current CFS research program is focused on ascertaining the incidence and prevalence of CFS in defined populations, describing risk factors for CFS, and describing its clinical course. The thrust of this research is to elucidate pathological mechanisms and possible molecular markers [17]. Thus far, CDC investigators have been unable to document any unusual occurrence of fatiguing illness among reported CFS clusters. CDC scientists are also comparing epidemiologic correlates of Gulf War illness and CFS and are actively investigating common molecular markers for the two illnesses. The CDC has ruled out a simple causal association between infectious agents or allergens and CFS [16].
A health survey will very likely not show that community health problems have a specific cause. A health survey is not the right tool to do that.
Our conclusions are not based on health outcome data alone. At the same time, these data do not reveal any unusual health outcomes in the community near the Mound Plant which would suggest a need to change our conclusions or recommend specific investigations.
Correct. We would like to know how many patients were exposed to contamination from the Mound Plant among those who were included in the Dayton Area Cancer Association database. However, the reports that the Dayton Area Cancer Association issued for the area hospitals did not provide exposure information. Thus, we cannot compare cancer rates for the "exposed" and "not exposed" populations because we don't know who was exposed and who wasn't. Moreover, we do not know what geographical base the hospitals drew their patients from (i.e., we do not know the population denominator), so we cannot even calculate population cancer rates using the cancer data listed in the reports. We have corrected the public health assessment.
Currently, risks are small and they were small in the 1970's.
Conrail employees began work to upgrade their bridge abutment located between the Miami-Erie Canal and the Dayton-Cincinnati Pike (South Main Street) in 1990 before contacting officials at Mound. When Mound officials learned of the bridge work they conducted tests to determine the spread of contamination. The tests included urinalysis of workers and wipe tests of clothing, vehicles, and residences. All urinalysis results from these workers were negative for plutonium-238. Only five surface samples (wipe samples) from 141 collected had detectable counts, and all of the positive wipe samples were below the regulatory limits (Nuclear Regulatory Commission) for unrestricted use of the contaminated area. DOE became involved with soils removal in the area before returning construction authorities to Conrail. Many soil samples were analyzed during the removal activities. All the data that was collected are available from DOE officials at Mound. ATSDR reviewed these data for this public health assessment.
We assumed the Conrail workers were exposed dermally to plutonium-238 because plutonium-238 was found on their clothing. There is no evidence that they were exposed internally through inhalation, ingestion, or through a cut.
Concern 4 refers to Conrail bridge workers who were exposed to plutonium-238 in soils. For the purposes of our response we will consider that these workers could have inhaled dust contaminated with plutonium-238, although there is no evidence that they did.
The smallest amount of inhaled plutonium-238 that will cause adverse health effects depends on the particle size and the solubility of the plutonium compound. Particle size and solubility will affect the rate the plutonium migrates from the lung to the lymph nodes and the blood, and will affect the relative doses to the target organs. The primary target organs are the lung, skeleton, and the liver [18, 19, 20, 21].
The smallest amount of inhaled plutonium-238 initially deposited in the lung that has been observed to cause adverse health effects in animals is 5,900 becquerels per kilogram of lung tissue (equal to approximately 159,000 pCi/kg lung tissue) [18]. In this study the health outcome to these animals at this dose was lung tumors.
The importance of this study is that the researchers exposed a group of animals (beagles) through inhalation to levels of plutonium-238 that did not result in any more or different adverse health effects than were seen in control animals. There are many uncertainties associated with this study in part because of the small numbers of animals in each dose group. Nevertheless, the data suggest that a threshold for adverse health effects from inhaled plutonium-238 lies between 1,000 Bq/kg lung tissue (where no increased adverse health effects were seen over those in control animals) and 5,900 Bq/kg lung tissue (where lung tumors were seen in excess of those in control animals). (These values in Bq/kg are approximately equal to 27,000 pCi/kg and 159,000 pCi/kg lung tissue, respectively. We also note that the average adult human lung weighs about one kilogram.)
Until more information becomes available, the threshold for adverse health affects from inhalation of plutonium-238 appears to occur above 1,000 becquerels (27,000 pCi) in the adult human. The threshold for any particular person will vary.
Finally, we note that the highest concentration of plutonium in soil found during the Conrail bridge project was in one sample containing 1,223 pCi/g soil (45.25 Bq/g). It would take more than 22 grams of soil at this plutonium concentration to contain 27,000 pCi (1,000 Bq) of plutonium-238. No one could accidentally breathe this quantity of soil over a short duration.
The radioactivity of 1 one-millionth of a gram of plutonium-238 is 6.34E+05 Bq or 1.71E+07 pCi. If inhaled, this amount of plutonium may cause a cancer death. However, it is instructive to note that there are many people who have inhaled measurable quantities of plutonium--some of them, many years ago--and have suffered no ill effects.
The effect of TCE on the immune system is uncertain, although evidence from animal and human health studies suggests that the immune system may be sensitive to TCE. The strongest evidence for an immune effect from TCE comes from occupational studies of workers exposed to TCE by direct skin contact and possibly inhalation. Workers in these studies were found to have increased occurrence of scleroses of the skin (sclerodermas) compared to unexposed workers. Sclerosis may be involved in the development of diseases such as diabetes, which may have an immune component [22, 23]. Diabetes has been reported in excess by the ATSDR TCE Subregistry population, although a causal relationship has not been established. Immunological effects have been suggested in community health studies involving exposure to TCE in drinking water. However, these findings are inconclusive because exposures occurred to a variety of organic solvents and other chemicals, and not TCE alone. We do not presently know the effect of TCE alone on immunological function.
The fence cannot limit dust; it can only limit trespassing. Mound engineers are using other means to limit the spread of dust.
We do not know how many kids played in the Miami-Erie Canal. The amount of plutonium in the Miami-Erie Canal soil (before remediation) was not harmful to children playing in the canal. Please see the ATSDR health consultation we released in 1993 for a more detailed discussion.
Thank you. This should read, "Appendix D". We have corrected this error.
Concern 16 is about someone who lived in Bud's Mobile Home Court for 12 years, drank the well water there, and now has numerous health problems. We considered the available data on the water collected from those wells. Mound scientists have analyzed the water in the wells in and near Bud's Mobile Home Court repeatedly for plutonium-238 (since 1971), tritium (since 1971), uranium (since 1987), and thorium (since 1995). Our response was that the contamination in these wells cannot account for any of the health problems of the individual. This is still true, to the best of our knowledge. We don't know what has caused this person's health problems.
Page 25. Concern 17. The same comment applies, in this instance, to the tumors, provided that there was a reasonable period of time (years) between the first exposure to the water and the development of the tumors.
We agree that it is possible that contamination in the wells could have caused people's health problems, but we don't think it did. We stated that the contamination in the wells could not account for the health problems these people reported. Our conclusions are drawn from the weight of evidence.
We have referred to ample data to address the question of whether and how likely the wells are contaminated with pollutants from Mound. Please look at any environmental monitoring report from Mound since 1975, the 1994 Mound well survey, and the appendices to this document. We do not agree that the presence of any amount of contamination poses a health hazard.
We have not seen any indication that VOCs in the aquifer beneath the Mound Plant have migrated beyond the site. We know that Mound has a pump-and-treat program for containing the VOCs in the groundwater beneath the site. Mound engineers monitor their on-site wells regularly, whereas, often, residents do not monitor their own well water. On the other hand, we know that nationwide, and in Miamisburg, private wells sometimes contain contamination, such as bacteria, lead, or pesticides, that might be a health problem. Without specific data, we cannot tell if a person's well water is safe. The recommendation offered is appropriate.
The Hillview Platt was not the focus of our investigation; we sampled environmental media in all directions from the Mound Plant. Because we found minimal contamination in any of our samples, we didn't think it was particularly critical that we sampled vegetables in Hillview Platt. Also; we needed to have large enough samples to conduct all of the laboratory analyses we planned to do. We were only able to locate large enough quantities of home-grown vegetables that people were willing to sell us or to give us at a few locations.
We do not see any contradiction. Mound released contaminants and there are several pathways by which people could have come in contact with them. The concentrations were not high enough to cause adverse health effects. We cannot say that all the local gardens are safe, because we didn't sample all of them and they could be contaminated from sources other than the Mound Plant.
There are fences and warning signs around most portions of the property. The most accessible portions of the site, and the most hazardous portions, are controlled.
We provided the address in our response to Concern 71. We should have provided this information earlier, in response to Concern 28. We have corrected this oversight.
We do not know how much soil was placed over the waste dump or what was put into the dump. We have area radiation surveys, and surface soil and air sampling data that do not show any radioactivity hazards. We do not have data on nonradioactive substances at this location. We looked at cancer mortality data, which are described in Appendix F.
Spills and removal actions have been described in Mound documents. See the Site Scoping Report, Volume 11 for Operable Unit 9. Some incidents occurred a long time ago and little information is available, but DOE investigated all incidents. We did not state, nor do we know, if the toxic waste burial sites have all been located. Our conclusions are based on the data we reviewed.
We did not analyze any samples that we collected for nonradioactive, hazardous substances. We sampled water from Hillview Platt wells, and we did not find a problem with radionuclides. None of our environmental samples indicated the Hillview Platt area is more contaminated than other areas.
DOE used several criteria, including public input, to design their 1994 sampling program. Private well water was collected within a 2-mile radius of the Mound site. Wells were sampled for nonradioactive substances both upstream and downstream in the aquifer from the Hillview Platt. The groundwater near the site and further south in the aquifer was not a problem, so we do not expect that the groundwater beneath the Hillview Platt was a problem.
It takes hundreds of rems to result in radiation burns or radiation sickness that can cause death. The quantity of radionuclides released from the Mound site to the environment was not nearly enough for cattle or people to receive this high of a dose.
Yes. See Appendix E and Mound's environmental monitoring reports.
Thank you.
Health officials have learned from many attempts over several decades that contamination in the environment does not, alone, warrant a health study. Exposures to environmental contamination rarely result in conditions necessary to conduct a meaningful health study [24]. We acknowledge that doubts, uncertainties, and distrust can lead to psychological stress and adverse health effects.
I disagree. Even without the data gaps, there is enough information about releases from Mound to conclude that these releases were capable of causing adverse health effects. The only question is how many, and whether or not you could ever detect them given the natural fluctuations in the incidence rates for these diseases.
We acknowledge the comment and we disagree.
Comment acknowledged.
The American Cancer Society estimated that new cases of brain and central nervous system cancers accounted for about 1.3 percent of all new cancer cases in the United States in 1996 [25]. This represents fewer than one new case in 10,000 people in the United States and is the reason we stated that three cases of brain cancer is unusual in any neighborhood. Although the numbers of cases of brain cancer nationwide are small relative to some other cancer types, brain cancer is becoming more prevalent for reasons that we don't understand. We also do not know where the person who raised this concern lives, or when the brain cancers in this neighborhood were diagnosed. We recommend that people who think cancer rates in their neighborhood are high should contact their state or local health departments.
Comment acknowledged.
Comment acknowledged.
The newsletter that is referenced in our response is the only one ATSDR publishes. ATSDR has not prepared a fact sheet for the Mound Plant.
"Disease clusters are not necessarily meaningful" means that although certain diseases may be found grouped together geographically, they do not share a common cause. We note that different types of cancer generally will not have the same cause and are not considered to be the same disease. The numbers of cancers provided in this comment may or may not be unusual, depending on the types of cancer, the age of the persons, and other factors.
There are risks in everything we do, and we agree that risks abound. We are obliged to make a public health call, which is an interpretation of those risks. Except where we noted, we don't believe that the risks from environmental contamination from Mound are significant.
A public health assessment is intended to identify both urgent public health threats and the need for further investigations. A public health assessment has a broader scope than a dose reconstruction study. Over the years, we have been successful in identifying public health issues through the public health assessment process.
For example, in addition to estimating high and low bounds on the historic releases of the key radionuclides, it should have also been possible to estimate not only high and low bounds for hypothetical individual exposures, but also for population exposures. Within the bounds of the historic population exposures you could then use the total dose estimates to calculate the number of cancers, birth defects, and other genetic diseases you might expect as a result of the exposures.
The public health assessment process results in an assignment of a hazard category to an exposure pathway or to the site as a whole. The estimates that this commenter describes are appropriate for further investigations, if warranted by the health assessment. Most of our calculations are for upper bound exposures to hypothetical individuals. The results from these calculations form the basis for assigning our hazard categories.
We did not estimate population doses; however, we estimated doses for hypothetically maximally exposed individuals. See the appendices for examples. We do not agree that it is very plausible that releases from Mound caused cancers and other diseases.
We will continue to address community concerns that are brought to our attention and review environmental data that become available. We do not plan to further investigate Miamisburg well #2, unless new information is brought to our attention. Trichloroethene was not detected in residential wells during Mound's 1994 investigation [26]. We are not aware that anyone is being exposed to trichloroethene, therefore the risks are zero. Statement #4 includes residents at Bud's Trailer Court.
Comment acknowledged.
The professionals who performed the peer review of the Mound Plant Public Health Assessment are as follows:
William O. Berndt, Ph.D.
Dean for Graduate Studies and Research
The University of Nebraska Medical Center
Omaha, Nebraska
Kathleen Buchi, Ph.D.
Commander
U.S. Army Center for Health Promotion and Preventive Medicine
Aberdeen Proving Ground, Maryland
Thomas A. Burke, Ph.D.
Department of Health Policy Management
Johns Hopkins University
School of Hygiene and Public Health
Baltimore, Maryland
Robert E. Faye, P.E.
Groundwater Specialist
Southeastern Region, U.S. Geological Survey
Norcross, Georgia
John L. Hesse
Division of Health Risk Assessment
Michigan Department of Health
Lansing, Michigan
Ronald L. Kathren
Professor of Health Physics and Director,
U.S. Transuranium and Uranium Registries
Washington State University
Richland, Washington
Gerald R. Petersen, Ph.D.
Senior Epidemiologist
Office of Epidemiological Studies
U.S. Department of Energy
Germantown, Maryland
Ross Vincent, P.E.
RVC Associates/Sierra Club
Pueblo, Colorado
The panel members (except for Mr. Petersen) were given copies of a draft version of the public health assessment several weeks before meeting in Atlanta. The panel (except for Mr. Hesse) met in a conference room at ATSDR in Atlanta on September 10, 1996, and discussed the public health assessment. Written comments were submitted by all panel members, except Mr. Vincent and Mr. Petersen. Changes were made to the public health assessment prior to publication of the Public Comment Release version, based on the comments received. Primarily, the comments concerned 1) ways of presenting the information--particularly distinguishing between past and present assessments, 2) the importance of distinguishing between regulatory and health-based comparison values, and 3) the scarcity of historical data. Written responses were not prepared for each individual's comments. No changes were made to the conclusions or recommendations based on the reviewers comments.
In a separate process, during the Spring of 1997, the Public Comment Release version of the Mound Plant public health assessment was sent to three additional health professionals outside ATSDR for review. Those who reviewed the document are as follows:
Murray M. Finkelstein, Ph.D., M.D.
Medical Consultant
Ontario Ministry of Labour
Toronto, Ontario
Lief Peterson, Ph.D.
Assistant Professor of Medicine
Center for Cancer Control Research
Department of Medicine
Baylor College of Medicine
Houston, TX
John R. Herbold, D.V.M., Ph.D.
Associate Professor of Epidemiology
School of Public Health
UT Health Science Center
San Antonio, TX
ATSDR asked these three reviewers to prepare written comments to specific questions, and, in return, ATSDR staff prepared written responses to each comment. ATSDR received all the reviewers' comments by May 21, 1997. They are included, along with our formal responses in the following table.
| Peer Review for Public Health Assessment for Mound Plant (USDOE), Miamisburg, Montgomery County, Ohio | |
| Peer Reviewer's Comment | Agency Response to Comments |
| 1. Is the purpose of the health assessment clear? Are the public health issues related to the site clearly presented? Why or why not? | |
| Yes. This document is very well written and concisely reviews the observed, expected, and projected health effects that would be likely to have occurred or occur in the future among populations living near the Mound site. The format and style of presenting the data take into account the latest information concerning risk education, risk perception, and very effectively communicates risk to the lay reader. There are no errors in spelling and the grammar is correct. There is ample information on former operations at the site, a full evaluation of background information and history of site activities, reports of known contamination, health outcome data, community health concerns, conclusions and recommendations. LEP |
Thank you. |
| The purpose of the assessment is clear and the public health issues are clearly presented. The public health assessment addresses the exposures of people to radioactive and non-radioactive substances released off site to the environment from the Mound facility. The public health issues are clearly presented. The authors considered all materials released from the plant both radioactive and nonradioactive, and considered their presence in air, water, vegetation, and soil offsite. MF | Thank you. |
| The purpose of the health assessment is addressed partially
in DOCUMENT NOTES (pages 3-5) and by inference in SUMMARY (pages 1-2). Recommend that the SUMMARY SECTION begin with a paragraph clearly stating the purpose of this health assessment. This paragraph should precede the current opening sentence. JRH |
Acknowledged. The purpose of the public health assessment is presented before the Summary on the inside front cover of the document and in the Foreword section (page i). |
| 2. Are the pathways/exposures well defined and presented clearly with regard to pathway elements? | |
| Yes. Exposures to various compounds and/or radionuclides are fully detailed in the text and especially in the Appendices. The "Environmental Contamination and Evaluation" section describes a) current exposures (radioactive substances, non-radioactive hazardous substances and air quality), b) past exposures (historic releases that could result in health problems, inconclusive historic releases, and releases that did not pose a health problem). LEP |
Thank you. |
| The pathways were well defined and presented clearly. This is nicely summarized in the responses to questions 5 and 6 on page 23 of the report. MF | Thank you. |
| The potential exposures and pathways are clearly presented and discussed. The use of appendices to supplement the text is very helpful. JRH | Thank you. |
| 3. Is the hazard conclusion category for each pathway clear? Is the explanation for the conclusion clear? | |
| Yes. The authors clearly describe and draw conclusions about observed and likely projected health effects for each major substance by providing monitoring results with past and current concentrations, baseline levels of contaminants in terms of naturally occurring concentrations, comparisons of measured or presumed levels with limits for members of the public, discussions of uptake and distribution of various contaminants in critical body organs, reviews of known health effects at certain concentrations, and discussion of observed and likely health effects at these concentration levels. When observed health effects are inconclusive the authors clearly state a biological reason as to why effects were not observed or why projected effects are unlikely. LEP |
Thank you. |
| The hazard conclusions and explanation are clear. The explanations essentially involve the magnitudes of the exposures, which are very small. MF | Thank you. |
| My overall impression was that although exposure to contaminants
of concern did in some instances occur and could not be ruled out in other
instances, all potential exposures would have occurred at levels that would
have no discernable health effect. If that's the message - I got it. Explanations for contamination of the environment with both radioactive and nonradioactive substances from the Mound facility and potential exposure pathways were clearly given, along with supportive laboratory data, where available. JRH |
Correct. That is the message. |
| 4. Are the community concerns addressed with scientific support, and are the answers presented such that the community can relate the information to their personal situations? | |
| Yes. A unique element of the report is that special consideration is given to all community concerns. Specific answers to questions and community concerns from members of the public are provided in the report to the extent possible, and this entails an immense amount of work on behalf of the authors. Answers were not only concise, but they were tailored to the particular needs and concerns of the community. Answers were not provided to questions that were vague, unclear, one-sided, or just bad questions. There were cases when certain community concerns addressed the entire constellation of risk factors to which the public is likely exposed, and responses to such questions made by the authors were inconclusive as the scientific information needed is not yet available or is unknown. LEP |
Thank you. |
| The responses to the Community concerns, as presented in the Question and Answer sections pages 22-47 are clear and well presented. MF | Thank you. |
| The COMMUNITY HEALTH CONCERNS SECTION begins at page 21. An 88 item Question and Answer format follows (pages 22-47). I do not believe the major health issues were summarized in a manner conducive to effective risk communication. Recommend the 88 item Question and Answer format be moved to an appendix and the community's concerns summarized in the body of the report under the author's 5 categories listed on page 22. JRH | We do not wish to move the Community Concerns section to an appendix because it is an integral part of the assessment; i.e., it is not merely support information. |
| 5. Are the conclusions and recommendations appropriate based on information presented in the public health assessment? | |
| Yes. The conclusions that releases at the Mound Facility do not pose an apparent public health hazard to off-site populations are warranted and justified. These conclusions state that a) releases of radioactive and non-radioactive substances are not currently hazardous, b) releases from the Mound sanitary sewage treatment facility created temporary hazard to swimmers, boaters, and people fishing downstream in the Great Miami River, c) there are insufficient data to determine if Po-210 releases were hazardous, and d) Pu-238 and H-3 do not appear to have ever been a hazard to the public near Mound. In light of no apparent health risk to the public near Mound, my recommendations are as follows: • At present, compensation for health or psychosocial effects that could presumably be related to Mound releases is not justified and is therefore not warranted. • At present, baseline physical examinations for an large-scale epidemiological and follow-up studies of populations near Mound to determine the association between releases and health effects are not justified and are therefore not warranted. • Site-specific community health education should be provided with the release of this document. • ATSDR should reevaluate the needs for follow-up health actions if new information about this site becomes available. LEP |
Recommendation 1. The determination of whether compensation
for health or psychosocial effects is warranted is not within the purview
of ATSDR.
Recommendation 2. We agree. At present, based on the information available, large-scale epidemiological and follow-up studies are not warranted. Recommendation 3. We are unsure what kind of community health education would be appropriate in this community. Representatives from ATSDR, Boston University, Ohio EPA, Ohio Department of Health, and DOE have presented seminars on radiation health and safety, epidemiology, and community health data in this community. We will suggest the Division of Health Education and Promotion consider a health education needs assessment for this community. Recommendation 4. We agree. |
| I believe that the conclusions and recommendations are appropriate based upon the analysis of exposures and pathways. The magnitudes of the exposures are small and do not appear to present any substantial health risk. MF | Thank you. |
| The conclusions (page 48) are supported by the background
information presented and decision process described in the body of the
report and appendices. Suggest that a comment be included in the RECOMMENDATIONS SECTION regarding whether or not Conclusion #3 should be a closed issue. JRH |
Thank you. As indicated in "A Note of Explanation" on the inside front cover of this document, all sections of this public health assessment are subject to revision if additional information becomes available that warrants a change in our conclusions, recommendations, or public health actions. In particular, we are reviewing the available information regarding plutonium and polonium releases from the Mound facility as a result of comments we received upon release of this (public comment) document. |
| 6. Are there any other comments that you wish to make about the public health assessment? | |
| No. LEP | Acknowledged. |
| (blank) MF | (blank) |
| No other comments. JRH | Acknowledged. |
| 7. Are there any comments on ATSDR's peer review process? | |
| No. LEP | Acknowledged. |
| (blank) MF | (blank) |
| (blank) JRH | (blank) |
| 8. Are there any other comments? | |
| No. LEP | Acknowledged. |
| (blank) MF | (blank) |
| (blank) JRH | (blank) |
As described above, ATSDR had this document peer reviewed a second time. The commenter does not state why a new peer review is requested, nor what abilities are particularly valuable in a reviewer. ATSDR maintains a pool of reviewers (which changes often) from many universities and organizations.
The commenter does not explain why the word "ever" makes the statement misleading. We think the word "ever" describes a timeframe and adds emphasis. We do not have any information that indicates Mound personnel ever released chemical (nonradioactive) wastes to the Miami-Erie Canal (as opposed to the Great Miami River).
Radionuclides with high specific activity and high-energy emissions that are taken internally are more toxic than those with lower specific activity and lower-energy emissions. However; "high" specific activity and "high" energy are relative terms. Specific activity is inversely proportional to half-life. For example, the specific activity of polonium-210 is higher than plutonium-238 because polonium-210 has a shorter half-life than plutonium-238. However; there are many radionuclides with shorter--and many with longer--half-lives than these two radionuclides. As for their alpha energies, both polonium-210 (5.3 Mev) and plutonium-238 (5.5 Mev) fall slightly below the middle in the range of alpha energies for typical alpha-emitters (approximately 3 to 9 Mev for most alpha-emitters). We acknowledge that appropriate radiation protection should be employed whenever anyone is knowingly handling quantities of radioactive materials. But we also note that radioactive substances are naturally occurring in the food we eat, in the air we breathe, in building materials, and virtually everywhere.
It means that Mound had stopped using polonium-210 and any polonium-210 that was in the environment as a result of Mound activities had decayed away. Mound scientists were seeing naturally occurring levels of polonium-210 in the environment in 1974.
Comment acknowledged.
In the context of historical polonium-210 releases, the ATSDR report states on page B-2 that "the lowest observed adverse health effect level that has been shown (in mice) to cause health problems is 0.01 µCi per kilogram of body weight". It was further claimed that inhalation of air with a polonium-210 concentration of 6.56 x 10-11 µCi/mL by an adult over an entire year would not exceed this exposure level. Using the dose conversion factors in Federal Guidance Report No. 11, this inhalation results in a committed effective dose equivalent of 5.3 rem/yr.
This dose is essentially correct.
The Mound Laboratory used many radioisotopes, including plutonium isotopes, before 1960. However, we have not seen documentation showing releases of plutonium to the environment before 1960.
Tritium oxide and elemental tritium released into the environment will become more dilute. Plants, animals, rocks, soils, and minerals may uptake or bind tritium, but they do not concentrate (or bioconcentrate) tritium. Tritium, in all of its chemical forms, will decay with a physical half-life of 12.35 years. From the available data, we predicted a worst-case exposure scenario. We see no reason for conducting a dose reconstruction or a health study.
There may be such records, but we did not ask for them because we do not need this information.
In this document, we provide a bibliography and references to most of the toxicologic information we used to evaluate environmental polonium and tritium from the Mound facility. See also the ATSDR health consultation and Toxicological Profiles for Plutonium and Ionizing Radiation [21, 27, 28].
Thank you.
We distributed, for comment, copies of our Work Plan for Environmental Studies in the Vicinity of the Mound Plant in September 1993. The Work Plan was sent to DOE, U.S. and Ohio EPAs, City of Miamisburg officials, and members of the community. Results from the ATSDR/NAREL environmental sampling program were distributed to many stakeholders in February 1996. Copies of the Work Plan and the sampling results (tables of data) are available in the CERCLA Public Reading Room on Central Avenue in Miamisburg. Additional laboratory documentation (QA/QC) is available upon request to ATSDR.
No; but this is correct.
Yes, we agree.
We reserve judgement on releases of polonium-210 because there may be important data in laboratory notebooks that we have not seen. Otherwise, we agree.
Breathing thorium dust can result in lung damage and an increased risk of lung cancer. Thorium may also affect the blood and liver, and may cause bone cancer when taken into the bloodstream in very large doses (10s of rads) [29].
This public health assessment does not address exposures to Mound workers; please see Document Notes, page 3. We included a short description of worker studies because of expressed community concerns and because we were interested in surveying all the health studies pertaining to the Mound Plant.
We expect that Mound workers would have been exposed to higher concentrations of polonium than the public. The mortality studies of Mound workers provide evidence that members of the public were not exposed to hazardous amounts of polonium from the site. However, this evidence is not sufficient to exonerate polonium. Mound workers were (and are) a healthy group, and their health is probably not representative of the health of the general public. Mound workers are less susceptible to adverse health effects from exposures to hazardous (and radioactive) substances than the less healthy members of the public. Also, the worker mortality studies haven't been updated in almost 20 years. Mortality studies do not consider health outcomes that are not fatal; and the latency from polonium exposure to death may have exceeded the temporal boundaries of the completed studies. We still consider that we have not seen sufficient polonium release data (from the Mound stacks or through the effluent outfall to the river) or environmental data to assure us that high exposures did not occur. We agree that historical Mound records (that we have not reviewed) might provide sufficient evidence to conclude that high exposures in the community did not occur. We are determining the feasibility of examining Mound's laboratory notebooks from their early years for further information.
Workers, on average, are healthier than the whole population, on average. Therefore, comparing workers' health to the health of the whole population may not be justified. The healthy worker effect occurs when an inappropriate control population is chosen to compare the worker population to. When a worker population shows fewer adverse health effects than the comparison population, the data may suggest to those unfamiliar with the study that exposures to hazardous materials can result in better health than if no exposures occurred--a trend opposite the one we would expect to find; this is the healthy worker effect.
Not necessarily. Out of the number of current Mound workers, we would expect that more than 7 people have, or have had, cancer. Also, these may be different kinds of cancer, which would suggest the cases are not related.
Voluntary Tracking System is a term included in the glossary. ATSDR funded a Voluntary Tracking System at one Superfund site (a landfill in New Jersey) to monitor health effects in the community. Surveys were sent to approximately 3,700 people and over 2,400 were returned. The results have not yet been analyzed.
Please see Concern 86 in the Community Concerns section. We are always looking for better ways to reach out to communities.
References
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