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PUBLIC HEALTH ASSESSMENT

CENTRAL MAINE DISPOSAL LANDFILL
(a/k/a CENTRAL MAINE DISPOSAL CORPORATION)
FAIRFIELD, SOMERSET COUNTY, MAINE


SUMMARY

The Agency for Toxic Substances and Disease Registry (ATSDR)reviewed availableenvironmental and health data in response to concerns regarding potential exposures tocontaminants at the Central Maine Disposal Landfill. According to past and current sampling data reviewed, the landfill does not pose a public health hazard. No adverse health effects would be expected to result from people drinking water from private wells that were sampled. Wells where coliform bacteria levels exceeded safe drinking water standards should be periodically monitored and the source of bacterial contamination identified. People who accessed the site for occasional dirt bike riding or other activities would not have been exposed to contaminants at levels of health concern.


PURPOSE AND HEALTH ISSUES

Residents of Fairfield, Maine petitioned ATSDR regarding concerns of potential exposure to contaminants from the Central Maine Disposal Landfill (CMD) and an increased incidence of brain cancer within their community. In 2000, the Maine Bureau of Health requested that ATSDR conduct a health assessment of the CMD Landfill. The purpose of this health assessment is to evaluate environmental data and other information on the release of hazardous substances into the environment in order to assess any past, current, or future impact on the community's health and to identify actions necessary to prevent adverse human health effects.


BACKGROUND

The CMD Landfill (Latitude 44º 38' 25" N; Longitude 69º 40' 16" W) is located on Middle Road (Route 104) in Fairfield, Somerset County, Maine (Figures 1, 2). From 1976 to the late 1980's, this six-acre parcel of land was leased by the Hapworth farm to the Central Maine Disposal Company [1]. Prior to that time the site was used for gravel mining and agriculture. The site is bordered by a dirt road off Route 104 and a residence to the north, Route 104 to the west, an intermittent unnamed stream to the south, and a gravel pit to the east. Surrounding land is primarily agricultural and rural.

In 1976, the Maine Department of Environmental Protection (MEDEP) licensed the CMD todispose of waste into two of four abandoned gravel pits (Hapworth pits) on site (Figure 3) [2, 3]. Prior to dumping, pits #2 and #3 were lined with a five-foot soil layer to prevent leaching into surrounding groundwater. The landfill operated under a MEDEP permit to accept fly ash, wood ash, and oil waste from paper mills operated by the Scott Paper Company. From 1976 to 1985, unapproved solid waste was disposed of in two other pits on site. MEDEP attempted to close the landfill in 1984; it remained open but was fined for violations. Reported violations included disposing of waste in non-permitted pits; disposal of waste material other than approved fly ash and lime by-products; illegal dumping of chemical drums, petroleum products and sludge ; burning of solid waste at the landfill; failure to erect a gate to limit access; and failure to provide daily cover over the waste material [3].

The site was closed in 1985 and capped in 1993 with an 18-inch-thick compacted clay cover and 6,622 cubic yards of vegetative cover material [4]. Arsenic, methylene chloride, acetone, naphthalene and other petroleum compounds were identified in soil and water samples collected on site. The landfill sits above a large sand and gravel aquifer that stretches along a small brook to Old Center Road. Residents along this road complained of foul smelling well water containing oily black particles.

On July 13, 2000, the MEDEP conducted a tour of the CMD landfill for ATSDR. The landfill islocated in a rural, wooded section of the community. The closest home is approximately 400 feetnorth of the landfill. During the site visit, no evidence of illegal dumping of trash and refuse wasobserved. Currently, there is little evidence of trespassing on the site. In the past, people accessedthe site for recreational activities including riding off-road vehicles, bike riding, playing in the ash,and shooting rats. ATSDR also toured the community to identify locations of residences, schools, playing fields, and municipal services.

Community Health Concerns

Fairfield residents were concerned with past and present exposure to contaminated air, surface water, sediment, soil, and groundwater from the CMD Landfill. Residentswere concerned about reported cases of brain tumors in Fairfield and the identification of a cancer cluster by the Maine Bureau of Health (MEBOH). They were also concerned withexposure during dirt bike riding and other recreational activities occurring on the site.

Demographics

Fairfield, Maine is in southern Somerset County, north of Waterville and south of Skowhegan. The town is bordered on the east by the Kennebec River and two interchanges US Rt. 201 and I-95. Two small commercial villages are Hinckley and Fairfield Center. As of 1997, the population was estimated at 7,140, with approximately 28% under the age of 18 years and 12% over the age of 65 [5]. The mean household income as of February 1999 is $26,536, and approximately 16.3% of the population in Somerset County are living below the poverty level.

No hospital, health center, day care center, elder care center, or school is located near the site. Fairfield is in the Waterville Hospital service area. The nearest private wells are within 0.25 miles of the CMD landfill along Middle Road, Route 104 [6]. The closest public water supply well is 2.7 miles northeast of the site. Approximately 1,522 people living within 4 miles of the site use groundwater as a source of potable water (public and private) [3].

The Governor's Contingency Fund has provided a grant to the Greater Waterville PlannedApproach to Community Health (PATCH), a group consists of community members and healthcare experts in the area, including representatives from Maine General Hospital, Inland Hospital, HealthReach, and United Way. PATCH is working with community membersin cooperation with town officials and local and state health agencies to conduct a health assessment to identify current health risks and future needs for the Waterville area.


DISCUSSION

During a health assessment, ATSDR obtains the community's concerns, environmental data, and othermedical, toxicological, demographic, and environmental information that may affect the health of acommunity. To determine if health effects are likely to occur within the community, ATSDR healthprofessionals consider various factors: the toxicity of the contaminant, the concentration (how much), thetime of exposure (how long), and how the chemical gets into the body (breathing, eating, drinking, or skincontact). Other factors: occupation, personal habits, age, nutritional status, general health, and geneticsare also considered. These factors affect how a contaminant is absorbed, distributed, metabolized, andeliminated from the body. A health assessment evaluates contaminants to determine whether exposure tothem is likely to have public health significance. ATSDR selects and compares on- and off-siteconcentrations of contaminants with ATSDR comparison values for non-carcinogenic and carcinogeniceffects (Appendix B). Comparison values are concentrations of contaminants in specific environmentalmedia (air, soil, and drinking water) that are not expected to produce adverse health effects in people whoare exposed acutely (up to 2 weeks), intermediately (>2 weeks to 1 year), and/or chronically (over 1year). These values are used only as screening values; therefore listing a contaminant in a table ofchemicals of concern does not mean that it will necessarily cause adverse health effects if exposure occursat that specified concentration. When the concentration of a contaminant detected on or off the site isabove the comparison value, it is designated a chemical of concern and is selected for further evaluation todetermine the potential for adverse health effects. The focus of the evaluation is on health effects thatcould plausibly result from exposures to site-related contaminants considering the estimated exposuresoccurring and the dose required to produce those effects. ATSDR considers both adults and children whendeveloping comparison values. The potential health effects on children is considered separately because incertain situations children may be more sensitive and more exposed to contaminants. ATSDR thenpresents its conclusions and recommends appropriate actions. (See Appendix B for additional information regarding comparison values).

Air

Burning of waste materials was reported to have occurred for a 5 to 6 year period (1976-1986) [3]. The MEDEP Air Bureau conducted air dispersion modeling (EPA's Industrial Source Complex Short Term Model [ISCST3]) ofpossible gaseous and particulate matter that may have been released during the burning of waste[7, 8]. The model used hypothetical air emissions data because there are no air sampling dataavailable for this site. This model was used to predict the dilution rate of contaminants atdistances from the landfill, under certain atmospheric and contaminant source assumptions. Itdoes not provide actual concentrations of contaminants that people may have been exposed to inthe past. ATSDR reviewed the results of the dispersion modeling analysis of dilution profiles forhypothetical air emissions from burning of wastes at the CMD landfill. The model does predict thedirection of long-term air dispersion and is an acceptable tool to help determine locations for long-term ambient air sampling. However, since no sampling data are available and the sourceparameters were all simulated and not based on real physical conditions, this model has limited usein predicting short-term exposures. Therefore, the dilution of potential past emissions from the site to locations where people live cannot be determined.

The Scott Paper Company sampled boiler ash and sludge, from piles at its Winslow Millplant, to identify potential contaminants that could be released into the atmosphere andpotentially inhaled during the period when similar waste materials were burned at the landfill [3]. Manganese, found at 7,800 ppm, was the only contaminant detected in the Winslow Mill soilsample above an ATSDR health screening value. ATSDR's soil reference dose media evaluation guide (RMEG) for a child is 3,000 ppm. The value detected in the Winslow Mill soil sample is not above the environmentalmedia evaluation guide (EMEG) for adults (40,000 ppm). Since the detected concentrations arespecific for boiler ash and sludge, media to which people currently have limited contact, noadverse health effects would be expected. No data were available to evaluatepast exposure scenarios such as dirt bike riding on exposed ash piles to determine if exposure occurred. No other contaminants were detected above health comparison inhalation values established for children or adults. The CMD site is capped and heavily vegetated with no indication of ash piles (Site Visit, June 2000). Therefore, it is unlikely that current or future air emissions from this site would pose an inhalation hazard to people living nearby.

Water

Groundwater-Onsite

Groundwater is found in two different zones below the surface. Overburden groundwater is found closest to the surface in a soil and gravel layer, and at the CMD Landfill, is between 8.4and 14.4 feet below the ground and flows in an easterly direction [6]. At the northeastcorner of the site, the groundwater begins to flow in a northeast direction [9]. Because it isrelatively close to the surface, overburden water is usually the first to be impacted bycontamination. It can be affected by contaminants leaching into the water through the soil, or bymixing with surface water. The second zone of groundwater is in the bedrock, which isunderneath the overburden layer. Bedrock is made up of different types of rock, and has fractureswhere water can be found. Most drinking water wells are located in bedrock because the water isless likely to be impacted by surface contaminants. Onsite groundwater monitoring began in 1985in an effort to determine if contaminants from the waste pits were leaching into the groundwaterbelow. Four monitoring wells, one in overburden and three in shallow bedrock, were installed in 1985 (Figure 4) [10].

On October 9 and 10, 1990, five groundwater samples were collected (Figure 4), four from monitoring wells onsite, including a replicate sample, and an additional blankreference sample. Each sample was analyzed for metals and volatile organiccompounds (VOCs) [6]. Arsenic was detected in monitoring wells (MW) # 1 and 2. However, only the sample from MW-2 was above the EPA Maximum Contaminant Level (MCL) of 10 ppb,with an estimated concentration of 48 ppb. Manganese was detected in MW-1,located north of the Hapworth pit, at 1,950 ppb. The RMEG for a child is 500ppb, and the adult RMEG is 2,000 ppb. No VOCs detected in these monitoring wells were above health comparison values for drinking water. The source of arsenic contamination is unknown and may be due to natural leaching of bedrock and/or prior use of pesticides during agricultural activities.

In 1991, groundwater from onsite monitoring wells was tested for semi-volatile organiccompounds (SVOCs), VOCs, and metals [11]. No contaminants were detected above comparisonvalues. Trace amounts of 1,1,1-trichloroethane (11 and 76 ppb) were detected at concentrations below the MCL of 200 ppb.

From 1997 to 1999, Kimberly-Clark conducted on-site groundwater sampling (Figure 5) for metals, pesticides, SVOCs, and VOCs from eight monitoring wells, 4 new and4 existing [12]. No SVOCs or VOCs were detected above health comparison values. Arsenic was detected in two monitoring wells, MW-B1 and MW-E at 149 ppb and 140 ppb,respectively. These values exceed the MCL of 10 ppb. However, these wells are notused for drinking water.

In April 2000, Kimberly-Clark Corporation submitted a revised Phase 2 Investigation Plan. This plan provided for the placement of additional permanent and temporary wells at locationsaround the landfill to evaluate the movement of groundwater beneath the site, particularly down-gradient, near residential private wells [13]. Figure 6 depicts the location of these additional wells.

In July 2000, Kimberly-Clark Corporation sampled on-site monitoring wells according to the Phase 2 Investigation Plan. Seven permanent and six temporary overburden wells, and 13 bedrock wellswere sampled and analyzed for metals, SVOCs, VOCs and water quality parameters (Figure 6). Arsenic was detected in seven of the overburden and three of the bedrock samples above the MCL (10 ppb). Manganese was detected in two wells above the ATSDR child RMEG of 500 ppb. Results are summarized in Table 1 below.

Table 1.

Well ID Description Arsenic (ppb) Manganese (ppb)
MW-B1 Downgradient Overburden 131 2900
MW-C Downgradient Overburden 27.7 140
MW-D Downgradient Overburden 73 15.6
MW-E Downgradient Overburden 116 85.6
TB-2 Downgradient Overburden 35.8 146
TB-3 Downgradient Overburden 75.3 128
TB-4 Downgradient Overburden 16.2 914
BR-D-D Downgradient Bedrock 11.9J 5.3
BR-D-S Downgradient Bedrock 341 16.2
BR-H-S Downgradient Bedrock 10.9 87.6
J-average value due to analytic limitations

Downgradient onsite wells appear to be affected by site contamination. However, onsite wells arenot being used for drinking water, and do not currently pose a public health hazard. Furthersampling of groundwater is planned to continue monitoring groundwater quality downgradientfrom the site. At least two additional monitoring wells will be installed by the Kimberly-ClarkCorp., as recommended by MEDEP, to further delineate the extent of the contamination (Figure 7).

Residential Wells-Offsite

Approximately 187 people living within a one mile radius of the site use private wells as theirsource of drinking water. The nearest residences are located within 0.5 miles of the eastern edgeof the landfill and there are three private residential wells located down-gradient of the landfill. Additionally, the Hinckley Home Farm School, located 2.7 miles northeast of the site, uses waterfrom two bedrock wells, and services approximately 140 people [3]. Public water from theKennebec Water District, which draws from a surface water source, is available to residents of Fairfield Center.

In June 1999, the MEDEP sampled 14 residential wells. Wells #1, 2, and 3, had arsenicconcentrations measured at 36, 41, and 5.0 ppb, respectively (Figure 5)[14, 15]. Two of these concentrations exceeded the MCL (10 ppb). Additional sampling was conducted in January 2000, to determine the extent of arsenic contamination, and if it was related to landfill activity or natural background concentrations. Arsenic is naturally occurring in Maine groundwater and may explain the presence of arsenic in these samples.

On January 11, 12, and 15, 2000, MEDEP sampled 11 private wells and one agricultural supplywell near the CMD landfill, including seven that were previously sampled (Figure 5). One is anoverburden well, while the other eleven are bedrock wells, ranging from 50-500 feet below theground surface. The overburden well was dug at a depth of 4 feet. Samples were analyzed for water quality parameters and some metals. Eight of the twelvewells were tested for VOCs. Five wells (# 2, 3, 15, 17, and 18) exceeded the total coliformstandard (0 colonies per 100 milliliters (mL) water); concentrations ranged from 1 to 727 coloniesper 100 mL of water. The concentrations of arsenic in three of the twelve wells (#1, 2,and 9) were 30, 35, and 36 ppb, respectively. All other wells sampled contained arsenic levelsbelow 3.0 ppb. The concentration of arsenic in these three wells exceeded the MCL of 10 ppb for drinking water.

Lead was found in well #19 at 21 ppb, exceeding the EPA action level for lead of 15ppb. Iron was also measured in well #19 at 5.3 ppm exceeding the secondarydrinking water standard (SMCL) of 0.5 ppm. However, during sampling, this well was pumpeddry and the elevated metal levels are most likely a result of this process [14]. The MEDEP re-sampled this well and lead was not measured above the EPA action level (D. Behr, MEDEP,personal communication, 2002). Results also showed that several wells exceeded the federalsecondary drinking water standards for odor, taste, and color.

Additional residential sampling was conducted by Harding ESE, for Kimberly-Clark, in July 2000to determine background water quality for the Fairfield area (Figure 8). Seventeen residentialwells and one well servicing a store and restaurant were sampled and analyzed for metals, SVOCs,VOCs and water quality parameters. No SVOCs or VOCs were detected in these samples. Arsenic was detected in seven of the samples above the MCL of 10 ppb, and manganese exceededthe child RMEG of 500 ppb in one well. These samples were used to compare well water quality inonsite monitoring wells, and up-gradient and down-gradient residential wells.

The MEDEP reviewed results for onsite monitoring wells and compared the water chemistry withthat from up-gradient residential wells and down-gradient residential wells. The MEDEPconcluded that while arsenic was detected in three residential wells down-gradient of the site, thechemistry of those wells do not match that of onsite monitoring wells [16]. Additionally,residential wells east of the site have different chemistry than wells west or south of the site,indicating that the cause for the difference in arsenic concentrations may be due to difference inthe natural hydrogeology of the area [16].

Surface Water/Sediment-Onsite

Surface water flows from the site to the south and east, entering into an unnamed stream to thesouth, approximately 1,000 feet from the site [3]. This intermittent stream flows to the TobeyBrook 0.5 miles southeast of the site. No drinking water intakes exist for 15 miles downstream ofthe entry point. Limited surface water samples collected in March 1983 were within normalranges for drinking water parameters. However, samples were not tested for VOCs or SVOCs. In1995, MEDEP collected two sediment samples near the point of entry into the unnamed stream,two wetland samples and one background sample. No VOCs or SVOC were detected and nometals detected were above ATSDR's soil comparison values. In 1999, MEDEP collected surfacewater samples and again no contaminants were detected.

Soil-Onsite

In October 1990, prior to capping the landfill, nine soil samples werecollected at depths ranging from 10-72 inches, from areas surrounding the pits (figure 4)[1]. Samples were tested for VOCs, SVOCs, polychlorinated biphenyls (PCBs), pesticides, and metals. No samples were tested for dioxin or furans. Methylene chloride (210 ppb), acetone (430 ppb),chlorobenzene (51 ppb), naphthalene (520 ppb), barium (790 ppm), calcium (91,800 ppm), andmanganese (5,700 ppm) were detected in only one sample, SS-08, collected from an ash pileonsite. These concentrations are not above health comparison values established for a child oradult.

Arsenic was detected in one sample (SS-04) from one of the smaller pits, at approximately 25 ppm,a concentration that slightly exceeds the chronic child EMEG for arsenic in soil (20 ppm). Silverwas found in a duplicate sample from SS-04, detected at 6,660 ppm, exceeding ATSDR's childRMEG of 300 ppm and adult RMEG of 4,000 ppm, but not exceeding the risk-basedconcentration of 10,000 ppm for industrial soils.

The pesticide 4,4'-DDT was detected in two samples, SS-03 and SS-05, at .031 ppm and .037ppm respectively, taken in an active agricultural area; these concentrations are almost 1,000times lower than the child RMEG of 30 ppm [3].

The landfill has been capped (1993) and the vegetative cover maintained, reducing current and future exposure.


PUBLIC HEALTH IMPLICATIONS

Toxicologic Evaluation

Residents of Fairfield were concerned with potential past and present exposure to contaminants at CMD Landfill. ATSDR reviewed available air, groundwater, surfacewater, and soil data to determine if a health hazard exists. Groundwater data were available formonitoring wells onsite and residential wells offsite. Arsenic was detected in some monitoringwells onsite at levels above theMCL. However, these wells are not used to supply potable water to residents. Concentrations ofarsenic detected in some private drinking water wells offsite also exceeded the MCL of 10 ppb.

Arsenic levels that exceeded the MCL were further evaluated by ATSDR. Arsenic levelsexceeded ATSDR's chronic EMEG value for arsenic in drinking water of 3 and 10 ppb, forchildren and adults respectively, and the Cancer Risk Evaluation Guide (CREG) of 0.02 ppb, insome drinking water wells tested. However, ATSDR does not consider the concentrations ofarsenic present in residential wells a health hazard. ATSDR comparison values are veryconservative and are designed to protect sensitive members of the population. ATSDR's CancerRisk Evaluation Guides (CREGs) are estimated contaminant concentrations based on one excesscancer case in a million persons, exposed to a chemical over a lifetime. ATSDR's CREG forarsenic is based on an EPA slope factor that was derived from a largeTaiwanese study. In the study, consumption of arsenic-contaminated well water (170 to800 ppb) was associated with an increased incidence of skin cancer. However, in other studies, noexcess cases of skin cancer were observed in people consuming higher concentrations [17-19]. In the United States, average levels of arsenic in drinking water are 5 ppb, much lowerthan in Taiwan. It was suggested that in the Taiwanese study, underestimated arsenic exposureled to an overestimation of risk. The villagers were believed to be exposed to high levels ofarsenic in both their food and drinking water. It is also likely that the protein-andmethionine-deficient Taiwanese population was more sensitive than typical U.S. populations, dueto a reduced ability to detoxify or methylate ingested arsenic [20, 21]. At low exposure levels,toxic inorganic arsenic compounds are effectively detoxified by methylation and excreted in theurine. Blood arsenic levels increase only after the methylation capacity of the liver is exceeded,resulting in adverse health effects. Saturation of this detoxification mechanism may explain whyboth the cancerous and noncancerous effects of arsenic exhibit a threshold somewhere between250 and 500 µg per day [20, 21]. Because ATSDR's CREGs (or rather the cancer slope factors from which they are derived) are based on a zero-threshold model for genotoxic carcinogens, they are not strictly applicable to non-genotoxic threshold carcinogens like arsenic.

Although the arsenic levels in groundwater exceeded the MCL and ATSDR's comparison valuesfor drinking water, ATSDR does not consider them a health hazard. It is unlikely thatpeople would suffer adverse health effects from drinking this water; however, arsenic exposure would be minimized as a prudent public health policy. Information about reducing arsenic in drinking water can be obtained from the Maine Bureau of Health.

Contaminants detected in surface water and soil on the CMD landfill would not pose a health threat to people who have accessed the site in the past and do not currently pose a threat.

Sludge data from other sites for comparison purposes

The MEDEP and MEBOH requested that ATSDR review ash and sludge data gathered in 1989-1996 from other paper mill locations that may historically represent dioxin levels present in thewaste landfill at CMD prior to capping in 1993. No information on sampling location, samplingdepth, quality control/quality assurance was included in this data packet. Chlorinated dibenzo-p-dioxins (CDDs) are a family of different compounds referred to as polychlorinated dioxins basedon the number of chlorine atoms in the compound. Tetra-chlorinated dioxins (2, 3, 7, 8-TCDD)may be formed during the chlorine bleaching process used by pulp and paper mills and is one of themost toxic and studied members of the dioxin family of compounds. Dioxin compounds arecommonly found in the environment from various sources [22]. TCDD is used as the toxicstandard to compare the toxicity of other "dioxin-like" CDDs, measured in toxic equivalency orTEQs. The toxicity of dioxin-like CDDs can be half or one tenth or some other fraction of that of2, 3, 7, 8-TCDD [22]. While the potential concentration of dioxin in the ash at the CMD is unknown (sampling data do not exist), exposure could have occurred in the past from the deposition of ash, before the landfill was covered. The concentration of dioxin at other locations may only indicate potential amounts deposited at the CMD site in the past.

The maximum concentration of TEQs detected (one sample-1990) was 73.65 ppt. Otherconcentrations of TEQs detected from samples collected at various locations during this 8year period were below ATSDR's child soil EMEG of 50 ppt. This EMEG is derived fromATSDR's chronic Minimum Risk Level (MRL) of 1 pg TCDD/kg b.w./day, which approximatesaverage background exposures to all dioxin-like compounds in the U.S [22]. ATSDR's MRLs areestimates of daily doses that would not be associated with any detrimental effects over a lifetime ofexposure. Virtually all known chronic, intermediate, and acute effects levels for TCDD rangeupward from 100, 1,000 and 100,000 picograms per kilogram body weight per day (pg/kg/day),respectively. For non-TCDD dioxins, known effect levels in animals exceed a million pg/kg/day or1 ug/kg/day [22].

The higher concentrations also exceed the EPA Region III risk based concentration (RBC) of 4.3ppt TCDD in residential soil. However, this screening value is based on the potential for cancereffects in humans, as extrapolated from animal studies, because the substantial epidemiologicaldatabase on dioxin does not, itself, support the existence of a causal relationship between low leveldioxin exposures and cancer in humans. Because the occupational epidemiologic studies areinsufficient on their own to demonstrate a causal association, the International Agency forResearch on Cancer (IARC) and EPA have based their recent reclassifications of TCDD as aknown human carcinogen on sufficient animal data supplemented with biologically plausibleassumptions regarding the currently unknown mechanism(s) of toxicity of TCDD [23, 24]. Noother "dioxin-like compound," other than a mixture of 1,2,3,6,7,8-HxCDD and 1,2,3,7,8,9-HxCDD, has been tested for carcinogenicity in laboratory animals. The latter mixture was only1/20th (i.e., 0.05 times) as potent a carcinogen as was TCDD, which is only half the potency thatits toxicity equivalency factor (TEF) of 0.1 would suggest [22, 25]. Thus, applying the TCDD-specific RBC to total TEQs would introduce more conservatism into this comparison value. Whileno data exist to evaluate dioxin levels at the CMD site, the maximum level detected at other sources would not be at concentrations where adverse heath effects are expected.

Residents expressed concern regarding potential exposure to contaminants during dirt bike ridingor other occasional recreational activities onsite. According to the environmental monitoringdata reviewed for this consultation, dirt bike riding and other occasional recreational activities onsite should not be associated with any significant chemical exposures. However, visitors to the site should be wary of the potential physical hazards that often exist around landfills and parents should always discourage their children from playing in restricted areas.

Health Outcome Data

According to the MEBOH, citizens of Fairfield expressed concernsregarding a perceived increase in brain cancer cases in the area. The MEBOH reviewed datafrom the cancer registry, hospitals, and conducted a case study of reported brain cancer cases(1983-2000) in Somerset County which includes Fairfield. In addition to looking at different timeperiods, geographic areas, and age groups, this survey also includes information on people accessingthe landfills. In October 1999, ATSDR provided technical assistance for the case study reviewand questionnaire.

MEBOH released a summary of their preliminary findings in their Case Series Investigation ofReportable Brain Tumors Among Young Adults in Fairfield, Maine in January 2001. Thepreliminary review determined that the overall cancer rate in Fairfield was not elevated. However, the brain cancer rate for all adults was two times the expected rate, and five times theexpected rate of brain cancer in people 15-44 years old during the period 1990-2000 whencompared to the state rate. While there appears to be a brain cancer cluster in Fairfield,no association with the landfills has been determined, nor is exposure to any of the landfill-relatedcontaminants evaluated associated with increased risk to brain cancer. [26]

Investigations of suspected cancer clusters can be limited by the current status of scientificknowledge and tools related to genetics; effects of environmental factors on humans; theavailability of statistics on cancer and other diseases by local area; and resources. Many clusterreports do not meet the scientific requirements for true cancer clusters. A true cancer clusterinvolves a large number of cases of one type of cancer, rather than several different types; a raretype of cancer rather than common types; or a number of a certain type of cancer in age groupsnot usually affected by that cancer. These situations may indicate a common source ormechanism of carcinogenesis (the process by which cancer develops). [27]

The health department is currently coordinating efforts with the MEDEP and members ofthe Greater Waterville PATCH Community Assessment Project Group. The MEBOH plans toenhance surveillance for brain tumors for at least an additional five years.


CHILD HEALTH INITIATIVE

ATSDR recognizes that children can react differently than adults when exposed to contaminationin their water, soil, air, or food. Their exposures are likely to be greater than those of adults forseveral reasons: children play outside more often than adults, increasing the likelihood that theywill come into contact with chemicals in the environment; because they are nearer to the ground,children breathe more dust, soil, and heavy vapors; children are also smaller, resulting in higherdoses of chemical exposure per body weight. The developing body systems of children can sustaindamage if toxic exposures occur during certain growth stages.

ATSDR evaluated the likelihood that children living in Fairfield are or were being exposed tocontaminants at levels of health concern. After a review of available environmental data,ATSDR has determined that adverse health effects would not result from exposure tocontaminants identified at this site. The levels of contamination are low and the opportunities for significant exposure are limited.


CONCLUSIONS

1. ATSDR reviewed available environmental data (groundwater, private wells, surfacewater/sediment, and soil) on the CMD Landfill site. Data indicates that no adverse health effects are expected and the site currently poses no apparent public health hazard.

2. The air dispersion modeling was conducted to predict dilution rates of potential aircontaminants released from the landfill during burning of waste in the past. Since no air data areavailable and the model uses simulated data, this method cannot effectively be used to predictshort-term past emissions. The model does predict the direction of long-term air dispersion and isan acceptable tool to help determine locations for long-term ambient air sampling. ATSDR isunable to evaluate potential exposures to contaminants that may have been released during theburning of waste at the landfill in the past.

3. People are not drinking water from on-site monitoring wells and would not be exposed to theconcentrations of arsenic or manganese detected in groundwater samples taken from on-sitemonitoring wells.

4. Arsenic was detected in three of the private. No adverse health effects are expectedas a result of drinking water with these arsenic levels; however, arsenic exposure should beminimized. No volatile or semi-volatile organic compounds were detected. Coliform was detectedin some private wells above safe drinking water standards, and may indicate the presence of otherbacteria.

5. Citizens are not exposed to volatile organic compounds, semi-volatile organiccompounds, or metals at levels of health concern from contact with on-site surface water or sediment samples.

6. Arsenic and silver were detected in on-site soil at one location in the past. Current exposure is limited since the site is capped and has a vegetative cover.

7. Sufficient data does not exist to determine whether people frequenting the site to ride dirtbikes and participate in other occasional recreational activities in the past would have been exposed to contaminants at levels of health concern.


RECOMMENDATIONS

1. The local, federal and state health agencies should continue to provide health education to this community regarding potential exposures to hazardous chemicals in the environment.

2. ATSDR recommends that the MEDEP continue to monitor private wells and provide education to residences where coliform bacteria levels exceed safe drinking water standards.

3. ATSDR concurs with the MEDEP's recommendation that Kimberly-Clark install two additional wells southeast of TB-4 and northeast of TB-3 to further delineate groundwater contamination outside the CMD landfill area.

4. ATSDR recommends that residents minimize arsenic exposure. Residents can contact their state health department for information regarding ways to reduce arsenic exposure.


PUBLIC HEALTH ACTION PLAN

Completed

1. On July 13, ATSDR conducted a site visit and meetings with the state health department andtown officials.

2. On July 13, 2000, ATSDR participated in a community meeting in Fairfield to gather health concerns and explain the public health assessment process.

Planned

1.ATSDR will continue to address questions from concerned citizens.

2. ATSDR will review other data collected, if it becomes available.


SITE TEAM/AUTHORS

Amanda Gonzalez
Environmental Health Scientist
Petition Response Section/Exposure Investigation Consultation Branch
Division of Health Assessment and Consultation, ATSDR

Adele M. Childress, Ph.D., MSPH
Environmental Health Scientist
Petition Response Section/Exposure Investigation Consultation Branch
Division of Health Assessment and Consultation, ATSDR

Frank C. Schnell, Ph.D., D.A.B.T.
Toxicologist
Petition Response Section/Exposure Investigation Consultation Branch
Division of Health Assessment and Consultation, ATSDR

Greg Zarus, M.S.
Atmospheric Scientist
Exposure Investigation Section/Exposure Investigation Consultation Branch
Division of Health Assessment and Consultation, ATSDR


REFERENCES

1. Young, P. NUS Corporation, Inc. Final screening site inspection, Central Maine Disposal Corporation, Fairfield, Maine. 1991 Jul.

2. Maine Department of Environmental Protection (MEDEP). History of Central Maine Disposal Landfill Site, 1976-1999. 1999 Aug. Available at http://www.state.me.us/dep/rwm/Fairfield/CMDhist.htm.

3. Maine Department of Environmental Protection (MEDEP). Final site inspection prioritization report for the Central Maine Disposal Corp., Fairfield, ME. September 1996.

4. Sevee and Maher, Inc. Final construction documentation, Central Maine Disposal Site. September 1993.

5. Richard M. Kelly, Chairman of the Fairfield Community Health Assessment PlanningCommittee, Greater Waterville PATCH. Fairfield Community Health Assessment. Draft. July2000.

6. Young, P. NUS Corporation, Inc. Trip report- site reconnaissance, soil and groundwater sampling. November 1990.

7. United States Protection Agency (EPA. OAQPS). Users guide for the ISCS dispersion model. Research Triangle Park, North Carolina: 1995 revised.

8. Maine Department of Environmental Protection (MEDEP), Bureau of Air Quality. Results froman ISCST3 modeling analysis of dilution profiles for the hypothetical air emissions from burning ofwastes at the Central Maine Disposal Corporation and the Green Road Demolition DebrisLandfills. July 2000.

9. Harding ESE. Phase 2 hydrogeologic investigation report Central Maine Disposal landfill Fairfield, Maine. October 2000.

10. Morrison Geotechnical Engineering. Closure plan for the Central Maine Disposal Ash landfill, MGE Job No. 2151. Fairfield, Maine: May 1986.

11. ABB Environmental Inc. Analytical laboratory data from onsite monitoring wells. Central Maine Disposal Site. March 1991.

12. Kimberly-Clark Corporation. Hydrogeologic investigation report. Central Maine Disposal Landfill, Fairfield, Maine. October 1999.

13. Kimberly-Clark Corporation. Final Phase II Hydrogeologic Investigation Plan. April 2000.

14. Maine Department of Environmental Protection, Bureau of Remediation and WasteManagement. Memorandum to Carole Cifrino from Dick Behr concerning domestic well data,Fairfield, Maine. March 21, 2000.

15. Department of Environmental Management, Department of Remedial and WasteManagement. Phase I hydrogeologic investigation of the Green Road Demolition Debris landfill. Fairfield, Maine. March 2000.

16. Maine Department of Environmental Protection, Bureau of Remediation and WasteManagement. Memorandum to Mike Parker from Dick Behr concerning Phase 2 hydrogeologicalinvestigation report Central Maine Disposal landfill Fairfield, Maine. January 26, 2001.

17. Agency for Toxic Substances and Disease Registry (ATSDR). 1992. Toxicological profile for arsenic. Atlanta, GA:U.S. Department of Health and Human Services, Public Health Service.

18. Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic (Update). Atlanta: U.S. Dept. of Health & Human Services, Public Health Service; 1993 Apr. Report No. TP-92/02.

19. Agency for Toxic Substances and Disease Registry. Toxicological profile for Arsenic (Update), Draft. , U.S. Dept. of Health & Human Services, Public Health Service. February 1999.

20. Marcus WL, Rispin AS. Threshold carcinogenicity using arsenic as an example." In: Advances in modern environmental toxicology, Vol. XV. Risk Assessment and Risk Management of Industrial and Environmental Chemicals. Princeton Scientific Publishing Co. 1998.

21. Stohrer, Gerhard. Arsenic: Opportunity for risk assessment. Archives of Toxicology 1991; 65: 525-31. 1991.

22. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Chlorinated Dibenzo-p-Dioxins (Update). U.S. Dept. of Health and Human Services, Public Health Service, December 1998.

23. International Agency for Research on Cancer. Polychlorinated Dibenzo-para-Dioxins and Polychlorinated Dibenzofurans, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 69, World Health Organization, Lyon, France, 1997.

24. United States Protection Agency (EPA). Exposure and Human Health Reassessment of2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. Part III: Integrated Summary and Risk Characterization for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. EPA/600/P-00/001Ag. June 2000. External Review Draft.

25. United States Protection Agency ( EPA). 1989. Interim procedures for estimating risksassociated with exposure to mixtures of chlorinated dibenzo--dioxins and dibenzofurans (CDDsand CDFs) and 1989 update. Risk Assessment Forum, Washington, DC.

26. Maine Bureau of Health. Case series investigation of reportable brain tumors among young adults in Fairfield, Maine, summary of preliminary findings. January 22, 2001.

27. Centers for Disease Control and Prevention, Cancer Clusters. Accessed May 13, 2002. Available at: http://www.cdc.gov/nceh/clusters/.


APPENDIX A: FIGURES AND HISTORICAL DATA

Intro Map
Figure 1. Intro Map

Area Map
Figure 2. Area Map

Site Map
Figure 3. Site Map

Site Sketch
Figure 4. Site Sketch

Fairfield - Residential Well Sampling Locations
Figure 5. Fairfield - Residential Well Sampling Locations

Arsenic Distribution in Groundwater - July 2000 Sampling Round
Figure 6. Arsenic Distribution in Groundwater - July 2000 Sampling Round

Suggested Monitoring Well Locations
Figure 7. Suggested Monitoring Well Locations

Site Map with Monitoring Wells and Cross-Section Locations - Phase 2 Hydrogeologic Investigation Report
Figure 8. Site Map with Monitoring Wells and Cross-Section Locations - Phase 2 Hydrogeologic Investigation Report

Completed Exposure Pathway

Medium Exposure Route Time of Exposure Exposure Activities Estimated Exposed Chemicals Public Health Concern
private wellwateroral, dermalpast, current, future drinking/eating 3 residences
(<10 people)
arsenic no

Potential Exposure Pathway

Medium Exposure Route Time of Exposure Exposure Activities Estimated Exposed Chemicals Public Health Concern
airinhalationpastoutsideactivitiesduringburning at thelandfill 100-200peoplearsenic Indeterminate

Historical Data

provided by MEDEP[2]

1976 MEDEP issues a license to operate a landfill in gravel pits on the Hapworth farm on MiddleRoad in Fairfield Center.

1976-81 Middle Road dump accepts approved wastes of fly ash, wood room waste and caustic limedregs from Scott Paper Co. mills in Skowhegan and Winslow. Unapproved wastes includingpetroleum products, 55-gal drums and chemicals also dumped.

1976-85 MEDEP visits the CMD 16 times, violations observed in most cases, including unacceptablewaste on-site, wasted deposited in unlicensed areas and unrestricted site access.

1979 Pond surface water samples taken from the site are found to be highly caustic, burning the skinof a MEDEP representative.

1981 MEDEP orders CMD to stop operations, but operations continue

1984 CMD taken to court by State attorney general

1985 Judge fines CMD $4,000 but allows operation to continue

1985 Monitoring wells are installed and water sampled. Sodium and sulfates found to be above thedrinking water standards. Site operations cease.

1985-93 CMD site not fenced or covered. Fires persist on site.

1986 CMD submits a closure plan, but is not acceptable to DEP

1990 Groundwater and soil testing finds three VOCs and one SVOC on site. Eight inorganiccompounds, including arsenic and mercury found at elevated levels in down-gradient ground watersamples.

1993 Landfill closed and capped under deep overlie.

1995 Kimberly-Clark Corp of Dallas, Texas buys Scott Paper Co.

1996 DEEP report shows unapproved wastes were dumped at the site

1997-99 Kimberly-Clark tests show arsenic in groundwater samples at the landfill to exceed drinkingwater standards.

1999 Residential wells tested by MEDEP in May and June at homes around the dump. Arsenicdetected in two wells at levels exceeding drinking water standards.

1999 Additional wells drilled for new groundwater testing in August.

1999 October, MEBOH announces the cancer cluster in Fairfield Center, with excess cases forbrain cancer and tumors in residents between the ages of 15 and 44.

2000 January, MEDEP samples 12 additional residential wells. Arsenic is detected in some of thesamples, and coliform levels are above the standard in some well samples.

2000 April, Kimberly-Clark submits Final Phase 2 Investigation Plan, providing for the placement ofadditional wells and additional monitoring of groundwater.

2000 July, Harding ESE, for Kimberly-Clark, completes another round of groundwater sampling andresidential well sampling according to the Phase 2 Investigation Plan.

2000 October, Phase 2 Hydrogeological Investigation Report submitted to MEDEP for Kimberly-Clark by Harding ESE summarizing findings from groundwater monitoring and residential wellsampling. Additional well installations are recommended for continued monitoring.

2001 January, MEBOH completes summary of preliminary findings for their Case SeriesInvestigation of Reportable Brain Tumors Among Young Adults in Fairfield, Maine.

The Maine Department of Environmental Protection (MEDEP) reviewed historical data and pastsampling information to identify the chemicals that may be present in either waste material orlandfill. The chemicals identified include polychlorinated dibenzodioxins and dibenzofurans,methylene chloride, acetone, chlorobenzene, naphthalene, arsenic, cadmium, chromium, lead, silver, manganese, and barium.


APPENDIX B: ATSDR'S COMPARISON VALUES

ATSDR comparison values are media-specific concentrations that are considered to be "safe" underdefault conditions of exposure. They are used as screening values in the preliminary identificationof "contaminants of concern" at a site. The latter is, perhaps, an unfortunate term since the word"concern" may be misinterpreted as an implication of "hazard". As ATSDR uses the phrase,however, a "contaminant of concern" is merely a site-specific chemical substance that the healthassessor has selected for further evaluation of potential health effects.

Generally, a chemical is selected as a contaminant of concern because its maximum concentrationin air, water, or soil at the site exceeds one of ATSDR's comparison values. However, it cannot beemphasized strongly enough that comparison values are not thresholds of toxicity. Whileconcentrations at or below the relevant comparison value may reasonably be considered safe, it doesnot automatically follow that any environmental concentration that exceeds a comparison valuewould be expected to produce adverse health effects. Indeed, the whole purpose behind highlyconservative, health-based standards and guidelines is to enable health professionals to recognizeand resolve potential public health problems before they become actual health hazards. Theprobability that adverse health outcomes will actually occur as a result of exposure to environmentalcontaminants depends on site specific conditions and individual lifestyle and genetic factors thataffect the route, magnitude, and duration of actual exposure, and not on environmentalconcentrations alone.

Screening values based on non-cancer effects are obtained by dividing NOAELs or LOAELsdetermined in animal or (less often) human studies by cumulative safety margins (variously calledsafety factors, uncertainty factors, and modifying factors) that typically range from 10 to 1,000 ormore. By contrast, cancer-based screening values are usually derived by linear extrapolation fromanimal data obtained at high doses, because human cancer incidence data for very low levels ofexposure simply do not exist, and probably never will. In neither case can the resulting screeningvalues (i.e., EMEGs or CREGs) be used to make realistic predictions of health risk associated withlow-level exposures in humans.

Listed and described below are the various comparison values that ATSDR uses to select chemicalsfor further evaluation, along with the abbreviations for the most common units of measure.

CREG = Cancer Risk Evaluation Guides
MRL = Minimal Risk Level
IMRL = Intermediate Risk Level
CMRL = Chronic Risk Level
EMEG = Environmental Media Evaluation Guides
aEMEG= Environmental Media Evaluation Guide based on acute Minimal Risk Level
IEMEG = Intermediate Environmental Media Evaluation Guides
RMEG = Reference Dose Media Evaluation Guide
RfD = Reference Dose
RfC = Reference Dose Concentration
EPAIII= EPA Region III
DWEL= Drinking Water Equivalent Level
CLHA= Child Longer-Term Health Advisory
LTHA= Drinking Water Lifetime Health Advisory
MCL = Maximum Contaminant Level
MCLG= Maximum Contaminant Level Goal (µg/L)
MCLA= Maximum Contaminant Level Action
NAAQS= National Ambient Air Quality Standards
PEL = Permissible Exposure Limit (OSHA)
REL = Recommended Exposure Limits (NIOSH)
TLV = Threshold Limit Value (ACGIH)
FDA = Food and Drug Administration
ppm = parts per million, e.g., mg/L or mg/kg
ppb = parts per billion, e.g., µg/L or µg/kg
ppt = parts per trillion, e.g., ng/L or ng/kg
kg = kilogram (1,000 grams)
mg = milligram (0.001 grams)
µg = microgram (0.000001 grams)
L = liter
m3 = cubic meter (used in reference to a volume of air equal to 1,000 liters)

Cancer Risk Evaluation Guides (CREGs) are estimated contaminant concentrations in water, soil,or air that would be expected to cause no more than one excess cancer in a million persons exposedover a lifetime. CREGs are calculated from EPA's cancer slope factors.

Minimal Risk Levels (MRL) are estimates of daily human exposure to a chemical (i.e., dosesexpressed in mg/kg/day) that are unlikely to be associated with any appreciable risk of deleteriousnon-cancer effects over a specified duration of exposure. MRLs are derived for acute (< 14 days),intermediate (15-364 days), and chronic (>365 days) exposures, and are published in ATSDR'sToxicological Profiles for specific chemicals.

Environmental Media Evaluation Guides (EMEGs) are concentrations of a contaminant in water,soil, or air that are unlikely to be associated with any appreciable risk of deleterious non-cancereffects over a specified duration of exposure. EMEGs are derived from ATSDR minimal risk levelsby factoring in default body weights and ingestion rates. Separate EMEGs are computed for acute(<14 days), intermediate (15-364 days), and chronic (>365 days) exposures.

Intermediate Environmental Media Evaluation Guides (IEMEG) are media-specificconcentrations that correspond to a minimal risk level, factoring in body weight and ingestion ratesfor intermediate exposures (i.e., >14 days and <1 year).

Reference Dose Media Evaluation Guide (RMEG) is the concentration of a contaminant in air,water or soil that corresponds to EPA's RfD of RfC for that contaminant when default values forbody weight and intake rates are taken into account.

EPA's Reference Dose (RfD) is an estimate of the daily exposure to a contaminant unlikely tocause non-carcinogenic adverse health effects over a lifetime of exposure. Like ATSDR's MRL,EPA's RfD is a dose expressed in mg/kg/day.

Reference Concentrations (RfC) is a concentration in air expected to be associated with nodeleterious health effects over a lifetime of exposure, assuming default body weights and inhalationrates.

Environmental Protection Agency Region III (EPAIII) values are similar to ATSDR'sAMBAGIOUS in that they are risk-based concentrations (RBCs) derived for carcinogens and non-carcinogens from RfDs and Cancer Slope Factors, respectively, assuming default values for bodyweight, exposure duration and frequency, etc. Unlike AMBAGIOUS, however, they are availablefor fish, as well as for water, soil, and air.

Drinking Water Equivalent Levels (DWEL) are based on EPA's oral RfD and representcorresponding concentrations of a substance in drinking water that are estimated to have negligibledeleterious effects in humans over a lifetime of exposure, at an intake rate of 2 L/day, and assumingthat drinking water is the sole source of exposure to the contaminant. Similar to ATSDR's RMEGfor drinking water.

Child Longer-Term Health Advisories (CLHAs) are contaminant concentrations in water thatthe Environmental Protection Agency (EPA) deems protective of public health (taking intoconsideration the availability and economics of water treatment technology) over a period of about7 years, using a child's weight (10 Kg) and ingestion rate (1 L/day).

Lifetime Health Advisories (LTHA) are calculated from the DWEL and represent theconcentration of a substance in drinking water estimated to have negligible deleterious effects inhumans over a lifetime of 70 years, assuming 2 L/day water consumption for a 70-kg adult, andtaking into account other sources of exposure. In the absence of chemical-specific data, theassumed fraction of total intake from drinking water is 20%. Lifetime HAs are not derived forcompounds which are potentially carcinogenic for humans.

Maximum Contaminant Levels (MCLs) represent contaminant concentrations in drinking waterthat EPA deems protective of public health (considering the availability and economics of watertreatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day.

Maximum Contaminant Level Goals (MCLGs) are drinking water health goals set at levels atwhich no known or anticipated adverse effect on the health of persons occurs, allowing for anadequate margin of safety. Such levels consider the possible impact of synergistic effects, long-termand multi-stage exposures, and the existence of more susceptible groups in the population. Whenthere is no safe threshold for a contaminant, the MCLG should be set at zero.

Maximum Contaminant Level Action (MCLA) are levels set by EPA under Superfund that triggera regulatory response when the contaminant concentration exceeds this value.

National Ambient Air Quality Standards (NAAQS) are established by the EPA, as mandated inthe Clean Air Act, for six criteria pollutants (carbon monoxide, sulfur dioxide, nitrogen dioxide,ozone, particulate, and lead). NAAQS are classified as either primary, which defining levelsdeemed protective of public health, or secondary, which in some instances establishing lower levelsto prevent adverse effects on vegetation, property, or other elements of the environment.

Permissible Exposure Limits (PELs) are air standards developed by the Occupational Safety andHealth Administration for the workplace. They are time-weighted average concentrations ofcontaminants considered safe for healthy workers over the course of an 8-hr workday and a 40-hrworkweek. A PEL may be exceeded for brief periods, but the sum of the exposure levels averagedover 8 hours must be equal to or below the PEL.

Recommended Exposure Limits (RELs) are established by the National Institute for OccupationalSafety and Health and are similar to OSHA's PELs. They are time-weighted average concentrationsfor the workplace deemed to be safe for up to 10 hours/day, for 40-hours/week.

Threshold Limit Values (TLV) are established by the American Conference of GovernmentalIndustrial Hygienists (ACGIH). The TLV is the time-weighted average concentrations for a normal8-hour workday and a 40-hour workweek, to which nearly all workers may be repeatedly exposed,day after day, without adverse effect. Many of ACGIH's TLVs were adopted by OSHA for use asPELs. TLVs and PELs, which were designed to protect healthy workers, are usually much higherthan the health-based values of ATSDR and EPA, which were designed to protect the health of thegeneral population, including the very young and the elderly. Although the ATSDR does not baseany of its community health decisions on TLVs or PELs, it sometimes cites such values in PublicHealth Assessments merely as a means of putting concentrations of site-specific contaminants into ameaningful perspective for the reader.

The Food and Drug Administration (FDA) has recommended concentration levels for certainsubstances in food, including fish. Levels above the FDA levels mean the food may be unsafe forhuman consumption.

COMPARISON VALUE REFERENCES

  1. Agency for Toxic Substances and Disease Registry. Health assessment guidance manual.Atlanta: U.S. Department of Health and Human Services; 1992 Oct.

  2. National Institute for Occupational Safety and Health. Pocket guide to chemical hazards. Washington D. C: U. S. Department of Health and Human Services; 1994 Jun.

  3. U. S. Environmental Protection Agency. New interim region IV guidance for toxicityEquivalent factors methodology for carcinogenic PAHs. Washington, D. C: 1992 Feb.


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