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 retail
facility operated on the property from 1948 to 1989. The pesticide blending operations were
conducted until 1967; retail sales of agricultural chemicals continued until 1989. In September of
1989, the U.S. Environmental Protection Agency (EPA) 
placed the site on the National Priorities
List (NPL) because the groundwater and soil were found to be contaminated with pesticides. The
pesticide lindane was detected in Aberdeen municipal wells in 1985. Subsequent investigations
by EPA and the companies involved (Ciba-Geigy Corporation, Olin Corporation, Kaiser
Aluminum, and Chemical Corporation) revealed that the groundwater was contaminated in a
plume extending west of the site.
The surface area of the site has been completely remediated. The responsible parties removed more than 7,000 tons of soil and debris in a series of remedial actions. The surface of the site is now covered with rye grass, wild flowers, and pine trees. In 1996, the companies involved installed seven extraction wells and constructed a groundwater treatment facility that is still in operation. Additional monitoring wells were installed in 1998 to evaluate the extraction process.
The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated the limited information concerning past consumption groundwater contaminated with low levels of pesticides. ATSDR concludes that there were no apparent public health hazards associated with the 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-site soil posed no apparent public health hazard. Past human exposure to airborne pesticides is an indeterminate public health hazard because no air measurements were taken in the surrounding community during the period of operation and thus there are no data to be analyzed. If high concentrations of pesticides had been present, on-site workers were more likely to have been exposed than the few nearby residents because the plant was separated from residential properties by a major highway and a railroad.
Based on the information reviewed, ATSDR finds no current or foreseeable future public health hazards associated with the Geigy site as long as groundwater remediation proceeds as planned and there are no changes in land use conditions. All residences and businesses in the downgradient area have now been connected to the municipal water supply system, which supplies water that meets drinking water standards. The companies involved had the residence of the last person using a private well immediately downgradient from the site connected to the municipal system in late 1999. The companies will continue to monitor the groundwater at the site in accordance with plans developed under the record of decision for the site, which was approved by EPA and the North Carolina Department of Environment Health and Natural Resources (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 Geigy site in Aberdeen, North Carolina. More specifically, ATSDR reviewed available environmental and health outcome data and community health concerns to determine whether adverse health effects 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 is required by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, often called the Superfund Law), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), to conduct public health assessments of sites placed on the National Priorities List.
This public health assessment focuses on pesticide contamination found in groundwater and soil at and near the Geigy site. Although trichloroethylene (TCE) has been detected at elevated levels in groundwater at Aberdeen, this report does not address TCE contamination. The companies involved have had a contractor, Rust Environmental and Infrastructure, conduct extensive groundwater investigations. These investigations have demonstrated that the source of the TCE detected in the groundwater is located hydraulically upgradient of the site. EPA has therefore concluded 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 in Moore County, North Carolina and other interested parties listed on the EPA mailing list for the site. Copies of the draft document were placed in the public repository for site documents at the Aberdeen 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 the community. The public comment period closed on February 25, 2000. No public comments were received concerning the draft public health assessment of the Geigy Chemical Corporation site.
A. Site Description and History
The Geigy site is a two-acre, triangularly shaped area bordered by Route 211 to the north, an active railway to the south (the Aberdeen and Rockfish railroad), and private property to the east and west (see Figure 1 in Appendix A). The property lies one-half mile east of the town of Aberdeen, North Carolina. The site was leased to various pesticide-blending facilities from 1948 to 1967, including Geigy (1948 to 1955) and the Olin-Mathieson Chemical Corporation (1956 to 1967). From 1967 to 1989, various companies used the property for retail sales and distribution of 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 inert materials to form the end products. The Olin-Mathieson Chemical Corporation also operated a pesticide formulation, packaging, and distribution facility at the site, using similar blends of organochlorines.
During 1985 and 1986, sampling and analyses of the Aberdeen municipal well water detected BHC in four wells. Later analyses of tap water in the system did not reveal any concentration of pesticides at or above a health concern level. As a prudent public health measure, the town of Aberdeen closed the most contaminated well, Municipal Well 1, in March 1986.
The NCDEHNR performed a preliminary assessment of the Geigy site in February 1987. The U.S. Environmental Protection Agency (EPA) conducted a site inspection in March 1988 to gather additional information. Based on the findings of the investigations, EPA placed the site on the 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 type and distribution of site-related contaminants (Rust, 1996). In addition to sampling the soil and groundwater, the companies removed more than 3,300 tons of contaminated soil and debris in two separate actions (Sirrine, 1992). Pesticides were detected directly underneath the site in the Surficial Aquifer, but not in the aquifers supplying drinking water (e.g., the Upper and Lower Black Creek aquifers). Pesticides were, however, detected in the Upper Black Creek Aquifer approximately 375 feet south of the site.
In August 1992, EPA issued a record of decision for the site, calling for the removal and proper disposal of the remaining contaminated soil (top 12 inches) and building foundations. In addition, 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 further define the presence and extent of pesticides detected in the groundwater during the remedial investigation, 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 to study the effects on the immune system of residential exposure to hazardous waste sites. The University 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 any follow-up health studies.
EPA and NCDEHNR approved the Geigy site remediation plan in March 1996, and, by the end of the year, the remedial action was completed. An additional 4,473 tons of contaminated soil were excavated, and the remaining concrete foundations were demolished. Seven extraction wells and six monitoring wells were installed. The groundwater treatment facility was constructed, and the groundwater extraction and treatment system began operating in January 1997. 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 while providing public health advice to EPA on removal activities associated with the nearby Aberdeen Pesticides NPL site.(1) ATSDR prepared a preliminary health assessment of the Aberdeen Pesticides site in 1988. At that time the Geigy site was not a suspected source of the municipal and 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, ATSDR participated 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.
PUBLIC HEALTH EVALUATION OF GROUNDWATER CONTAMINATION
The possible public health impact from contaminated groundwater is evaluated in this section of the report for two past exposure situations, private well water and municipal water. Table 1 summarizes the results of these evaluations.
No Aberdeen residents are currently exposed to contaminated groundwater. The town of Aberdeen has closed contaminated municipal wells and informed EPA that it will not install any new wells in the areas downgradient of the site (EPA, 1988). All residences and businesses in the downgradient area have now been connected to the municipal water system, which supplies water that meets drinking water standards.
The companies have clearly defined the extent of groundwater contamination. They began extraction and treatment of contaminated water on the site in 1997 to reduce contaminant levels and 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.
TABLE 1: PAST EXPOSURE TO CONTAMINATED GROUNDWATER
| Situations | Contaminants of Concern | Receptor Population | Route of Exposure | Frequency of Exposure | Public Health Classification |
| Municipal water | BHC isomers | 2,296* | ingestion dermal |
daily | No apparent public health hazard |
| Private well water | BHC isomers | 10** | ingestion dermal |
daily | No apparent public health hazard |
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 Creek Aquifer--supplies drinking water. The Black Creek Aquifer is divided into two distinct units, the Upper Black Creek Aquifer and the Lower Black Creek Aquifer, and is located approximately 50 to 90 feet underground. It lies between the uppermost aquifer (the Surficial Aquifer) and the lowest aquifer (the Cape Fear Aquifer). Pesticides used in activities at the Geigy site leached through the soil into the groundwater.
C. Environmental Contamination
ATSDR reviewed groundwater data and selected several contaminants for more detailed evaluation of public health significance. A description of the process for selecting these contaminants of concern is provided in Appendix C. Readers are advised to read the public health implications section before making any conclusions about contaminant levels in groundwater. As described in Appendix C, finding a contaminant level above a comparison value only means that further evaluation is needed. It does not necessarily mean that the contaminant would cause adverse health effects.
Past Exposure to Contaminated Municipal Water Supplies
Lindane and other BHC isomers(3) were measured in 4 of the 9 Aberdeen municipal wells beginning in 1986. During the February 1986 monitoring, measurements for pesticides were also made from two drinking water taps (Austin Apartments and Town Hall) within the system, as well as from three fire hydrants. Austin Apartments and the fire hydrant were resampled in March 1986. The maximum concentration of lindane was 11.4 parts per billion (ppb), which was measured in a March 1986 sample from Municipal Well Number 1 (Table 2). To prevent any adverse health effects from potential future increases in contaminant levels, Municipal Well Number 1 was disconnected from the public water system in March 1986. Municipal Well Number 4 was closed in January 1992 after a maximum lindane concentration of 4 ppb was detected in March 1987.
TABLE 2: ABERDEEN PUBLIC WATER SUPPLY SYSTEM MUNICIPAL WELL DATA
| Chemical | Maximum Concentration Detected (ppb) |
Location of Maximum Concentration | Comparison Value (ppb) |
Comparison Value Reference |
| alpha-BHC | 2.9 | MUW-04 | 0.006 | CREG |
| beta-BHC | 4.9 | MUW-01 | 0.02 | CREG |
| gamma-BHC (lindane) |
11.4 17 0.8 (n=4) 1.2 (n=7) |
MUW-01(before) MUW-01 (after) Tap water hydrant |
0.1 0.4 |
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. |
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Past Exposure to Contaminated Private Well Water
In 1987 NUS Corporation sampled 10 private wells in the vicinity of Geigy (9 off site and 1 on site) for EPA, and detected BHC isomers at low levels in two wells, one south and the other southeast 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 April 1994 and March 1995, identifying nine private wells downgradient of the site. The companies sampled water from private wells during 1994-1996.
Of these nine wells, five were no longer in use, either because the residences were unoccupied or had been hooked up to, and were using, municipal water (Hilliard, 1996). Of the remaining four wells, two were used for gardening or washing cars; one had an activated carbon treatment system installed on it in June 1994; and one (PW-17) was used for filling the swimming pool and watering 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).
TABLE 3: PRIVATE WELL DATA (UNFILTERED WATER)
| Chemical | Maximum Concentration Detected (ppb) |
Date | Location of Maximum Concentration | Comparison Value (ppb) |
Comparison Value Reference |
| alpha-BHC | 6.4 | 5/12/95 | PW-17 | 0.006 | CREG |
| beta-BHC | 12 | 5/12/95 | PW-17 | 0.02 | CREG |
| gamma-BHC (lindane) |
6.5 | 5/12/95 | PW-17 | 0.1 0.4 |
Child EMEG(I) Adult EMEG (I) |
| dieldrin | 0.13 | 4/11/95 | PW-17 | 0.002 | CREG |
| 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. |
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Monitoring wells are used strictly for testing for levels of contaminants in groundwater. They are not used for drinking water. EPA, and Geigy's contractor, Rust, sampled for pesticides from monitoring wells on numerous occasions from 1990 to 1995. Groundwater sampling from these wells indicated that the Surficial Aquifer was contaminated with pesticides directly beneath the Geigy site, and that pesticides were migrating from this aquifer into the Upper Black Creek Aquifer approximately 300 feet south of the site. Pesticide contamination in the Upper Black Creek Aquifer was limited to the area south of Route 211, and was partially bounded by McFarland's Branch to the west. Pesticide contamination in the Lower Black Creek Aquifer was primarily limited to the area west of the site where the aquifers mix (Rust, 1996). For a more detailed description of the monitoring well investigations, see Appendix D.
Approximately 70% of Aberdeen residents using the municipal water supply may have been exposed to very low levels of lindane and other BHC isomers. The Aberdeen municipal water wells are divided into two service areas. Municipal wells 2, 3, 6, and 7 are located in the northern area 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 estimated 30% of the population (Monroe, 1999). The other wells serve the rest of the community. The town of Aberdeen blends the water from the wells in each service area before distributing it to individual taps.
The 70% of area residents supplied with water from the other service area may have been exposed 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 of years that Aberdeen residents may have been exposed to low levels of lindane in their drinking water.
Exposure may have occurred through ingestion of contaminated groundwater, and through inhalation and dermal absorption of contaminants. Volatile compounds, such as some pesticides, can escape as gases during showering, bathing, or cooking. However, because most of the pesticides 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 levels in only a few of these wells. Residents using private well water from these wells may have been exposed to BHC isomers and other pesticides in the past. Exposure was possible as early as the 1980s, when the wells were identified and sampled, but could have begun earlier. As of the release of this report, the companies have connected the residence of the last person who consumed drinking water from private well water in the downgradient area to the municipal water supply system. (Previously, the companies had installed a carbon filter on that resident's well, and periodically monitored it to ensure that the filter was working properly and that harmful levels of pesticides were not being consumed.) Occupants of two other residences continue to use their wells for watering lawns and gardens. All other residences and businesses with private wells in 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 the community might have been exposed to daily and how that estimated dosage compares to doses that may produce health effects, both carcinogenic and noncarcinogenic.
Based on likely, site-specific considerations, and using conservative assumptions about how often people drink and how much they drink, ATSDR estimated the doses of pesticides which people might have received from using contaminated groundwater. These estimates allow ATSDR to evaluate the likelihood, if any, that pesticides in groundwater are associated with adverse health effects. See Appendix C for further discussion on how ATSDR determines the public health implications at a given site.
ATSDR assumed that residents drank 2 liters (approximately 2 quarts) of tap water each day, and that the average resident weighed 70 kilograms (kg), or about 150 pounds. This is a conservative assumption because many individuals obtain their liquid requirements from other sources such as milk, 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 for noncancer and cancer effects. Dieldrin was evaluated for cancer effects.
Residents served by the contaminated municipal wells are unlikely to have received doses causing adverse health effects. Although lindane was measured in Municipal Well 1 at 11.4 ppb, the concentration of lindane measured at two drinking water taps and three hydrants was at or below 1 ppb.
Using 1 ppb as the maximum level of lindane detected in tap water, calculated doses of lindane were 0.0000625 milligrams per kilogram per day (mg/kg/day) for children and 0.000028 mg/kg/day for adults. Although the estimated dose to children is higher than the MRL(4) (0.00001 mg/kg/day), the MRL 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 neither pesticide was tested for in tap water, it can be safely assumed that, like lindane, concentrations of these pesticides were also lower at the tap than in the wells. Assuming that these pesticides would have been present in tap water at a maximum concentration of 1 ppb (but could have been as much as tenfold lower, or 0.3 for alpha-BHC and 0.5 for beta-BHC), estimated doses to both adults and children 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 sampling rounds in 1987, and from 1994 to 1996. It is unlikely that residents were exposed to these pesticides at levels capable of causing adverse health effects.
Alpha-BHC, beta-BHC, and dieldrin(6) exceeded only the CREG comparison value for cancer risk. The estimated 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 in laboratory animals. The doses estimated for dieldrin were 10,000 times lower than the doses causing cancer 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 unfiltered water as a potential indicator of past exposure (6.5 ppb). The estimated doses for lindane exposure to children and adults were greater than the MRL. However, these doses are at least 200 times lower than 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 human variability and other issues. Therefore, ATSDR believes it is unlikely that Aberdeen residents were exposed at levels of health concern.
F. Conclusions and Recommendations
Conclusion: ATSDR concludes that the past groundwater exposure situations at the Geigy site posed no apparent public health hazard. Harmful exposures to lindane and other pesticides were prevented by the timely public health actions of disconnecting the contaminated municipal wells from the Aberdeen water supply system and providing safe alternative water supplies or treatment for residents using contaminated domestic wells.
Conclusion: Present and potential future exposure to contaminated groundwater poses no public health 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 Geigy site, and remediation efforts are underway to remove and treat contaminated water.
Recommendation: ATSDR recommends that the companies 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 to ensure that no contaminants affect public or private water wells in use.
PUBLIC HEALTH EVALUATION OF CONTAMINATED SOIL
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 intentionally carry contaminated soil off site.
Starting in 1987, EPA and the companies conducted a series of soil remediations, removing more than 7,000 tons of contaminated soil and debris, from both on and off the site. In 1996, Rust sampled the soil to verify that the remediation had achieved its goals. The results of this sampling effort indicated that the remediation reduced pesticide contamination in surface soils to EPA performance standards, which are generally no more than 10 times greater than ATSDR Comparison Values (See Appendix G). However, because a few individual samples exceeded performance standards, the companies excavated an additional 129 cubic yards of surface soil, at the request of the NCDEHNR (Rust, 1997a).
TABLE 4: PAST EXPOSURE TO CONTAMINATED SOIL
| Situations | Key Contaminants | Receptor Population | Route of Exposure | Frequency of Exposure | Public Health Classification |
| Off-site soil | Chlordane DDT Toxaphene |
20* | Ingestion Dermal contact |
unknown | No apparent public health hazard |
C. Environmental Contamination
ATSDR reviewed soil data and selected several contaminants for more detailed evaluation of public health significance. A description of the process for selecting these contaminants of concern is provided in Appendix C. Readers are advised to read the public health implications section before making any conclusions about contaminant levels in soil. As described in Appendix C, finding a contaminant level above a comparison value only means that further evaluation is needed. It does not necessarily mean that the contaminant would cause adverse health effects.
Chlordane, DDT, and toxaphene were identified as contaminants of concern for the off-site soil exposure 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.
TABLE 5: GEIGY OFF-SITE SOIL DATA (CONTAMINANTS OF CONCERN)
| Chemical | Maximum Concentration
Detected (ppm) |
Date | Comparison Value (ppm) |
Comparison Value Reference |
| Chlordane (tech. mixture) | 4.3 | 3/23/87 | 30 400 0.5 |
Child EMEG (Chronic) Adult EMEG (Chronic) CREG |
| 4,4'-DDT | 9.3 | 3/23/87 | 30. 2. |
Child RMEG CREG |
| Toxaphene | 100 | 3/23/87 | 50 700 0.6 |
Child EMEG (Intermediate) Adult EMEG (Intermediate) CREG |
| 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) |
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Exposure to contaminated soil is a potential past exposure pathway. Residents may have been exposed to off-site surface soils via dermal contact or incidental ingestion. Residents may also have been sporadically exposed to on-site soils before the site was secured in 1989. However, because the plant was separated from residential properties by a major highway and a railroad, on-site workers are more 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 with contaminated soil. These estimates allow ATSDR to evaluate the likelihood, if any, that pesticides in soil are associated with adverse health effects.
For soil, ATSDR assumed that adults ingested 100 milligrams (mg) of contaminated soil each day for 40 years, and that the average resident weighed 70 kilograms. Children were assumed to ingest 200 mg of contaminated soil for six years, and to weigh on average 16 kilograms. Soil ingestion can occur by the inadvertent consumption of soil on hands or food items. Children may also ingest soil by putting objects in their mouths, or from ingesting non-food items. Exposure can occur in the home when 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 in off-site soil, and that residents were not necessarily exposed to these levels.
Chlordane
Chlordane was detected in off-site soil at a low level exceeding only the CREG comparison value for cancer risk. The estimated child and adult doses of chlordane from off-site soil were more than 10,000 times lower than the lowest dose that caused cancer in animals (1.21 mg/kg/day, Khasawinah and Grutsch, 1989).(8) ATSDR therefore concludes that nearby residents would not have experienced an increased cancer risk from exposure to chlordane in off-site soils.
DDT
DDT was detected in off-site soil at a level 5 times higher than the CREG. The estimated dose of DDT from off-site soil exposure, however, is at least 1,000 times lower than the doses fed to laboratory animals who developed cancer (ATSDR, 1994). Because the estimated doses are based on conservative assumptions, ATSDR concludes it is unlikely that exposure to DDT in soil would have resulted in an increased cancer risk to Aberdeen residents.
Toxaphene
The estimated soil dose for children (0.00125 mg/kg/day) slightly exceeded the MRL. The estimated adult dose was lower than the MRL. The MRL is based on exposure levels in an animal study at which no adverse effects were seen (0.35 mg/kg/day), and has an uncertainty or safety factor of 300 built into it. The lowest dose that has been shown to cause adverse effects in animals given toxaphene in their feed was approximately 1.8 mg/kg/day, which is more than 1,000 times higher than estimated doses for Aberdeen children.
Because the estimated doses are based on conservative assumptions, ATSDR considers it unlikely that Aberdeen residents were exposed to toxaphene in off-site soils at levels capable of causing noncancer health effects.
Although toxaphene was detected in soil at a level exceeding the conservative CREG, the estimated doses to both children and adults at Geigy were at least 10,000 times lower than the dose fed to laboratory animals that resulted in thyroid and liver cancers.(9) ATSDR therefore concludes it is unlikely that Aberdeen residents would have experienced an increased cancer risk due to toxaphene exposure in off-site soils.
F. Conclusions and Recommendations
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 public health hazard. The companies have remediated the contaminated soil, and subsequent investigations have shown that contaminants are below performance standards.
Recommendations: The results of the evaluation do not warrant any recommendations.
PUBLIC HEALTH EVALUATION OF AIRBORNE CONTAMINANTS
The possibility of public health impact by airborne contaminants is evaluated in this section of the public 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 likely led to pesticide releases to the air.
C. Environmental Contamination
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 residents may have been exposed to airborne contaminants when the facility was active as a pesticide-blending plant. Nearby residents may also have inhaled pesticide containing dusts originating from contaminated soils. Although no air sampling data were collected to evaluate the extent, if any, to which contaminants may have been released, exposure by this pathway was likely minimal because the area immediately adjacent to the plant is sparsely populated.
Because no data are available regarding the past releases of pesticides, ATSDR is unable to estimate the quantity of the pesticides that people might have been exposed to, and whether the amount was sufficient to result in adverse health effects.
F. Conclusions and Recommendations
Conclusion: ATSDR concludes that past exposure to airborne pesticides at the Geigy site is an indeterminate public health hazard. No data are available for evaluating this pathway.
Recommendations: ATSDR's evaluations did not identify any issues warranting recommendations.
HEALTH OUTCOME DATA EVALUATION
In 1994, the University of North Carolina conducted a study to determine whether Aberdeen residents were exposed to pesticides as a result of living near the Geigy and Aberdeen sites and, if so, whether such exposures could be associated with any adverse effects to the immune system. In their study, the University of North Carolina researchers included both the Geigy site and the five Aberdeen pesticide sites and interviewed 1,642 residents from Aberdeen, Pinebluff, Taylortown, and Pinehurst.
For Phase I of the study, University of North Carolina researchers investigated whether Aberdeen residents were more likely to develop infectious diseases, such as herpes zoster (shingles)(10) in comparison to "nonexposed" persons (e.g., persons not living near a known waste site). The researchers found that residents aged 18-40 years were two times more likely to develop herpes zoster in comparison to residents of nearby communities. Although these results support the possibility that exposure to the pesticides dump sites in Aberdeen may be associated with immune suppression, ATSDR cannot conclude this with certainty because the researchers did not directly study the link between exposure and immune suppression.
For Phase II of the study, researchers studied (1) whether living near the Aberdeen and Geigy sites was associated with higher levels of (organochlorine) pesticides in the blood; (2) whether living near the sites was associated with adverse effects on the immune system, as measured by specific immune system changes, and (3) whether higher levels of DDE (a breakdown product of DDT) in the blood were associated with the immune system changes.
Researchers collected blood samples and more in-depth information from a random sample of 302 participants 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.
CONCLUSIONS AND RECOMMENDATIONS
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.
John Mann
Environmental Health Scientist
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Meg Wilcox
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
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