PUBLIC HEALTH ASSESSMENT
MEDLEY FARMS
GAFFNEY, CHEROKEE COUNTY, SOUTH CAROLINA
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
Data in this section are from the February, 1991 Final Remedial Investigation Report. This represents the latest information for this site. However, these data have not been through the standard review process. Any changes in these data will necessarily lead toward a reassessment of this section and the Public Health Implications section of this document.
Contaminants identified as being of concern are presented in table form in this section. We evaluate these contaminants in the subsequent sections of this public health assessment and determine whether exposure to them has public health significance. SCDHEC and ATSDR select and discuss these contaminants based upon the following factors:
In the data tables that follow under the On-site and the Off-site Contamination
subsections, the listed contaminant does not mean that it will cause adverse
health effects from exposures. Instead, the list indicates which contaminants
will be evaluated further in the public health assessment.
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The data tables and narrative include the following abbreviations: |
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= Cancer Risk Evaluation Guide |
| = Environmental Media Evaluation Guide | |
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= Maximum Contaminant Level Goal |
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= Maximum Contaminant Level |
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= Proposed Maximum Contaminant Level Goal |
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= EPA Maximum Contaminant Level |
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= Reference Dose |
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= Lifetime Health Advisory |
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= parts per million |
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= parts per billion |
Comparison values for public health assessments are contaminant concentrations in specific media that are used to select contaminants for further evaluation. These values include EMEGs, CREGs, and other relevant guidelines. CREGs are estimated contaminant concentrations based on one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors. EPA's MCLG is a drinking water health goal. EPA believes that the MCLG represents a level at which "no known or anticipated adverse health effect on human health occurs which allows an adequate margin of safety." PMCLGs are MCLGs that are being proposed. MCLs represent contaminant concentration that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day. While MCLs are regulatory concentrations, PMCLGs and MCLGs are not. EPA's RfD is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects.
Toxic Chemical Release Inventory (TRI)
The Toxic Chemical Release Inventory (TRI) is a database managed by the EPA since 1987. The inventory contains information on the annual estimated releases of over 300 toxic chemicals into the environment (air, water and land) by industry. Mandated by federal regulations, Title III of the Superfund Amendments and Reauthorization Act (SARA) of 1986, facilities with 10 or more full-time employees are required to report to the EPA on releases of any of those 300 toxic chemicals during their business activities. Based on these reports, a database has been established and continuously been updated annually. The database records the names and addresses of facilities which manufacture, process, or use these toxic chemicals, as well as amounts released to environment or transferred to waste sites.
We searched TRI data for the area within a 1-mile radius of the Medley site using both geographic coordinates and area zip codes. The TRI data search did not contain any information on toxic chemical release in the area around the Medley site.
Groundwater - Monitoring Wells
The groundwater investigation conducted during the RI was intended to determine the nature and extent of groundwater contamination resulting from previous site activities and to characterize the nature of groundwater contamination in the underlying aquifers. The RI was also intended to provide geologic and hydrogeologic information about the site. Hydrogeologic data indicate that groundwater flow on the site is primarily to the southeast towards Jones Creek. Jones Creek and its tributaries serve as zones for groundwater discharge from the site (10).
Twenty one on-site groundwater monitoring wells were installed during phase one and phase two of the site investigations conducted for the preparation of the RI/FS (Figure 2). Three wells (BW1, BW2, and BW3) were constructed in the bedrock aquifer (BW), three wells (SW1, SW3, and SW4) were constructed in the saprolite (or shallow) aquifer, and one water level piezometer well (PZ1) was constructed for water level measurement only (PZ) during Phase I of the RI. Fourteen additional monitoring wells and one additional piezometer well were installed during Phase II of the RI, Figure 2. (Seven of these wells were installed in the saprolite wells, and seven were constructed in the bedrock aquifer).
Contaminants detected in this media consisted of volatile organic compounds (VOCs) from the saprolite and bedrock wells. The saprolite (shallow) aquifer generally serves as a porous medium of groundwater flow. The groundwater in the bedrock (deep) aquifer at the site is under semi-confined to confined conditions and is not conducive to groundwater flow. The saprolite wells have an average depth of 33 feet, while the bedrock wells have an average depth of 100 feet. The highest concentrations of VOCs were found directly beneath the source area. No VOCs were detected in samples SW1, BW1-2, BW3-2, BW4-1, and BW4-2. No groundwater plume has been identified to indicate that contaminant migration has reached Jones Creek (10). Table 2 presents the contaminants identified as being of concern in this media. There are no private wells on-site.
TABLE 2
CONTAMINANTS OF CONCERN
ON-SITE GROUNDWATER - MONITORING WELLS
MEDLEY FARM SITE REMEDIAL INVESTIGATION / FEASIBILITY STUDY10
| Contaminant | Saprolite Wells Maximum Wells |
Bedrock Wells Maximum Wells |
Comparison Value | |||
| Sample (µg/L) |
Location | Sample (µg/L) |
Location | Source | Value (µg/L) | |
| Methylene Chloride | 38 BJ | SW106-4 | 110 D | BW2-1 | PMCL | 5 |
| Chloroform | 4 | 19 DJ | BW2-1DL | CREG | 6 | |
| 1,1,1-Trichloroethane | 3300 E | SW4-1 | 310 D | BW2-1 | MCL | 200 |
| 1,1,2-Trichloroethane | 13 | SW4-1 | 3 J | BW2-1 | PMCL | 5 |
| 1,1-Dichloroethylene | 3500 | SW4-1 | 440 D | BW2-1 | CREG | 0.06 |
| Trichloroethylene | 190 | SW3-3 | 720 D | BW2-1 | CREG | 3 |
| Benzene | 0.7 | 95 | BW103-1X | CREG | 1* | |
µg/L = micrograms per liter
B = Compound detected in corresponding blank.
D = Sample diluted for this analysis.
E = Estimated value. Analyte concentration exceeded the calibration range. These values are approximate.
J = Estimated value. Analyte concentration below the calibration range. The concentration and
identification of the compound are tentative.
* The comparison values used in this Table are lifetime exposure levels set by the Drinking Water
Health Advisories. They are based on a lifetime (70 years) at an exposure rate of 2 Liters of water
consumption per day.
PMCL = EPA Proposed MCL
MCL = EPA Maximum Contaminant Level
CREG = Cancer Risk Evaluation Guide
Soil
The soil investigation conducted during the RI was performed to determine the nature and extent of soil contamination attributable to former disposal activities at the site. The RI concluded that on-site contaminants were present in the immediate vicinity of the disposal area. Contaminants were detected primarily in shallow soil. Contamination appears to be localized to the former disposal areas. The highest contaminant concentrations were detected in samples from the former lagoon areas.
During the RI, soil borings and test pits were positioned to investigate suspected lagoon and drum disposal areas (Figure 5). The test pit program was designed to determine the potential presence and remaining concentrations of residual chemicals, if any, at the previous disposal and storage areas. The soil borings were drilled to investigate the vertical and horizontal extent of residual chemicals in the soils.
The RI also included a series of sampling rounds (referred to as "surface soil" in the RI) of the top twelve inches of soil. The referenced "surface soil" in the RI does not represent surface soil samples as defined by ATSDR. Surface soil is defined by ATSDR to be soil from the top three inches of soil because this soil is considered the most likely depth that people would normally be exposed to. This public health assessment has evaluated all the data presented in the RI and the sampling locations for "surface soils" is presented in Figure 6.
The primary contaminants found in this media were chlorinated aliphatic compounds (CACs) and semi-volatile organic compounds (SVOCs). No vertical patterns of contaminant distribution are apparent. Elevated chemical concentrations were generally found in samples collected from depths less than 17 feet (10). The 1983 site clean-up removed an unidentified amount of surface soil and is believed to have removed a major portion of the source material and contaminated soils. Table 3 presents contaminants identified as being of concern in this media.
TABLE 3
CONTAMINANTS OF CONCERN
ON-SITE SOIL*
| Contaminant | Comparison Value (ppm) | ||||
| Concentration Range (mg/kg) |
Location | Concentration Range (mg/kg) |
Location Depth |
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| Chloroethylene** | ND - 0.5 E | TP 3-1 | ND | 1 EMEG | |
| Tetrachloroethene | ND - 61 E | TP 3-1 | ND - 0.012 | SB7 5-7 ft. |
10,000 EMEG |
| 1,2,4-Trichlorobenzene | ND - 710 D | TP 3-1 | ND - 12 | SB3 15-17 ft. |
500 RMEG |
| Bis(2-Ethylhexyl) Phthalate |
ND - 161 | TP 5-1 | ND - 1.7 | SB6 15-17 ft. |
50 CREG |
| PCB-1254 | 2.4 | TP10-1 | 10 EMEG | ||
| Contaminant | Comparison Value (ppm) | ||
| Concentration Range (mg/kg) |
Location | ||
| Chloroethylene** | ND - 0.21 | HA-3 | 1 EMEG |
| Tetrachloroethene | ND - 0.69 | HA-6 | 10,000 EMEG |
| 1,2,4-Trichlorobenzene | ND - 1.2 | HA-11 | 500 RMEG |
| Bis(2-Ethylhexyl) Phthalate |
ND - 33 D | HA-6 | 50 CREG |
| PCB-1254 | ND - 1.9 | HA-8 | 10 EMEG |
Groundwater - Private Wells
In June 1983, EPA detected methylene chloride (Figure 3) in four private wells (Wells 2, 3, 5, and 6) in levels ranging from 10.9 to 16.2 µg/L (micrograms per liter). In July 1984, methylene chloride (678 µg/L) and 1,2-dichloroethane (2.51 µg/L) were detected in Well 2 which is approximately 125 feet upgradient from the site. No contaminants were detected in wells 3, 5, and 6 at that time. In the 1989-90 sampling, however, a monitoring well located between the site and Well 2 did not reveal the presence of contaminants (10).
Hydrogeologic data indicate that the presence of compounds in Well 2 does not appear related to the Medley site because the well is upgradient of the site and no contaminants were detected in a monitoring well and two background wells located between Well 2 and the site. Water level measurements in Well 2, the background wells (SW1 and BW1), and the piezometer located northwest of the source area indicate that Well 2 and the background wells are hydraulically upgradient and have therefore not been impacted by the Medley site. SCDHEC has advised the private well owner that the well should not be used; the owner now uses municipal water. Private wells have not been sampled since 1984.
Soil
No off-site soil samples were collected during the RI. Therefore, no data are available for review.
Surface Water and Sediments
Jones Creek serves as a discharge area of the Medley Farm site. No site-related contaminants were detected in surface water samples or sediment samples from Jones creek. Sampling included collections of upstream and downstream sediments and surface water. Surface water was collected prior to collecting stream sediment samples to avoid suspended sediments in the water samples. Downstream samples were taken first to avoid any potential impact from collecting the upstream samples (10).
C. Quality Assurance and Quality Control
The data in this section are from the February 1991 RI/FS. The conclusions drawn in this public health assessment are based on the assumption that the data and information presented in the RI/FS are reliable and valid. SCDHEC assumes that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting.
The monitoring wells currently in use at the Medley site appear to be constructed according to SCDHEC standards to allow collection of representative groundwater samples.
We saw some abandoned vehicles and appliances behind the property owner's residence during the
1988 and 1992 site visits, but these were not easily accessible to persons other than the residents. We noted no other hazards.
To determine whether nearby residents are exposed to contaminants migrating from the site, ATSDR evaluates the environmental and human components that lead to human exposure. This pathways analysis consists of five elements: A source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population.
ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. Completed pathways have all five elements and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential pathways, however, have at least one of the five elements missing, but it could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present.
A past completed exposure pathway was identified for a private well user near the Medley site. Contaminants detected in this well were not considered to be site related. Potential exposure pathways have been identified for this site. In this section, we will discuss the potential for human exposures to contaminants found in these media.
A. Completed Exposure Pathways
A past completed exposure pathway has been identified from a private well user in proximity to the site. In 1983, SCDHEC advised the private well users to discontinue use of this well; they have complied. Contaminants detected in Well 2 are not considered to be related to previous activities at the Medley site. Hydrogeologic data and the site topography indicate that groundwater flow on the site is primarily to the southeast toward Jones Creek. This contamination is not considered to be site related. The length of exposure to contaminants from this source is not known and cannot be estimated; therefore, this past exposure pathway cannot be evaluated further.
B. Potential Exposure Pathways
Table : Potential Exposure Pathways
| Exposure Pathway Elements | Time | ||||
| Source | Environmental Medium |
Point of Exposure |
Route of Exposure |
Exposed Population |
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| Medley | Soil | On-Site | Ingestion Dermal Contact |
Children Adults |
Past Present Future |
| Medley | Groundwater- Private Wells |
On-Site Off-Site |
Ingestion Dermal Contact Inhalation |
Children Adults |
Past Future |
| Medley | Surface Water and Sediment |
Off-Site | Ingestion Dermal Contact |
Children Adults |
Present Future |
Groundwater Pathway
Exposure to groundwater off-site is not a pathway of concern at this time because the groundwater plume containing site-related chemicals is presently confined to the site and local residents are not utilizing groundwater as a drinking water supply. Methylene chloride and 1,2-dichloroethane were detected in Well 2; however, the owner was informed of this contamination, advised to discontinue well use and has complied. Therefore, no exposures to contaminants from this well are currently occurring or are anticipated to occur in the future. The contaminants detected in Well #2 are not considered to be site-related because topographic data indicate that the well is located upgradient of the site and hydrogeological data indicate that groundwater flow is to the southeast toward Jones creek and not toward Well 2. Additionally, samples collected from monitoring wells located between Well 2 and the site do not show contamination. We recommend that other sources of contamination in the area be characterized.
Hydrogeologic data presented in the RI indicate the contaminated groundwater plume does not underlie any existing residential buildings. Samples collected in 1984 did not include contaminants of concern. However, private well samples have not been collected since 1984 and this pathway cannot be evaluated further at this time.
This potential exposure pathway could become a completed exposure pathway if the site becomes further developed and a private well is drilled and utilized on the site property. Exposures could occur through ingestion, inhalation of water vapors while bathing or cooking, and through dermal contact with the contaminated groundwater from a private on-site well. We recommend that SCDHEC restrict the issuance of well drilling permits for drinking water wells in this area.
Surface Water and Sediment Pathway
In 1990, very low levels of several contaminants were found in Jones Creek. The contaminants detected did not exceed ATSDR comparison values and are not considered to be of concern to the public at this time. Because the creek is not used as a drinking water source or for agricultural or industrial purposes, the only potential for public exposure to surface water would be through accidental ingestion and skin contact. In the future, if contaminant levels in surface waters increase, adverse health effects may occur; however, this possibility is considered very unlikely at this time. Additional sampling data will be evaluated to better ascertain the possibility of exposures to the public.
Soil Pathway
Past, current, and future exposures to contaminated soil may have resulted at the Medley site. While the future development of the site could lead to exposure pathways, we believe that only on-site areas represent likely points of exposure.
The migration of the residual chemicals in soil is insignificant on the site due to the site topography, limited access to the site, dense forests surrounding the site, the vegetative cover of the site, and limited mobility of chemical residuals. There is no concern of soil erosion at this time due to the vegetative cover on the site and the dense forests that surround the site.
Topographic analyses indicate that surface soil contaminants could enter Jones Creek through runoff during rain storms. However, sampling shows that no site-related contaminants have reached Jones Creek and no point of exposure exists from this medium.
Exposure to contaminants in soil is unlikely since these contaminants were detected in localized areas at depths greater than 1 foot and at 15 to 17 feet respectively. A number of contaminants have been detected in shallow (0-1 foot) soil samples. There is no data available to indicate the concentration of contaminants found within the top 3 inches of soil. Since most of the site is covered with weeds and grasses, with small areas of bare soil, exposures to these contaminants would be unlikely. People most likely to be exposed include the property owner's family (if they spend time on the site), trespassers, and hunters who may stray onto the property. The only possible route of human exposure may be inhalation of chemical vapors during soil excavation activities. This is unlikely as there are no excavation activities on site at this time.
Air Pathway
No air monitoring data is available for review. Contaminants attached to soil particles could be carried by the wind. However, dust generation is unlikely because the site is surrounded by forest on three sides and there are few areas of exposed surface soil. In addition, there are no homes other than that of the property owner immediately adjacent to the site. Therefore, no evidence for transport of site-related contaminants through air exists.
Food Chain Pathway
Any potential exposures to site-related contaminants due to ingestion of blackberries or wild game found on site is unlikely. The site is covered by clean fill; and plants growing on clean fill should not be able to access any site-related chemicals. Additionally, the site is not readily accessible to the general public because of its remote location.
Jones Creek does not appear to be large enough for fishing. Contaminants have not been detected in the creek at levels of concern.
Hunting is popular in the vicinity of the site, but substantial accumulation of contaminants in wildlife
is not likely. Wild game do not feed exclusively on the site. Surface clean-up has been thorough and
significant surface water contamination has not been detected. Site-related contaminants are unlikely
to be transported via this pathway.
In this section we will discuss the health effects in persons exposed to specific contaminants, evaluate state and local health databases, and address specific community health concerns.
To evaluate health effects, ATSDR has developed Minimal Risk Levels (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily human exposure to the respective contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, ingestion, inhalation and dermal contact, and for three different lengths of exposure, acute (less than 14 days), intermediate (15 to 365 days) and chronic (greater than 365 days). ATSDR presents these MRLs in Toxicologic Profiles. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status.
A past completed exposure pathway has been identified for one private well user located upgradient from the site. This contamination is not considered to be site related, the length of exposures is not known, there are no data available for review, and the private well user has discontinued use of the well; therefore, this pathway cannot be evaluated for past exposures and no current exposures are known to be occurring.
Currently available data show no completed pathways to be occurring at the present time. Exposures to contaminated groundwater could occur in the future if private wells are drilled on the site property or in the vicinity of Well #2. The future residential development of the site should be monitored to prevent exposures to contaminants in the future. If the future residential development is not restricted, persons may be exposed to contaminated drinking water. Therefore, this section explains the health implications of ingesting contaminants at the maximum concentrations detected in soil, groundwater, surface water and sediments. Because this is a hypothetical exposure based on assumptions of groundwater movement and human activities at the site, the discussion is brief.
The information provided in this section is based on estimated doses that are derived following several standardized assumptions. These estimated doses are computed estimations of the amount of chemicals a person can be exposed to. The computations are based on the assumptions that an adult weighs 70 kilograms (154 pounds) and a child weighs 10 kilograms (27 pounds). An adult ingests 2 liters of water per day, and a child drinks half that amount. During the course of the day, adults typically ingest 50 to 100 milligrams of soil per day (mg/day); by inhalation of small soil particles carried in the air, and by placing soiled hands and other objects in the mouth. We assume that small children ingest a greater amount of soil, typically 200 mg/day, because they generally tend to place objects in their mouths.
These assumptions and the respective exposure scenarios are used to determine the estimated doses for each chemical. The estimated doses will be compared to health guidelines and the available scientific literature to determine if health effects are likely to occur.
Benzene
No exposures to benzene are occurring at the present time; therefore, no health effects are expected. If on-site groundwater is used as a drinking water source, the amount of benzene that would be consumed would result in an increased risk of developing cancer. The EPA classifies benzene as a known human carcinogen (1).
Chlorinated Aliphatic Compounds (CACs)
This class of chemicals includes methylene chloride, chloroform, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1-dichloroethylene, and trichloroethylene (Table 2).
As these compounds exhibit similar toxicologic and chemical properties, one may assume that a mixture of these compounds is at least as toxic as the effects of each compound. Evidence in laboratory animals indicates that, for some limited combinations of these compounds, the toxicity of the mixture is greater than would be expected from the toxicity of each compound (2,3,4,5,6).
The ingestion of small amounts of these compounds over a prolonged period of time may lead to damage of the liver and kidneys. The compounds whose names contain "ethane" appear less likely to produce kidney damage. The EPA classifies several compounds in this class as probable human carcinogens (Group B2). A Group B2 classification is used to characterize a chemical for which there is sufficient evidence of carcinogenicity in animals but inadequate evidence or no data from human epidemiological studies (2,3,4,5,6). These include methylene chloride and chloroform. The EPA classifies 1,1,2-trichloroethane as a possible human carcinogen (5).
If on-site groundwater was used as a drinking water source, the amount of each contaminant consumed would exceed ATSDR minimal risk levels. Hypothetically, individuals consuming this water could develop noncarcinogenic health effects (that is, liver, kidney, and possibly nervous system damage).
Since these compounds are mainly probable human carcinogens, individuals who consume this water would have an increased risk of developing cancer. However, currently there is no consumption of on-site water and based on available information there is no exposure to this group of contaminants.
Semi-Volatile Organic Compounds
1,2,4-Trichlorobenzene was found at a concentration of 710 mg/kg (milligrams per kilogram) in samples of the test pits. This concentration however, has been diluted for this analysis. This compound was also found in soil borings of 15-17 feet at a maximum concentration of 12 mg/kg of soil. In addition, 1,2,4-trichlorobenzene was found in the samples taken from 0-1 feet range at a concentration of 1.2 mg/kg (10).
Since exposures to this compound are unlikely to occur, it is not considered a health threat at this time. Available information on the toxicological properties and the long-term health impact of exposure to 1,2,4-trichlorobenzene is limited (11). EPA has not classified this chemical as to human carcinogenicity.
B. Health Outcome Data Evaluation
As no health outcome data exists for the Medley site, health outcome data cannot be evaluated at this time.
C. Community Health Concerns Evaluation
The community expressed concern about possible contamination of their water supplies and the health effects that may occur from this contamination. We responded to these concerns by sampling the water supply wells in 1984. The only well that showed contamination is Well 2 located approximately 125 feet upgradient of the site (Figure 3). Groundwater monitoring conducted in 1989 - 1990 of a monitoring well located between the well of concern and the site showed no contaminants. Well 2 contamination is not considered site-related as it is located upgradient of the site and a monitoring well located between the well and the site showed no contaminants. The owner of Well 2 was advised to discontinue use of the well and is now using municipal water.
Since the other private wells showed no contaminants of concern, they are not considered to be a health risk at this time. Municipal water supply lines are now available to the community and no further concerns have been expressed.
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