PUBLIC HEALTH ASSESSMENT
GEIGY CHEMICAL CORPORATION SITE
[a/k/a GEIGY CHEMICAL CORPORATION (ABERDEEN PLANT)]
ABERDEEN, MOORE COUNTY, NORTH CAROLINA
The Geigy Chemical Corporation Site is a property of approximately two acres in Moore County,North Carolina, about half a mile east of the town of Aberdeen. A pesticide blending and retailfacility operated on the property from 1948 to 1989. The pesticide blending operations wereconducted until 1967; retail sales of agricultural chemicals continued until 1989. In September of1989, the U.S. Environmental Protection Agency (EPA) placed the site on the National PrioritiesList (NPL) because the groundwater and soil were found to be contaminated with pesticides. Thepesticide lindane was detected in Aberdeen municipal wells in 1985. Subsequent investigationsby EPA and the companies involved (Ciba-Geigy Corporation, Olin Corporation, KaiserAluminum, and Chemical Corporation) revealed that the groundwater was contaminated in aplume extending west of the site.
The surface area of the site has been completely remediated. The responsible parties removedmore than 7,000 tons of soil and debris in a series of remedial actions. The surface of the site isnow covered with rye grass, wild flowers, and pine trees. In 1996, the companies involvedinstalled seven extraction wells and constructed a groundwater treatment facility that is still inoperation. Additional monitoring wells were installed in 1998 to evaluate the extraction process.
The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated the limitedinformation concerning past consumption groundwater contaminated with low levels ofpesticides. ATSDR concludes that there were no apparent public health hazards associated withthe reported low levels in the municipal and private water supplies.
ATSDR also evaluated off-site soil data and concluded that past exposure to pesticides in off-sitesoil posed no apparent public health hazard. Past human exposure to airborne pesticides is anindeterminate public health hazard because no air measurements were taken in the surroundingcommunity during the period of operation and thus there are no data to be analyzed. If highconcentrations of pesticides had been present, on-site workers were more likely to have beenexposed than the few nearby residents because the plant was separated from residentialproperties by a major highway and a railroad.
Based on the information reviewed, ATSDR finds no current or foreseeable future public healthhazards associated with the Geigy site as long as groundwater remediation proceeds as plannedand there are no changes in land use conditions. All residences and businesses in thedowngradient area have now been connected to the municipal water supply system, whichsupplies water that meets drinking water standards. The companies involved had the residence ofthe last person using a private well immediately downgradient from the site connected to themunicipal system in late 1999. The companies will continue to monitor the groundwater at thesite in accordance with plans developed under the record of decision for the site, which wasapproved by EPA and the North Carolina Department of Environment Health and NaturalResources (NCDEHNR).
Soil investigations performed after remediation show that the levels of the contaminants found on the site are below EPA performance standards and posed no public health threats.
In this public health assessment, ATSDR evaluated the public health significance of the Geigysite in Aberdeen, North Carolina. More specifically, ATSDR reviewed available environmentaland health outcome data and community health concerns to determine whether adverse healtheffects were possible. In addition, evaluations considered whether actions are needed to reduce,prevent, or further identify the possibility for site-related adverse health effects. ATSDR isrequired by the Comprehensive Environmental Response, Compensation, and Liability Act of1980 (CERCLA, often called the Superfund Law), as amended by the Superfund Amendmentsand Reauthorization Act of 1986 (SARA), to conduct public health assessments of sites placedon the National Priorities List.
This public health assessment focuses on pesticide contamination found in groundwater and soilat and near the Geigy site. Although trichloroethylene (TCE) has been detected at elevated levelsin groundwater at Aberdeen, this report does not address TCE contamination. The companiesinvolved have had a contractor, Rust Environmental and Infrastructure, conduct extensivegroundwater investigations. These investigations have demonstrated that the source of the TCEdetected in the groundwater is located hydraulically upgradient of the site. EPA has thereforeconcluded that the source of the TCE is not related to the former pesticide facility (Rust 1996).
A draft of this public health assessment was issued for public comment on January 12, 2000.Four hundred factsheets concerning the draft public health assessment were mailed out citizens inMoore County, North Carolina and other interested parties listed on the EPA mailing list for thesite. Copies of the draft document were placed in the public repository for site documents at theAberdeen Town Hall. ATSDR conducted a public availability session in the town of Aberdeen,North Carolina on January 19 to answer questions about the site and elicit comments from thecommunity. The public comment period closed on February 25, 2000. No public commentswere received concerning the draft public health assessment of the Geigy Chemical Corporation site.
The Geigy site is a two-acre, triangularly shaped area bordered by Route 211 to the north, anactive railway to the south (the Aberdeen and Rockfish railroad), and private property to the eastand west (see Figure 1 in Appendix A). The property lies one-half mile east of the town ofAberdeen, North Carolina. The site was leased to various pesticide-blending facilities from 1948to 1967, including Geigy (1948 to 1955) and the Olin-Mathieson Chemical Corporation (1956 to1967). From 1967 to 1989, various companies used the property for retail sales and distributionof agricultural chemicals. The last occupant abandoned the property in March 1989.
Geigy's operation involved blending of technical-grade pesticides including 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), toxaphene, and benzene hexachloride (BHC) with inertmaterials to form the end products. The Olin-Mathieson Chemical Corporation also operated apesticide formulation, packaging, and distribution facility at the site, using similar blends oforganochlorines.
During 1985 and 1986, sampling and analyses of the Aberdeen municipal well water detectedBHC in four wells. Later analyses of tap water in the system did not reveal any concentration ofpesticides at or above a health concern level. As a prudent public health measure, the town ofAberdeen closed the most contaminated well, Municipal Well 1, in March 1986.
The NCDEHNR performed a preliminary assessment of the Geigy site in February 1987. TheU.S. Environmental Protection Agency (EPA) conducted a site inspection in March 1988 togather additional information. Based on the findings of the investigations, EPA placed the site onthe National Priorities List (NPL) in September 1989.
In 1990, EPA entered into an agreement with the companies to conduct a remedial investigation(RI) and feasibility study. The purpose of the remedial investigation was to determine the typeand distribution of site-related contaminants (Rust, 1996). In addition to sampling the soil andgroundwater, the companies removed more than 3,300 tons of contaminated soil and debris intwo separate actions (Sirrine, 1992). Pesticides were detected directly underneath the site in theSurficial Aquifer, but not in the aquifers supplying drinking water (e.g., the Upper and LowerBlack Creek aquifers). Pesticides were, however, detected in the Upper Black Creek Aquiferapproximately 375 feet south of the site.
In August 1992, EPA issued a record of decision for the site, calling for the removal and properdisposal of the remaining contaminated soil (top 12 inches) and building foundations. Inaddition, the record of decision required that groundwater be extracted and treated on site.
From 1993 to 1995, Rust conducted several field investigations for the companies to furtherdefine the presence and extent of pesticides detected in the groundwater during the remedialinvestigation, and to collect data needed to design the remedial activities.
In 1993, ATSDR awarded a grant to the University of North Carolina School of Public Health tostudy the effects on the immune system of residential exposure to hazardous waste sites. TheUniversity of North Carolina research team chose the town of Aberdeen as their research area.This choice was independent of ATSDR. ATSDR has not recommended the Geigy site for anyfollow-up health studies.
EPA and NCDEHNR approved the Geigy site remediation plan in March 1996, and, by the endof the year, the remedial action was completed. An additional 4,473 tons of contaminated soilwere excavated, and the remaining concrete foundations were demolished. Seven extractionwells and six monitoring wells were installed. The groundwater treatment facility wasconstructed, and the groundwater extraction and treatment system began operating in January1997. Additional monitoring wells were installed in 1998.
Appendix B contains a more detailed chronology of site-related events.
ATSDR first became involved with the municipal well contamination problem in 1986 whileproviding public health advice to EPA on removal activities associated with the nearby AberdeenPesticides NPL site.(1) ATSDR prepared a preliminary health assessment of the AberdeenPesticides site in 1988. At that time the Geigy site was not a suspected source of the municipaland private well water contamination.
ATSDR regional representatives visited the Aberdeen area several times between 1986 and 1998. In 1994, ATSDR staff members again surveyed the Geigy site. On September 7, 1995, ATSDRparticipated in an EPA-sponsored public meeting to assess the level of community concerns.ATSDR later visited the Geigy site in 1997 to survey the progress of site remediation.
The possible public health impact from contaminated groundwater is evaluated in this section ofthe report for two past exposure situations, private well water and municipal water. Table 1summarizes the results of these evaluations.
No Aberdeen residents are currently exposed to contaminated groundwater. The town ofAberdeen has closed contaminated municipal wells and informed EPA that it will not install anynew wells in the areas downgradient of the site (EPA, 1988). All residences and businesses in thedowngradient area have now been connected to the municipal water system, which supplieswater that meets drinking water standards.
The companies have clearly defined the extent of groundwater contamination. They beganextraction and treatment of contaminated water on the site in 1997 to reduce contaminant levelsand the potential for migration of contaminants.
The evaluation led ATSDR to conclude that the past Geigy groundwater exposure situations posed no apparent public health hazard.
|Situations||Contaminants of Concern||Receptor Population||Route of Exposure||Frequency of Exposure||Public Health Classification|
|Municipal water||BHC isomers||2,296*||ingestion |
|daily||No apparent public health hazard|
|Private well water||BHC isomers||10**||ingestion |
|daily||No apparent public health hazard|
** Based on the assumptions that no more than 4 homes were affected by the contaminant plume and that each home had 2.5 residents.
Both municipal and private water supplies are derived from aquifers(2) in the Aberdeen area.Although three aquifers lie beneath the Geigy site (Rust, 1995a), only one--the Black CreekAquifer--supplies drinking water. The Black Creek Aquifer is divided into two distinct units, theUpper Black Creek Aquifer and the Lower Black Creek Aquifer, and is located approximately 50to 90 feet underground. It lies between the uppermost aquifer (the Surficial Aquifer) and thelowest aquifer (the Cape Fear Aquifer). Pesticides used in activities at the Geigy site leached through the soil into the groundwater.
ATSDR reviewed groundwater data and selected several contaminants for more detailedevaluation of public health significance. A description of the process for selecting thesecontaminants of concern is provided in Appendix C. Readers are advised to read the publichealth implications section before making any conclusions about contaminant levels ingroundwater. As described in Appendix C, finding a contaminant level above a comparison valueonly means that further evaluation is needed. It does not necessarily mean that the contaminant would cause adverse health effects.
Lindane and other BHC isomers(3) were measured in 4 of the 9 Aberdeen municipal wellsbeginning in 1986. During the February 1986 monitoring, measurements for pesticides were alsomade from two drinking water taps (Austin Apartments and Town Hall) within the system, aswell as from three fire hydrants. Austin Apartments and the fire hydrant were resampled inMarch 1986. The maximum concentration of lindane was 11.4 parts per billion (ppb), which wasmeasured in a March 1986 sample from Municipal Well Number 1 (Table 2). To prevent anyadverse health effects from potential future increases in contaminant levels, Municipal WellNumber 1 was disconnected from the public water system in March 1986. Municipal WellNumber 4 was closed in January 1992 after a maximum lindane concentration of 4 ppb wasdetected in March 1987.
|Chemical||Maximum Concentration Detected |
|Location of Maximum Concentration||Comparison Value |
|Comparison Value Reference|
|Child EMEG (I) |
Adult EMEG (I)
|MUW = municipal well |
before = before well closure
after = after well closure
n = number of samples
CREG = cancer risk evaluation guide. See Appendix H for an explanation.
RMEG = reference dose media evaluation guide. See Appendix H for an explanation.
In 1987 NUS Corporation sampled 10 private wells in the vicinity of Geigy (9 off site and 1 onsite) for EPA, and detected BHC isomers at low levels in two wells, one south and the othersoutheast of the site. Lindane was detected at 1.3 ppb and alpha-BHC at 1.7 ppb (NUS, 1988).EPA sampled again in 1989.
The companies conducted a field survey of private wells in the vicinity of the Geigy site in April1994 and March 1995, identifying nine private wells downgradient of the site. The companiessampled water from private wells during 1994-1996.
Of these nine wells, five were no longer in use, either because the residences were unoccupied orhad been hooked up to, and were using, municipal water (Hilliard, 1996). Of the remaining fourwells, two were used for gardening or washing cars; one had an activated carbon treatmentsystem installed on it in June 1994; and one (PW-17) was used for filling the swimming pool andwatering the yard, but was abandoned in August 1995. Shortly before this well was abandoned,BHC isomers and dieldrin were detected in it at levels exceeding ATSDR's comparison values(See Table 3).
|Chemical||Maximum Concentration Detected |
|Date||Location of Maximum Concentration||Comparison Value |
|Comparison Value Reference|
|Child EMEG(I) |
Adult EMEG (I)
|PW = private well |
CREG = cancer risk evaluation guide. See Appendix H for an explanation.
EMEG (I) = environmental media evaluation guide, Intermediate exposure. See Appendix H for an explanation.
Monitoring wells are used strictly for testing for levels of contaminants in groundwater. They arenot used for drinking water. EPA, and Geigy's contractor, Rust, sampled for pesticides frommonitoring wells on numerous occasions from 1990 to 1995. Groundwater sampling from thesewells indicated that the Surficial Aquifer was contaminated with pesticides directly beneath theGeigy site, and that pesticides were migrating from this aquifer into the Upper Black CreekAquifer approximately 300 feet south of the site. Pesticide contamination in the Upper BlackCreek Aquifer was limited to the area south of Route 211, and was partially bounded byMcFarland's Branch to the west. Pesticide contamination in the Lower Black Creek Aquifer wasprimarily limited to the area west of the site where the aquifers mix (Rust, 1996). For a moredetailed description of the monitoring well investigations, see Appendix D.
Approximately 70% of Aberdeen residents using the municipal water supply may have beenexposed to very low levels of lindane and other BHC isomers. The Aberdeen municipal waterwells are divided into two service areas. Municipal wells 2, 3, 6, and 7 are located in the northernarea of the town, essentially upgradient from any known sources of pesticide contamination.These 4 wells serve residences and businesses in the northern portion of the town, an estimated30% of the population (Monroe, 1999). The other wells serve the rest of the community. Thetown of Aberdeen blends the water from the wells in each service area before distributing it toindividual taps.
The 70% of area residents supplied with water from the other service area may have beenexposed to contaminated groundwater up to January 1992 when Municipal Well 4 was closed.Because no municipal well data exist prior to 1986, ATSDR does not know the exact number ofyears that Aberdeen residents may have been exposed to low levels of lindane in their drinkingwater.
Exposure may have occurred through ingestion of contaminated groundwater, and throughinhalation and dermal absorption of contaminants. Volatile compounds, such as some pesticides,can escape as gases during showering, bathing, or cooking. However, because most of thepesticides detected at Geigy are not very volatile, ATSDR concludes that inhalation is not a significant route of exposure.
Nine private wells were located downgradient of the site. Pesticides were detected at low levelsin only a few of these wells. Residents using private well water from these wells may have beenexposed to BHC isomers and other pesticides in the past. Exposure was possible as early as the1980s, when the wells were identified and sampled, but could have begun earlier. As of therelease of this report, the companies have connected the residence of the last person whoconsumed drinking water from private well water in the downgradient area to the municipalwater supply system. (Previously, the companies had installed a carbon filter on that resident'swell, and periodically monitored it to ensure that the filter was working properly and that harmfullevels of pesticides were not being consumed.) Occupants of two other residences continue to usetheir wells for watering lawns and gardens. All other residences and businesses with private wellsin the downgradient area have been connected to city water that meets drinking water standards.
This section of the health assessment focuses on estimating how much of the pesticides people in thecommunity might have been exposed to daily and how that estimated dosage compares to doses thatmay produce health effects, both carcinogenic and noncarcinogenic.
Based on likely, site-specific considerations, and using conservative assumptions about how oftenpeople drink and how much they drink, ATSDR estimated the doses of pesticides which people mighthave received from using contaminated groundwater. These estimates allow ATSDR to evaluate thelikelihood, if any, that pesticides in groundwater are associated with adverse health effects. SeeAppendix C for further discussion on how ATSDR determines the public health implications at agiven site.
ATSDR assumed that residents drank 2 liters (approximately 2 quarts) of tap water each day, and thatthe average resident weighed 70 kilograms (kg), or about 150 pounds. This is a conservativeassumption because many individuals obtain their liquid requirements from other sources such asmilk, juice, or soda. Children were assumed to drink 1 liter of tap water each day and to weigh 16 kg(about 35 pounds).
Lindane was evaluated for noncancer effects, and the other BHC isomers were evaluated fornoncancer and cancer effects. Dieldrin was evaluated for cancer effects.
Residents served by the contaminated municipal wells are unlikely to have received doses causingadverse health effects. Although lindane was measured in Municipal Well 1 at 11.4 ppb, theconcentration of lindane measured at two drinking water taps and three hydrants was at or below 1ppb.
Using 1 ppb as the maximum level of lindane detected in tap water, calculated doses of lindane were0.0000625 milligrams per kilogram per day (mg/kg/day) for children and 0.000028 mg/kg/day foradults. Although the estimated dose to children is higher than the MRL(4) (0.00001 mg/kg/day), theMRL contains a safety factor of 1,000 to account for human variability and other issues.
Alpha-BHC and beta-BHC exceeded only the comparison value for cancer risk.(5) Although neitherpesticide was tested for in tap water, it can be safely assumed that, like lindane, concentrations ofthese pesticides were also lower at the tap than in the wells. Assuming that these pesticides wouldhave been present in tap water at a maximum concentration of 1 ppb (but could have been as much astenfold lower, or 0.3 for alpha-BHC and 0.5 for beta-BHC), estimated doses to both adults andchildren for each isomer were at least 10,000 times lower than doses causing cancer in laboratory animals.
BHC isomers and dieldrin were detected at low levels in a few private wells during multiple samplingrounds in 1987, and from 1994 to 1996. It is unlikely that residents were exposed to these pesticidesat levels capable of causing adverse health effects.
Alpha-BHC, beta-BHC, and dieldrin(6) exceeded only the CREG comparison value for cancer risk. Theestimated doses to both children and adults for alpha-BHC (0.0004 and 0.00018 mg/kg/day) and beta-BHC (0.00075 and 0.00034 mg/kg/day) were at least 1,000 times lower than doses causing cancer inlaboratory animals. The doses estimated for dieldrin were 10,000 times lower than the doses causingcancer in laboratory animals. Note that there are no comparable studies for human exposure.
ATSDR calculated doses using the maximum concentration of lindane detected in the unfilteredwater as a potential indicator of past exposure (6.5 ppb). The estimated doses for lindane exposure tochildren and adults were greater than the MRL. However, these doses are at least 200 times lowerthan the lowest dose shown to cause health effects in an animal study from which the MRL is derived(Meera et al., 1992).(7) In addition, the MRL contains a safety factor of 1,000 to account for humanvariability and other issues. Therefore, ATSDR believes it is unlikely that Aberdeen residents were exposed at levels of health concern.
Conclusion: ATSDR concludes that the past groundwater exposure situations at the Geigy site posedno apparent public health hazard. Harmful exposures to lindane and other pesticides were preventedby the timely public health actions of disconnecting the contaminated municipal wells from theAberdeen water supply system and providing safe alternative water supplies or treatment for residentsusing contaminated domestic wells.
Conclusion: Present and potential future exposure to contaminated groundwater poses no publichealth hazard. Currently no residents are exposed to contaminated private or municipal well water.The companies have well defined the extent of groundwater contamination associated with the Geigysite, and remediation efforts are underway to remove and treat contaminated water.
Recommendation: ATSDR recommends that the companies continue periodic groundwatermonitoring at the Geigy site in accordance with the plans developed under the record of decision andapproved by EPA and the NCDEHNR to ensure that no contaminants affect public or private water wells in use.
The possibility of public health impact by soil contaminants is evaluated in this section of the report for one exposure situation, off-site soils.
No Aberdeen residents are currently exposed to pesticides in off-site soils at levels of health concern.The companies have completed soil remediation at the site.
The evaluation led ATSDR to conclude that the past Geigy soil exposure situation posed no apparent public health hazard.
Activities at Geigy resulted in significant pesticide contamination of on-site soils. Pesticide-contaminated soil can migrate off the site through storm water runoff, or as wind-borne particulates.People and equipment (e.g., earth-moving, or transportation) can also inadvertently or intentionallycarry contaminated soil off site.
Starting in 1987, EPA and the companies conducted a series of soil remediations, removing morethan 7,000 tons of contaminated soil and debris, from both on and off the site. In 1996, Rust sampledthe soil to verify that the remediation had achieved its goals. The results of this sampling effortindicated that the remediation reduced pesticide contamination in surface soils to EPA performancestandards, which are generally no more than 10 times greater than ATSDR Comparison Values (SeeAppendix G). However, because a few individual samples exceeded performance standards, thecompanies excavated an additional 129 cubic yards of surface soil, at the request of the NCDEHNR (Rust, 1997a).
|Situations||Key Contaminants||Receptor Population||Route of Exposure||Frequency of Exposure||Public Health Classification|
|Off-site soil||Chlordane |
|unknown||No apparent public health hazard|
ATSDR reviewed soil data and selected several contaminants for more detailed evaluation of publichealth significance. A description of the process for selecting these contaminants of concern isprovided in Appendix C. Readers are advised to read the public health implications section beforemaking any conclusions about contaminant levels in soil. As described in Appendix C, finding acontaminant level above a comparison value only means that further evaluation is needed. It does notnecessarily mean that the contaminant would cause adverse health effects.
Chlordane, DDT, and toxaphene were identified as contaminants of concern for the off-site soilexposure situation. BHC isomers, DDE, and dieldrin were also detected, but not at concentrations meriting further evaluation.
Table 5 summarizes the maximum concentration of pesticides detected in off-site soil prior to initial remediation efforts in 1987. For more information on soil sampling, see Appendix D.
|Chemical||Maximum Concentration Detected |
|Date||Comparison Value |
|Comparison Value Reference|
|Chlordane (tech. mixture)||4.3||3/23/87||30 |
|Child EMEG (Chronic) |
Adult EMEG (Chronic)
|Child RMEG |
|Child EMEG (Intermediate) |
Adult EMEG (Intermediate)
|CREG = cancer risk evaluation guide (See Appendix H for an explanation) |
EMEG = environmental media evaluation guide (See Appendix H for an explanation)
ppm = parts per million
RMEG = reference dose media evaluation guide (See Appendix H for an explanation)
Exposure to contaminated soil is a potential past exposure pathway. Residents may have beenexposed to off-site surface soils via dermal contact or incidental ingestion. Residents may also havebeen sporadically exposed to on-site soils before the site was secured in 1989. However, because theplant was separated from residential properties by a major highway and a railroad, on-site workers aremore likely to have been exposed than the few nearby residents. For this reason, ATSDR did not evaluate potential exposure to on-site soils.
ATSDR estimated the doses of pesticides to which people may have been exposed from contact withcontaminated soil. These estimates allow ATSDR to evaluate the likelihood, if any, that pesticides insoil are associated with adverse health effects.
For soil, ATSDR assumed that adults ingested 100 milligrams (mg) of contaminated soil each day for40 years, and that the average resident weighed 70 kilograms. Children were assumed to ingest 200mg of contaminated soil for six years, and to weigh on average 16 kilograms. Soil ingestion can occurby the inadvertent consumption of soil on hands or food items. Children may also ingest soil byputting objects in their mouths, or from ingesting non-food items. Exposure can occur in the homewhen contaminated soil is brought into the home on the feet of family members and pets.
It is important to stress that soil doses were based on the maximum level of contaminants detected inoff-site soil, and that residents were not necessarily exposed to these levels.
Chlordane was detected in off-site soil at a low level exceeding only the CREG comparison value forcancer risk. The estimated child and adult doses of chlordane from off-site soil were more than10,000 times lower than the lowest dose that caused cancer in animals (1.21 mg/kg/day, Khasawinahand Grutsch, 1989).(8) ATSDR therefore concludes that nearby residents would not have experiencedan increased cancer risk from exposure to chlordane in off-site soils.
DDT was detected in off-site soil at a level 5 times higher than the CREG. The estimated dose ofDDT from off-site soil exposure, however, is at least 1,000 times lower than the doses fed tolaboratory animals who developed cancer (ATSDR, 1994). Because the estimated doses are based onconservative assumptions, ATSDR concludes it is unlikely that exposure to DDT in soil would haveresulted in an increased cancer risk to Aberdeen residents.
The estimated soil dose for children (0.00125 mg/kg/day) slightly exceeded the MRL. The estimatedadult dose was lower than the MRL. The MRL is based on exposure levels in an animal study atwhich no adverse effects were seen (0.35 mg/kg/day), and has an uncertainty or safety factor of 300built into it. The lowest dose that has been shown to cause adverse effects in animals given toxaphenein their feed was approximately 1.8 mg/kg/day, which is more than 1,000 times higher than estimateddoses for Aberdeen children.
Because the estimated doses are based on conservative assumptions, ATSDR considers it unlikelythat Aberdeen residents were exposed to toxaphene in off-site soils at levels capable of causingnoncancer health effects.
Although toxaphene was detected in soil at a level exceeding the conservative CREG, the estimateddoses to both children and adults at Geigy were at least 10,000 times lower than the dose fed tolaboratory animals that resulted in thyroid and liver cancers.(9) ATSDR therefore concludes it isunlikely that Aberdeen residents would have experienced an increased cancer risk due to toxaphene exposure in off-site soils.
Past exposure to off-site soil contaminated with pesticides posed no apparent public health hazard.
Current and potential future exposure to contaminated soil off-site at Geigy pose no apparent publichealth hazard. The companies have remediated the contaminated soil, and subsequent investigationshave shown that contaminants are below performance standards.
Recommendations: The results of the evaluation do not warrant any recommendations.
The possibility of public health impact by airborne contaminants is evaluated in this section of thepublic health assessment for one exposure situation--the Geigy site vicinity.
From 1948 to 1967, the Geigy site was used as a pesticide blending facility. Activities on site likelyled to pesticide releases to the air.
No data are available to evaluate the extent, if any, to which contaminants were released to the air.
Exposure to pesticide-contaminated air is a potential past exposure pathway. Some nearby residentsmay have been exposed to airborne contaminants when the facility was active as a pesticide-blendingplant. Nearby residents may also have inhaled pesticide containing dusts originating fromcontaminated soils. Although no air sampling data were collected to evaluate the extent, if any, towhich contaminants may have been released, exposure by this pathway was likely minimal becausethe area immediately adjacent to the plant is sparsely populated.
Because no data are available regarding the past releases of pesticides, ATSDR is unable to estimatethe quantity of the pesticides that people might have been exposed to, and whether the amount wassufficient to result in adverse health effects.
Conclusion: ATSDR concludes that past exposure to airborne pesticides at the Geigy site is anindeterminate public health hazard. No data are available for evaluating this pathway.
Recommendations: ATSDR's evaluations did not identify any issues warranting recommendations.
In 1994, the University of North Carolina conducted a study to determine whether Aberdeen residentswere exposed to pesticides as a result of living near the Geigy and Aberdeen sites and, if so, whethersuch exposures could be associated with any adverse effects to the immune system. In their study, theUniversity of North Carolina researchers included both the Geigy site and the five Aberdeen pesticidesites and interviewed 1,642 residents from Aberdeen, Pinebluff, Taylortown, and Pinehurst.
For Phase I of the study, University of North Carolina researchers investigated whether Aberdeenresidents were more likely to develop infectious diseases, such as herpes zoster (shingles)(10) incomparison to "nonexposed" persons (e.g., persons not living near a known waste site). Theresearchers found that residents aged 18-40 years were two times more likely to develop herpeszoster in comparison to residents of nearby communities. Although these results support thepossibility that exposure to the pesticides dump sites in Aberdeen may be associated with immunesuppression, ATSDR cannot conclude this with certainty because the researchers did not directlystudy the link between exposure and immune suppression.
For Phase II of the study, researchers studied (1) whether living near the Aberdeen and Geigy siteswas associated with higher levels of (organochlorine) pesticides in the blood; (2) whether living nearthe sites was associated with adverse effects on the immune system, as measured by specific immunesystem changes, and (3) whether higher levels of DDE (a breakdown product of DDT) in the bloodwere associated with the immune system changes.
Researchers collected blood samples and more in-depth information from a random sample of 302participants from Phase I of the study. They analyzed the participants' blood samples for 20 different(organochlorine) pesticides and for immune system markers, such as white blood cells.
With one exception, of all 20 pesticides studied, the researchers detected only DDE in the participants' blood.(11) DDE levels in blood were low, however, in comparison to nationwide plasma DDE levels measured shortly after the 1972 ban on DDT. The researchers further found that living near the Aberdeen and Geigy sites was associated with higher levels of DDE in the blood. This association was statistically significant for Aberdeen residents aged 40-49 years who lived within one mile of Geigy or any of the five Aberdeen sites.
The researchers also found that living near the Aberdeen and Geigy sites was associated with changes in immune system markers, and that plasma DDE levels were associated with some of these changes. The magnitude of these immune system changes, however, did not appear to be clinically important (i.e. not at a level known to cause illness) (ATSDR, 1998).
In this section, ATSDR addresses community concerns related to possible exposure to site-related contamination. At public meetings with EPA and ATSDR in 1986, residents expressed some concern about the potability of their public and private well water. However, most concerns at that time were focused on the soil removal and plans for thermal destruction of contaminated soils associated with the Aberdeen pesticides sites and not specifically the Geigy site.
Since 1994, EPA and pesticide companies' representatives have held regular meetings with area residents. The purpose of these meetings is to keep community members informed about site-related activities and to provide a forum for community members to voice their concerns. At meetings attended by ATSDR representatives, no health concerns have been raised concerning past exposures from contaminants from the Geigy site. As a part of the health assessment process, the draft document will be released for public comment and ATSDR will respond to the public health concerns raised during the public comment period.
Community Concern: In the 1980s community residents expressed concern about the potability of their private and public drinking water supplies.
ATSDR Response: In the past, several private wells downgradient of the Geigy site were found to be contaminated with low levels of BHC isomers and dieldrin. As of the release of this report, the companies had connected the residence of the last person using private well water in the downgradient area to the municipal water system. (Previously, the companies had installed a carbon filter on that well, and periodically monitored it to ensure that the filter was working properly and that harmful levels of pesticides were not being consumed.) All other residences and businesses in the downgradient area have already been connected to city water that meets drinking water standards.
By 1992, the town of Aberdeen had closed municipals wells 1 and 4, which were found to contain low levels of lindane. The town of Aberdeen informed EPA that it will not install any new municipal wells in the downgradient area (EPA, 1998). Aberdeen public works officials also initially monitor all new municipal wells for pesticides on a quarterly basis (Monroe, 1998). Furthermore, the companies began extraction and treatment of contaminated water on site in 1997 to reduce the level of contamination and the potential for migration of contaminants.This groundwater remediation will be carried out for a period of 30 years, or until groundwater quality conditions satisfy the requirements of the Performance Standards Verification Plan. (EPA, no date).
ATSDR therefore concludes that prudent and appropriate preventative measures have been taken to ensure that Aberdeen residents are not at current or future risk of exposure to contaminated drinking water from public or private wells. However, to ensure the continued safety of drinking water supplies, ATSDR recommends that the companies continue regular groundwater monitoring in the area in accordance with the Downgradient Remedial Action Work Plan and the Site Groundwater Remediation Permit.
Based on the information reviewed, ATSDR finds no current, or foreseeable future, public health hazards associated with the Geigy site, provided that groundwater remediation proceeds as planned and there are no changes in land use conditions. As of the release of this report, all residences and businesses in the downgradient area have been connected to city water that meets drinking water standards. The companies will continue periodic groundwater monitoring at the Geigy site in accordance with the plans developed under the record of decision and approved by EPA and the NCDEHNR.
Soil investigations post-remediation have shown that contaminants on the site are at levels below EPA performance standards. Conclusions and recommendations specifically associated with groundwater, soil, and air exposure situations are provided on pages 10, 15, and 16, respectively.
ATSDR recommends that the companies continue groundwater monitoring in accordance with the plans developed under the record of decision and approved by EPA and the NCDEHNR.
Environmental Health Scientist
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Environmental Health Scientist
Eastern Research Group
ATSDR, 1988. Agency for Toxic Substances and Disease Registry. Preliminary Health Assessment Aberdeen Pesticides Dumps, Aberdeen North Carolina, January 21, 1988.
ATSDR, 1993a. Toxicological Profile for Aldrin/Dieldrin, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, April 1993.
ATSDR, 1994a. Toxicological Profile for 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, May 1994.
ATSDR, 1994b. Toxicological Profile for Chlordane, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, May 1994.
ATSDR, 1996. Toxicological Profile for Toxaphene, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, August 1996.
ATSDR, 1997. Toxicological Profile for alpha-, beta-, gama-, and delta-hexachlorocyclohexane, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, September 1997.
ATSDR, 1998. Environmental Exposures and their Effects on the Immune System, Moore County, North Carolina. U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, November 1998.
Environmental Response Team (ERT), 1987. Environmental Response Team's Final Report on the Aberdeen Pesticide Sites, Aberdeen, North Carolina. June 1987.
Fitzhugh O.G., Nelson A.A., and Quaife M.L. 1964. Chronic oral toxicity of aldrin and dieldrin in rats and dogs. Food Cosmet Toxicol 2:551-562. As cited in ATSDR, 1993a.
Geigy Chemical Corporation, 1996. Correspondence to John Mann of ATSDR, concerning raw data for private well sampling. December 10, 1996.
Geigy Chemical Corporation, 1995. Site Downgradient Groundwater Investigation Status Meeting. June 5, 1995.
Hilliard, 1996. Correspondence from Garland Hilliard of Geigy Chemical Corporation to John Mann of ATSDR regarding private well monitoring, December 10, 1996.
Khasawinah A.M. and Grutsch J.F. 1989. Chlordane thirty-month tumorigenicity and chronic toxicity test in rats. Regul Toxicol Pharmacol. 10:95-109. 1989. As cited in ATSDR, 1994b.
Meera P., Rao P.R., Shanker R., et al. 1992. Immunomodulatory effects of -HCH (lindane) in mice. Immunopharmacol Immunotoxicol 14:261-282. 1992. As cited in ATSDR, 1997.
Monroe, 1998. Telephone conversation between Rick Monroe, Aberdeen Public Works Department, and Meg Wilcox, Eastern Research Group, regarding status of municipal wells. August 26, 1998.
NUS Corporation Superfund Division (NUS), 1988. Final Sampling Investigation Report, Geigy Chemical Corporation Site, Aberdeen North Carolina, NCD981927502. March 18, 1988.
Rust Environment and Infrastructure (Rust), 1995a. Preliminary Design Report. Rust E&I Project No. 86619.500. January 1995.
Rust, 1995b. Final Design Report. Geigy Chemical Corporation Site. Rust E&I Project No. 86619.600. December 1995.
Rust, 1996. Downgradient Groundwater Investigation Data Summary Report, Geigy Chemical Corporation Site. Rust E&I Project No.33288.610. March 1996.
Rust, 1997a. Remedial Action Report for Soils, Performance Standards Verification, Geigy Chemical Corporation Site. June 1997.
Rust, 1997b. Downgradient Groundwater Remedial Action Work Plan, Geigy Chemical Corporation Site. Project No. 201165.10300. November 1997.
Sirrine Environmental Consultants, 1992. Feasibility Study Report, Geigy Chemical Corporation Site, Aberdeen, NC. Sirrine Project No. G-1024.20. March 1992.
U.S. EPA, no date. Superfund Preliminary Close-Out Report, Geigy Chemical Corporation NPL Site, Aberdeen, North Carolina.
U.S. EPA, 1992a. Superfund Proposed Plan Fact Sheet, Geigy Chemical Corporation Site, March 1992.
U.S. EPA, 1992b. Record of Decision Fact Sheet, Geigy Chemical Corporation Site, September 1992.
U.S. EPA, 1994. Superfund Fact Sheet Update, Geigy Chemical Corporation Site, February 1994.
U.S. EPA, 1995. Superfund Fact Sheet Update, Geigy Chemical Corporation Site, September 1995.
U.S. EPA, 1996. Remedial Design Fact Sheet, Geigy Chemical Corporation Site, March 1996.
U.S. EPA, 1997. Explanation of Significant Difference Fact Sheet, Geigy Chemical Corporation Superfund Site. November 1997.
U.S. EPA, 1998. Explanation of significant differences to the remedial action. Geigy chemical corporation site, Aberdeen, Moore County, North Carolina. January 1998.
U.S. Geological Survey, 1993. Hydrogeology and Simulation of Ground-Water Flow in Aquifers at the Aberdeen Superfund Sites, North Carolina, U.S. Geological Survey Administrative Report for EPA Region IV, February 26, 1993
1. A separate public health assessment has been prepared for the Aberdeen Pesticides Site.
2. An aquifer is an underground area of sand, gravel, or rock which stores water.
3. BHC, or benzene hexachloride, is a chemical that exists in a number of different forms, known as isomers. Technical grade BHC, once used as an insecticide throughout the country, is a mixture of several of these different forms. The BHC isomers detected at and around the Geigy site include alpha (µ)-BHC, beta (b)-BHC, delta (d)-BHC, and gamma (g)-BHC. Gamma-BHC is commonly called lindane and is produced and used as an insecticide on fruit, vegetable, and forest crops. It is also used to treat head and body lice and scabies (ATSDR, 1997).
4. MRL stands for minimum risk level. It is an exposure level at and below which adverse health effects are considered unlikely to occur. The MRL considers only noncancer effects. See Appendix H for more information.
5. EPA has classified alpha-BHC as a probable human carcinogen and beta-BHC as a possible human carcinogen. It has not been able to determine whether lindane is a human carcinogen.
6. EPA has determined that dieldrin is a probable human carcinogen.
7. In this study, immunologic changes were observed in mice fed 0.012 mg/kg/day lindane in their food.
8. EPA has determined that chlordane is a possible human carcinogen.
9. EPA has classified toxaphene as a probable human carcinogen.
10. UNC researchers selected herpes zoster because (1) nearly 100% of the population are exposed to the virus that causes the disease by the time they are 20 (and 50% by age 5); (2) people with known immune suppression are more likely to contract the disease; and (3) the symptoms are severe enough to be remembered.
11. Heptachlor epoxide was detected in one individual.