PUBLIC HEALTH ASSESSMENT
CARDINAL LANDFILL
FARMINGTON, STRAFFORD COUNTY, NEW HAMPSHIRE
The Cardinal Landfill site is on Watson Corner Road in Farmington, New Hampshire. Starting in the late 1960s, Textron Automotive Company or its predecessors in interest (Textron) began disposing hazardous wastes in the Cardinal Landfill. Following an inspection of the Textron facility in 1981, the State prohibited this practice. For the next 10 years (until 1991), Textron continued to use the landfill for non-hazardous wastes. A series of environmental investigations have been conducted at the site starting in 1982. The most recent studies have focused on contamination in soil gas. In August 1999, the Agency for Toxic Substances and Disease Registry (ATSDR) was petitioned to conduct a public health assessment for the Cardinal Landfill site. The New Hampshire Department of Health and Human Services (DHHS) has a cooperative agreement with ATSDR to conduct public health assessments and consultations for sites in New Hampshire. DHHS completed the Cardinal Landfill Public Health Assessment under the cooperative agreement.
What kind of chemical contamination has been found on the site?
The primary forms of contamination at the site are waste solvents and other volatile organic compounds (VOCs) in groundwater. These contaminants were disposed in the northeastern portion of the landfill ("the primary landfill") between the late 1960s and 1981. The hazardous materials were covered by solid wastes, primarily plastic scraps, during the following decade.
Shallow groundwater flow carries the contaminants mostly towards the Cocheco River. The groundwater contamination in the shallow overburden has decreased considerably over time, yet concentrations of some VOCs still remain very high or unchanged on the site. The groundwater beneath a portion of the site is anaerobic (lacking oxygen). This condition has caused some metals, primarily arsenic, iron, and manganese, to dissolve from minerals in the soil and enter the groundwater. It is uncertain whether groundwater contamination from the landfill has crossed under the Cocheco River. However, it is clear that the highest concentrations of contaminants in groundwater are located beneath the site.
Many of the chemicals discarded in the landfill have a tendency to evaporate into the air. As a result, some of these chemicals have been found in the air spaces in the soil ("soil gas") above areas of groundwater contamination or waste. During winter, when frost or snow seals the top of the landfill, the contaminated soil gas could migrate laterally, potentially affecting areas beyond the extent of the landfill groundwater contamination or waste.
Low-level contamination has also been detected in ambient (outdoor) air; soils and surface waters on the site; and Cocheco River water, sediments, and fish.
How might I be exposed to chemical contamination on the site?
Currently, there are no exposures to contaminants from the site at levels of health concern. In the past, there were two main pathways by which people could have been exposed to contaminants.
(1) Private Drinking Water Wells
In the past, residents of five homes with contaminated water supplies were exposed by drinking and bathing with contaminated groundwater, and inhaling VOCs that had evaporated into the indoor air. The homes affected by this contamination were along Watson Corner Road between the Peaceful Pines Mobile Home Park and Route 153 (Lots 7, 9, 11, 17, and 18 on Tax Map R-19, see Figure 2). All of these wells have been abandoned. Currently, there are no significant exposures to contaminants in drinking water. All of the residents near the landfill either receive water from the town supply or are served by a well that has not shown contamination above health comparison values.
(2) Soil Gas and Indoor Air
The chemicals found in the groundwater onsite can evaporate into the air spaces between soil grains ("soil gas") and gradually work their way to the surface. If there is a home in an area of soil gas contamination, the compounds may be pulled into the indoor air of the home. Residents would then be exposed by inhaling chemicals in the indoor air.
Soil gas tests and modeled comparison values indicate that the only area where there is currently the potential for this type of exposure is the buffer zone between the Peaceful Pines Mobile Home Park and the landfill (see Figure 2). The indoor air of the three homes in this area was tested in 1999 and 2000. All three homes have been either moved or abandoned, but exposures along this pathway at these and other nearby homes were possible in the past.
What health effects might result from exposure to chemical contamination at the site?
(1) Private Drinking Water Well Pathway
Currently, all of the homes near the landfill either receive water from the town supply or are served by a well where any contamination is below a level of health concern. The well that served the Peaceful Pines Mobile Home Park until 1995 was not affected by contamination at the site. The park currently receives water from the Town of Farmington municipal supply.
In the past, there were exposures to several VOCs in five of the private wells near the site. The most serious exposures were for the residents of Lot 7 where exposure to vinyl chloride could potentially cause non-cancerous effects on the liver and a low to moderate theoretical risk of cancer, particularly angiosarcoma of the liver. For the other four wells, the known exposures were unlikely to result in non-cancer health effects for adult residents. However, young children or developing fetuses could have been affected by the exposures. Also, there would be a low theoretical risk of cancer from long-term (i.e., 10-year) exposures to tetrachloroethene, trichloroethene, and 1,2-dichloroethene in the wells serving Lots 9, 11, and 18. It is not known whether any residents of these houses lived there long enough or if the contamination began early enough for such long-term exposures to occur.
(2) Soil Gas to Indoor Air Pathway
Currently, there are no exposures to site contaminants in the indoor air.The three homes in the Peaceful Pines Mobile Home Park where there recently was the potential for this type of contamination were moved or abandoned in 1999. In the recent past (1999), exposures to the contaminants measured in the indoor air of these homes were unlikely to result in adverse health effects for the residents, except for perhaps reversible irritation of the upper respiratory tract and eyes caused by formaldehyde. Formaldehyde is not exclusively a "site contaminant" because it is an expected constituent of indoor air of homes with pressed wood products (e.g., manufactured homes) [68]. However, in the previous decade (particularly 1989-1997), groundwater contamination near these homes was more severe, which could have resulted in higher concentrations of contaminants in the indoor air. Therefore, indoor air exposures before 1999 may well have been higher than those observed in 1999-2000, but are uncertain.
(3) Other Pathways
Exposures to contaminants in ambient (outdoor) air, on-site surface water and sediments, Cocheco River surface water and sediments, and Cocheco River fish are not expected to result in adverse health effects.
All the exposure pathways considered in the public health assessment and the ATSDR Health Hazard Category that has been assigned to each are summarized in Table 18.
Could exposures to chemical contamination at the site cause an increased rate of cancer in the community?
Due to the possible carcinogenicity of the site contaminants and because of concerns expressed by local residents, DHHS reviewed and summarized cancer incidence data for Farmington between 1987 and 1997. The rates of 21 out of 23 cancer types in Farmington, New Hampshire, were within their expected ranges. The two types of cancer with significantly elevated rates were cervical cancer in females and lung cancer in females. The primary risk factors for these types of cancer are behavioral in nature. Therefore, the elevated rates are not likely to be related to exposures to site contaminants.
Can exposure to the site contaminants cause birth defects?
Currently, there are no exposures to contaminants from the site at levels of health concern. For each of the major exposure pathways at the site in the past, DHHS reviewed what is known about the susceptibility of young children and fetuses to the effects of the chemicals. This included a review of developmental effects as a result of exposures in utero (i.e., during pregnancy). For the drinking water pathway, some of the chemicals, such as trichloroethene, have been associated with developmental effects following in utero exposures [77]. Therefore, at the five residences along Watson Corner Road with contaminated drinking water wells (Lots 7, 9, 11, 17, and 18), past exposures to chemicals had the potential to affect the developing fetus of any pregnant women living there before the wells were abandoned (between 1985 and 2000 depending on the well). For the soil gas to indoor air pathway, the chemicals of concern have only been associated with effects on a fetus at high enough exposures to also have toxic effects on the mother. Indoor air concentrations of this magnitude were not observed. However, there is uncertainty regarding past indoor air exposures because groundwater contamination near the buffer zone was higher in the past.
What are the major recommendations of the public health assessment?
DHHS has made several recommendations for actions to protect the community around the site, the key elements of which are:
Will an epidemiological study be done?
DHHS and ATSDR do not plan to conduct a full-scale epidemiological study of the community around the Cardinal Landfill. To determine the need for an epidemiological study, sufficient exposure and toxicological information must suggest that: (1) a relationship between the environmental hazards at a site and adverse health outcomes is biologically plausible, and (2) the exposure affects a large enough population for effects to be observed statistically. While there were significant exposures to VOCs in drinking water for five homes along Watson Corner Road, the number of people exposed by this pathway would not be enough to detect low to moderate theoretical cancer risks. The same could be said for exposures to contaminants in the three mobile homes that were evaluated as part of the soil gas to indoor air pathway. The remaining completed exposure pathways at the site were not expected to result in adverse health effects based on the levels of contamination. Therefore, an epidemiological study of the community around this site would not be able to provide any more information about health impacts to the community.
Where can I get more information?
The text and appendices of the public health assessment for this site contain more information about the health issues discussed in this summary. To ask questions about this public health assessment or to obtain extra copies of this document, please contact Phil Trowbridge in the DHHS Bureau of Health Risk Assessment at (603) 271-4664 or (800) 852-3345 ext. 4664 (toll-free in N.H.). You can also send an email to the Bureau at healthrisk@dhhs.state.nh.us or visit its website at www.dhhs.state.nh.us/bhra where the report is available online. Additional copies of this public health assessment will be available at the Reference Desk at the Goodwin Library, 9 South Main Street, Farmington, New Hampshire (Phone: 603-755-2944). If you would like more information on the site cleanup efforts, please contact Jim Hewitt of the Department of Environmental Services at (603) 271-3503.
In August 1999, the Agency for Toxic Substances and Disease Registry (ATSDR) was petitioned to conduct a public health assessment for the Cardinal Landfill site in Farmington, New Hampshire. As mandated by Congress, ATSDR performs public health assessments at hazardous waste sites on the National Priorities List, or when petitioned by a citizen to evaluate a chemical release to the environment (see 55 FR 5136, 2/13/90). The New Hampshire Department of Health and Human Services (DHHS) has a cooperative agreement with ATSDR to conduct public health assessments and consultations for sites in New Hampshire. DHHS completed this public health assessment under the cooperative agreement.
A public health assessment is a triage tool to determine if and what kind of activities are needed to protect the public health of a community near a hazardous waste site, and to determine the need for follow-up health activities (e.g., health studies). To achieve this goal, this assessment contains three types of evaluations: (1) the identification of pathways of exposure to site contaminants and an evaluation of their public health implications; (2) a summary of relevant and available health outcome data (i.e., cancer registry data); and (3) evaluations of specific community health concerns about the site. This assessment did not evaluate current or future environmental risks that the Cardinal Landfill poses to public drinking water resources such as overburden or bedrock aquifers or surface water bodies, which fall under the purview of the New Hampshire Department of Environmental Services and other environmental regulatory agencies.
(A) Site Description and History
The Cardinal Landfill site is on Watson Corner Road in Farmington, New Hampshire. The site covers approximately 30 acres. It is bordered on the west and east by the Farmington Municipal Landfill and the Peaceful Pines Mobile Home Park, respectively, both of which cover similar acreage as the landfill itself. To the north of the landfill, there are private homes along Watson Corner Road. Undeveloped land abuts the landfill to the south.
The Town of Farmington and the Cardinal Landfill are situated in the Cocheco River valley. The Cocheco River flows from north to south and passes just to the west of the Farmington Landfill. The soils beneath the site are sand and gravel deposits approximately 30-80 feet thick, and are underlain by bedrock. Groundwater generally flows to the northwest and west towards the Cocheco River, passing beneath the Farmington Landfill and some of the properties along Watson Corner Road [25].
Between the late 1960s and 1981, Textron Automotive Company or its predecessors in interest (Textron), manufacturers of plastic shells and foam moldings for automotive interiors, disposed an average of 700-800 cubic yards of waste material per week in the Cardinal Landfill. Based on historical reports, the wastes consisted of: polyvinyl chloride (PVC) trimming scraps, rejected polyurethane foam products, acrylonitrile-butadiene-styrene inserts, paint wastes, drums of waste solvents, still bottoms from a methylene chloride recovery process, scrap metal, and general waste (e.g., cardboard, wood pallets, construction debris) [6,17]. Specific chemicals, primarily volatile organic compounds (VOCs), that have been reported to be in the waste are: degreasing or cleaning solvents (methylene chloride, tetrachloroethene, trichloroethene), paint solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, xylenes, toluene), and chemicals to make foam or plastics (liquid plastisol, polyol, and isocyanate) [17]. The hazardous wastes were placed in a 9 acre section in the northeast corner of the site called the "primary landfill". Other areas of the site either received non-hazardous wastes, such as wooden pallets, or were not used at all [17].
By 1978, three or four major fires had occurred at the site. The most recent fire in 1978 affected a 1-acre area of exposed waste materials in what is now the center of the primary landfill. The fire lasted 5 hours and several explosions of drums containing waste materials were reported. Following this fire, 12-20 feet of sand and solid waste was placed over the hazardous waste in the primary landfill to prevent future fires [8].
Following an inspection of the Textron facility in 1981, the State of New Hampshire's Office of Waste Management prohibited the continued disposal of hazardous wastes in the Cardinal Landfill. For the next 10 years, until 1991, Textron continued to use the Cardinal Landfill to dispose of non-hazardous wastes, primarily plastic trimmings and scraps. In 1991, Textron ceased to use the Cardinal Landfill for any waste disposal [17].
The State inspection in 1981 also precipitated a series of environmental investigations at the Cardinal Landfill. The first series of studies in 1982-1985 [1-5] discovered VOCs in the groundwater, surface water, and in private drinking water wells near the site. Drums of waste were discovered in the primary landfill, 5-17 feet below the surface [6]. In another section of the landfill closer to the center, evidence of past disposal of sewage sludge was discovered in one groundwater monitoring well [1]. The area affected by this sludge appeared to be small and the type of contamination was primarily bacterial.
Since 1985, Textron has completed a series of environmental investigations at the site. The major milestones in this process have been:
The most recent investigations in 1999 and 2000 have focused on contamination of the soil gas at and near the site [20,21,27,31]. Tests in March and May 1999 demonstrated that contaminated soil gas affected not only the site but also a small portion of the neighboring mobile home park. The New Hampshire Department of Environmental Services (DES) gave Textron three options for managing the potential health risks from contaminated soil gas: (1) institutional controls, (2) engineering controls, or (3) intensive long-term monitoring [22]. The responsible party and the owners of the Peaceful Pines Mobile Home Park subsequently decided to establish an easement to create a buffer zone between the landfill and the mobile home park, and to relocate the three homes within the proposed buffer. To date, two of the three homes in the buffer zone have been moved. The third home remains within the buffer zone but has been unoccupied since February 1999.
As of August 2000, DES and Textron were still negotiating over the final remedy for the cleanup of the site.
Throughout the environmental investigations on the site, DHHS has provided advice to DES on questions of human health risk, which is a primary role for DHHS under its mandate from RSA 125-H. DHHS staff have commented on reports, completed assessments of exposure, performed several site visits, and conducted outreach activities to the community near the site to learn about community health concerns. Some highlights of DHHS involvement to date are provided below.
Overall, aside from being timely responses to emerging health issues at the site, DHHS' actions at the site to date have helped to gather the information needed to conduct this public health assessment.
According to the U.S. Census, the population of Farmington in 1990 was 5,755. Children less than 14 years old and adults over 65 years old accounted for 35% of the population. The total number of people living within one-mile of the Cardinal Landfill Site was 696, which is 12% of the town population (Figure 1). The properties around the site are lightly-settled with the exception of the Peaceful Pines Mobile Home Park along the eastern side of the landfill. DHHS' survey of the Peaceful Pines Mobile Home Park revealed that most of the residents who returned the survey (73%) had lived in their current home for less than five years.
(D) Quality Assurance/Quality Control (QA/QC)
In preparing this document, DHHS relied on the information provided in the referenced documents. Only data collected using appropriate sampling and laboratory methods were considered in this analysis. Data with demonstrated QA/QC problems were excluded from summary tables or exposure calculations unless they provided unique and relevant information. Data for exposure point concentrations were mostly taken directly from laboratory data sheets, while secondary source documents were relied upon for background information on contamination at the site. For example, all soil gas and indoor air data and 80% of private drinking water tests data were taken directly from laboratory data sheets. Background information on groundwater contamination at the site, however, was taken from Textron's electronic database of test results, which may have errors or omissions. Environmental testing at the site has spanned nearly two decades. Older test results were considered less credible than recent ones. The health outcome data used in this evaluation were also checked for quality control purposes, and measures were taken to ensure that these data were appropriate.
III. ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
An integral element of every public health assessment is a review of environmental contamination on the site. In the following section, the results from environmental testing at the Cardinal Landfill Site are summarized for each different media (e.g., groundwater, soil gas, soils, etc.).
Concentrations of chemicals in each of the media have been compared to media-specific health-based comparison values to decide whether any of the compounds need further evaluation. Health-based comparison values are derived using information on the toxicity of the chemical and assuming frequent opportunities for exposure to the contaminated media (e.g., a residential setting). For non-cancer toxicity, DHHS typically uses ATSDR's Minimal Risk Levels or the U.S. Environmental Protection Agency's (EPA's) Reference Doses, which are estimates of daily human exposure to a contaminant that is unlikely to cause adverse non-cancer health effects over a lifetime. Cancer risk comparison values are based on EPA's chemical-specific cancer slope factors and an estimated excess lifetime cancer risk of one in one million. Therefore, if the concentration of a chemical is less than its comparison value, it is unlikely that exposure would result in adverse health effects, and further evaluation of exposures to that chemical is not warranted. If the concentration of a chemical exceeds a comparison value, adverse health effects from exposure are not necessarily expected, but potential exposures to that chemical at the site should be evaluated. As a result, the following summary of environmental data highlights the chemicals that have been found on the site at concentrations above health-based comparison values. In the Discussion section later in this document, the public health implications of exposures to these contaminants are evaluated in detail.
Please note that, to be consistent with previous indoor air evaluations at this site, indoor air measurements have also been compared to DES' residential indoor air screening values and EPA Region III's risk based concentrations (RBCs) for air. The lowest of the three comparison values was used to identify compounds for further evaluation.
(A) Site Conceptual Model - An Overview of the Cardinal Landfill
A site conceptual model is a general description of the processes and the conditions that have been observed at a particular site. It is meant to provide the reader with an overview so that the detailed information provided in the following sections can be taken in context.
The primary forms of contamination at the site are waste solvents and other VOCs in groundwater. These contaminants were disposed in the northeastern portion of the landfill ("the primary landfill") between the late 1960s and 1981. The hazardous materials were covered by solid wastes, primarily plastic scraps, during the following decade.
Shallow groundwater flow carries the contaminants mostly towards the Cocheco River. Several homes along Watson Corner Road were forced to abandon their private wells in the mid 1980s due to chemical contamination from the landfill. The groundwater contamination in the shallow overburden has decreased considerably over time, yet concentrations of some VOCs still remain very high or unchanged on the site. The groundwater beneath a portion of the site is anaerobic (lacking oxygen). This condition has caused some metals, primarily arsenic, iron, and manganese, to dissolve from minerals in the soil and enter the groundwater. Consequently, these metals have been detected at elevated concentrations in the groundwater beneath the site. It is uncertain whether groundwater contamination from the landfill has crossed under the Cocheco River. However, it is clear that the greatest groundwater contamination is located beneath the site.
Many of the chemicals discarded in the landfill have a tendency to evaporate into the air. As a result, some of these chemicals have been found in the air spaces in the soil ("soil gas") above areas of groundwater contamination and waste. During winter, when frost or snow seals the top of the landfill, the contaminated soil gas could migrate laterally, potentially affecting areas beyond the extent of the landfill groundwater contamination and waste.
The hazardous material in the primary landfill is covered with a layer of fill material. For the most part, the waste that is present at the surface of the landfill consists of plastic scraps. In the past, large puddles that formed on the site contained high concentrations of solvents that had leached from the recently discarded waste.
Discharges of contaminated groundwater to the Cocheco River may affect the quality of the river water, sediments, and fish.
Groundwater on and in the vicinity of the site is contaminated with VOCs. The compounds that have been detected in a majority of the wells on the site are:
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This suite of chemicals is what would be expected following the natural degradation of the VOCs that were reportedly disposed in the landfill. Five of the compounds on this list - 1,2-DCE, methylene chloride, PCE, TCE, and vinyl chloride - have been consistently measured on-site at concentrations one hundred times higher than their health based comparison values for drinking water. A number of other VOCs have been detected at the site besides these major contaminants. Please see Table 1 for a full list and a summary of results for monitoring wells on the landfill, on the Farmington Landfill, and on other neighboring properties for the period between 1984-1999.
In general, the degree of groundwater contamination in April 2000 was lower than in the 1984-1999 period (Table 2). Nine of the 14 VOCs listed above showed dramatic decreases in concentration (greater than 75% on average). However, the concentrations of vinyl chloride and 1,1-DCA increased slightly in 2000. Concentrations of the cis isomer of 1,2-DCE, ethylbenzene, toluene, and xylenes only decreased a small amount.
Three new monitoring wells were installed on the Peaceful Pines Mobile Home Park property in February 2000, bringing the total number of wells on this property to four. None of the three new monitoring wells showed any contamination when tested in April 2000. The other monitoring well in the park, MW201, has been tested at least 29 times since it was installed in 1989. No significant contamination has been found in this well. The only confirmed measurement was 2.4 micrograms per liter (ug/L) of methyl tert-butyl ether (MTBE) during a test in May 1999, which is below the health comparison value for this chemical (13 ug/L). Trace concentrations of 1,2-DCE, toluene, and methylene chloride were reported in 1993. No compounds were detected in this well in April 2000.
All 18 of the private drinking water wells that have the potential to be affected by the site contamination have been tested. The highest concentrations of each chemical detected in any of the wells are listed in Table 3. The site-related VOCs that were detected above health comparison values are: 1,2-DCA, 1,2-DCE, methylene chloride, PCE, TCE, and vinyl chloride. The elevated concentrations of these compounds were found in five drinking water wells along Watson Corner Road. All of these wells have been abandoned. The results of tests for each of the private wells are listed in Table 4.
The private well serving the Peaceful Pines Mobile Home Park was tested nine times between 1982 and 1995, when it was taken off-line. The only chemicals that were detected above comparison values were disinfection byproducts (chloroform and dichlorobromomethane) in one test in 1985. These compounds were not detected in a duplicate test taken the same day. The well pump was reportedly cleaned with bleach prior to this date, which is the likely source of the temporary presence of disinfection byproducts in the water. The well is over 1000 feet upgradient of the groundwater contamination on the site. Therefore, contamination of this water supply would not be expected, as confirmed by the testing results. Radon, a naturally occurring gas, was detected in the well but at an average concentration of 1,300 picoCuries per liter (pCi/L), which is less than the average concentration recommended by DHHS' Radiological Health Bureau (2,000 pCi/L). This well also periodically contained coliform bacteria, which are common in the environment and are generally not harmful.
Also of note is the low-level contamination that has been observed in the Town of Farmington's former municipal water supply well, GP-2. GP-2 is 2000 feet west of the site, on the opposite side of the Cocheco River from the landfill. It was installed in 1944. In 1983, VOCs were discovered in the well water and from this point forward the water was only used by Textron's manufacturing facility on Route 11. The predominant chemicals detected in the well water were 1,2-DCE, TCE, and PCE. The State tested the water in 1985 and 1986 and found concentrations of these chemicals at concentrations between 5 and 10 ug/L [7]. Subsequent tests of the well in 1995 through 1999 continued to detect these chemicals at equivalent or lower concentrations. The well was permanently shut down in January 2000 when the Town of Farmington brought a new municipal well online. The source of the contamination of GP-2 is uncertain; however, DES suspects either the Textron facility on Route 11, the Farmington Landfill, or the Cardinal Landfill. Private wells on lots R-19/14, R-19/16, R-32/18, and R-32/19 in the vicinity of GP-2 have contained similar trace contamination. However, the VOC concentrations in these wells were below health comparison values, and some residents continue to use them for drinking water. The property next to GP-2 is a day care center which receives its water from the municipal supply, not GP-2. Since the area around GP-2 is residential and contains a day care facility, DHHS believes that it would be prudent to discover and remove the source of contamination in this area. Any effects that this contamination may have had on the town water supply prior to 1983 are uncertain.
Several metals and other inorganic compounds have also been detected above health comparison values in monitoring wells at and near the landfill. Tables 5 and 6 summarize the results from 1995 and 1998-2000, respectively, which were the most representative data for the site. The metals of primary importance are arsenic, iron, and manganese which have dissolved from minerals in the anaerobic (lacking oxygen) environment created by the landfill. Other compounds - antimony, lead, thallium, nitrate, and nitrite - were occasionally detected at concentrations above comparison values, but the detections did not indicate a consistent pattern of contamination that warrants concern.
Even though the concentrations of iron are very high at the site, exposures would not be of health concern. Iron is an essential nutrient. Adults should receive approximately 1.0-1.5 milligrams per day (mg/d) of absorbed iron. Because iron is inefficiently absorbed by the digestive system, it is recommended that adults consume 10-15 mg/d (30 mg/d when pregnant) [45]. According to the National Research Council, adverse health effects from ingesting iron are expected only after long-term exposure to iron at levels 340-1,700 times greater than the recommended levels [71] which would be equivalent to drinking water containing 1,700,000-15,300,000 ug/L of iron. The maximum measured concentration of iron in groundwater beneath the site (370,000 ug/L) is approximately 20% of this level. Therefore, even though significant amounts of iron have been mobilized by the site, the iron is not toxic and not of public health concern.
The average concentrations of arsenic and manganese beneath the site have remained very stable over the past five years, approximately 170 ug/L and 2,500 ug/L, respectively. The elevated concentrations are mostly beneath the Cardinal and Farmington Landfills. However, one monitoring well on Lot 9 along Watson Corner Road has consistently contained very high concentrations of both metals (180 ug/L for arsenic and 2400 ug/L for manganese on average). These are 9000 and 5 times higher than their respective comparison values for drinking water.
No elevated concentrations of metals were detected in the drinking water well that served the mobile home park until 1995. None of the other private wells have been tested for metals, so the concentrations of metals in these wells are uncertain. However, the drinking water wells closest to the area with elevated arsenic and manganese concentrations have been abandoned.
In 1984 and 1989, the groundwater in the worst-case locations on the site was tested for semi-volatile organic compounds (SVOCs) to determine if this type of contamination was present [12]. The results of the tests are summarized in Table 7. Two SVOCs were detected at concentrations above drinking water comparison values in 1984. However, these chemicals were not detected again in 1989. Therefore, the detections in 1984 do not appear to be significant since they were not repeatable and the compounds were not detected in other wells on the site. Furthermore, tests of waste materials in 1990 for SVOCs did not indicate that this type of contamination is a concern at the site [14].
The chemicals found in the groundwater and waste on-site can evaporate into the air spaces between soil grains ("soil gas") and gradually work their way to the ground surface. The concern regarding contaminants in soil gas is that they would be carried into nearby homes where people would inhale them. Effects of soil gas on the ambient (outdoor) air are less likely because of the considerable dilution that would occur.
Using comparison values for air to evaluate soil gas is not appropriate because the soil gas concentrations will be many times higher than the air concentrations that people actually breathe inside a house. There have been many studies and models that attempt to relate soil gas concentrations to indoor air concentrations. Much of this work has been done to assess the risks from naturally-occurring radon in soils around the basements of homes. In these studies, the attenuation coefficient (AC) between radon in soil gas and radon in the indoor air of homes has been observed to be approximately 0.001 [52]. The attenuation coefficient is the ratio of indoor air to soil gas concentrations and depends on the rate of soil gas infiltration into the home, physical dilution, and chemical degradation. For example, if the AC is equal to 0.001, the concentration in soil gas multiplied by 0.001 would equal the concentration in indoor air. For VOCs, such as are present at the Cardinal Landfill site, environmental transport models have estimated the AC to be in the range of 0.01-0.0001 depending on the soil type and the building configuration [49,52,53]. Field studies of VOCs in soil gas and indoor air have found AC values over a wider range than predicted by the models, 0.1-0.000001 [51,54,55]. These studies and the modeling work from Sanders and Talimcioglu [50] highlight the importance of site-specific conditions, especially soil type and soil moisture content to accurately predict the value of AC.
A site-specific AC value can be derived for the mobile homes near the Cardinal Landfill using the soil gas and indoor air measurements that were taken in 1999-2000 [20,21,27,31]. The compounds found in the soil gas at the highest concentrations (Freon 11 and 113) have the properties of being good indicators of attenuation. Freon 11 and 113 were measured at high concentrations in soil gas so any influence from sources inside the homes should be small. They were also consistently detected so their concentrations are known, not estimated from method detection limits. Furthermore, they do not break down in the lower atmosphere [84] so any attenuation observed is from physical dilution, not degradation. Therefore, the ratio of the concentrations of these compounds in soil gas and indoor air should provide a good indication of the AC for mobile homes in this area.
The average AC for Freon 11 and 113 in the three mobile homes tested in 1999-2000 is approximately 0.003. This value falls in the middle of the AC range predicted for VOCs by environmental transport models (0.01-0.0001) [49,52,53]. Recognizing that there can be variability in the AC value due to housing type and geology, it would be prudent to use the lowest modeled AC value (0.01) to ensure that potential soil gas hazards are identified. Nevertheless, the site-specific AC value derived from Freon measurements provides clear evidence that an AC value of 0.01 is a conservative choice for mobile homes at this site. Moreover, the AC estimate of 0.01 should be appropriate for not just the mobile homes in the park, but also the conventional homes with basements along Watson Corner Road. This value is an order of magnitude less than the average AC derived for radon intrusion into homes with basements (0.001) [52]. The AC for radon is expected to be higher than for VOCs because radon is emitted from soils flush to the basement walls, while VOCs must migrate through soil pore spaces to reach the foundation [52]. Therefore, on Tables 8 and 9, site-specific soil gas comparison values were derived by multiplying comparison values for air by 100 (1/AC).
In 1988 and 1990, concentrations of contaminants in soil gas were measured on the site (Table 8) [10,13,14]. Most of the VOCs detected had very high concentrations. Another soil gas study was done earlier in 1988 but this did not report concentrations of chemicals, only the general movement of chemicals, so the results are difficult to interpret [9].
Table 9 summarizes the soil gas measurements taken in 1999 and 2000 [20,21,27,31]. On the landfill itself, several compounds exceeded the modeled comparison values, including PCE, 1,2-DCE, 1,1-dichloroethene (1,1-DCE), vinyl chloride, and benzene, among others. The highest concentrations were found along the border with the mobile home park, adjacent to the drainage swale (see Figure 2). The soil gas tests in 1999-2000 were conducted on the perimeter of the site and the neighboring properties exclusively. The soil gas concentrations in the middle of the landfill were not measured.
In the buffer zone section of the park (see Figure 2), five compounds have been detected in the soil gas at concentrations greater than the modeled comparison values and, hence, have the potential to affect indoor air: 1,1,-DCE, chloroform, TCE, PCE, and formaldehyde. However, the first four of these compounds only have high concentrations in the undeveloped area along the edge of the site by the swale, which is adjacent to the locations on the site where high concentrations were also observed. In other areas of the buffer zone, the average concentrations in the soil gas were close to or below modeled comparison values. The last compound, formaldehyde, has only been measured in soil gas on Lot 13A of the mobile home park and in the highly contaminated area by the swale. The highest concentration of formaldehyde, 19 micrograms per cubic meter (ug/m3), was detected near a mobile home on lot 13A in 1999. When retested in 2000, the formaldehyde concentration at this location was in the range of 0.83-1.8 ug/m3. The soil gas in the highly contaminated area near the swale was only tested once for formaldehyde (in 1999) and it was found to contain 5.7 ug/m3. The source of this formaldehyde in the soil gas is uncertain. DHHS has recommended that any potential onsite sources of formaldehyde should be characterized by, at a minimum, groundwater tests for formaldehyde and its hydrolysis products [32].
In the rest of the mobile home park, the only compound that was detected in soil gas above a modeled comparison value was benzene. However, the elevated concentration of benzene appears to be related to a small gasoline spill on one of the residential lots [27]. In this area, the concentrations of toluene, ethylbenzene, xylenes, and MTBE are elevated also (but below modeled comparison values), which is what would be expected from a small gasoline spill. Benzene was also detected at relatively low concentrations (19 ug/m3) in one soil gas probe on the edge of the buffer zone in the undeveloped swale area. Probes between this one an the rest of the mobile home park did not contain VOCs greater than modeled comparison values. Therefore, aside from the small area affected by the presumed gasoline spill, there is no soil gas contamination greater than modeled comparison values in the developed area of the mobile home park.
On the properties along Watson Corner Road, to the north of the site, no VOCs were detected in the soil gas at concentrations above modeled comparison values. While still below modeled comparison values, the average concentrations of PCE and Freon 11 on these properties are five and fifty times higher, respectively, than in the unaffected areas of the mobile home park. This suggests that additional monitoring is needed to ensure that the soil gas plume in this area is adequately mapped.
Finally, the soil gas tests in 1999 and 2000 only reflect conditions during this recent period. Groundwater contamination in the monitoring well closest to the three homes in the buffer zone (MW1) was significantly higher in the past (Figures 2 and 3). The concentration of 1,2-DCE (total) in this well was 1,600 ug/L on average during 1999 and 2000. However, for the period between 1989 and 1997, the average 1,2-DCE concentration in this well was 13,000 ug/L and the maximum value was 52,000 ug/L. The concentrations also fluctuate on a yearly cycle, with the highest concentrations appearing in late fall and winter, the lowest in spring and summer. Therefore, soil gas contamination in the vicinity of MW1 could have been greater in the past.
In May 1999, Textron tested the indoor air of the three mobile homes in the park that were adjacent to the primary landfill area. Later, on February 18 and March 21, 2000, contractors for DES retested the indoor air of one of these homes under winter conditions (frozen ground, snow cover), which are considered the worst-case for indoor air contamination. The other two homes were not retested in February and March 2000 because they had already been moved away from the area.
The mean daily temperatures for New Hampshire in 1999 and 2000 are plotted in Figure 4. While the indoor air tests in May 1999, February 2000, and March 2000 were not done at the extremes of temperature (e.g., July and January), they cover a wide range of climatic conditions, including frozen ground and snow cover conditions in both February and March 2000. Therefore, the combination of tests should generally reflect the range of indoor air concentrations over the seasonal cycle.
The results of all the indoor air tests in the three homes are summarized in Table 10. Ten compounds were detected in the indoor air of these homes at concentrations above comparison values for air: chloromethane, methylene chloride, benzene, MIBK, toluene, formaldehyde, acetaldehyde, carbon tetrachloride, hexanal, and 1,4-dioxane.
Methylene chloride, benzene, toluene, and chloromethane have been identified by DES as potentially migrating from the site to the mobile home on Lot 13A [29]. MIBK, although not identified by DES, is a major contaminant of groundwater on the site and may be site-related.
Formaldehyde, acetaldehyde, and hexanal all belong to the class of chemicals known as aldehydes. They are commonly found in the indoor environment due to their use in resins in pressed wood particle board [68].
1,4-Dioxane and carbon tetrachloride were both detected once in the indoor air of the homes. They have not been detected in the soil gas near the homes. Carbon tetrachloride was detected in some groundwater samples on the site but not in the vicinity of the homes.
As discussed in the preceding section, higher concentrations of chemicals in the indoor air could have been possible in the past because groundwater contamination near the homes was more severe (Figure 3). It is not possible to estimate the effect this may have had on the indoor air quality of the homes during that time.
When soil gas reaches the ground surface, the contaminants will pass into the ambient (outdoor) air. Therefore, if there is enough soil gas contamination, the outdoor air near the site could become contaminated. Samples of outdoor air in the mobile home park were collected in 1999 and 2000. These results are summarized on Table 10. Five compounds have been detected at concentrations higher than comparison values: chloromethane, benzene, formaldehyde, acetaldehyde, and 1,4-dioxane. All of these compounds were also detected in the indoor air samples at similar or higher concentrations. For instance, the average formaldehyde concentrations were much lower in the ambient air (1.2 ug/m3) than in the indoor air (55 ug/m3) and approximately equal to the expected background concentrations in ambient air (0.2 ug/m3) [68].
(F) Onsite Soil and Surface Water
Soils on the site were tested for VOCs during a 1990 subsurface investigation to characterize the wastes in the landfill [14]. In 1988, on-site surface soils and stream sediments were tested for base-neutral extractable organics [12]. The results of these tests (Table 11) showed that PCE and polycyclic aromatic hydrocarbons had maximum concentrations above comparison values for residential soils. However, the elevated concentrations of PCE were only found in one test pit that contained waste material. In other areas, the PCE concentrations in the soil were below the residential comparison value. Likewise, the concentrations of PAHs were within the range of concentrations found in urban areas of New England [46]. Recent tests of surface soils across the site in August 2000 did not detect any polycyclic aromatic hydrocarbons [34].
In the past, large puddles would form on the site during wet periods. In 1982-1984, the concentrations of methylene chloride and acetone in these puddles exceeded the comparison values for drinking water [1,2]. Additional tests in 1990 did not discover contamination exceeding drinking water quality in surface waters on the site (Table 12) [12,13].
Please note that comparison values for residential soils and drinking water have been used to screen the testing results for on-site soil and surface waters. Since exposure to this contamination would only occur during infrequent trespassing, the use of these comparison values is very conservative.
(G) Cocheco River Surface Water and Sediment
Contaminated groundwater from the site discharges to the Cocheco River. The contaminants are quickly mixed with the rest of the surface water or evaporate, yet some contamination persists. The concentrations of VOCs and metals in the river water and sediments are shown in Tables 13-14. The contaminants with concentrations higher than comparison values for drinking water are all VOCs: methylene chloride, PCE, TCE, 1,2-DCE, and vinyl chloride. Concentrations greater than comparison values were detected between 1982-3 and 1990. In 1998, all the measured concentrations were below comparison values. No compounds were detected above comparison values in the sediments in 1990 or 1998. As discussed in the previous section, comparison values for drinking water are very conservative for intermittent exposures while swimming or wading.
Fish can accumulate contaminants in their tissues. Two composite samples of fish from the river (containing 11 and 21 individual fish) were tested for VOCs in November 1986 [8] and the results are shown in Table 15. None of the measured concentrations were above risk-based concentrations for fish tissue derived by the Superfund Technical Support Section of EPA Region III. However, only very small fish (1-5 inches long) were collected, which are not representative of fish that people could eat. Also, a major contaminant at the site, methylene chloride, was not measured in the fish due to laboratory error. Therefore, the 1986 fish tissue tests are of questionable quality.
The physical hazards present at this site are similar to those found at other landfills. In municipal waste landfills, the decomposition of wastes can produce landfill gas which is primarily methane and carbon dioxide. At high enough concentrations, methane gas can cause an explosion. Landfill gas concentrations in the Cardinal Landfill were measured in March 1996 and were found to be less than 11% of the lower explosive limit (LEL), which is the concentration above which there is the potential for an explosion [18]. However, there are elevated concentrations of methane in groundwater at the site (6000 ug/L average, 150,000 ug/L maximum, see Table 6). These are higher than the predicted groundwater concentration at equilibrium with the LEL (1,200 ug/L). Therefore, the potential exists for explosive levels of methane gas in the landfill. There are no adverse health effects related to human exposure to non-explosive levels of methane gas. We recommend that the explosive risks from the site be better characterized as part of the continuing soil gas and groundwater testing protocols.
Carbon dioxide is the other main landfill gas. Elevated concentrations of carbon dioxide could potentially present an asphyxiation hazard for people working on the site in confined spaces (e.g., trenching, installing utility corridors).
IV. PATHWAYS OF HUMAN EXPOSURES
(A) Completed Exposure Pathways
Human contact with environmental contamination is only possible when a completed exposure pathway exists. A completed exposure pathway exists when all of the following five elements are present: (1) a source of contamination; (2) transport through an environmental medium; (3) a point of exposure; (4) a route of human exposure; and (5) an exposed population. For the Cardinal Landfill, the completed exposure pathways are listed in the following table.
Completed Exposure Pathways
| Source | Environmental Transport And Media | Exposure Point | Exposure Route | Exposed Population | Time Frame | Status |
| Landfill Waste | Waste to Groundwater to Private Well | Homes near the landfill with private wells | Ingestion Dermal Inhalation |
Off-site residents | Past | Completed |
| Present | Potential | |||||
| Future | Potential | |||||
| Landfill Waste | Waste to Groundwater to Soil Gas to Indoor Air | Homes above groundwater or soil gas contamination | Inhalation | Off-site residents | Past | Completed |
| Present | Potential | |||||
| Future | Potential | |||||
| Landfill Waste | Waste to Soil Gas to Ambient Air | Homes near the landfill, especially those down-wind | Inhalation | Off-site residents | Past | Completed |
| Present | Completed | |||||
| Future | Completed | |||||
| Landfill Waste | Waste to Surface Soil and Surface Water | On-Site | Ingestion Dermal |
Trespassers Workers |
Past | Completed |
| Present | Completed | |||||
| Future | Completed | |||||
| Landfill Waste | Waste to Groundwater to Surface Water and Sediment | Cocheco River | Ingestion Dermal |
Swimmers Waders |
Past | Completed |
| Present | Completed | |||||
| Future | Completed | |||||
| Landfill Waste | Waste to Groundwater to Surface Water to Fish | Cocheco River | Ingestion | Fishers | Past | Completed |
| Present | Completed | |||||
| Future | Completed |
In the following sections, each of these completed pathways of exposure will be outlined in more detail. The public health implications of the exposures will be evaluated in the Discussion section of this document.
(1) Private Drinking Water Wells
The pathway of exposure to chemicals in groundwater is through the use of private drinking water wells. Residents with contaminated water supplies would be exposed by drinking and bathing with contaminated water, and inhaling VOCs that had evaporated into the indoor air. Originally, all of the residences near the site used groundwater for their drinking water supplies. Starting in 1982, some of the private wells near the site were discovered to be contaminated with solvents. A water main was extended along Watson Corner Road in 1985 and a number of these homes abandoned their wells at that time. The rest of the wells or properties were abandoned between 1985 and 2000. The well that served the Peaceful Pines Mobile Home Park until 1995 was not affected by contamination at the site. Since 1995, the mobile home park has received water from the Town of Farmington's municipal water supply.
(2) Soil Gas and Indoor Air
The chemicals found in the groundwater and waste on-site can evaporate into the air spaces between soil grains ("soil gas") and gradually work their way to the surface. If there is a home in an area of soil gas contamination, the compounds may be pulled into the indoor air of the home. Residents would then be exposed by inhaling chemicals in the indoor air.
Soil gas tests and modeled comparison values indicate that the only area where there is currently the potential for this type of exposure is the buffer zone between the mobile home park and the landfill (see Figure 2). The indoor air of the three homes in this area was tested in 1999 and 2000. All three homes have been either moved or abandoned, but exposures along this pathway at these and other nearby homes were possible in the past.
(3) Ambient Air
When soil gas reaches the ground surface, the contaminants will pass into the ambient (outdoor) air. Therefore, if there is enough soil gas contamination, the outdoor air near the site could become contaminated with VOCs and nearby residents could be exposed by breathing the air. In general, however, exposures to chemicals in the ambient air will be much lower than those from indoor air contamination.
(4) On-Site Soil and Surface Water
Trespassers on the site could contact contaminated soils, waste material, or contaminated surface puddles and be exposed to chemicals. The highest concentrations of contaminants on the site were detected in the 1980s and probably do not represent current conditions.
(5) Cocheco River Surface Water and Sediment
People who swim or wade in the Cocheco River near the site could be exposed to VOCs in the water and sediments. Exposure could occur by ingesting small amounts of water and sediment or by absorbing chemicals through bare skin. Similar to onsite surface water measurements, the highest concentrations were found in the 1980s. Recent tests have not indicated contamination at greater than health comparison values.
(6) Cocheco River Fish
Contaminated groundwater from the site discharges to the Cocheco River. These contaminants can accumulate in the tissues of fish living in the river. People who eat fish caught from the river would be exposed to chemicals in the tissues of the fish.
(B) Potential Exposure Pathways
Potential exposure pathways are routes along which exposure could be possible except that one or more of the five critical elements is missing. In some cases, this means that the exposure is not possible now but may be possible in the future. In other cases, an exposure may be possible but cannot be confirmed because data are not available. The potential exposure pathways that exist at the Cardinal Landfill are summarized in the following table.
Potential Exposure Pathways
| Source | Environmental Transport And Media | Exposure Point | Exposure Route | Exposed Population | Time Frame | Status |
| Landfill Waste | Waste to Groundwater to Surface Water and Sediment | Swale in Peaceful Pines MHP | Ingestion Dermal |
Off-site residents | Past | Potential |
| Present | Potential | |||||
| Future | Potential | |||||
| Landfill Waste | Waste to Groundwater to Private Well | Homes near the landfill with private wells | Ingestion of arsenic and manganese | Off-site residents | Past | Potential |
| Present | Potential | |||||
| Future | Potential |
(1) Surface Water and Sediment in Peaceful Pines Mobile Home Park Swale
The low lying area between the old and new sections of the mobile home park ("the swale") is adjacent to waste buried in the landfill, which was encountered when MW405 was installed (see Figure 2)[33] . Before the landfill was created, the swale carried water west from the park to the Cocheco River. Piles of waste dumped on the landfill interrupted this natural flow path. Now, water accumulates in the swale during wet periods of the year and gradually infiltrates into the ground.
The waste that has blocked the path of flow in the swale could potentially contaminate the water in the swale. If this occurs and if children from the park were to play in this area, they would have opportunities for exposure to contaminants. No VOCs were detected in the two sediment samples collected from the swale in 1999 [21]. However, because of the proximity of wastes next to the swale, it is possible that this waterway was contaminated in the past or could become contaminated in the future.
Potential exposures from this pathway cannot be evaluated because the exposure point concentrations are not known. DHHS recommends that the extent of waste in this area and its potential effects on the water quality in the swale be determined. Specifically, the following investigations are needed: (1) Determine if any landfill wastes are outside the perimeter fence; (2) Survey the elevations of the buried waste, the water table (yearly maximum elevation), and the lowest topographic point in the swale; and (3) Test ponded water in the swale and continue to test groundwater and soil gas in the vicinity.
(2) Arsenic and Manganese in Private Drinking Water Supplies
Anaerobic conditions created by the landfill have released arsenic and manganese from minerals, causing concentrations of these metals to build up in the groundwater to levels greater than health comparison values. The highest concentrations are on the site, but elevated levels have also been found on some of the Watson Corner Road properties. Therefore, it is possible that some of the residents of these properties were exposed to high levels of arsenic and manganese in addition to VOCs from the site. This exposure cannot be confirmed because the private wells were not tested for metals. However, private wells near the site should be tested for arsenic and manganese to ensure that current or future exposures to these metals do not occur.
(C) Eliminated Exposure Pathways
DHHS also reviewed four other pathways of concern to the public. They were found to not be possible or significant and, hence, were eliminated from further evaluation.
Eliminated Exposure Pathways
| Source | Environmental Transport and Media | Exposure Point | Exposure Route | Exposed Population | Time Frame | Status |
| Landfill Waste | Waste to Surface Soil | Homes built on top of landfill waste | Ingestion Dermal |
Off-site residents | Past | Eliminated |
| Present | Eliminated | |||||
| Future | Eliminated | |||||
| Landfill Waste | Waste to Soil Gas to Surface Soil | Homes near the landfill | Ingestion Dermal |
Off-site residents | Past | Eliminated |
| Present | Eliminated | |||||
| Future | Eliminated | |||||
| Landfill Waste | Waste to Groundwater to Soil Gas to Indoor Air to Indoor Surfaces | Homes above groundwater or soil gas contamination | Ingestion Dermal |
Off-site residents | Past | Eliminated |
| Present | Eliminated | |||||
| Future | Eliminated | |||||
| Landfill Waste | Waste to Combustion to Ambient Air and Surface Soil | Homes near the landfill | Inhalation Ingestion Dermal |
Off-site residents | Past | Eliminated |
| Present | Eliminated | |||||
| Future | Eliminated |
(1) Residential homes built on top of waste
Some residents of the Peaceful Pines mobile home park were concerned that the park itself was built on top of waste material. Drilling reports do not show any subsurface waste in the monitoring well between the primary landfill and the park. Therefore, the pathway regarding residential homes built on top of waste of concern does not seem possible. However, there does appear to be waste at the edge of the property in the swale area. Potential contamination of the swale due to this waste was discussed as a potential pathway in the preceding section.
(2) Residential soil contamination from soil gas vapors
Significant amounts of VOCs from the soil gas would not attach to particles in the soil due to their physical-chemical properties [63,64,68]. Therefore, someone touching the soil would not have significant contact with the soil gas contaminants.
(3) Contamination of surfaces inside homes
Some of the residents have expressed concern that they would be exposed to the chemicals inside their homes not just through inhalation but also by touching surfaces contaminated with the chemicals. VOCs in air will adsorb to soft surfaces inside a building (e.g., carpets, partition walls) [48]. This process is essentially reversible, equilibrium partitioning of the chemical from the air to an environment (such as a plastic fiber) for which it has a greater affinity [48]. However, inhaling contaminants in the indoor air is a more potent route of exposure than dermal contact with chemicals adsorbed to surfaces. Therefore, exposures to contaminants on indoor surfaces are not expected to be significant compared to exposures from inhaling indoor air.
(4) Exposure to contamination from fires on the site
There have been several major fires on the site. At least one of the fires in 1978, involved burning hazardous waste. Nearby residents could have been exposed to fumes and smoke created by the fires for a short period of time. These exposures could have caused short term health or irritant effects for residents downwind of the fire. However, without measurements of chemicals in the smoke during the fires it is not possible to conclusively determine the effects of this exposure. Some residents were also concerned that dioxin might have been created and spread by the fire. Such a process is theoretically possible, given that waste PVC and other plastics would have been combusted by the fire, but dioxin exposures under these circumstances are not likely to be significant. In support of this, ATSDR has noted that the magnitude of dioxin exposure, if any, from such a source would likely be considerably lower than that encountered in various epidemiological studies which have reported an association between dioxin exposure and health effects [30].
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