PUBLIC HEALTH ASSESSMENT
IOWA ARMY AMMUNITION PLANT
MIDDLETOWN, IOWA
EVALUATION OF ENVIRONMENTAL CONTAMINATION AND POTENTIAL EXPOSURE PATHWAYS
In this section, exposure pathways are evaluated to determine whether people accessing or living near IAAAP could have been (past scenario), are (current scenario), or will be (future scenario) exposed to installation-related contaminants. In evaluating exposure pathways, ATSDR determines whether exposure to contaminated media has occurred, is occurring, or will occur through ingestion, dermal (skin) contact, or inhalation of contaminants. When exposure to contaminated media occurs, the exposure pathway is regarded as "complete." To determine whether completed pathways pose a potential health hazard, ATSDR compares contaminant concentrations to health-based comparison values. Comparison values are calculated from available scientific literature on exposure and health effects. These values, which are defined for each of the different media, reflect the estimated maximum contaminant concentration for a given chemical that is not likely to cause adverse health effects, given a standard daily ingestion rate and standard body weight. If contaminant concentrations are above comparison values, ATSDR further analyzes exposure variables (for example, duration and frequency) and the toxicology of the contaminant. This exposure evaluation process is summarized in Figure 3.
Contaminants have been detected in on-site groundwater, surface water, soil, sediment, and local biota and in off-site groundwater and surface water. RDX is the primary contaminant of concern, although other explosive chemicals, VOCs, SVOCs, and some metals were detected at low concentrations. ATSDR evaluated available on- and off-site information on potential contamination in groundwater (Figures 4 and 5), surface water, soil, sediment, and local agricultural produce and deer to determine if these media pose any past, current, or future public health hazards. ATSDR concluded that public exposures to groundwater, surface water, soil, sediment, and local biota are not likely to result in adverse human health effects because, when detected, contaminant concentrations were too low to pose a health hazard and/or were not accessible to the general public. Information on these exposure pathways is summarized in Table 2 and the following text. A detailed evaluation of potential public health hazards associated with all 33 RI/FS sites is summarized in Appendix A. Figure 6 shows the locations of these 33 RI/FS sites, in addition to 11 other no further action sites identified during the PA/SI.
The following discussion evaluates community concerns about potential human exposure via contaminated groundwater, soil, sediment, and local biota. This section states each concern, presents a brief summary of ATSDR's conclusions, and describes in more detail any identified exposure pathways and the basis for ATSDR conclusions. ATSDR's conclusions regarding the past, present, and potential future exposures to various environmental media on and in the vicinity of IAAAP are based on the evaluation of data gathered from remedial site investigations, groundwater monitoring data, on- and off-site drinking water well data, and the observations compiled during site visits.
Could exposure to RDX or other contaminants in groundwater result in adverse human health effects for residents of neighboring communities or for former residents, employees, or visitors of IAAAP?
Conclusions
After detailed review of the available data, ATSDR has drawn several conclusions regarding past, present, and possible future exposures to contaminated groundwater at IAAAP. These conclusions are outlined below.
Present and Potential Future Exposures
Past Exposures
Discussion
IAAAP's Hydrogeology
The two main aquifers affected at IAAAP are the loess/till aquifer (drift aquifer) and the underlying upper bedrock aquifer. The majority of contaminant movement takes place in the drift aquifer. The groundwater table in the drift aquifer generally occurs within 10 feet of the ground surface, and often less. Shallow groundwater flow closely parallels the ground surface. Thus, shallow groundwater flow throughout the installation is from high points, including most of the Line and Yard areas, toward surface drainages, particularly the larger streams such as Spring, Brush, and Long Creeks and the Skunk River. The water in the upper bedrock aquifer generally flows to the south and east, toward the Skunk and Mississippi Rivers. In some on-site areas, including the southwestern part of IAAAP, the upper bedrock aquifer is exposed at ground surface and discharges into surface waters. Elsewhere at IAAAP, the upper bedrock aquifer lies at depths of more than 50 or 100 feet.
Groundwater Use
IAAAP has five on-site production wells, none of which have ever been used for drinking water purposes. Four of these five wells were installed in 1941 and remained functional until 1977, when IAAAP began using public water from the city of Burlington.2 Three of these on-site wells were never used, apparently due to low recharge rates. The fourth well served (but was never used) as an alternate water source for the water treatment facility (Hicks, 1999). In 1981, IAAAP installed a fifth on-site well to provide sanitary water to the facility buildings. It currently supplies sanitary water to the MILVAN Facility and there are no plans to abandon it. Because none of the on-site wells ever supplied IAAAP drinking water, exposure to on-site RDX-contaminated groundwater never occurred.
IAAAP does not control the use of groundwater once it migrates off property boundaries. Prior to the early 1990s, all local residents south and southeast of the installation used private wells for drinking and irrigation. After groundwater contamination was documented in 1992, all potentially-impacted households were afforded the opportunity to connect to the Rathbun Rural Water System at the Army's expense (Allison, 1999a). By the fall of 1994, 154 residents living south and southeast of IAAAP were connected to the Rathbun Rural Water System. Rathbun water is filtered and treated to meet all federal and state drinking water standards. The closest public or municipal wells are located over 3 miles away from IAAAP property and are not at risk from installation-related contamination.
According to Army accounts, 15 households refused the Army's offer to connect local residences to the Rathbun Rural Water System (Allison, 1999a). Fourteen of these 15 households draw water from uncontaminated aquifers so no past or current exposures to contaminants have occurred. The fifteenth household obtains its well water from an aquifer impacted by RDX. The Army did connect this residence to the Rathbun Rural Water System in 1993, but the individuals at the residence refused to abandon the private well. Instead, the residents connected the contaminated well to another structure on the property. The well (identified as Well 2 in the Groundwater Quality section below) provides all potable water to this other structure. Despite repeated Army outreach efforts and recommendations to abandon the well, the household chooses to continue to use the well for domestic purposes and to knowledgeably assume any associated risks with drinking this water. Except for this one household, no one is exposed to potentially harmful levels of contaminants because all local drinking water meets (and will continue to meet) federal and state drinking water standards. It has, however, been reported to ATSDR by local residents that some other residents' wells are still used for irrigation and some residents now apparently utilize some of those wells for bathing and other purposes not directly involved with drinking or cooking.
Groundwater Quality
ATSDR's records search found that in the early 1950s, IAAAP discharges were suspected of contaminating a few shallow wells located close to Brush Creek outside of the IAAAP property. ATSDR was unable to locate any studies or data to confirm or quantify these events. This problem was reportedly (IAAAP records) alleviated by making changes in disposal methods, including treatment and filtration of process waters prior to discharge.
Quantitative groundwater monitoring began at IAAAP and off-site locations in the 1980s. RDX is the only contaminant that has been detected above ATSDR comparison values in off-site groundwater. Underlying different sites within IAAAP, however, on-site groundwater contained contaminants variably exceeding proposed site cleanup goals, including:
Because contaminants underlying IAAAP are inaccessible and groundwater is not used as a source of drinking water, there is no exposure (past, present, or potential future) to these contaminants on site (Marquess, 1997; Mason and Hanger Corporation, 1997).
In 1985, the Army sampled off-site private wells adjacent to IAAAP's southern boundary. Contaminants were not detected in any off-site wells and all well water met federal and state drinking water standards (AEHA, 1985).
Off-site contamination was first detected above ATSDR comparison values in September 1992 during Phase I of the RI. Groundwater samples were collected from six residential wells (Well 1 through Well 6 in Table 1) located on the south/southeast border of IAAAP in the Brush Creek watershed. Well 1 and Well 2 contained explosives at levels (15.5 parts per billion [ppb] and 27.5 ppb, respectively) above the available screening value, EPA's lifetime health advisory limit (HAL), of 2.0 ppb for RDX. These wells were re-sampled on March 15, 1993; the presence of RDX at similar levels in the same wells was confirmed (ACE, 1997b,c).
In response to the findings of off-site contamination during the Phase I RI, the Army conducted an extensive off-site sampling and analysis program. This program investigated all residences located in areas of suspected groundwater contamination and in the watersheds associated with surface water leaving the IAAAP. The Phase II RI, beginning in April 1993, included the sampling of 54 residential wells in the IAAAP vicinity. Three wells (Well 7, Well 8, and Well 9 in Table 1) contained RDX above the HAL of 2.0 ppb. Two of these residences are located at the extreme southwest boundary of IAAAP, near the town of Augusta, on a tributary of the Skunk River. The third residence is located along the Brush Creek watershed adjacent to the first two homeowners whose wells tested positive for RDX. Because all reported RDX values were near the HAL of 2.0 ppb, the wells were re-sampled to corroborate initial sampling results. The second round of well samples at the three affected residences showed RDX contamination at similar levels (ACE, 1997b,c).
Table 1: RI Groundwater Results
| Sample/ Re-sample (Well name assigned during Phase I RI) |
Well Depth (Feet Below Ground Surface) |
Watershed | ATSDR Comparison Valuea |
Maximum RDX Concentration |
When Detected |
| Well 1 (RBW-GW-25) |
35 | Brush Creek | 2.0 ppbb | 15.5 ppb 16.0 ppb 6.0 ppb |
September 1992 March 1993 August 1998 |
| Well 2 (RBW-GW-26) |
45 | Brush Creek | 2.0 ppb | 27.5 ppb 22.8 ppb 6.2 ppb |
September 1992 March 1993 August 1998 |
| Well 3 (RBW-GW-27) |
40 | Brush Creek | 2.0 ppb | <2 ppb <2 ppb |
September 1992 March 1993 |
| Well 4 (RBW-GW-28) |
28 | Brush Creek | 2.0 ppb | <2 ppb <2 ppb |
September 1992 March 1993 |
| Well 5 (RBW-GW-29) |
35 | Brush Creek | 2.0 ppb | <2 ppb <2 ppb |
September 1992 March 1993 |
| Well 6 (RBW-GW-30) |
800 | Brush Creek | 2.0 ppb | <2 ppb <2 ppb |
September 1992 March 1993 |
| Well 7 | 60 | Skunk River Tributary | 2.0 ppb | 2.1 ppb 2.9 ppb <2 ppb |
April 1993 May 1993 August 1998 |
| Well 8 | 60 | Skunk River Tributary | 2.0 ppb | 3.3 ppb 3.3 ppb |
April 1993 May 1993 |
| Well 9 | 40 | Brush Creek | 2.0 ppb | 2.1 ppb 6.7 ppb |
April 1993 May 1993 |
a = U.S. Environmental Protection Agency's lifetime health advisory limit
b = ppb = parts per billionSources: (Allison, 1999b; Plant Protection Office, 1998; ACE, 1997b,c; JAYCOR, 1996)
The Army's most recent sampling event, a supplemental groundwater investigation conducted in August 1998, indicates that RDX concentrations have decreased since 1993. Two wells (Wells 1 and 2) currently contain detectable concentrations of RDX (6.0 ppb and 6.2 ppb, respectively) (ARDL, 1998).
These studies indicate that off-site groundwater contamination appears limited to areas surrounding Brush Creek and the southern boundary of IAAAP. Current concentrations of off-site RDX-contaminated groundwater near the IAAAP boundary are generally less than 10 ppb (ACE, 1997b,c). Concentrations have been observed to be more diluted with greater distance from the installation. Due to natural dilution factors, RDX concentrations in groundwater may decrease further with time.
Potential Human Health Hazards from Past Off-site Exposures
Although not well documented in the administrative record for this installation, the earliest indication of off-site contamination noted in the area south of IAAAP dates to the 1950s. At this time, contamination in surface water was noted. Shortly thereafter, the Army first provided bottled water and then provided individual household water filtration units to some area residents to ensure the availability of safe drinking water. Also during this time interval, some area residents hauled water for their domestic animals.
In the early 1970s, contaminant levels had reportedly declined and, in 1973, the Army ceased to provide funding for the continued use of individual household water filters. Some area residents continued to use these filters for a while, but most residents started to use bottled water for drinking water and cooking purposes. No data are available to quantify the actual levels of RDX-contamination in drinking water or the time interval(s) that contaminated water may have been ingested. Thus, ATSDR is not able to evaluate the possible health hazards associated with this past episode of off-site contamination. The measures taken by the Army and the residents themselves during this time period were protective of public health and the ingestion of contaminated groundwater was probably minimized or largely eliminated.
Beginning in 1975 and continuing to present, the numerous investigations conducted by the Army and EPA provide sufficient data for ATSDR to evaluate past off-site exposure to contaminated groundwater.
In 1985, community residents living along the southern border of IAAAP expressed concern about potential environmental impacts of disposed wastes and the migration of contaminants from IAAAP into their private drinking water wells adjacent to Long Creek. Suspecting munitions or radiological contamination (emanating from past AEC activities at IAAAP), the Army and EPA thoroughly investigated the matter and sampled local groundwater. No organic constituents were detected and all metals concentrations met regulatory standards in the potable water consumed by the residents. This, combined with the absence of contaminants at the perimeter monitoring wells on site, indicates that no contamination was emanating from IAAAP and impacting off-site potable water supplies at the time.
When RDX was detected in private wells in 1992, the Army immediately provided bottled water to all affected residences. The Army then contracted with the Burlington Municipal System and Rathbun Water Company to connect 154 residences in the area to the public water supply. Even though most residences were not directly impacted by groundwater contamination, the Army took preventative measures and conservatively defined the affected area as all residences south of the IAAAP, between Brush Creek at the IAAAP's southeastern boundary, to an unnamed tributary south of Line 3A, at the IAAAP's southwestern boundary, south to the Skunk River. Fifteen households in this area declined the Army's offer to connect them to the Rathbun Rural Water System. Fourteen of these 15 households use uncontaminated private wells. The fifteenth household knowingly chooses to continue to use a well that draws from a contaminated aquifer despite the Army's repeated recommendations to discontinue using this private well water.
ATSDR Exposure Dose Estimates3
To evaluate whether health hazards are associated with exposure to area groundwater, ATSDR estimated the potential exposure doses for adults and children who drank water from affected wells. To estimate human exposure doses, ATSDR used very conservative assumptions believed to greatly overestimate the levels of actual exposure. These assumptions, ATSDR's methods, and the estimated exposure doses for ingestion of RDX-contaminated water are provided in Appendix B.
The estimated doses for an adult and a child are less than those associated with adverse health effects. ATSDR, therefore, concludes that off-site past exposure to RDX-contaminated groundwater via private drinking wells posed no apparent public health hazards.
Could exposure to RDX or other contaminants in surface water result in adverse human health effects for people exposed to Skunk River, Brush Creek, Spring Creek, Long Creek, and other surface water bodies near IAAAP?
Conclusions
Discussion
IAAAP property has several streams, rivers, and other surface water bodies. Totaling an area of approximately 13 acres, 30 ponds and small impoundments are located on the installation (JAYCOR, 1996). The average creek width within IAAAP varies from about 50 to 200 feet. The three primary watersheds draining IAAAP are Brush Creek, Long Creek, and Spring Creek.
Brush Creek runs from IAAAP's northern boundary, through the central part of the base, down to the southeastern corner of the property. It runs through the locations where most activity associated with facility operations occurs, draining the majority of industrial operations: Lines 1, 2, 3, 6, 7, 9, 800, the Line 800 Pinkwater Lagoon, the former Line 1 Impoundment, parts of Lines 4A and 5A, the Pesticide Pit, and the Sewage Treatment Plant. Long Creek flows east from IAAAP's western boundary into Mathes Lake, which is located in the central part of the installation. Long Creek surface waters remain uncontaminated. Until 1977, treated surface water from Mathes Lake served as IAAAP's primary drinking water source. Spring Creek flows south along the installation's eastern boundary. RDX is the main contaminant of concern, although other explosives and some metals have been detected in Brush and Spring Creeks.
In the past, Brush Creek "ran pink" from IAAAP explosives contamination. ATSDR found no studies or technical reports quantifying this claim, but several documents said that this community concern about pink water was raised during the World War II era (ACE, 1997b,c). Past employees of IAAAP verified that explosives contamination continued to be dumped into the Pinkwater Lagoon throughout the 1960s and 1970s. One former IAAAP employee reported that "chunks of TNT and Composition B as large as my fist were in the sump water dumped into the lagoon" (Public Comment Responses, 1999). This same employee indicated that surface water samples may have been drawn from the creeks in the 1960s and 1970s. ATSDR found no record of these sampling efforts, so it is impossible to conclusively know what caused Brush Creek to run pink. In general, however, LAP operations generally produce pink water during the explosive TNT washdown operations when water is used to remove solvents from the product. Pink water is a TNT solution that is approximately 99% water with a TNT concentration of approximately 5 ppm (McCarley, 1998). Because ATSDR could not determine the specific nature and extent of IAAAP past contamination, however, ATSDR concludes that past exposures to on- and off-site surface water pose an indeterminate public health hazard.
Currently, public exposure to contaminated surface waters--defined as surface waters that fail to meet ATSDR's drinking water comparison values and health advisory levels--is extremely limited, if it occurs at all. The primary contaminant in surface water is RDX, with other explosives (including TNT) detected in trace amounts. Contaminant concentrations, especially those detected in Brush Creek, fluctuate and have not been fully characterized, but public exposure to these contaminants is limited due to military security measures, perimeter fencing, and natural dilution factors.
There are several water-related recreational facilities on IAAAP and in the immediate area surrounding the installation, but none of these recreational facilities have been affected by contaminated surface waters. Mathes Lake (also called Long Lake) is located on IAAAP. On the water front area of Mathes Lake, where Long Creek feeds into the Lake, there is a small scout camp site. A boat ramp is located on the east shore of Mathes Lake that is used by fishermen. South of IAAAP is the Skunk River, which has two boat launch access areas and one small park located on its banks, most of which are located in the area known as Augusta. The Skunk River is used for all types of recreation, such as boating, water skiing, swimming, and fishing. Brush Creek is too small to be suitable for typical recreational activities such as swimming, boating, or fishing, but it may be used for recreational purposes by children. Children only have access to Brush Creek after it leaves IAAAP property.
Based on installation geology and hydrogeololgy, on-site contaminants could be carried off site via surface water, primarily Brush Creek and the small unnamed tributaries of Skunk River in the southwest. Off-site concentrations of explosive contaminants, including RDX, varied widely among different sampling events. Generally, RDX levels detected in Brush Creek surface water near the IAAAP boundary remained below 10 ppb. After a rain event in April 1995, however, these RDX concentrations reportedly reached 22 ppb. The Army does not currently understand the complete extent and role of contributing factors that cause such surface water concentration changes, but on-going Brush Creek studies are investigating these fluctuating concentrations. RDX levels in un-named Skunk River tributaries slightly exceeded 2.0 ppb. Public exposure to surface water in Brush Creek and Skunk River tributaries is likely to occur infrequently and for short durations of time. Incidental ingestion of and/or dermal contact with such low-level contaminated surface water, if it occurred at all, would not be associated with adverse health effects. ATSDR concludes that present and potential future exposures to on- and off-site surface water pose no apparent public health hazard.
Could exposure to soil and sediment contaminants at IAAAP result in adverse health effects for employees, residents, or visitors of the installation?
Conclusions
Discussion
Forty-four sites of known or suspected soil contamination have been identified at IAAAP. Thirty-three of these sites required further investigation under the RI and were thoroughly evaluated in this Public Health Assessment (Appendix A). Metals and explosives were the primary contaminants of concern in soils. ATSDR compared on-site metal levels to soil comparison values, IAAAP background samples, and detection limits to define contamination.
Site investigations reported the most significant contamination at Lines 1, 2, 3, and 3A, the Explosive Disposal Area, the Firing Site, and the Fire Training Pit (Engineered Efficiency 1996, 1997). Prior to remediation efforts, two subsites, the Line 1 Impoundment and Line 800 Pinkwater Lagoon, were considered to be the greatest sources of explosives contamination at IAAAP. At other sites investigated, soil and sediment contamination was localized, if detected at all, and generally at low levels (Engineered Efficiency 1996, 1997).
Public access to contaminated sites is restricted and prevented because (in addition to perimeter fencing at IAAAP) secondary fencing and security measures surround almost all industrial areas and installation facilities where soil contamination occurs. Unfenced sites with potentially-contaminated soil/sediment include the Inert Landfill, Construction Debris Landfill, and Demolition Area. Surface soils at these three sites contain contaminant concentrations below levels associated with health effects and/or are undergoing remedial activities to reduce contaminant concentrations to levels protective of human health. Public exposure to on-site contaminated sediments is prevented because the sediments lie underwater, beneath on-site surface water bodies. For some of the year, low surface water flows may allow for the public to walk through the streams, but on-site exposure to sediments appears minimal because on-site visitors are likely to wear shoes or boots and will not regularly be exposed to these sediments.
Deer hunting is permitted on the installation and at areas surrounding IAAAP, so deer hunters may have come in contact in the past to contaminated soils at the unfenced sites, specifically at the Inert Landfill. ATSDR believes that incidental exposure to soil contamination is extremely minimal, if it occurs at all, for two primary reasons: 1) the amount of time deer hunters spend in contact with on-site contaminated soil is likely to be very brief and will not occur on a regular basis, and 2) the hunters will likely stay in forested areas and their margins, rather than venture into the open fields or industrial areas where the soil contamination occurs.
Army-approved groups (e.g., the Boy Scouts of America) and trespassers may access forested and agricultural areas on site, but it is extremely unlikely that they will access contaminated sites. No contaminated areas are located near the scout camp at Mathes Lake and no contaminated areas are located near IAAAP's perimeter. No likely exposures are near the Inert Landfill or other areas of known soil contamination (Appendix A).
The Army has initiated NTC removal actions to address soil contamination at several areas across the IAAAP (O&M, 1998; OHM Remediation Services Corp., 1996). The Army is remediating soil contamination even though there is little, if any, public exposure to contaminated soils, to prevent the potential movement of contaminants to underlying groundwater. Remediation sites include the Inert Landfill, the Pesticide Pit, the former Fire Training Pit, explosives-contaminated sumps, and the Line 1 Impoundment and Line 800 Pinkwater Lagoon subsites. All major sources of contamination at IAAAP either have been or will be remediated (e.g., landfill consolidation, capping, bioventing, or soil vapor extraction) (O&M, 1998) (see Completed Soil Actions of the Public Health Action Plan). ATSDR concludes that past, present, and future exposures to on- and off-site soil and sediment do not pose a public health hazard.
Has contamination from IAAAP affected local agricultural products, deer, or cattle populations and potentially harmed those individuals consuming local produce, venison, and beef?
Conclusions
Discussion
Crops in the vicinity of IAAAP may be irrigated with RDX-contaminated water and grow in soil containing RDX (maximum detected concentration of 1.4 parts per million [ppm]). To better characterize the potential for RDX to accumulate in on-site plants, the Army conducted a study in the summer of 1994 (Center for Environmental Restoration Systems, 1995a). This study found that the potential exists for RDX to enter the food chain via fruit- and nut-bearing trees, as well as in locally-grown grains. RDX was found in the shoots and roots of some plants growing on RDX-contaminated soils at sites surveyed at IAAAP. Plant concentrations of RDX varied greatly by species.
ATSDR examined potential health impacts associated with IAAAP plants consumed by people, specifically corn and soybeans. Only one sampled agricultural area, a small area in one cornfield, contained detectable RDX in the soil. Corn grown in this contaminated soil did not contain detectable RDX concentrations in its corn leaf, stalk, grain, or root samples. Similarly, corn grown in uncontaminated soil contained no detectable RDX concentrations (Center for Environmental Restoration Systems, 1995a). These findings are consistent with other studies indicating that at relatively low levels of RDX in soil (< 0.3 ppm ) or in irrigation water (< 0.1 ppm), RDX does not bioaccumulate in crops (USAEC, 1996). Soybean crops were not sampled at IAAAP, but other studies indicate that soybean and corn bioaccumulate RDX in similar concentrations (i.e., little or no bioaccumulation at lower soil and water concentrations; bioconcentration factors increase at higher levels of RDX in soil and water) (Checkai and Simini, 1996). Because IAAAP crops are not grown in highly contaminated soil, are not irrigated with highly contaminated water, and the Army study indicates that no RDX is bioaccumulating in corn, ATSDR concludes that local crops are safe for human consumption.
Another community concern addresses the safety of human consumption of venison and beef from animals which feed on the installation. Specifically, community members expressed concern that deer and cattle caught on the installation might be unfit for human consumption because the animals may eat plants containing RDX and/or drink from contaminated surface water. Although no IAAAP studies specifically address this issue, ATSDR identified several deer tissue studies of explosives uptake conducted at other facilities. According to the literature, explosives (including RDX) do not bioaccumulate significantly at the concentrations typically seen in the environment (EPA, 1997; ATSDR, 1996; Whaley and Leach, 1994; Shugart et. al., 1990). At another facility, the Joliet Army Ammunition Plant, with similar contamination issues, a study found that on-site deer tissue did not contain any detectable explosives or explosive residues in either deer muscle or deer liver (Whaley and Leach, 1994). Although ATSDR identified no cattle studies, ATSDR expects that RDX levels in beef would be comparable to those found in venison because both cattle and deer are ruminants (belong to the mammalian suborder Ruminantia) that have similar metabolic processes (ATSDR, 1996). From these toxicologic and ecological studies, ATSDR concludes that deer and cattle residing on IAAAP property are unlikely to contain significant levels of RDX, if any.
ATSDR concludes that past, present, and future consumption of local crops, deer, and cattle
does not pose a public health hazard.
ATSDR identified community health concerns by talking with local citizens, meeting with
IAAAP employees, and reviewing IAAAP RAB discussions. ATSDR found that the
community's greatest health concerns involve issues pertaining to groundwater contamination
and radiological contamination.4 In the past, local citizens expressed concern about potentially
developing cancer and/or other health problems from exposure to IAAAP-contaminated
groundwater. Local newspapers printed articles about the reported health problems of a family
living south of IAAAP. No toxicological studies or health outcome data were ever gathered to
verify such public health effects. Based on the concentrations of environmental contaminants
in the vicinity of IAAAP and toxicological information, however, it does not appear that
installation-related contaminants can be causally related to public health effects. There is only
limited exposure, if any, to the environmental contaminants at IAAAP. Adverse public health
impacts are not likely from the exposures that would reasonably be expected to occur or would have reasonably been expected to have occurred in the past.
ATSDR recognizes that infants and children may be more sensitive to exposures than adults in communities with contamination in their water, soil, air, or food. This sensitivity is a result of a number of factors. Children are more likely to be exposed to soil or surface water contamination because they play outdoors and often bring food into contaminated areas. For example, children may come into contact with and ingest soil particles at higher rates than adults do; also, some children with a behavior trait known as "pica" are more likely than others to ingest soil and other nonfood items. Children are shorter than adults, which means they can breath dust, soil, and any vapors close to the ground. Also, they are smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Because children depend completely on adults for risk identification and management decisions, ATSDR is committed to evaluating their special interest at sites such as IAAAP, as part of the ATSDR Child Health Initiative. ATSDR has attempted to identify populations of children in the vicinity of IAAAP and any completed exposure pathways to these children.
In the IAAAP area, ATSDR identified several populations of children. Several active schools, day care facilities, and church facilities are all located off site. The closest active school is in Danville, Iowa, which is over 4 miles from IAAAP. Several inactive schools (e.g., the Buena Vista School and Brush College) are located on or near IAAAP, but all these educational facilities are located on uncontaminated soil.
None of the identified child populations have been exposed to contaminant levels associated with adverse health effects in children. There are no child exposures (past, present, or potential future) to on-site RDX-contaminated groundwater, soil, sediment, or surface water. On-site recreational facilities, including the scout camp on Mathes Lake, are not associated with any known contamination. There is no known contamination associated with off-site soil, sediment, or local biota. As outlined in Appendix B, past exposures to RDX in off-site private drinking water wells were at levels below those associated with health effects in children.5
Low-level RDX contamination (generally less than 10 ppb) has impacted off-site surface water south and southeast of IAAAP. The maximum detected concentration in off-site surface water is below drinking water levels associated with adverse health effects in children (Appendix B). No one, however, drinks this surface water. Child exposures are limited to dermal contact and/or incidental ingestion when swimming or playing in the creeks. Exposure is further limited by Iowa's climate; according to local community members, children only swim in the creeks during Iowa's summer months (ATSDR, 1998). Therefore, surface water exposure does not currently pose a public health hazard for children.
It is possible that in the past children were exposed to higher concentrations of RDX and other explosive contaminants (e.g.,TNT) in surface water. Surface waters were not sampled during the 1950s when off-site creeks ran pink. ATSDR does not believe that it posed any child health risks because it is highly improbable that children would have swam or played in contaminated pink waters when abundant uncontaminated surface waters (e.g., Long Creek) were located in the immediate vicinity. Past child exposures would have been further limited by seasonal swimming due to Iowa's climate. It should also be noted that ATSDR was unable to identify any specific health complaints or symptoms (child or adult) that community members associated with past IAAAP activities. Because, however, this past exposure is not fully characterized and remains unquantifiable, ATSDR concludes that past surface water exposure poses an indeterminate health hazard for children. For all other exposure pathways, on- and off-site groundwater (past, present, and future), surface water (present and future), and soil (past, present, and future), ATSDR concludes that these exposures pose no or no apparent public health hazard for children.
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