PETITIONED PUBLIC HEALTH ASSESSMENT ADDENDUM
SOUTHERN WOOD PIEDMONT
AUGUSTA, RICHMOND COUNTY, GEORGIA
Since the time of the initial SWP public health assessment, the presentation of environmental data in health assessments has evolved in a way that will make conclusions about environmental contamination clearer to the reader. The following introductory paragraphs describe the analytical methods now used in public health assessments and in this addendum.
The tables in the subsections below list contaminants in each medium. Subsequent sections of this addendum contain discussions of the contaminants and potential public health significance of exposure to them. Several factors influence ATSDR's selection and closer review of contaminants. Factors include on-site and off-site concentrations, the quality of the field and laboratory data, sample design, comparison of on- and off-site concentrations to public health assessment comparison values for noncarcinogenic and carcinogenic endpoints, and community health concerns.
When the maximum concentration of a contaminant exceeds a comparison value, this does not mean that it will cause adverse health effects if exposure occurs at the specified concentration. Comparison values govern selection of contaminants for further review. ATSDR and other agencies developed comparison values to provide guidelines for estimating contaminant concentrations that are unlikely to cause adverse health effects, given a standard daily ingestion rate and standard body weight. ATSDR used toxic equivalent factors for benzo(a)pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) respectively to calculate the total polycyclic aromatic hydrocarbons (PAHs) and dioxins/furans discussed below. See Appendix 1 for a description of the comparison values and toxic equivalent factors used in this addendum. The Public Health Implications section of this addendum includes discussions of the potential for adverse health effects resulting from exposure to contaminants of health concern.
As mentioned in the Site Description and History section, remediation is ongoing at SWP, and the GA EPD approved actions to prevent migration of contamination off site until remediation is complete. Before remediation activities began in 1989, SWP staff members first characterized on-site soil contamination. They took 36 soil samples at various depths and analyzed them for wood-treating chemicals and metals. They found pentachlorophenol (PCP) at an average level of 610 milligrams per kilogram (mg/kg) in 20 of the samples. They also found PAHs in more than 20 of the samples. The maximum level of carcinogenic PAHs found was approximately 450 mg/kg. They found arsenic and zinc in all of the samples. The average level of arsenic was approximately 45 mg/kg; the maximum level was 640 mg/kg. Figure 1 (page 4) identifies the areas of greatest on-site contamination, which have since been remediated. See pages 2-8 2-10 in Appendix 2 for more details about on-site soil contamination.
Groundwater beneath the site is also contaminated with site-related chemicals, and this contamination has migrated off-site. Figure 4 (page 13) identifies the estimated boundaries of the contamination plume from 1990 groundwater monitoring data. The Off-site Contamination subsection contains further discussion of groundwater contamination.
1993 results See ATSDR's Health Consultation (Appendix 3), which contains discussion of the public health implications based on results of off-site monitoring that EPA Region IV staff members conducted in 1993. The environmental monitoring data give the most current picture of environmental contamination in all neighborhoods surrounding SWP.
Environmental Monitoring Data Between 1990 and 1993
In January 1990, representatives of Geraghty and Miller, Inc. took 10 surface soil grab samples from areas designated "Marshall and Roberts Class Action Properties." They analyzed Roberts Class Action Property samples for semi-volatile organic compounds (SVOCs), metals, and four volatile organic compounds (VOCs): benzene, toluene, ethyl benzene, and xylenes. They analyzed Marshall Class Action Property samples for SVOCs, metals, VOCs, polychlorinated biphenyls (PCBs), and 22 known wood preservative constituents. ATSDR did not receive information either on sampling location and methodology. The Marshall Class Action Property samples revealed PCB levels above available health comparison values .
Representatives of the GA EPD sampled surface soil along Nixon Road and Lynchburg Street in October 1990. They took three grab samples and analyzed them for extractable organic compounds. Results showed low levels of PAHs and one elevated level of bis(2-ethylhexyl) phthalate (BEHP) .
Staff members from the University of Georgia Cooperative Extension Service (Extension service) conducted soil sampling for arsenic, chromium, and copper in 15 residential yards and gardens in the Hyde Park Area in September 1991. They took one grab sample per yard and chose samples randomly at depths of 6 - 8 inches. Arsenic levels averaged 76 mg/kg, with a maximum level of 170 mg/kg. Chromium levels averaged 21 mg/kg, with a maximum level of 48 mg/kg. Copper was found only at low levels .
Geraghty and Miller staff members conducted surface soil sampling throughout the Hyde Park Area in October 1991. They took 23 samples and analyzed them for VOCs, SVOCs, PCBs, and metals. ATSDR received no information on sampling and analytical methods.Arsenic and chromium levels detected were substantially lower than those found in samples taken by the Extension service. One sample had arsenic at 110 mg/kg; however, this was the only sample in which arsenic exceeded the environmental media evaluation guide (EMEG) of 15 mg/kg. PAHs, beryllium, and cadmium were also detected at levels above available comparison values .
Maximum concentrations of contaminants found in the above three sampling rounds are combined on tables 1 and 2 (pages 15 and 16). Health comparison values are not available at this time for many of the contaminants detected. Later sections of this addendum contain discussions of the public health implications of exposure to these contaminants in residential soils.
Representatives of the Governor's Task Force compiled the available data on a computer graphics system in October 1992. The graphical representation of sampling data indicated certain trends. The PAH contamination is not widespread in residential yards, but exists in a few areas adjacent to ditches north, west, and east of the site. Overall, arsenic soil levels were highest along Nixon Road and Winter Road adjacent to SWP. Elevated lead levels were localized around Goldberg and Richmond Recycling .
ATSDR has received information on nine rounds of soil and sediment sampling from ditches surrounding SWP. Private consultants and representatives of state and regional federal agencies conducted the sampling between July 1988 and October 1991. We received very little information on sampling techniques and methodology. Table 3 (page 17) presents the maximum concentrations of contaminants found in ditches. Arsenic, PAHs, beryllium, cadmium, PCBs, and dioxins/furans exceeded available health comparison values [1, 2, 4, 5]. The extent of arsenic, PAH, and dioxin/furan contamination is further described below.
The Extension service detected the highest levels of arsenic (343 mg/kg) in 1991 southeast of SWP. About a third of the samples from ditches around SWP had arsenic levels above the child EMEG of 15 mg/kg . These ditches were north of and adjacent to SWP, southeast of SWP, and south of Clara Jenkins Elementary School [1, 2, 4, 5]. All of these ditches except the ones near the elementary school have since been remediated.
Law Environmental representatives detected the highest levels of total PAHs northeast of SWP (58.8 mg/kg) in 1990. PAHs consistently exceeded health comparison values in ditches abutting the northern border of SWP, south of Clara Jenkins Elementary School, and along Walnut Street and Dan Bowles Road [1, 2, 4, 5]. Ditches abutting the northern border of SWP have since been remediated. Total PAHs were calculated using Toxic Equivalency Factors for benzo(a)pyrene (Table 4, page 18).
EPA staff members detected the highest level of total dioxins (8,487 parts per trillion or ppt) southeast of SWP in 1991 . Levels of dioxins/furans exceeded health comparison values in ditches abutting SWP north and east, east of Clara Jenkins Elementary School, and along Dan Bowles Road [1, 6, 7]. The ditches abutting SWP to the north and east have since been remediated (Figure 2, page 6). Total dioxins/furans were calculated using Toxic Equivalency Factors for 2,3,7,8-TCDD (Table 5, page 18).
Representatives from the Governor's Task Force found some trends in off-site ditch contamination. They found PAHs, naphthalene, dioxin, and arsenic contamination primarily in ditches east of and downgrade from SWP. The contamination was generally present in ditches bordering the Virginia subdivision but did not extend into Hyde Park. Lead contamination was localized in ditches around the recycling industries locations .
All of the maximum concentrations found in the data discussed above are found in tables 3, 4, and 5. ATSDR does not have health comparison values available for many of the contaminants detected in ditch sediments. The Public Health Implications section contains further discussions of these contaminants.
Phinizy Swamp Sediments
EPA representatives investigated Phinizy Swamp as part of a Case Development Investigation/Evaluation under the RCRA Regulations in 1991. They analyzed two soil samples and five sediment samples from Phinizy Swamp for metals and extractable organics. The sampling depth was not indicated. Three of the samples were taken from ditches along the south end of Gravel Pit Road, three from ditches in Phinizy Swamp, and one from the intersection of Old Savannah Road and Rocky Creek. Arsenic, PAHs, and beryllium exceeded available comparison values (Tables 6 and 7, page 19) .
Rocky Creek Sediments
GA EPD staff members obtained samples of Rocky Creek sediments in 1985, 1986, and 1987. The GA EPD representatives took two samples from Rocky Creek at its confluence with the east ditch. They analyzed the sediment samples for VOCs, SVOCs, and metals. Law Environmental representatives obtained samples of creek sediments at five points along the creek in 1987 and analyzed them for metals and chemicals related to wood-treating . Law Environmental representatives also sampled sediments at 12 points, about 500-foot intervals, along Rocky Creek between the east ditch confluence and Phinizy Swamp in 1990. They obtained a control sample just upstream from the east ditch confluence. They took samples at depths of 0 - 0.5 feet and 2.5 - 3 feet and analyzed them for VOCs, SVOCs, and metals .
Tables 8 and 9 (page 21) summarize maximum concentrations detected in all the sediment samples described above. Arsenic and PAHs exceeded available comparison values. Levels tended to be highest in the ditch running between SWP and Rocky Creek. This ditch has since been remediated (Figure 2, page 6).
Ditch Surface Water
Geraghty & Miller staff members obtained samples of surface water from ditches in residential areas north and east of SWP in 1991. They took six samples and analyzed them for VOCs, SVOCs, PCBs, and metals. We received information on sampling depths and analysis techniques . Table 10 (page 22) summarizes maximum concentrations detected. Arsenic, PAHs, beryllium, cadmium, copper, isophorone, lead, nickel, n-nitrosodimethylamine, and PCBs exceeded comparison values. The comparison values used are those for long-term or chronic exposures to water; they tend to be very conservative comparison values for characterizing the public health implications of playing or working in the ditches. Therefore, the Public Health Implications section of this addendum contains discussions of the public health implications more specific to the short-term or acute surface water exposure that would be associated with ditch water.
Groundwater in Monitoring Wells
SWP installed monitoring wells north and east of the site in 1989. Their staff members sampled groundwater every 2 months and analyzed it for heavy metals, benzene, and toluene. Corrective Action Reports Volumes 1 - 5, submitted individually to the GA EPD, summarized data retrieved between 1989 and 1992 . Arsenic, barium, benzene, chromium, lead, nickel, selenium, and zinc exceeded comparison values. Table 11 (page 22) summarizes the maximum concentrations. The data indicate elevated levels of arsenic in aquifers east-southeast of the site and elevated levels of benzene and toluenenortheast of the site near waste oil storage tanks. Toluene did not exceed comparison values [18, 19].
See pages 2-8 2-10 and 2-13 2-15 in Appendix 2 for more information concerning groundwater contamination.
Groundwater in Private Wells
ATSDR did not receive additional monitoring data for private wells; however, the EPA is
conducting a private well survey as part of an overall project to characterize off-site
contamination . ATSDR staff members will examine this information, when it becomes
available, to determine whether there is need for further public health actions. (See pages 2-10
and 2-13 2-15 in Appendix 2 for information on past private well contamination.) Figure 5 (page 24) summarizes arsenic data from groundwater monitoring before 1988. All detected levels were above ATSDR's CREG of 0.02 µg/L and ATSDR's adult EMEG of 10 µg/L. Municipal well water lines were last extended into the area in 1989.
Figure 5. Arsenic Data from Groundwater Monitoring Prior to 1988.
SWP staff members conducted ambient air quality investigations, as required by the GA EPD, during on-site soil remediation in April 1990. They quantified ambient total suspended particulates (TSP) for 14 consecutive days and PAHs, PCP, and dioxins/furans for 4 of the 14 days. Reported levels of PAHs, PCP, and dioxins/furans represented the highest constituent combined total mass obtained on the glass fiber filters during each 24-hour period. Monitoring took place at four on-site and two off-site locations. The highest level of TSP (.173 mg/m3 [milligrams per cubic meter]) was detected off-site on day 12. Dioxin/furan concentrations were totaled as 2,3,7,8-TCDD equivalents. The highest total equivalent 2,3,7,8-TCDD concentration was 8.99E-11 mg/m3. None of the PAH or PCP concentrations exceeded detection limits .
Additional ambient air quality investigations took place during off-site ditch soil excavation. Geraghty & Miller representatives used EPA methods to monitor for dioxins/furans, PCP, naphthalene/benzo(a)pyrene, and benzene during November and December of 1991. They chose four off-site monitoring locations east-southeast of SWP along the railroad tracks. Benzene did exceed the ATSDR health comparison value of 0.0001 mg/m3 on one occasion; however, the detection limit for benzene also exceeded 0.0001 mg/m3, so it is impossible to characterize the extent of off-site benzene ambient air contamination fully. (See table 12 on page 25 for a summary of the maximum contaminant levels detected off site) .
Considering the quantities and purposes of wood preservative solutions used at the SWP Wood-Treating Facility, consultants for SWP estimated annual off-site PCP and benzene levels in ambient air. The consultants cited EPA methodologies used in calculating the estimates. Estimated annual concentrations were highest for benzene during 1979 (0.0055 mg/m3) and for PCP during 1985 (0.0000195 mg/m3). According to estimates, benzene exceeded the cancer risk evaluation guide (CREG) of 0.0001 mg/m3 every year between 1973 and 1985, with an average level of about 0.003 mg/m3 each year. No healthcomparison value exists for PCP. Estimated PCP levels averaged about 0.000012 mg/m3 between 1972 and 1987 .
The GA EPD obtained fish tissue samples from Rocky Creek in 1986 and 1987. Staff members sampled 10 fish species by electroshock sampling during the 2-year period and analyzed them for VOCs, SVOCs, and metals. They detected trace amounts of some contaminants, none of which exceeded comparison values. Only 2 of the 10 fish species sampled were edible, and none of the samples were of edible size. Contaminants detected in Rocky Creek sediments were not detected in Rocky Creek fish .
Unfortunately, ATSDR received much of the above data without information on sampling methodology and quality assurance/quality control (QA/QC) information, so it is difficult to evaluate the data quality fully. The available QA/QC information and issues are presented below.
Inconsistencies exist in much of the residential soil data, especially among the arsenic concentrations detected by Geraghty & Miller, the GA EPD, and the Extension service. The latter found arsenic levels 12 to 15 times higher than those found by both Geraghty & Miller and the GA EPD . The Extension service reports using the accepted arsine gas generation method for measuring arsenic contamination in soil; however, its staff members did not use blanks or quality assurance samples during sampling. Therefore, we cannot verify these samples and should probably consider them suspect . ATSDR staff members evaluated the public health implications of past exposure to contaminated soils in this addendum as accurately as possible, although we recognize that our evaluation is limited by such inconsistencies as those mentioned above.
Detection limits for PAHs in ditches and benzene in air presented a problem for the public health evaluation of this site. Currently, detection limits for these contaminants are higher than health comparison values; thus, it is impossible to fully characterize the public health implications for PAH ditch contamination and benzene air contamination off site.
Law Environmental staff members provided QA/QC information for sampling of Rocky Creek sediments conducted in 1990. The procedures followed the accepted EPA protocol. They cleaned all equipment thoroughly after they took each sample to minimize cross contamination of samples. They transferred samples to the appropriate containers, labeled them, and shipped them with completed chain of custody records to the laboratory performing the analysis.
EPA representatives collected sediment samples from Phinizy Swamp in accordance with the Environmental Compliance Branch Standard Operating Procedures and Quality Assurance Manual. They analyzed samples in accordance with the Analytical Support Branch Laboratory Operations and Quality Control Manual. They did not take control samples during the investigation.
BEHP (bis-2-ethylhexyl-phthalate) was reported in the monitoring results on several occasions, especially for surface soil results. BEHP is also a constituent of the gloves the investigators used while sampling environmental media. The BEHP reported in the data probably resulted from cross contamination from the gloves used by samplers and is unlikely to be reflective of actual contamination in surface soils.
Again, ATSDR staff members realize that the quality assurance problems with the environmental data affect our discussion of the public health implications of past exposure. Because of the inconsistencies and quality assurance problems outlined above, ATSDR representatives requested that the EPA Region IV office staff characterize off-site soil thoroughly so that they can make public health decisions about the health implications of current exposure as responsibly as possible. The EPA has provided ATSDR with the results of its off-site sampling program, which is addressed separately in a health consultation, released March 3, 1994 (Appendix 3).
No physical hazards were noted at or near SWP. However, ditches adjacent to the Clara Jenkins Elementary School, unrelated to SWP, may be a hazard for children at the school. The ditches are about 10 feet deep and have very steep slippery clay edges. No warning signs were posted, and access to the ditches from the school yard is unrestricted. A potential for injury exists if children playing near the ditches accidentally slip and fall into the ditches. There is sufficient water in the ditches to create a concern for drowning as well .
To determine whether people are exposed to contaminants released from the SWP site, ATSDR evaluated the environment and human components that lead to human exposure. As explained in the SWP Petitioned Public Health Assessment, the pathway analysis consists of five elements:
- 1) source of contamination;
2) environmental medium in which the contaminants may be present or to which they may migrate;
3) points of human exposure;
4) routes of human exposure, such as ingestion, inhalation, or dermal absorption; and
5) receptor population.
In the SWP Petitioned Public Health Assessment, ATSDR categorized pathways by media. For improved clarity, ATSDR now identifies exposure pathways as completed, potential, or eliminated. A completed exposure pathway exists in the past, present, or future if all five elements, mentioned above, link the contaminant source to a receptor population. Potential pathways, however, are situations in which at least one of the five elements is missing, but 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. Pathways are eliminated when at least one of the five elements is missing and will never be present. Suspected completed and potential pathways may also be eliminated when they are unlikely to exist or be significant. Table 13 (page 28) presents all completed and potential exposure pathways at SWP.
Available sampling data for residential soils indicate that populations residing in residential areas adjacent to the site (along Nixon and Winter roads) may be exposed to elevated levels of surface soil contaminants, primarily arsenic and PAHs. These contaminants were also found at elevated levels on site. Populations residing near the recycling facilities may be exposed to elevated levels of lead in soil. Populations residing in the Hyde Park and Virginia subdivisions may also be exposed to contaminated soils; however, it would be necessary to perform further environmental sampling to evaluate the public health implications of exposure. For this reason, EPA representatives completed an extensive off-site soil sampling program (refer to ATSDR's Health consultation in Appendix 3).
Levels of arsenic, heavy metals, PAHs, and PCBs exceeded comparison values for surface soils in yards north of SWP. As stated in the SWP Petitioned Public Health Assessment, "...wastewaters containing [wood-treating chemicals] were discharged to drainage ditches adjacent to the site by SWP in the past. Also, during episodes of heavy rainfall, surface water runoff from the facility could also flow off-site into drainage ditches. It is possible that wastewaters that were discharged to these ditches contained high concentrations of wood treatment chemicals."
Surface water in one ditch flows toward residential areas north of the site (Figure 6, page 30). Ditch surface water drainage could have transported on-site wood-treating chemicals, such as arsenic and PAHs, to off-site residential areas. Residents report periodic flooding of yards during heavy rainfall. Flooding could have deposited contaminated surface water and sediments from ditches into soils in adjacent yards. The data do indicate that arsenic levels are highest in yards near SWP and associated drainage ditches. PAH contamination does not appear to be widespread in yards, but it has shown up in a few spots near ditches .
Contaminated soils in residential yards are a significant point of exposure. Children playing in yards or adults working outdoors will experience the most exposure to contaminated soils. Ingestion and dermal absorption are possible routes of exposure, with ingestion being the more significant. Estimates indicate that, children between the ages of 1 and 6 will incidentally ingest up to 100 mg/day of soil and adults will ingest 50 mg/day through normal hand-to-mouth activity .
Children who have played or adults who have worked in off-site ditches have been exposed intermittently and for short periods of time to elevated levels of arsenic, heavy metals, PAHs, dioxins/furans, and PCBs in sediments via ingestion and dermal contact.
As stated above, some of the ditch contamination, including arsenic and PAHs, likely resulted from SWP waste management practices and runoff of on-site surface waters into ditches during periods of heavy rainfall. Contaminants in surface waters probably deposited and accumulated in ditch sediments; however, it is highly unlikely that SWP is responsible for all of the contamination.
Ditch surface water flows north towards Clara Jenkins Elementary, east towards Phinizy Swamp, and west and south toward the Virginia subdivision (Figure 6, page 30). Ditches with the highest levels of arsenic contamination were primarily north of and adjacent to SWP, southeast of SWP, and south and east of the elementary school. PAH, naphthalene, and dioxin contamination extended north towards the elementary school and east towards Rocky Creek. Generally, no significant amount of contamination extended beyond the elementary school. Lead was found in
ditches surrounding the recycling facilities only. Some of the ditches described above
and closest to SWP have already been remediated (Figure 2, page 6).
Figure 6. Surface Drainage in and around Site & Vicinity.
Human exposure to ditch sediments may occur via ingestion or dermal absorption. Ingestion may occur through normal hand-to mouth activity when people play or work in contaminated ditches. Dermal absorption may occur via direct skin contact to ditch sediments; however, ingestion is the more significant route of exposure.
Ditches around SWP have posted warning signs. Citizens in the community report children continue to play in ditches and homeowners "clean out ditches" seasonally. Citizens also reported workers coming in contact with ditch sediments while installing utility poles. Workers involved with ditch remediation and other activities that require contact with ditch sediments may be exposed to elevated levels of contamination, depending on worker safety practices. Exposures to ditch sediments has probably been only intermittent or acute (fewer than 14 days at a time), unlike the chronic low-level exposures predicted for residential yards.
Residents located southeast of SWP and workers have been exposed to elevated levels of benzene in air via inhalation during ditch remediation activities and while SWP was in operation between 1973 and 1985. Exposures to elevated levels of benzene may continue to occur until ditch excavation activities are completed.
Benzene is a VOC that ditch excavation and past SWP operations may have liberated from deep sediments or groundwater. Given the atmospheric conditions of the area, benzene would have an estimated half-life of about 4-6 hours (20). Wind dispersion and attenuation would also decrease ambient benzene concentrations.
Estimates indicate that residents in "neighborhoods" surrounding SWP may have inhaled elevated levels of benzene between 1973 and 1985. We did not receive enough information to determine which neighborhoods experienced the most exposure. Residents east and southeast of SWP were exposed to benzene vapors through inhalation of contaminated ambient air during ditch remediation activities. Because of benzene's short half-life, the latter exposure was probably intermittent (i.e., limited to periods of active ditch remediation). Detected levels of benzene were similar to those found in many urban areas of the United States.
Past monitoring data indicated that private well users were exposed to elevated levels of naphthalene and other creosotes, as indicated on pages 2-13 2-15 in Appendix 2. Private well users may also have been chronically exposed to elevated levels of arsenic, heavy metals, and benzene via ingestion, inhalation, and dermal absorption of contaminated groundwater. Private well users residing east and southeast of SWP along Gravel Pit and New Savannah roads and in the Virginia subdivision were at highest risk for elevated arsenic exposures, since arsenic levels detected from monitoring wells in those areas were above comparison values. Municipal water lines were extended into areas of New Savannah and Gravel Pit roads in 1989 and to areas adjacent to SWP in the mid-1970s; therefore, we do not expect current and future exposures to contaminated groundwater.
People working or playing in Phinizy Swamp may be intermittently exposed to elevated levels of PAHs, arsenic, and beryllium via ingestion and dermal absorption. This pathway remains "potential," since we do not know whether populations come into contact with swamp sediments.
Drainage ditches adjacent to SWP drain into Rocky Creek, which empties into Phinizy Swamp 4,000 feet east and southeast of the site. Contaminants on site, such as arsenic and PAHs, may have migrated to Phinizy Swamp via drainage ditches and Rocky Creek and then deposited in swamp sediments (Figure 6, page 30).
Human exposure to swamp sediments may occur via ingestion or dermal absorption. People may experience Ingestion through normal hand-to-mouth activity while playing or working in the swamp. Dermal absorption may occur via direct skin contact to swamp sediments; however, ingestion is probably the more significant route of exposure.
The EPA reports that the Department of Transportation has accepted plans for a road to be constructed very near and perhaps through a portion of Phinizy Swamp. Road construction crews working in this area in the future are at significant risk of sediment exposure and should consider worker safety issues before commencing construction in this area. In addition, people using Phinizy Swamp for recreational or other purposes are also at risk for sediment exposure, although we do not know whether these exposures occur.
People engaged in recreation around Rocky Creek may be exposed acutely and intermittently to elevated levels of arsenic and PAHs in sediments via ingestion and dermal absorption.
Ditches south of SWP empty into Rocky Creek (Figure 6, page 30). There is a high probability that on-site contamination has consequently migrated and is deposited in Rocky Creek sediments. PAH contamination was detected at the highest levels along the creek banks, where human exposures would probably be more frequent, not in sediments on the creek bottom. Law Environmental representatives estimated that the potential for human exposure is low, since only a small number of residents along Gravel Pit Road have direct access to the creek. Also, other areas around the creek are either industrial or undeveloped.
People who have played or worked in off-site ditches have been exposed acutely and intermittently to elevated levels of arsenic, heavy metals, PAHs, PCBs, and VOCs in surface water via ingestion and dermal contact. Since surface water levels are shallow in the ditches and swimming is impossible, it is unlikely that significant amounts of surface water would have been absorbed.
Pica is the habitual ingestion of non-food items. Children between the ages of 1 and 3 are at highest risk for practicing pica. In areas where soil contamination exists, children who practice pica are of special concern, since they may ingest between 5,000 and 10,000 mg of soil per day . We have not confirmed any cases of children with pica behavior in any of the residential areas surrounding SWP; however, as long as the possibility exists, we will continue to classify pica behavior as a potential exposure pathway.
Elevated levels of PAHs were detected in Rocky Creek sediments. However, PAHs identified in sediments did not appear in fish tissue sampled in 1986 and 1987. Some species of fish bioconcentrate PAHs from sediments; however, fish tend to metabolize and excrete PAHs rapidly. This tendency explains why PAHs do not appear or appear only at low levels in fish tissues from environments heavily contaminated with PAHs [34, 35]. Also, the potential for human exposure to elevated levels of PAHs via fish ingestion is very low because there is a limited potential for humans to access the creek and none of the fish sampled in the creek were of edible size. However, since the potential for the fish population to be exposed to contaminated sediments remains high and fish consumption rates for humans are unknown at this time, we will continue to classify fish as a potential pathway .
This section contains discussions of health effects that could result from exposures to site contaminants. People can be exposed to a site contaminant only if they come in contact with it. In order to understand health effects a specific chemical may cause, we must consider four factors affecting the human body's response to exposure: the exposure concentration (how much); the duration of exposure (how long); frequency of exposure; and the route of exposure (breathing, eating, drinking or skin contact). Lifestyle can affect exposure duration and likelihood. Individual characteristics of each human, such as age, sex, nutritional status, overall health, and genetic predisposition can affect the way the body absorbs, distributes, metabolizes or eliminates a contaminant. Together, these factors determine the individual's response to chemical contaminants and what the health effects may be for that individual.
ATSDR examines its own toxicological profiles, a series of scientific studies and reports for individual contaminants. ATSDR uses these data to evaluate the chemicals' potential to harm human health and determine chemical levels that can reasonably (and conservatively) be taken as harmless. These data are part of guidelines for evaluating a site's relative health risks, and the guidelines contain safety factors to ensure protection of especially sensitive populations. ATSDR staff members use two kinds of guidelines as comparison values. The environmental guidelines can help them determine the safety of a compound's environmental concentration. These comparison values are specific for air, water, and soil.
ATSDR also uses minimal risk levels (MRLs) as health guidelines. MRLs are dose estimates of daily human exposure to a substance that are unlikely to result in an adverse health effect. Staff members uses information in the Pathway Analysis Section to estimate the dose people may receive from contaminants at the site. They compare this value to the MRL to determine whether there is potential for exposure sufficient to cause harmful health effects.
Appendix 1 contains a description of the types of ATSDR health guidelines used.
Since we do not have additional data to assess on-site contamination, this public health assessment addendum addresses only the additional off-site sampling data. We have used information from ATSDR toxicological profiles [34, 39-44] for the appropriate chemical and reference .
Compounds Found at Elevated Levels Both On site and Off site
The following compounds were found at elevated levels both on and off site, and are commonly used at wood-treating facilities. It is possible that the elevated amounts of these compounds are related to activities at SWP.
Arsenic contamination was widespread off site, appearing at levels above comparison values in groundwater; surface water; soil; and ditch, swamp, and creek sediment. Because remediation has not yet taken place in some of these areas, continued arsenic exposure is possible. Arsenic exposure for children in contact with ditch sediments is sufficient to cause concern. Chronic exposure to the maximum levels of arsenic detected in some off-site residential soils might pose a health threat to children as well. Groundwater was sufficiently contaminated with arsenic that chronic ingestion would present an increased risk for skin cancer.
Arsenic is used (or generated) in smelting and as a pesticide. Burning of fossil fuels can also release arsenic. Low levels of arsenic are also present in nature. The average naturally occurring arsenic soil level in the Eastern United States is 4.8 mg/kg. About 95% of the background samples taken had arsenic levels below 8 mg/kg.
Various effects of arsenic have been noted at high doses not relevant to the levels seen at this site. Effects of the low-level, long-term exposures that are likely to be seen at the site include the development of skin irritation. Concentrations of arsenic in soil are not sufficient to cause an increased cancer risk; however, chronic ingestion of arsenic- contaminated groundwater at levels found off site increases the risk for skin cancer .
Prior (i.e., before EPA's 1993 sampling) chromium levels in groundwater; ditch, swamp, and creek sediments; and off-site surface soil exceeded comparison values (RMEGs). They also exceeded health guideline reference doses in all these media. Chromium was a past health concern in the above media; however, it is only a current problem in groundwater. Since residents in the area are consuming municipal water for potable and nonpotable uses, elevated chromium levels in the groundwater is currently not of public health concern (refer to Appendix 3 for more information) . Chromium is used in plating and making special steels, while chromium salts are used as dye mordants, tanning agents, pigments, wood preservatives, and anti-corrosive and cleaning agents. Major environmental sources include industrial emissions from the combustion of fossil fuels. Chromium can irritate the stomach, nasal passages, and lungs and can be toxic to the liver and kidneys. Prior to 1993, it was possible to expect that chronic exposure to residential soils at the levels of chromium found off site might cause such adverse health effects .
Benzene occurs in off-site groundwater and air at levels exceeding comparison values; the levels in off-site groundwater are of potential health concern. Ideally, benzene exposure should be zero. The health concern is that children drinking this water for a long time might be at an increased risk for the development of leukemia. Off-site groundwater is listed as a completed exposure pathway because of the high probability that this water was consumed by private well users in the past.
Air is another possible exposure route; however, we lack data on past air concentrations. Current air levels of benzene are similar to levels in many urban areas. Benzene was one of the most common industrial solvents in the past but is rarely used now. The primary reason for this reduction has been concern over its ability to cause leukemia after long-term, low-level exposures. Benzene affects the blood, the central nervous system, skin, bone marrow and its ability to generate new white blood cells, eyes, and the respiratory system. Skin contact with benzene may result in reddening and swelling of the skin at the point of contact. Benzene levels off site, typical of levels found in urban air, were above comparison values; however, these levels would not be expected to result in adverse health effects.
Cresol, which may actually be a mixture of three closely related compounds, is a commonly used wood preservative. The compounds occur naturally in wood, coal, oil, tar, smoke, and some foods. Cresol was found in on-site groundwater at levels that might cause health effects in children drinking this water for long periods of time. (See page 2-8 in Appendix 2). This on-site groundwater has reportedly never been used as a drinking water source. The effects that might be seen at chronic, low doses are primarily neurological: twitches, decreased activity, and lethargy. We do not know whether off-site private wells are contaminated with cresol and whether residents are still drinking water from private wells .
Carbazole (diphenylene amine) is a common component of creosote. The concentrations found are a health concern for children ingesting creek or swamp sediments. Acute health effects, such as respiratory and eye irritation, are possible but unlikely. Carbazole is also an intermediate in the production of dyes and is used in color photographic processes.
PCP (Pentachlorophenol) was detected at levels exceeding health guidelines in on-site groundwater. A commonly used wood preservative PCP has been released into soils, air, and water at numerous wood treatment sites. It can cause both cancer and noncancerous health effects (birth defects and damage to liver, kidney, skin, blood, lungs, and the nervous system) in laboratory animals. Effects in humans are not as well studied . Exposure to low levels of PCP in on-site groundwater that would ever be used as a drinking water source is a potential health concern. This concern includes the potential for development of increased cancer risk. Off-site exposure to PCP in groundwater has not been verified by environmental monitoring .
Polycyclic Aromatic Hydrocarbons (PAHs). In general, PAHs form as products of ordinary combustion and thus are everywhere. They are in smoke, tobacco smoke, soot, and coal. They are generally natural products with no known use. They biodegrade slowly. We do not have health guidelines for all PAHs in all media, and it is difficult to predict potential health effects from mixtures of these compounds. Carcinogenic PAHs tend to be metabolized into more reactive forms. There is little known noncancer toxicity, although some PAHs are fetotoxic and reproductively toxic. Some carcinogenic forms are immunosuppressive and/or genotoxic in in vitro tests. PAHs generally have low water solubility and strong absorption to soil and thus do not migrate well in the environment. They may interact with each other, enhancing or reducing carcinogenic potential (reduction is the more common experimental result), but these interactions are ill defined for most PAHs .
Certain PAHs are not known to cause cancer. These include the following: acenaphthene, acenaphthylene, anthracene, fluoranthene, fluorene, methylated naphthalenes, naphthalene, phenanthrene, and pyrene. Sufficient evidence exists to accept that the following PAHs are also carcinogenic: benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[g,h,i]perylene, benzo[k]fluoranthene, chrysene, dibenzo[a,h]anthracene, and indeno[1,2,3-c,d]pyrene.
PAH levels found in groundwater (on and off site), soil, and sediments (off site) are sufficient to result in exposures that exceed health guidelines. There is a risk of the development of adverse health effects, especially to children, from PAHs in these environments. These risks include acute effects and an increased risk of the development of cancer. Individual PAHs, which may also exceed exposure limits, include acenaphthene, anthracene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(g,h,i)perylene, dibenzo(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3)pyrene, 2-methylnaphthalene, naphthalene, phenanthrene, and pyrene.
Dioxins and furans in ditch sediments were at concentrations above health guidelines. Dioxins and furans are related classes of compounds formed in the manufacture of various chlorinated products, including herbicides like 2,4,5-T (a component of Agent Orange) and other chlorinated cyclic hydrocarbons, in paper bleaching, and as a contaminant in PCP. They can also result from combustion of various chemicals, industrial wastes, and municipal wastes. They form naturally in most combustion processes. Forest fires have generated low background levels throughout the world. Dioxins and furans include compounds with various levels of chlorination. Isomers with 4 chlorine molecules include the most toxic forms, and congeners with chlorines in the 2,3,7 and 8 positions are the most toxic within each isomer group. The most toxic congener is 2,3,7,8-TCDD, while the related furan is only slightly less toxic. Other dioxins and furans can range from slightly less toxic to 1,000 times less toxic. Scientists dealing with mixtures of dioxins and furans have developed a system to weigh concentrations of congeners and isomers by factors that relate their toxicity to that of 2,3,7,8-TCDD, generating "TCDD equivalency factors." These factors are then used to assess the health risks from a dioxin/furan mixture.
In animals, 2,3,7,8-TCDD causes reproductive failure, birth defects, immunosuppression, thymic atrophy, liver damage and enzyme induction, "wasting" (severe loss of weight and body fat over several weeks), changes in iron in the blood, thickening of the skin (a rapid response), and hormonal changes. We do not yet know the actual cause of animal death, but it may involve alterations in the hormonal systems. Development of intoxication signs may be delayed, and death can require several weeks .
While we see many of these effects in animals, there are wide species differences in effect and levels needed to cause particular effects. Undefined factors also cause a great many individual differences in susceptibility. The only proven effect of 2,3,7,8-TCDD in humans is development of chloracne, a severe skin condition that may be disfiguring and long lasting. A number of chlorinated hydrocarbons can cause chloracne, and there is a wide range of susceptibility to this disease. It has been associated most often with massive doses of chlorinated compounds found during industrial and/or occupational exposures. Chloracne from the low levels seen in the environment has been very rare, and the levels found at the site would be unlikely to have this effect.
Dioxins were present in ditch sediment in sufficient concentration to pose a risk for increased incidence of cancer in children ingesting the material. Acute effects (chloracne) were also possible; however, these ditches have been remediated and no longer pose a threat.
Dibenzofuran was found in swamp and ditch sediment. Available data do not clarify whether this analysis represents the unchlorinated compound or one or more of the chlorinated forms. The EPA analysis method for these compounds is specific for the unchlorinated compound, so we assume that the data report on the unchlorinated compound. The unchlorinated form would be less toxic than the chlorinated and unlikely to cause significant health effects.
Compounds Found Off site Not Associated with Wood-Treating
Other substances found off site at levels that may be of health concern had no clear relation to activities at SWP. These are discussed below.
Beryllium levels exceeded comparison values in off-site sediments from the ditch and swamp, in ditch water, and in surface soil. Exposure estimates exceeded health guidelines in these media as well, except in ditch water. However, the threat from beryllium is due to the potential for increased cancer rates in the area because of inhalation of contaminated dusts derived from beryllium-contaminated soils. Generation of a large amount of dust from ditch and swamp sediments is very unlikely. Therefore, beryllium's presence in off-site media does not present a health threat.
Beryllium is used in strengthening alloys, primarily of copper, but also of aluminum and nickel. The major environmental source is combustion of coal . Thus, SWP is probably not the source of beryllium.
Cadmium exceeds comparison values in off-site surface water and surface soil. Predicted exposures to off-site soil are sufficient to be a health concern for children, especially pica children. Cadmium is commonly ingested with food and is also present in combustion ash from incinerators or fossil fuels and in tobacco smoke. The source of cadmium contamination is unlikely to be from SWP. Chronic, low-level exposures to surface soil contaminated with cadmium might increase the risk of kidney and liver damage. Cancer does not normally result from cadmium ingestion .
Lead is sometimes found at wood treatment sites; however, the highest levels of lead were found near the recycling facilities, not near SWP. It occurred there in off-site groundwater; surface water; soils; and ditch, swamp, and creek sediments at concentrations exceeding health guidelines. Exposure doses would be of concern only to children and pica children ingesting residential or ditch soil near the recycling facilities. The primary effects of lead are on the peripheral and central nervous systems, blood cells, and calcium metabolism. Nervous system effects include neuropathy, decreased nerve conduction velocity, slowed speech and language processing, shortened attention span, decreased IQ, decreased motor skills and coordination, and lessened concentration. Lead has effects on the fetus and newborn child, but these would not occur in a pica child ingesting contaminated soil or sediment .
Nickel occurs above comparison values in groundwater; surface water; soil; and ditch, creek, and swamp sediments, but exposure estimates indicate that it is not sufficiently concentrated to pose a health problem. Nickel is used in electroplating and in the manufacture of steel, alloys, and batteries. It is also found in tobacco smoke and a byproduct from the combustion of fossil fuels. Small amounts of nickel are essential nutrients .
Thallium is a metal utilized in electrical devices and glass. It concentrates in plants and is high in cigarette smoke. Thallium was found in ditch sediment. Although acute exposures to thallium in high doses may have harmful effects, humans or animals have shown almost no effects as the result of long-term exposure to small amounts. However, there are limited numbers of studies. Thallium has not been classified for its ability to cause cancer . The maximum level of thallium in ditch sediments does exceed health guidelines for children; however, the validity of this concentration level is questioned and may not exist because of the following:
- it was the only sample out of 40 that showed a level above the detection limit,
- the sample was acquired in an isolated location , showing no direct relationship with an identifiable source, and
- QA/QC protocols are suspect (i.e., both lead and thallium levels in the sample are exactly the same, 42 mg/kg).
Even if the level is a true concentration for the specified location, the area may not pose a health risk to children since they must inadvertently ingest sediment there on a daily basis for many years to produce chronic adverse health effects.
BCIE (bis-2-chloroisopropyl ether) was found in off-site soil at levels sufficient to pose a slight increase in the rate of cancer for children ingesting the soil over a long period of time. BCIE is a waste contaminant from manufacturing processes for chemicals, rubber, and insecticides. In higher concentrations, it can irritate eyes and the respiratory system.
3,3-dichlorobenzidine was found in off-site soil at levels sufficient to cause an increased risk of cancer in a child ingesting soil daily over a long period of time (greater than 365 days); however, no acute (short term exposure usually of 14 or fewer days) health effects would be expected at this level of exposure. 3,3-dichlorobenzidine is used in dyes and pigments, and most information on its toxicity comes from studies of workers exposed to high levels. Some persons exposed to low levels over long time periods have experienced liver damage. The compound is a carcinogen in animal assays and can cause leukemia in animals.
N-nitrosodimethylamine (NDMA) was found in surface water in the ditch. Once used as a rocket fuel, it now appears most often as an unwanted contaminant of alkylamines. NDMA breaks down quickly in the environment. Long-term, low-level ingestion exposure can lead to liver damage and both liver and lung cancer. However, these types of exposures to ditch water are not likely.
PCBs occurred in surface water and off-site soil at levels exceeding comparison values. PCBs are a group of 209 related compounds once used widely in industry because they are excellent insulators for electrical devices or equipment. Therefore, they were used as coolants, lubricants, hydraulic fluids, and plasticizers, especially in electric capacitors and transformers. They were manufactured from 1929 until 1977, when production and sale of PCBs was banned in the United States. However, equipment containing PCBs remains in use, and they have been found at numerous waste sites, former electrical equipment repair sites, and a variety of other manufacturing sites. PCBs are persistent in the environment and can bioaccumulate in the body.
PCBs were generally made in a crude fashion, resulting in complex, inconsistent, and poorly characterized mixtures of the various possible forms. Thus, PCBs are usually found at contaminated sites as complex mixtures. Some PCBs have been studied more thoroughly than others. In general, acute effects are slight and require high doses to develop. These effects in humans might include development of a skin rash called chloracne (also caused by a variety of chlorinated organic materials) and nausea (perhaps leading to a vomiting reflex). Other effects, involving liver, reproductive functions, and the immune system have been observed at high doses in animals but not in humans .
With long-term, low-level exposures that occur around contaminated sites, there is little known effect from PCB exposure. Some PCBs are thought to cause cancer, primarily liver cancer, in humans, but the evidence is not definitive. To be safe, ATSDR considers all PCBs potentially carcinogenic.
PCBs are present in sufficient concentration in off-site soils and ditch sediments to pose a small, probably unmeasurable, increase in the risk of cancer.
Pica children are children that habitually eat large amounts of dirt (one to two small handfuls of dirt a day). This practice is inherently unhealthy, since even "clean" soil contains heavy metals and other organic material. Pica children residing near hazardous wastes sites are at increased risk for health effects. Dioxin, arsenic, PAHs, lead, and several other substances have been found at levels of concern for children in some off-site areas, including ditches near the site and the recycling operations. Available data indicate that antimony, barium, cobalt, copper, mercury, selenium, vanadium, and zinc are also at levels of health concern for pica children in some areas.
A professor at Mercer University conducted a health status assessment in December 1991, and representatives of the University of Alabama and Emory University reviewed the assessment. The reviewers found methodological flaws. They concluded specifically that the twofold to threefold increase in all major causes of death found in residents of the Virginia-Hyde Park area was an artifact of inaccurately enumerating the population at risk. The absence of a corresponding increase in overall morbidity supports their conclusion. Furthermore, the reviewers state: "The report provides no basis for making any inference about the health of the residents of Virginia-Hyde Park [13, 14]."
Dr. Paveen Varma, Instructor at the Morehouse School of Medicine, and members of the Governor's Task Force have reported cases of chloracne and arsenical keratosis .
ATSDR representatives are conducting a community health investigation that will include a review of area residents' medical records and a review of the health evaluations and/or medical exams conducted in the area by medical personnel from Mercer University, Morehouse School of Medicine, the Medical College of Georgia, and the Governor's Task Force. The Recommendations section of this addendum contains proposed public health actions for the area.
Appendix 4 addresses community health concerns and public comments on this document.