PUBLIC HEALTH ASSESSMENT
ASARCO HAYDEN SMELTER SITE
(a/k/a ASARCO INCORPORATED HAYDEN PLANT)
HAYDEN, GILA COUNTY, ARIZONA
The Arizona Department of Health Services (ADHS) has prepared this public health assessment (PHA) under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). The objective of this PHA is to evaluate whether a public health hazard exists as a result of environmental exposures in Hayden and Winkelman, Arizona.
The towns of Hayden and Winkelman, Arizona are located near a smelter operated by ASARCO, Inc. Some of the residents of these towns have expressed concerns that metals from smelter emissions over the years have been causing health problems. The ADHS Office of Environmental Health (OEH) was made aware of these community health concerns through the United States Environmental Protection Agency (EPA) Region IX Environmental Justice Programs office.
This report uses environmental data collected from water, soil, and air in the Hayden and Winkelman area to estimate environmental exposures. The study also evaluates available health outcome data from previous epidemiological and biological-monitoring studies conducted in the area.
The report concludes that exposure to sulfur dioxide occasionally poses a short-term public health hazard to sensitive asthmatics. These episodes of higher levels of sulfur dioxide occur infrequently. They do not appear to pose a health hazard to persons without sensitive airways or asthma. Other environmental exposures do not appear to pose a public health hazard.
1.1 SITE DESCRIPTION AND HISTORY
Hayden, Arizona, is located approximately 90 miles southeast of Phoenix on State Highway 177, along the Gila River, below the confluence of the Gila and San Pedro Rivers. The town was founded in 1912 to provide housing for the workers at the Ray open pit mine complex and the copper smelter complex, originally built by the Kennecott Copper Company. The town has a current population of approximately 900, and shares many services, including the local school district, with the town of Winkelman, population 600, located one mile to the south. The towns also share a common history regarding the emissions from the smelter operations.
There have been several smelters on the site of the current Asarco smelter, with emissions being discharged into the air in Hayden and Winkelman since operations began in 1909. Historic emissions contained large quantities of lead, arsenic, sulfur dioxide (SO2), particulate matter, and other materials. These contaminants drifted over the entire region in the air and many of the materials contained in these emissions fell out of the atmosphere and settled on the ground.
The first emission controls placed upon the smelters were installed in 1920. These electrostatic precipitators were designed to remove particulate matter from the stack emissions. The smelters within the complex operated with these minimal emission controls prior to 1969, when requirements under the forthcoming Clean Air Act amendments of 1970 required that controls be installed to limit SO2 emissions. Acid plants were added in 1969 and 1971 to reduce SO2 and particulate emissions. Additional controls were added to the current smelter in 1984, further reducing the SO2 emissions. The current smelter stack height was designed to elevate the emissions above the valley air shed and better facilitate dispersion.
The residential areas of Hayden are located on two ridges that run parallel to each other, in an east/west direction, east of Highway 177. Houses line the main street on the north ridge. Houses on the south ridge are scattered among several streets intersecting Velasco Avenue.
The main street in Hayden is Hayden Avenue, which runs east-west from the smelter property line on the eastern edge of town, to Fourth Street, a distance of approximately 3/8 mile. It is along this street that the primary business district is located.
The ASARCO smelter is a large complex of approximately 200 acres at the eastern end of the town. Two large emission stacks dominate the horizon. One is about 1,000 feet tall and the other is 250 feet tall. There are also several smaller stacks visible at buildings throughout the complex. A large slag pile, a solid glass-like waste material, is on the eastern end of the facility, adjacent to the town.
Winkelman is one mile south of Hayden. The schools for children in the area are in Winkelman. There are several streets of houses as well as a few businesses along Highway 177.
ADHS staff visited the area several times, beginning January 7, 1999. Specific dates are:
| January 7, 1999 | ADHS obtained soil samples from the area. |
| April 5, 1999 | ADHS met with local community leaders to determine the best course of action to meet community needs. |
| April 19, 1999 | ADHS presented the biomonitoring project to Hayden Town Council. |
| May 10, 1999 | ADHS presented the biomonitoring project to Winkelman Town Council. |
| May 17, 1999 | ADHS answered questions from the Hayden Town Council. |
| June - Oct. 1999 | Public health surveys were conducted in Hayden and Winkelman. |
| March 16, 2000 | ADHS presented findings of the public health survey and biomonitoring project to the community during 2 open house meetings. |
| May 20, 2002 | ADHS presented the Public Health Assessment--Draft for Public Comment to the Hayden Town Council. |
| June 10, 2002 | ADHS presented the Public Health Assessment--Draft for Public Comment to the Winkelman Town Council. |
| June 18, 2002 | ADHS presented the Public Health Assessment--Draft for Public Comment during a public meeting at the Senior Center in Hayden. |
These site visits consisted of meeting with community members during City Council meetings or informal gatherings to provide the community with updated information on the progress of the research being conducted in the area. A number of health education and informational sheets were distributed during the site visits
Site visits also included observations of the current site conditions and operations.
1.3 DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE
Demographics
The towns of Hayden and Winkelman consist of homes primarily built during the 1940s and 1950s to accommodate the large worker population needed in the area to operate the Ray open pit copper mine and the copper smelter in Hayden.
The area is typical of rural Arizona, with churches, small stores, and other facilities located along the main street of the town. Hayden is east of Highway 177, on a hillside, below the actual smelter works. The entire town covers an area of less than one square mile, and contains approximately 365 homes. The schools for the area are in Winkelman, and consist of an elementary and high school. Winkelman has approximately 100 homes in the developed area of the town. The approximate population of Hayden and Winkelman is 1,500 people.
Land Use
The actual smelter site consists of a large complex of buildings, many of which are former smaller smelters, replaced by the current large smelter now in operation. The entire complex covers approximately 200 acres. The smelter facility is on the east side of Hayden. In addition a large pile of waste product called mine tailings is directly east of Hayden on the west side of Highway 177. The mine tailings pile rises approximately 100 feet above the lowest area and extends for approximately ½ mile along the west side of Highway 177. The town of Hayden is divided by a private road used by the trucks hauling ore from the railroad unloading site to the smelter. This division takes place in a naturally occurring low area between the ridges upon which Hayden is built. The downtown area lies within the south portion of town and consists of storefronts along Hayden Avenue. The largest concentration of homes is along San Pedro Avenue on the northern ridge of the town.
There are 28 active production water wells in the area. These wells serve the towns of Hayden and Winkelman and consist of several separate water systems and public water suppliers.
There have been several studies conducted over the past 10 years examining possible adverse health effects from environmental exposures, including lung cancer, as a result of living near non-ferrous metal smelters in Arizona.
A study completed in December 1995 examined lung cancer mortality rates in six Arizona copper smelter towns (Globe, Kearny, Superior, Miami, Hayden, and Winkelman). This study was prompted by a 1990 ADHS study, which found lung cancer mortality rates 50% higher for the Gila Basin residents compared to the Phoenix/Tucson metropolitan areas [1].
The 1995 study provided little evidence of a positive association between lung cancer mortality and any of the indices of residential smelter emissions considered. Some variation in the estimated risk of lung cancer was found for males and for females by town of residence at the time of death, though these associations were not statistically significant. Also, there were some slightly increased risks of lung cancer for males and females for the calculated measures of residential smelter emissions. However, the odds ratios did not clearly increase with level of exposure and were not statistically significant. A parallel study of four other Arizona copper smelter towns also found little evidence of a positive association between lung cancer risk and any indices of residential exposure to smelter emissions considered [2].
The validity of these findings for residential smelter emissions is supported by the major strengths of this study which include the high response rates and the completeness of the individual-level residential, occupational, and smoking data obtained via proxy respondents. The 1995 study found that among male residents, there was some evidence of an association between lung cancer risk and copper smelter-related occupational exposure that differed by town of residence at the time of death [1]. The study grouped all of the smelter towns together, and no individual conclusions regarding Hayden and Winkelman were drawn.
In 1999, the Arizona Prevention Center, an affiliate of the University of Arizona (UA) dealing with environmental and occupational issues, and ADHS conducted a health survey of the residents of Hayden and Winkleman to determine childhood blood lead levels and child and adult urinary arsenic levels. This survey was conducted over a two-month period during June and July 1999, by graduate students and faculty of the UA Medical School. Funding for this study was provided through an agreement between ASARCO and the Arizona Department of Health Services.
Random sampling of residents was conducted, with the emphasis placed on screening children less than 3 years of age for blood lead. Adults and children were screened for urinary arsenic. The urinary arsenic analysis measured both organic and inorganic arsenic compounds. Inorganic arsenic compounds were the focus of this screening since organic arsenic is significantly less toxic than inorganic arsenic.
All 14 children tested in Hayden and Winkelman had blood lead concentrations below the CDC intervention level of 10 micrograms per deciliter (µg/dL), with an average blood lead concentration of 3.6 µg/dL. No evidence of excessive environmental lead exposure was found in the study participants.
The average urinary total arsenic concentration of individuals tested in Hayden and Winkelman was 13.7 micrograms per liter (µg/L), which is substantially less than the study reference level of 30 µg/L. Urinary arsenic concentrations were not adjusted for creatinine. The reference level of 30 µg/L was established as the marker level by the UA investigators for persons who consume water with an arsenic concentration of 50 µg/L.
Five (2%) of 224 individuals tested in Hayden and Winkelman had inorganic urinary arsenic concentrations exceeding 30 µg/L. The maximum concentration measured was 47 µg/L. The possible adverse effects of such levels are not known. Recent renovation activities in these three households, including removal of old paints, may have resulted in exposure to arsenic containing house dust. Section 5.2 provides more details about the study results and design.
ADHS has spoken with members of the community regarding their concerns about exposure to the emissions from the smelter. Some members were concerned the emissions were impacting their health, while others were not. Most persons accepted the fact that the smelter produced air pollution, and that by working and living in the area they would be exposed to whatever was being emitted from the smelter. While most of the residents did not say they did not like the air pollution the smelter was producing, they spoke in veiled references to it. Comments such as "not being able to have a barbeque at night, because going outside makes you sick" were common.
Many people expressed their health concerns to the UA survey teams. Persons expressing concern cited emissions from the smelter as a cause of illness in the community.
3.0 ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in this section list the contaminants of concern. These contaminants are evaluated in the subsequent sections of the public health assessment to determine whether exposure to them has public health significance. ADHS selected the contaminants based upon the following factors:
Contaminants were selected as chemicals of concern based upon a comparison of site concentrations to various environmental standards including ATSDR Comparison Values; Residential Arizona Soil Remediation Levels (SRLs); USEPA Maximum Contaminant Levels (MCLs); and Arizona Air Quality Guidelines (AQGs). AQGs are guidelines calculated by ADHS for airborne chemicals for use by permitting agencies to establish emissions limits from industrial sources.
Identifying a contaminant as a chemical of concern does not mean that the contaminant will cause adverse health effects from exposures. Instead, the list indicates which contaminants will be evaluated further in the public health assessment.
A toxicological evaluation of the potential health impact was conducted for those contaminants selected as chemicals of concern. Dose calculations were compared to Minimum Risk Levels (MRLs) established by ATSDR for exposure to specific contaminants.
3.1 ENVIRONMENTAL CONTAMINATION
Water delivered to the residents of both Hayden and Winkelman comes from a number of wells in the area and under the control of several different water systems.Testing of the water from each of these systems for contaminants is conducted under the Federal Safe Drinking Water Act. The two water systems that serve Hayden and Winkelman are currently in compliance with these requirements, according to the Arizona Department of Environmental Quality.
The latest information on testing for contaminants under the Safe Drinking Water Act standards shows there are measurable amounts of several contaminants in each of the water systems that serve Hayden and Winkelman. These contaminants are arsenic, antimony, beryllium, cadmium, chromium, fluoride, mercury, selenium, and thallium. In addition, the water supply was also tested for asbestos fibers. The amounts were all below the EPA Maximum Contaminant Level (MCL) for each metal, and asbestos was below the maximum fiber count. Concentrations of the contaminants were also compared to ATSDR Comparison Values (CVs) to determine if they should be further evaluated.
ATSDR has developed CVs for common chemicals to determine if contaminants are present in the environment at levels that warrant further human exposure evaluation. The CV is a concentration of a chemical in water below which adverse health effects are unlikely to occur regardless of how people may come into contact with the contaminant. CVs are not used to determine the specific adverse health effects from exposure, rather they are used to determine if there is the need for a more thorough, contaminant-specific investigation.
Arsenic concentrations in the various water systems serving the area were below the CV for adults, but above the CV for children, and arsenic has been selected as a contaminant of concern in drinking water. None of the other contaminants were selected as contaminants of concern since average concentrations were below CVs. See Table 1 for results of water quality testing of local wells.
Table 1. Water Quality Information from Local Water Systems
| Chemical | Number of samples | Mean of samples in µg/L | EPA MCL* | ATSDR Comparison values (CVs) µg/L | Mean Above MCL or CV | Selected as COC** |
| Arsenic | 13 | 6.5 | 50 | 3 | Yes | Yes |
| Antimony | 5 | 3.7 | 6 | 4 | No | No |
| Asbestos | 8 | 0.2 | 7 MFL# | NA | No | No |
| Beryllium | 5 | 2.6 | 4 | 10 | No | No |
| Cadmium | 11 | 2.5 | 5 | 5 | No | No |
| Chromium | 14 | 15 | 100 | 100 | No | No |
| Fluoride | 23 | 1,592 | 4,000 | NA | No | No |
| Mercury | 16 | 1.2 | 2 | NA | No | No |
| Selenium | 13 | 6 | 50 | 50 | No | No |
| Thallium | 5 | 1.5 | 2 | NA | No | No |
All units in micrograms per liter (µg/L)
Minimum concentrations for all metals were at the non-detect level for the analysis
method
* Maximum Contaminant Level established for drinking water provided by a regulated
water supplier
** Contaminant of Concern
# MFL micro fibers per liter
The Arizona Department of Environmental Quality (ADEQ) maintains a dicot particulate sampler at the Hayden Jail. This sampler collects particulate samples in the range of less than 2.5--10 microns. The samples are analyzed for metals including lead, arsenic, cadmium, and zinc. The samples collected over the past several years have shown that arsenic and SO2 present in concentrations that exceed the ATSDR CVs in air.
Arsenic
The ATSDR CV for arsenic of 0.0002 micrograms per cubic meter (µg/m3)
for an annual average was used to select arsenic as a contaminant of concern
in air. Annual averages of arsenic in outdoor air have consistently been in
excess of the CV, and arsenic has been selected as a contaminant of concern
in air.
Table 2. Arsenic air quality data from Hayden, Arizona monitor
| Year | Arsenic Annual Average in µg/m3* | ATSDR Comparison Value(CV) µg/ m3 | Exceeds CV? |
| 1991 | 0.200 | 0.0002 | Yes |
| 1992 | 0.168 | 0.0002 | Yes |
| 1993 | 0.102 | 0.0002 | Yes |
| 1994 | 0.095 | 0.0002 | Yes |
| 1995 | 0.092 | 0.0002 | Yes |
| 1996 | 0.111 | 0.0002 | Yes |
| 1997 | 0.184 | 0.0002 | Yes |
| 1998 | 0.080 | 0.0002 | Yes |
Lead
No CV exists for lead in air, so the EPA air quality standard for lead,
set at 1.5 µg/m3 average per calendar quarter was used as a reference
value for lead. Lead levels in outdoor air have consistently been below this
reference value, and lead has not been selected as a contaminant of concern
in outdoor air.
Table 3. Lead air quality data from Hayden, Arizona monitor for quarterly average in micrograms per cubic meter (µg/ m3), 1993-1997
| Year | Lead 1st Quarter µg/m3 | Lead 2nd Quarter µg/m3 | Lead 3rd Quarter µg/m3 | Lead 4th Quarter µg/m3 | Annual Average | National Ambient Air Quality Standard | Exceeds NAAQs? |
| 1993 | 0.07 | 0.07 | 0.1 | 0.13 | 0.09 | 1.5 | No |
| 1994 | 0.46 | 0.41 | 0.26 | 0.23 | 0.34 | 1.5 | No |
| 1995 | 0.24 | 0.18 | 0.42 | 0.58 | 0.35 | 1.5 | No |
| 1996 | 0.42 | 0.32 | 0.26 | 0.21 | 0.3 | 1.5 | No |
| 1997 | 0.27 | 0.42 | 0.29 | 0.51 | 0.37 | 1.5 | No |
Sulfur dioxide (SO2)
ADEQ also analyzes the samples for sulfur dioxide particulates, since this
area is a non-attainment area for SO2 air quality standards.
A review of the sample results over the past five years indicates the area has
not exceeded the USEPA standard for sulfur dioxide. However, average annual
sulfur dioxide levels have consistently been in excess of the ATSDR CV; therefore,
sulfur dioxide is selected as a contaminant of concern in outdoor air.
Table 4. Sulfur Dioxide 3 hour maximum concentrations
| Year | 3 Hour Maximum µg/ m3 | ATSDR Acute Exposure Comparison Value µg/ m3 | Exceeds CV? |
| 1990 | 1,137 | 25 | Yes |
| 1991 | 511 | 25 | Yes |
| 1992 | 815 | 25 | Yes |
| 1993 | 372 | 25 | Yes |
| 1994 | 464 | 25 | Yes |
| 1995 | 435 | 25 | Yes |
| 1996 | 527 | 25 | Yes |
| 1997 | 697 | 25 | Yes |
| 1998 | 595 | 25 | Yes |
In January 1999, soil samples from a depth of 0-6" were taken by ADHS from various areas of the two communities, and a control sample was also taken several miles north of Hayden, for comparison purposes. Samples were analyzed in the Arizona state laboratory using a screening test based upon EPA test methods for heavy metals. Table 5 summarizes the soil sampling results.
Table 5. Metal Concentrations in soils collected from a depth of 0-6"
Hayden, Arizona January 1999
| Metal | # of samples | Mean Soil Concentration mg/kg | ATSDR Comparison Value(CV) mg/kg | Residential Arizona Soil Remediation Level(SRL)* mg/kg | Exceeds CV or SRL? |
| Arsenic | 10 | 5 | 20 | 10 | No |
| Barium | 10 | 29 | NA | 5,300 | No |
| Cadmium | 10 | 59 | NA | 38 | No |
| Chromium | 10 | 1.7 | NA | 2,100 | No |
| Cobalt | 10 | 8 | NA | 4,600 | No |
| Copper | 10 | 6 | NA | 2,800 | No |
| Lead | 10 | 643 | NA | 400 | Yes |
| Manganese | 10 | 237 | NA | 3,200 | No |
| Nickel | 10 | 9.6 | NA | 1,500 | No |
| Selenium | 10 | 20 | 300 | 3,380 | No |
| Silver | 10 | 1 | NA | 380 | No |
| Zinc | 10 | 66 | 20,000 | 23,000 | No |
* SRL: Soil Remediation Level is a clean-up standard adopted in administrative rule by the ADEQ. SRLs are protective of human health (AAC R18-7-201 through R18-7-208).
None of the metals for which analyses were conducted exceeded CVs or Residential SRLs. However, both lead and arsenic were selected as COCs in soils because of community concerns and because lead slightly exceeded the SRL.
3.2 PHYSICAL AND OTHER HAZARDS
Because the entire area surrounding the smelter, including Hayden and Winkelman proper, are considered on-site, there were many observed physical hazards.These included exposed metal piping, abandoned vehicles, and steep terrain.There are many areas of discarded machinery as well as the large slag pile at the north side of Hayden that could be considered attractive for playing children.
ADHS evaluated the environmental and human components that lead to human exposure to determine whether people are exposed to contaminants from the site. An exposure pathway consists of five elements: a source of contamination; transport through an environmental medium; a point of exposure; a route of exposure; and a receptor population.
ADHS categorizes an exposure pathway as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. In completed exposure pathways, all five elements exist, and exposure to a contaminant has occurred in the past, is occurring, or will occur in the future. In potential pathways, at least one of the five elements is missing but could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring or could occur in the future.
An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. Table 6 identifies the completed exposure pathways. Table 7 estimates the number of exposed persons for completed exposure pathways. The discussion that follows these two tables incorporates only those pathways that are important and relevant to the site. The tables also illustrate some of those exposure pathways that have been eliminated.
4.1 COMPLETED EXPOSURE PATHWAYS
Currently, complete exposure pathways exist in the area on and around the site. Tables 6 and 7 present this information in a summarized format.
Table 6. Completed Exposure Pathways
| Pathway | Exposure Pathway Elements | Time | ||||
| Source | Medium | Point of Exposure | Route of Exposure | Exposed Population | ||
| Surface Soil | ASARCO Smelter | Surface Soil | Surface soil throughout entire area | Ingestion Inhalation Dermal |
Residents of entire area | Past Present Future |
| Water | Natural and possibly ASARCO | Groundwater (Public wells) |
Residences, tap water | Ingestion | All residents of area | Past Present Future |
| Air | ASARCO Smelter | Air | Entire Area | Inhalation | Residents in entire area | Past Present Future |
Table 7. Estimated population for completed exposure
| Estimated Populations that are affected by a Completed Exposure Pathway* | ||
| Location | Estimated Persons | Pathway |
| Hayden/Winkelman | 1,500 | Surface Soil Public Water Supply Ambient Air |
* Refer to Table 6 for completed exposure pathways.
One source of the exposures to contaminants in air is emissions from the smelter; however, other sources, such as vehicle exhaust, can also contribute to ambient air pollution. Transport occurs by physical movement of the emissions from the smelter into the air and from fugitive dust emissions from soils in the area. This would include the large deposit of waste tailings west of the towns. All persons who are in the towns are exposed through inhalation of the contaminants. In addition to the emissions from the smelter, soil particles containing the contaminants that are blown into populated area are inhaled, contributing to the total amount of contamination that is taken into the exposed individuals.
Water delivered to the residents of Hayden and Winkelman contains measurable concentrations of arsenic. Regular testing by the local water providers for arsenic has resulted in arsenic detection. Drinking water is obtained from several wells located throughout the area. Because of the ore bearing nature of the soils, arsenic is commonly present in these bodies, and as a result is present in many groundwater aquifers. These levels range from 2.5 micrograms per liter (µg/L) to 34.5µg/L, as reported by the local water providers in the latest sampling data available. The mean level of arsenic in the drinking water is 6.5 µg/L. The mean concentrations are below the 50 µg/L maximum contaminant level (MCL) set by the EPA for drinking water. The current MCL for arsenic will be lowered to 10 µg/L beginning in 2006. Persons are exposed through ingestion and dermal contact with water containing arsenic.
Because contaminated dust particles deposit on soil and other surfaces, people are expected to come into direct contact with the contaminants when they play outside or garden. Incidental ingestion of soil containing the contaminants of concern results primarily from hand to mouth activity. Children are most likely to ingest more soil because of the way they play.
4.2 POTENTIAL EXPOSURE PATHWAYS
Should high winds occur at the time air emissions are highest, people living and working beyond the area defined as the currently exposed population could also be exposed. Additionally, if groundwater contamination extends to drinking water supplies beyond the defined area, then additional people could be exposed to contaminants in their drinking water. These scenarios are not likely to occur often, if at all; therefore, exposures outside the defined areas around the site are unlikely.
5.0 PUBLIC HEALTH IMPLICATIONS
5.1 EXPOSURE AND TOXICOLOGICAL EVALUATION
ADHS based this toxicological evaluation on previously described exposure scenarios for the residents of the area and health effect studies. These evaluations consist of the analysis of exposures of persons exposed to contaminants in the air, in soil, and in the water. The contaminants of concern for this site are lead, arsenic, and sulfur dioxide.
Quantifying Exposures
ADHS has made several assumptions regarding dose intake and assumptions
used to quantify exposures. Many variables were based on observations made at
the site and on conversations with members of the community and with staff from
ADEQ.
Persons in these communities are exposed to the contaminants present in emissions from the site, in contaminated dust and soil, and in water. Contaminated dust and emissions can settle on objects, such as toys left outside. Children are especially prone to putting their hands and toys in their mouths without washing them first. Any contamination or naturally occurring metals present on surfaces that people have contacted with their hands can then be ingested.
When evaluating exposure, ADHS assumes that these persons will breath contaminated fugitive dust and emissions from the site 24 hours per day for 30 years. Persons living in the area are assumed to have dermal contact with the soil for 30 years. In addition, adults residing in the area are assumed to drink water containing arsenic at the rate of two liters of water per day for 30 years. Higher soil ingestion rates and lower body weights were assumed when estimating children's exposure in order to more accurately evaluate health risks for children. The equations used to estimate exposure doses are presented in the Appendix.
Exposures to the contaminants of concern have been quantified using standard exposure assessment methods. Inhalation, ingestion, and dermal absorption are the routes of exposure for the completed exposure pathways. Although the dermal exposure pathway is evaluated, the actual dermal absorption of the contaminants of concern is not quantified. This is because little, if any, of the contaminants of concern go through the skin.
Exposures to arsenic present in drinking water were evaluated based on the assumption that groundwater is the source of all drinking water. Surface water runoff from waste piles into the Gila River is a possible source of some of the groundwater arsenic because the Gila River recharges groundwater in some areas. No data were available to conclusively link surface runoff with the groundwater arsenic levels.
Evaluating Exposure Levels
To evaluate health effects, ATSDR has developed a Minimal Risk Level (MRL)
for contaminants commonly found at hazardous waste sites. The MRL is an estimate
of daily human exposure to a contaminant below which non-cancer, adverse health
effects are unlikely to occur. MRLs are not used to predict specific adverse
health effects from exposure. MRLs are established as screening tools to use
to determine whether further evaluation of the contaminant is warranted. MRLs
are not used to establish a safe level of contaminants at a site. MRLs are developed
for each route of exposure, such as inhalation and ingestion, and for a length
of exposure, such as acute (less than 14 days), intermediate (14 to 365 days),
and chronic (greater than 365 days).
Chemical-specific information is contained in documents known as toxicological profiles, which are published by ATSDR. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status. In the following discussion, we used ATSDR Toxicological Profiles for arsenic, lead, and sulfur dioxide. In addition to the Toxicological Profiles, ADHS also used information from a number of other sources. These sources are listed in the reference section of this PHA.
Additional evaluation is necessary to determine whether a health hazard exists when exposure estimates exceed MRLs. Literature sources are reviewed to determine what doses and exposure scenarios are associated with specific health effects. The No Observed Adverse Effect Level (NOAEL) is the exposure dose at which no adverse effect was observed on the animal or human population in the study. The Lowest Observed Adverse Effect Level (LOAEL) for a contaminant is the lowest exposure dose observed that resulted in a measurable adverse health effect in the animal or human population in the study. Whenever possible, NOAELs and LOAELs obtained from human studies are reviewed when evaluating possible health effects as a result of exposure to the contaminant. However, if no human studies exist, studies on laboratory animals are reviewed, and the health assessor might include safety factors to address human differences when evaluating whether health effects might be possible.
In addition to NOAELs and LOAELs used to evaluate non-cancer health effects, Cancer Exposure Levels (CELs) have been established for chemicals known to cause cancer in humans. The CEL is the lowest exposure level associated with the onset of carcinogenesis in experimental or epidemiologic studies. EPA assesses cancer effects by calculating the risk that any one individual might develop cancer as a result of exposure of one million people to the contaminant.
Arsenic
Exposure Dose Calculations
ADHS used standard default exposure calculations (EPA 1991 OSWER directive)
to determine the average daily absorbed dose of arsenic for both adults and
children. The adult calculations assume that adult residents inhale 20 cubic
meters of air per day for 30 years, drink two liters of water per day for 30
years, have an incidental soil ingestion rate of 100 milligrams per day, have
approximately 5,000 square centimeters of exposed skin, and have a body weight
of 70 kilogram. Calculations for children are based upon inhalation of 10 cubic
meters of air per day for six years, ingestion of one liter of water per day
for six years, incidental soil ingestion of 200 milligrams per day, 2,000 square
centimeters of exposed skin, and have a body weight of 15 kg.
Screening Levels for Arsenic
No Observed Adverse Effect Levels, or NOAELs, range from 0.0004 to 0.0009mg/kg/day.
Based upon these data, the acute oral MRL has been established at 0.005 mg/kg/day,
and the chronic oral MRL is 0.0003 mg/kg/day. These MRLs were derived by dividing
the NOAEL of 0.0008 mg/kg/day by an uncertainty factor of 3 for human variability.
The study used to derive the MRL was conducted by Tseng, et al., and the form
of arsenic was specified only as inorganic arsenic [3].
No MRL has been established for inhalation or dermal absorption of arsenic [3]. Chronic NOAELs for human inhalation of arsenic range from 0.000055 mg/m3 to 0.6 mg/m3 . The LOAELs for human inhalation range from 0.6 mg/m3 to 0.0007 mg/m3. No CEL has been established for inhalation of arsenic. CELs for ingestion of arsenic range from 0.0011 mg/kg/day for lung cancer to 3.67 mg/kg/day for bladder cancer. Exposure to arsenic is also associated with skin cancer. The lowest CEL for skin cancer is 0.014 mg/kg/day.
Arsenic in Drinking Water
Mean concentrations of arsenic in the primary water system that serves
the area are lower than the newly adopted EPA Maximum Contaminant Level of 10
µg/L. The current MCL for arsenic is 50 µg/L, but EPA has set a more protective
standard of 10 µg/L to go into effect in 2006.
The adult estimated exposure dose for arsenic of 0.0003 mg/kg day is equal to the MRL, suggesting that arsenic exposure from drinking water does not pose a non-cancer health hazard. The childhood estimated exposure dose for arsenic of 0.00065 mg/kg/day is approximately twice the MRL and is in the middle of the NOAELrange of 0.0004 to 0.0009mg/kg/day. A child's estimated dose of 0.00065 mg/kg/day is approximately 10 times lower than the LOAEL of 0.005 mg/kg/day, suggesting that exposure to arsenic in drinking water does not pose a health hazard.
The adult estimated dose does not exceed a CEL; therefore, cancer is not likely to result from exposure to arsenic in the drinking water. If estimating cancer risk, the lifetime excess cancer risk estimate from exposure to arsenic in drinking water is approximately 2 in 10,000, which is a moderate increased cancer risk. Cancer risk estimates are conservative and likely overestimate the actual risk.
Arsenic in Soils
Mean concentrations of arsenic in soil samples collected in the area are
5 mg/kg, which is less that the CV for arsenic in soil of 20 mg/kg. The adult
estimated exposure dose for arsenic of 0.000009 mg/kg day and the estimated
child dose of 0.00009 mg/kg/day are lower than the MRL of 0.0003, suggesting
that arsenic exposure from soils does not pose a non-cancer health hazard. The
lifetime excess cancer risk estimate from exposure to soils is estimated to
be approximately 6 in 1 million. Exposure to that level does not exceed a CEL
and would not present an increased cancer risk.
Arsenic in Ambient Air
The average annual concentration of arsenic in ambient air in the area
between 1991 and 2000 was 0.129 µg/m3, which is equivalent to a daily
childhood dose of 0.00008 mg/kg/day and an adult dose of 0.000004 mg/kg/day.
No MRL has been established for inhalation of arsenic [3]. The chronic NOAELs for childhood exposure through inhalation range from 0.00003 mg/kg/day to 0.4 mg/kg/day. LOAELs for childhood inhalation exposure range from 0.0004 mg/kg/day to 0.4 mg/kg/day.
The estimated arsenic dose for adults is 10 times less than the lowest limit of the NOAEL range. The estimated exposure dose for children is at the lowest limit of the NOAEL range, and 5 times less than any LOAEL, suggesting that arsenic does not present a non-cancer health hazard for children or adults.
No CEL has been established for inhalation of arsenic. The lifetime excess cancer risk estimate from exposure to arsenic in air is estimated to be approximately 7 in 100,000. This is a slight increased cancer risk.
Arsenic Exposure from All Pathways
The total childhood estimated exposure dose from all pathways for arsenic
of 0.0008 mg/kg/day is within the NOAELrange of 0.0004 to 0.0009mg/kg/day. Estimated
adult exposure of 0.0001 mg/kg/day is less than the NOAEL range. A child's estimated
dose of 0.0007 mg/kg/day is 10 times lower than the LOAEL of 0.005 mg/kg/day,
suggesting that exposure to arsenic does not pose a non-cancer health hazard.
Long-term ingestion of arsenic is associated with development of cancer, primarily skin cancer. The lifetime excess cancer risk estimate from exposure to arsenic from all sources is estimated to be approximately 2 in 10,000. This is a moderate increased cancer risk. Arsenic in drinking water is responsible for the majority of the total exposure and cancer risk. See the Health Outcome Data section of this document for information on arsenic urine screening performed in the community.
Table 8. Comparison of Estimated Exposed Dose to Health Guidelines for Arsenic
| Pathway | Child Exposure Dose (mg/kg-day) |
Health Guideline* mg/kg-day |
||
| MRL | NOAEL | LOAEL | ||
| Water Ingestion
Soil Ingestion Inhalation |
0.00065
0.00009 0.00008 |
0.0003
0.003 N/A |
0.0004
0.0004 0.00003 |
0.005
0.005 0.0004 |
*Bold items indicate estimated dose exceeds guideline
Lead
Lead is a soft metal often found in combination with other valuable
metals in soils mined for their metal content. Because of the varied nature
of lead-containing compounds, ATSDR has not developed an MRL for lead; however,
ATSDR has developed a mathematical model designed to estimate the amount of
lead taken into the body based upon the actual concentrations of lead in soil
(See Appendix for model). EPA has found that lead in soil above 400 mg/kg may
pose a health hazard if absorbed by humans [5].
Children less than 6 years of age are most at risk of exposure to the lead from the smelter
emissions. This is because of increased sensitivity to lead, higher absorption and retention rates
of lead, and increased exposure due to hand to mouth activities. Some adverse health effects
have been documented in children at blood lead levels of 10 micrograms per deciliter (µg/dL)
of whole blood, but the Centers for Disease Control and Prevention (CDC) is considering
whether subtle effects might occur at lower levels. The most common health effects among
children with elevated blood lead levels are decreased performance on psychometric tests, fine
motor dysfunction, and altered behavioral patterns [5]. The most likely exposure pathway for
these children is ingestion of lead through hand to mouth activity. Dermal contact with lead
contaminated soils can result in increased ingestion of lead through hand to mouth behavior [5].
Inhalation of the soil particles also may contribute to the overall uptake of lead from this site.
People are exposed to the smelter emissions through inhalation of emissions and contaminated
dust particles. Once inhaled, the contaminated particles can then be ingested or enter directly
into the lung. Because of the size of contaminated particles, they are more likely to enter the
body through the digestive tract rather than through the lung.
ADHS used ATSDR's integrated exposure regression analysis method to estimate exposure doses. (See Appendices for the Lead Model).
Table 9. Estimated blood lead levels from exposure to environmental and dietary lead for Hayden and Winkelman
| Media | Concentration* | Relative Time Spent (fraction of a day) | Slope Factor** | Estimated Blood Lead Level micrograms per deciliter (µg/dL) | |
| Outdoor Air | 0.366 µg/m3# | 0.2 | 1.32 (low)1 | 0.0965 | |
| 2.52 (high)1 | 0.184 | ||||
| Indoor Air | 0.03 µg/m3 | 0.8 | 1.32 (low)2 | 0.1288 | |
| 2.52 (high)2 | 0.2459 | ||||
| Food | 5 µg/day | 1 | 0.24 3 | 1.2 | |
| Water | 4 µg/day | 1 | 0.16 4 | 0.64 | |
| Soil | 29 mg/kg ## | 0.2 | 0.00583 (low)5 | 0.0336 | |
| 0.00777 (high)5 | 0.0449 | ||||
| Dust | 70 mg/kg | 0.8 | 0.00628 (low)6 | 0.3517 | |
| 0.008 (high)6 | 0.448 | ||||
| Total | 2.45 | 2.76 | |||
# 6 year average ambient air concentrations as measured by
the ADEQ monitor in Hayden/Winkelman
## Average concentration of samples collected and analyzed by ADHS from Hayden/Winkelman
area
* Suggested default values references:
| Outdoor Air | 0.1-0.2 µg/m3 | Eldred and Cahill 1994 [7] |
| Indoor Air | 0.1-0.2 µg/m3 | EPA 1986 [8] |
| Food | 5 µg/day | Bolger et al 1991 [6] |
| Water | 4 µg/day | EPA 1991 [9] |
| Dust | 10-70 mg/kg | Shacklette and Boerngen 1972 [10] |
** Slope values references
| 1,2Outdoor, Indoor air | 1.32 (low)-2.52 (high) | µg/dL per µg Pb/m3 | Angle et al 1984 [11] |
| 3Food | 0.24 | µg/dL per µg Pb/day | Ryu et al 1983[12] |
| 4Water | 0.16 | µg/dL per µg Pb/day | Laxen et al 1977 [13] |
| 5Soil | 0.00583 (low)-0.008 (high) | µg/dL per µg Pb/kg | Angle et al 1984 [11] |
| 6Dust | 0.00628 (low)-0.008 (high) | µg/dL per µg Pb/kg | Angle et al 1984 [11] |
This model suggests that childhood blood lead levels will not exceed 10 µg/dL. However, because most houses in the Hayden/Winkelman area were built before 1978, they may contain lead-based paint. If the paint is deteriorating, it would increase the amount of lead-containing dust in the home, and could increase lead exposure, especially in children. See the Health Outcome Data section for information on blood lead screening performed in the community.
Sulfur Dioxide
Sulfur Dioxide (SO2) is a colorless gas with a strong odor.
Ambient SO2 results largely from stationary sources that burn coal
and oil, refineries, pulp and paper mills, and from nonferrous metal smelters.
In the Hayden/Winkelman area SO2 is present as a result of stack
emissions from the smelter. The odor threshold for SO2 is approximately
7,500 µg/m3.
SO2 and other oxides of sulfur combine with oxygen to form sulfates, and with water vapor, form aerosols of sulfurous and sulfuric acid. These acid mists can irritate the respiratory systems of humans and animals and injure plants. Particulate sulfates also reduce visibility.
SO2 acts as a chemical irritant to the respiratory tract. Exposure to 13,000 µg/m3 for durations of 1 to 4 hours do not alter the pulmonary function of healthy individuals [14,15,16,17]. However, controlled clinical studies suggest that asthmatics are more sensitive to exposure to sulfur dioxide than persons without asthma.
The Lowest Observed Adverse Effect Level (LOAEL) for sensitive persons, such as asthmatics, with hypersensitive airways is between 250 to 1,300 µg/m3. Exercising asthmatics are sensitive to the pulmonary effects of sulfur dioxide at concentrations as low as 250 µg/m3. Reactions can include bronchoconstriction, increased airway resistance, decreased expiratory flow rates, and wheezing. The time required for SO2 to elicit bronchoconstriction in exercising asthmatics is short. Measurable changes may occur after only two minutes of exposure to 1,000 to 2,600 µg/m3. Following a single exposure during exercise, airway resistance in asthmatics appears to recover to normal levels within one to two hours [14, 15, 16, 17].
Developing a No Observed Adverse Effect Level (NOAEL) for sulfur dioxide in humans is very difficult because moderate exercise, weather conditions, infectious diseases, and other environmental triggers can also affect airway reactivity.
Monitoring data in Hayden suggest that there are short-term episodes when sulfur dioxide concentrations can affect the airways of asthmatics and other sensitive individuals (Table 10). Three-hour maximum concentrations from 1991 to 2001 exceeded the MRL and the LOAEL at least once per year in Hayden. Maximum 3-hour averages ranged from 372 µg/m3 to 1,137 µg/m3. These data suggest that a potential health hazard periodically exists for asthmatics and other sensitive individuals from exposure to sulfur dioxide. Most persons without sensitive airways are unlikely to be affected by these periodic episodes of increased sulfur dioxide levels because the lowest effect level for healthy non-asthmatic individuals is approximately 2,500 µg/m3.
Annual average sulfur dioxide levels are consistently approximately equal to the MRL of 25 µg/m3, with annual averages ranging from 16 to 30 µg/m3. Annual concentrations are consistently 10 times less than the short-term LOAEL of 250 µg/m3, however this LOAEL has been developed for acute exposures. No LOAEL has been established for long-term exposure to sulfur dioxide. Due to the lack of data regarding the long-term effects of exposure to low levels of sulfur dioxide, it is unknown whether a long-term health hazard exists in the area.
Table 10. Maximum 3-hour sulfur dioxide averages from ADEQ monitor in Hayden, Arizona, 1990-2001
| Year | 3 hour maximum µg/m3 |
LOAEL µg/m3 |
Exceeds LOAEL? |
| 1990 | 1,137 | 250 | Yes |
| 1991 | 511 | 250 | Yes |
| 1992 | 815 | 250 | Yes |
| 1993 | 372 | 250 | Yes |
| 1994 | 464 | 250 | Yes |
| 1995 | 435 | 250 | Yes |
| 1996 | 527 | 250 | Yes |
| 1997 | 697 | 250 | Yes |
| 1998 | 595 | 250 | Yes |
| 1999 | 475 | 250 | Yes |
| 2000 | 322 | 250 | Yes |
| 2001 | 785 | 250 | Yes |
Table 11. Average annual sulfur dioxide concentrations
in Hayden, Arizona, 1990-1999
| Year | Average annual SO2 concentration µg/m3 |
MRL | Exceeds MRL? |
| 1990 | 26 | 25 | Yes |
| 1991 | 27 | 25 | Yes |
| 1992 | 24 | 25 | No |
| 1993 | 16 | 25 | No |
| 1994 | 25 | 25 | Yes |
| 1995 | 30 | 25 | Yes |
| 1996 | 30 | 25 | Yes |
| 1997 | 26 | 25 | Yes |
| 1998 | 23 | 25 | No |
| 1999 | 26 | 25 | Yes |
1999 Blood Lead and Urinary Arsenic Study
A child blood lead and basic population urinary arsenic survey was
conducted in Hayden and Winkelman between June 25 and October 17, 1999. This
survey was conducted by the University of Arizona Center for Prevention under
a contract with ADHS. The specific goals were to establish a baseline for blood
lead levels in children less than 3 years of age and urinary arsenic levels
for the population as a whole in Hayden and Winkleman. This survey was conducted
over a 4-month period by graduate students and faculty of the University of
Arizona. [19]
Sampling of residents was conducted, with the emphasis placed on screening children less than 3 years of age for blood lead. Adults and children were screened for urinary arsenic. The urinary arsenic analysis measured both organic and inorganic arsenic compounds. Inorganic arsenic compounds were the focus of this screening because organic arsenic is less toxic than inorganic arsenic.
The University of Arizona developed a reference level for urinary arsenic of 30 µg/L. Residents who tested higher than 30 µg/L were contacted to determine if a source of the arsenic could be found. The reference level was based on the approximate median level found in several clinical studies.
The investigators elected to measure total and inorganic arsenic levels as opposed to arsenic levels controlled for creatinine. Biological monitoring for urinary arsenic levels in a clinical setting are often measured and reported as total arsenic in mg/L of urine, and clinical management and treatment decisions are developed following measurement of urinary arsenic levels without controlling for creatinine levels [20]. This method is acceptable for screening purposes; however, to better measure exposure to inorganic arsenic and determine when follow-up should occur, ATSDR controls for creatinin and uses 20 µg/L as the comparison value.
All children aged 6-36 months in Hayden and Winkelman were eligible for blood lead testing, and all individuals able to collect urine in a cup were eligible for urinary arsenic testing. The study was approved by the Human Subjects Committees at the University of Arizona and ADHS. Participation was voluntary, and written informed consent was obtained from participants or their guardians.
All housing units in Hayden and Winkelman were approached by door-to-door survey, with each unit revisited up to five times before a household was considered unreachable. For study participants, a brief questionnaire was used to collect demographic and potential metal exposure information. Blood for lead analysis was collected from children by finger stick. Urine samples for arsenic were obtained from participating individuals, generally as a first morning void. Between July 11 and October 17, 1999, seven children from 6-36 months of age were tested according to the protocol and study design. At the request of their parents, an additional seven children younger than six months or older than 3 years of age were tested. Blood lead concentrations ranged from below detectable limits to 9 µg/dL, with an average blood lead level of 3.6 µg/dL. Children with blood lead levels less than 10 µg/dL are not considered lead poisoned, based on current CDC guidelines. Although no information was available from children in families choosing not to participate in this voluntary study, no cases of lead poisoning in children from Hayden or Winkelman were found. Limitations of the investigation include the fact that blood lead testing only capture exposures that occurred recently. The results do not indicate what past exposure might have been or predict what future exposure may be.
Between June 25 and October 17, 1999, 224 people in Hayden and Winkelman were tested for urinary arsenic concentrations. Participation rates in eligible households were 52% in Hayden and 46% in Winkelman. For all urine samples, the average total arsenic concentration was 13.7 µg/L, ranging from below detectable limits to 114 µg/L. For the 18 samples with total arsenic concentrations exceeding 30 µg/L, speciated analysis was used to measure inorganic arsenic. Five samples from three households were found to contain more than 30 µg/L of inorganic arsenic, with concentrations ranging from 30 to 47 µg/L. No further follow-up was performed to resample those people and control for creatinine or to determine what exposure sources might be, such as seafood consumption. Investigators did learn that some home renovations, including painting, had occurred recently in all three households. Some paints contain arsenic or mercury as mildew retardants.
The average urinary total arsenic concentration in Hayden and Winkelman was 13.7 µg/L, which is substantially less than the study reference level of 30 µg/L. Five (2%) of 224 individuals tested in Hayden and Winkelman had inorganic urinary arsenic concentrations exceeding 30 µg/L. The maximum concentration measured was 47 µg/L.
Test results from the blood lead screening and the urinary arsenic screening were provided to participants. Participants were encouraged to share their results with their health care providers if they wanted medical advice.
5.3 COMMUNITY HEALTH CONCERNS EVALUATION
ADHS continues to answer questions regarding the health of residents in the area, although specific, personal health conditions are usually not discussed during these conversations. ADHS has attended several open house events in Hayden and Winkelman to answer questions from the public. ADHS has also issued advertisements in the local paper that detailed findings from the University of Arizona (UA) survey. In two meetings on March 15, 2000, the first was held after lunch and attended by senior citizens from the area, while no one from the community attended the later afternoon meeting to discuss the survey results. Numerous "quality of life" issues, such as inability to spend evenings outdoors because of unpleasant odors, were raised during the survey. ADHS did not receive any telephone calls from area residents regarding the survey results.
5.4 ATSDR'S CHILD HEALTH INITIATIVE
ADHS has included the following information in accordance with ATSDR's Child Health Initiative.
ATSDR recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also 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. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care.
For this PHA, specific dose calculations for arsenic and lead were used to estimate doses children would receive. Data obtained from the various monitors in the Hayden and Winkelman area were used to determine if the doses would exceed the MRLs or other guidelines. These guidelines were used to determine if adverse health effects could be present in the children of the area.
The MRLs and LOAELs used to evaluate the potential health effects from sulfur dioxide reflect conditions that might affect sensitive asthmatic children and adolescents. The conclusion that sulfur dioxide may periodically pose a health risk to sensitive individuals is specifically focused on children and adolescents with asthma.
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