PUBLIC HEALTH ASSESSMENT
QUEEN'S 41st AUTO SALVAGE
(a/k/a QUEENS 41 AUTO)
LAND O'LAKES, PASCO COUNTY, FLORIDA
The Queen's 41st Auto Salvage site (the site) is at 6600 Land O' Lakes Boulevard, Land O' Lakes, Pasco County, Florida. In March 1997, a neighboring property owner reported that the Queen's 41st Auto Salvage business had dumped oil products and antifreeze into a sinkhole on the Queen's property. He also charged that this dumping had contaminated his private well. In response, local, state, and federal environmental agencies sampled the potable well on the Queen's property and two nearby residential wells. Water from the on-site well contained chlorinated solvents at concentrations that exceed Florida drinking water standards. Water from the two nearby residential wells contained similar contaminants, but not at levels exceeding the Florida drinking water standards. To better characterize the nature and extent of contamination, the Florida Department of Environmental Protection and the Environmental Protection Agency collected additional soil, sediment, and ground water samples on- and off-site.
The site is categorized as an indeterminate public health hazard from past exposures. However, because the length of time the on-site drinking water well was contaminated prior to 1997 is unknown, the Florida Department of Health (Florida DOH) cannot estimate the public health risk from using this well in the past. Past use of water from nearby, off-site drinking water wells, however, is unlikely to have caused illness.
For current exposures, the site is categorized as a no apparent public health hazard. The on-site drinking water well is equipped with a filter and use of off-site ground water is unlikely to cause illness.
This site may be categorized as a public health hazard in the future. Future use of on-site ground water without a filter may increase the risk of illness. In the future, lifetime drinking and showering with tetrachlorotheylene-contaminated ground water from on the site could cause a "low" to "moderate" increased risk of cancer. Nearby, off-site drinking water wells should be monitored to ensure that they do not become a health hazard in the future.
Environmental agencies did not detect elevated levels of any of the contaminants in on- or off-site surface soil. However, subsurface soils (2 to 8 feet below ground) contain levels of arsenic that exceed the ATSDR comparison value. Because humans do not regularly contact subsurface soil, Florida DOH concludes that exposure to arsenic in subsurface soil is unlikely. Like the subsurface soil, sediment samples from the drainage ditch also contained detectable concentrations of arsenic. Ingestion of arsenic in sediment would not result in a dose that would cause illness. Neither surface nor subsurface soil contained any of the organic contaminants at levels that exceed the ATSDR comparison value. Therefore, these contaminants in soil are unlikely to cause illness.
The Florida DOH recommends unfiltered ground water from the site not be used for drinking or showering. Furthermore, the movement of contaminated ground water should be monitored by regularly testing the on- and off-site monitoring wells and the nearby off-site drinking water wells.
In this Public Health Assessment (PHA), Florida DOH, in cooperation with the Agency for the Toxic Substances and Disease Registry (ATSDR)(1), assesses the public health threat from exposure to chemicals in the environment at and around the Queen's 41st Auto Salvage site. Florida DOH estimates which groups of people may be at risk under past, current, and future conditions. Florida DOH then estimates if these exposures may have caused illness in the past, could be causing illness now, or could cause illness in the future. Finally, Florida DOH recommends actions to reduce or prevent these exposures and therefore, the illnesses.
3.1 Site Description and History
The five acre Queen's 41st Auto Salvage site (the site) is at 6600 Land O' Lakes Boulevard, Land O' Lakes, Pasco County, Florida. It is at the intersection of Carricker Road and Treasure Lane, one block northeast of Land O' Lakes Boulevard (a.k.a. U.S. Hwy. 41) (Figure 1, Appendix A) (EPA, 2000a). Two businesses share the property. The Queen's 41st Auto Salvage business occupies most of the property, while Queen's Motors, a used car business, occupies the western corner (Figure 2, Appendix A). The auto salvage business consists of a garage/office building, a storage shed, and semi trailers used for storage (Figure 2, Appendix A). The caretaker of the salvage yard lives in a mobile home on the west side of the property. The property is bounded to the southwest, northwest and west by Treasure Lane, Carricker Road, and the intersection of these roads (Figure 2, Appendix A). Across both Treasure Lane and Carricker Road are light woods with a few private residences. The nearest residence lies immediately south-southeast of the property. To the east, north and northeast are largely vacant areas with light woods and a few residences. A drainage ditch runs along the southeast border of the property and carries surface run-off to a wetland across Land O' Lakes Blvd. (Figure 2, Appendix A).
The property has been a salvage yard for more than 30 years. Little information exists about the business and waste operations before 1990, when the current owners purchased the property. Currently, the Queen's 41st Auto Salvage business employs two individuals and conducts operations similar to the activities of the previous owner, but on a smaller scale. To reduce pollution and contamination, the workers reportedly remove the engine, the fuel tank, and the oil from the automobile before crushing. The engines are stored on a covered, concrete area. The batteries are disposed of off-site and gasoline is either reused or stored in 75-gallon above-ground tanks. Used oil and antifreeze are stored in 55-gallon drums in one of the semi trailers. Waste containers are appropriately labeled and all wastes are disposed of off-site, in accordance with local, state and federal regulations (FDEP, 1997; 1998; EPA, 2000a).
In March 1997, a neighboring property owner reported that Queen's 41st Auto Salvage dumped oil products and antifreeze into a sinkhole and charged that this dumping had contaminated his private well. The neighbor also reported that the owners put down clean fill on the site. In response to these reports, the U.S. Environmental Protection Agency (EPA), the Florida Department of Environmental Protection (FDEP), and the Pasco County Health Department (CHD) collected and analyzed water samples from the potable and irrigation wells of the neighboring property owner. These agencies also collected and analyzed a sample from the potable well on the Queen's property. Both EPA and FDEP detected benzene, tetrachlorotheylene, methyl-tertiary-butyl-ether, and xylene in the neighboring residential drinking water well, at concentrations below the Maximum Contaminant Level (MCL) (FDEP, 1998; EPA, 2000a). The MCL is the highest level of a contaminant that is allowed in drinking water (EPA, 2000b). In contrast, ground water from the potable well on the Queen's property contained tetrachlorotheylene and trichloroethylene at concentrations well in excess of the MCL. The Queen's property owners have since installed a filtering system on the potable well and the private well at the neighboring residence is no longer used for potable water (FDEP, 1998).
On October 19th 1999, Davis Daiker and Randy Merchant of the Florida DOH, Bureau of Environmental Epidemiology, visited the site and the surrounding areas. They saw that unauthorized access to the sales office is possible but that access to the salvage yard is restricted by a metal privacy fence.
3.3 Demographics, Land Use and Natural Resource Use
3.3.1 Demographics
Based on 1990 census information, approximately 400 residents live within 1 mile of the site (Table 1, Appendix B), 110 are under the age of 17. Of this population, 92% are white, 1% are black, and 7% are Hispanic or from other racial/ethnic groups (U.S. Census, 1990). The number of persons residing around the site decreases to approximately 100 when the radius is reduced to 0.5 miles.
3.3.2 Land Use
Land use in the area is a mix between light commercial (e.g., Queen's 41st Auto Salvage) and low-density residential. Surrounding the site is a sparse distribution of residences among wooded areas. The nearest school is a high school and is slightly less than 1 mile to the northwest just off of U.S. Hwy 41. A senior citizen care center is within 0.5 miles of the site.
3.3.3 Natural Resource Use
This region of Florida has both the surficial and Floridan aquifers. The top of the surficial aquifer can be first encountered from just below the ground surface during the rainy season, to up to 10 feet below the ground surface during the dry season. The surficial aquifer extends to a depth of approximately 32 feet, where a semi-permeable clay layer, 6 to 10 feet thick, separates the surficial aquifer from the Floridan aquifer. Because this clay layer is semi-permeable, contaminants of the surficial aquifer may migrate slowly down into the Floridan aquifer. The Floridan aquifer lies beneath the clay layer and extends several hundred feet down. The ground water in the surficial aquifer reportedly flows west, toward Lake Wisteria, approximately 0.5 mile away. The ground water in the Floridan aquifer reportedly flows to the south (EPA, 2000a). In 1998, FDEP reported several private and public supply wells within a 1 mile radius of the site (FDEP, 1998). These wells may be drilled into either aquifer, but most potable wells are completed in the upper portion of the Floridan aquifer. Two municipal water companies also supply drinking water to much of the area. The municipal water is derived from several Floridan aquifer wells more than 3 miles from the site. This site will, therefore, not likely affect the municipal water.
PHAs use wide safety margins when setting health-related threshold values. The assumptions, interpretations, and recommendations made throughout this PHA err in the direction of protecting public health.
4.1 Environmental Contamination
We used the following ATSDR standard comparison values (ATSDR 1992a; 1999a), in order of priority, to select potential contaminants of concern at this site:
We use ATSDR standard comparison values to select chemicals for further consideration, not for determining the possibility of illness. Identification of a contaminant of concern (COC) in this section does not mean that exposure will cause illness. If a contaminant is detected at a concentration that exceeds the medium-specific comparison value, that chemical is chosen as a COC. Identifying COCs helps narrow the focus of the PHA to those contaminants that are most important to public health. When we select a COC in one medium (i.e., soil), we report that contaminant in all other media (i.e., ground water). We evaluate the COC in subsequent sections and estimate whether exposure is likely to cause illness. Florida DOH evaluated all available documents in identifying the COCs. The environmental data are presented in Tables 2 through 5 (Appendix B). For this health assessment, Florida DOH considers the surficial and Floridan aquifers a single source of ground water because the clay layer that separates the aquifers is semi-permeable.
4.1.1 On-Site Contamination
For this PHA, "on-site" refers to the property within the boundaries of Queen's Motors and Queen's 41st Auto Salvage, as shown in Figure 2 (Appendix A). FDEP and EPA collected soil samples from the surface (top 12 inches) and the subsurface (2 to 8 feet below ground), and ground water samples from both the surficial and Floridan aquifer. This sampling was done to identify a possible source of contamination and to define the extent of contamination (FDEP, 1998; EPA, 2000a).
Five of the seven surface soil samples and six of the 12 subsurface soil samples contained tetrachlorotheylene (Table 2, Appendix B). One on-site subsurface sample also contained trichloroethylene. In general, soil samples from north of the Queen's 41st Auto Salvage shop contained the highest levels of tetrachlorotheylene (Sample I.D. 06-SBB, Figure 5, Appendix A), but contaminants were found site-wide. The concentrations of these organic compounds, however, do not exceed the ATSDR soil comparison value. Therefore, based on soil data, Florida DOH did not choose these compounds as COC. In contrast, two on-site subsurface soil samples contained arsenic concentrations that exceed the ATSDR comparison value. However, arsenic was not chosen as a COC based on its presence in subsurface soil because humans do not regularly contact subsurface soil. Table 2 (Appendix B) is a summary of the data for on-site soil.
FDEP and EPA collected on-site ground water samples by (1) sampling the existing on-site well, (2) installing monitoring wells, and (3) using direct-push technology. Direct-push technology allows the environmental agencies to collect ground water from multiple depths at the same sample location. This helps to determine the vertical extent of contamination. On-site ground water contained tetrachlorotheylene, trichloroethylene, benzene, chromium, and arsenic at concentrations above their respective ATSDR ground water comparison value. Ground water from the areas of junk car storage contains tetrachlorotheylene, trichloroethylene, and benzene at concentrations that exceed the ATSDR ground water comparison value ([Sample I.D. 04-GW 06-GW, 10-GW, and DP-7], (Figures 4 and 5, Appendix A). The on-site potable well contained tetrachlorotheylene and trichloroethylene at concentrations that exceed the ATSDR ground water comparison value. More importantly, contamination of this potable well indicates that the contaminants have migrated into the Floridan aquifer. In addition to the solvent contamination, 3 of the 11 ground water samples contained arsenic concentrations that exceed the ATSDR comparison value. The arsenic concentrations, however, are within the bounds of what can typically be found in the surficial aquifer. Florida DOH chose arsenic, chromium, benzene, tetrachlorotheylene, and trichloroethylene as COCs based on their presence in ground water. Table 3 (Appendix B) summarizes the data for on-site ground water.
4.1.2 Off-site Contamination
For this PHA ,off-site refers to the area surrounding the property boundaries of Queen's Motors and Queen's 41st Auto Salvage, as shown in Figure 2 (Appendix A). FDEP and EPA collected surface (top 12 inches ) and subsurface (2 to 8 feet below) soil samples, sediment samples, and ground water samples, to identify the extent of contamination off-site (FDEP, 1998; EPA, 2000a).
FDEP and EPA collected soil samples from the surface (top 12 inches) and the subsurface (2 to 8 feet below ground), and sediment samples from the drainage ditch on the southeast border of the property (Figures 2 and 3, Appendix A). In 1998, sediment samples collected from the drainage ditch contained tetrachlorotheylene at a concentration well below the ATSDR soil comparison value (FDER, 1998). More recent sediment samples from this ditch did not contain detectable levels of tetrachlorotheylene (EPA, 2000a). Of the 10 sediment samples collected from the drainage ditch, 2 contained arsenic concentrations that exceed the ATSDR soil comparison value. Only one off-site subsurface sample contained a concentration of arsenic above the ATSDR comparison value. Table 4 (Appendix B) summarizes the COCs for off-site soil, the frequency of detection of each COC, and the highest concentration of each COC.
Six of 11 off-site ground water samples contained chromium at concentrations that exceed the respective ATSDR comparison value. In addition, one sample, collected from a monitoring well to the south, contained arsenic and lead at concentrations that exceed the respective ATSDR comparison value (QN-14-GWC, Figure 5, Appendix A). The only off-site ground water sample that contained tetrachlorotheylene at a concentration exceeding the ATSDR ground water is ground water from the irrigation well at the nearby residence (41APW02, Figure 3, Appendix A). However, the potable well at this same residence contained none of the COCs at levels that exceed the ATSDR comparison value (EPA, 2000a). Table 5 (Appendix B) lists the COCs for off-site ground water, the frequency of detection, and the highest concentration detected. The presence of the organic contaminants in the residential wells south of the site suggests that the contamination may be migrating south with ground water flow.
4.1.3 Contaminants of Concern
Florida DOH chose benzene, tetrachlorotheylene, and trichloroethylene as COCs for this site based on the presence of these contaminants in on- and off-site ground water. Arsenic, lead, and chromium were chosen as COCs due to their presence in either ground water or soil.
4.2 Quality Assurance and Quality Control
Florida DOH has reviewed the data and the quality assurance and quality control measures that were taken in the gathering of the referenced data. Florida DOH believes that the data is sufficient to support the conclusions made in this document. Appropriate chain-of-custody and data reporting procedures were followed and appropriate laboratory, equipment, and sample controls were analyzed. The completeness and reliability of the referenced information determine the validity of the analyses and conclusions drawn in this PHA.
Mr. Daiker and Mr. Merchant did not observe any on- or off-site physical hazards during the October 19, 1999 site visit.
To estimate whether nearby residents have been or are likely to be exposed to contaminants migrating from the site, we evaluated the environmental and human components of exposure pathways. Exposure pathways consist of five elements: 1) a source of contamination (e.g., chemical spill), 2) an environmental medium (e.g., ground water), 3) a point of exposure (e.g., tap water), 4) a route of human exposure (e.g., oral), and 5) a receptor population (e.g., area residents).
We eliminate an exposure pathway if at least one of the five elements is missing and will never be present. Exposure pathways that we do not eliminate are either completed or potential. With completed pathways, all five elements exist and exposure to a contaminant has occurred, is occurring, or will occur. A pathway is classified as potential if at least one of the five elements is missing, but may be present in the future. For both complete and potential pathways, Florida DOH estimates the likely dose of each COC and this dose serves as the basis of a toxicological evaluation.
4.4.1 Complete Exposure Pathways (Table 6, Appendix B)
Florida DOH identified three completed exposure pathways at this site. The completion of an exposure pathway does not mean that illness is likely; it means that exposure was or is probable. Florida DOH considers the incidental ingestion of on-site soil or sediment from the drainage ditch under past, current, and future time-frames as a completed exposure pathway. We also consider the use of the on-site well and the use of the potable well at a nearby residence as completed pathways in the past.
4.4.2 Potential Exposure Pathways (Table 7, Appendix B)
Florida DOH evaluated two potential exposure pathways in this PHA: (1) the use of on-site ground water by future residents and (2) the domestic use of off-site ground water in the future time-frame. These pathways are considered potential because either no exposure point exists or no receptor population exists. Currently, the on-site well is fitted with a filter and the nearby residential well is no longer used for potable water.
4.4.3 Eliminated Exposure Pathways
Because surface soil contained no contaminants at concentrations that exceed the ATSDR soil comparison values, Florida DOH eliminated the incidental ingestion of on- and off-site soil by trespassers or area residents. In this PHA, Florida DOH assumes that persons can readily contact only the top 6 inches of soil.
4.5 Public Health Implications
In this section, we calculate the dose of a chemical which both adults and children could potentially receive by all likely routes of exposure. We then review the ATSDR Toxicological Profile for each COC and determine if the estimated dose could cause illness. For this site, we calculated potential doses from exposure to soil and ground water, both on- and off-site (Tables 8 through 11, Appendix B).
4.5.1 Toxicological Evaluation
In this section, we discuss illnesses that could occur following exposure to COCs at this site. To evaluate the risks of illness, ATSDR has developed Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous waste sites. An MRL is a conservative estimate of daily human exposure to a contaminant below which noncancerous illnesses are unlikely to occur. The calculation of the MRL is based on animal and human studies, when available. It is calculated very conservatively because the goal of the MRL is to protect public health. MRLs exist for each route of exposure, such as ingestion and inhalation, and for different lengths of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than 365 days). ATSDR presents these MRLs in Toxicological Profiles. Toxicological Profiles are chemical-specific and provide information on the health effects, environmental transport, human exposure, and regulatory status of a specific chemical.
To apply the MRL, we estimate the daily dose for each of the COCs using standard exposure parameter estimates (e.g., average volume of water consumed per day, average shower time). Using these parameters, we estimate the number of milligrams of contaminant ingested per day (mg/day) and then divide these by the average human body weight. The dose is expressed as the number of milligrams of chemical per kilogram of body weight per day (mg/kg/day). In calculating the potential dose, we assume people are exposed to the maximum concentration detected for each contaminant in each medium. In Tables 8 through 11 (Appendix B), we summarize the estimated dose for each contaminant for each exposure pathway using the maximum COC concentration (bold text indicates that the estimated dose exceeds the MRL). Because MRLs are conservatively calculated to protect public health, a dose that exceeds the MRL does not necessarily mean that it will cause illness. A dose that does not exceed the MRL, however, is not likely to cause noncancerous illness.
The exposure parameters that we used to estimate the daily doses for each exposure scenario are given below the tables. The values used are standard values for this type of analysis (EPA, 1991; 1997). For ground water, we estimated the dose of chemical that could be ingested from drinking, absorbed through the skin during showering, and the air concentration that could be inhaled during showering. For soil exposures, we estimated the dose from incidental ingestion of soil and the dose from breathing contaminated dust.
4.5.1.1 Arsenic
Neither on-site nor off-site surface soil contained arsenic at concentrations that exceed the ATSDR soil comparison value. Therefore, incidental ingestion of arsenic in surface soil is unlikely to cause illness. The concentration of arsenic in the ditch sediment, however, does exceed the ATSDR comparison value. Florida DOH estimated that incidental ingestion of sediment would deliver a dose of arsenic to children and adults that is less than the oral MRL and therefore, unlikely to cause illness (Tables 8 and 10, Appendix B).
Florida DOH estimates that ingestion of on-site ground water could deliver a dose of arsenic to a child or adult that would exceed the MRL (Tables 9, Appendix B). Florida DOH, however, does not anticipate illness from ingestion of arsenic in ground water. Studies have shown no deleterious effects of comparable doses of arsenic from drinking water over an exposure period of up to 45 years (ATSDR, 1998a; Tseng et al., 1968; Southwick et al., 1981). In addition, other studies reported that a dose over 14-times higher than the doses estimated for this site is required to cause illness in humans (Tseng et al., 1968). Ingestion of off-site ground water would deliver a dose of arsenic that does not exceed the oral MRL (Table 11, Appendix B) and is, therefore, not likely to cause illness.
Arsenic is a known human carcinogen based on the association of lung cancer with inhalation exposure to arsenic. Skin, bladder, lung, and liver cancers have also been associated with ingestion of arsenic in ground water. In studies where arsenic is associated with skin cancer, the exposure periods were at least 14 years and the dose was at least 9-times greater than the highest dose estimated for this site (Zaldivar et al., 1981; ATSDR, 1998a). Florida DOH considers arsenic exposure from ground water or soil unlikely to cause cancer because of the low concentrations present and the unlikelihood of a prolonged exposure.
4.5.1.2 Benzene
Neither on- nor off-site soil contained benzene. Therefore, exposure to benzene by incidental ingestion of soil is unlikely to cause illness.
Exposure to benzene by ingestion of on-site ground water by children or adults would not likely cause illness. The lowest dose of benzene shown to cause illness in experimental animals is 1,000 times higher than the highest possible oral dose estimated for this site (Table 9, Appendix B) (Hsieh et al., 1988; ATSDR, 1997).
Florida DOH estimated that the use of on-site ground water for showering could produce an air concentration of benzene that would exceed the inhalation MRL. However, Florida DOH does not anticipate this inhalation exposure to cause illness because of the low air concentration and the short-term duration of the shower exposure. Benzene air concentrations of at least 10-fold higher and exposures of longer duration (i.e., 8 hours) have been associated with alterations in the immune system in humans (Xia et al., 1995; ATSDR, 1997). Little evidence, however, exists to suggest that short-term exposure to the low concentration at this site would cause illness.
Benzene is classified as a "human carcinogen." In experimental animals, both inhalation and oral exposure to high levels of benzene have been associated with cancer. The lowest oral dose in animal studies shown to cause cancer, however, is more than 1,000 times higher than the highest dose estimated at this site. Little evidence exists to suggest that oral exposure to these levels of benzene would cause cancer in humans (ATSDR, 1997). Florida DOH also does not anticipate an increased risk of cancer due to inhalation exposure to benzene in shower air. The potential exposures would be of a shorter duration than the occupational exposures that suggested that inhalation exposure to benzene could cause leukemia (Ott et al., 1978).
4.5.1.3 Chromium
None of the soil samples analyzed contained chromium at a concentration that exceeds the ATSDR soil comparison value. Therefore, Florida DOH does not anticipate incidental ingestion of chromium in soil to cause illness.
Both on- and off-site ground water contain chromium at concentrations that exceed the ATSDR ground water comparison value. Slightly higher doses than those estimated for this site have been shown to exacerbate previous skin abnormalities due to chronic, contact exposure to chromium (Tables 9 and 11, Appendix B)(Goitre et al., 1982; Kaaber and Veien, 1977; ATSDR, 1998b). Florida DOH concludes that because of the low concentrations present in ground water, chromium ingestion is unlikely to cause illness.
Inhalation exposure to chromium has been associated with cancer in humans. However, few studies have shown that ingestion of chromium causes cancer (ATSDR, 1998b).
4.5.1.4 Lead
Neither on- nor off-site soil contained a level of lead that exceeds the FDEP cleanup level for lead. Therefore, incidental ingestion of lead in soil is unlikely to cause illness.
One ground water sample contained lead at a concentration that exceeds the FDEP ground water comparison value. This sample was collected from near the residence immediately southeast of the site. Florida DOH does not anticipate ingestion of lead in drinking water to cause illness. The lowest dose studied in humans caused no deleterious effects and is 10-times higher than the dose that could result from ingestion of off-site ground water (Table 11, Appendix B) (ATSDR, 1999). In addition, the private well that is closest to where this sample was collected is reportedly not used for drinking water. In addition, recent sampling of this private well detected a lead concentration well below the MCL.
Currently lead is classified as a "possible human carcinogen." No studies have demonstrated the cancer-causing effect of lead in humans. In animal studies, lead was shown to be carcinogenic at doses at least 200 times the estimated doses for this site (ATSDR, 1999). Therefore, it is unlikely that lead ingestion will cause cancer.
4.5.1.5 Tetrachlorotheylene
On- and off-site soil and off-site sediment did not contain tetrachlorotheylene at concentrations that exceed the ATSDR soil comparison value. Therefore, exposure to tetrachlorotheylene in soil or sediment is unlikely to cause illness.
Past use of off-site ground water is unlikely to have caused illness. EPA, FDEP and the Pasco County Health Department (CHD) detected no MCL violations in past sampling of the neighboring private well.
Because the length of time the on-site drinking water well was contaminated prior to 1997 is unknown, Florida DOH is unable to estimate the public health risk from using this well in the past. Currently this well is equipped with a filter that removes the tetrachlorotheylene. Future use of on-site ground water without a filter may increase the risk of illness.
On-site ground water contains a tetrachlorotheylene concentration well in excess of ATSDR comparison values. The effect in humans of drinking tetrachlorotheylene-contaminated ground water at concentrations found on-site, however, is not known. Drinking unfiltered on-site ground water would deliver a dose that exceeds the ATSDR oral MRL (Table 9, Appendix B). The study used to establish the MRL found that repeated exposure to a dose 50-times higher than that estimated at this site caused hyperactivity in adult mice when treated as pups (ATSDR, 1997b; Fredriksson, 1993). Florida DOH estimates that use of on-site ground water for showering could produce an air concentration of tetrachlorotheylene that exceeds the ATSDR inhalation MRL.
Tetrachlorotheylene is classified as a "probable human carcinogen" (ATSDR, 1997b). In the future, lifetime drinking and showering with tetrachlorotheylene-contaminated ground water from on the site could cause a "low" to "moderate" increased risk of cancer.
4.5.1.6 Trichloroethylene
On- and off-site soil did not contain trichloroethylene at concentrations that exceed the FDEP soil comparison value. Therefore, exposure to trichloroethylene in soil is unlikely to cause illness.
The dose of trichloroethylene that a child or adult could receive from ingestion of on- or off-site ground water does not exceed the oral MRL (Tables 9 and 11, Appendix B). Therefore, ingestion of trichloroethylene-contaminated ground water is unlikely to cause illness.
Use of on-site ground water for showering could produce an air concentration that would exceed the inhalation MRL. Florida DOH, however, does not anticipate this inhalation exposure to cause illness because of (1) the short duration of shower exposure, (2) the low air concentration and, (3) the conservative nature in which the MRL is calculated. The lowest air concentration shown to cause any effect in animals is over 10 times greater than the air concentration estimated by Florida DOH (Aranyi et al., 1986; ATSDR, 1997).
Trichloroethylene is classified as a possible human carcinogen. In animal studies, doses up to 1,000 times those estimated at this site increased kidney and liver tumors. No conclusive evidence exists, however, to suggest that consumption of these doses of trichloroethylene at this site would cause cancer.
4.5.1.7 Mixtures
The literature on the effects of exposure to mixtures focuses on high doses and reports that doses well in excess of typical environmental concentrations are required to produce the effects associated with mixtures. Except for tetrachlorotheylene, the concentrations of all of the contaminants at this site are far below levels known to produce adverse health effects. Therefore, the effect of exposure to a mixture of these contaminants is not likely to be of public health concern.
4.5.2 Children and Other Unusually Susceptible Populations
The unique vulnerabilities of infants and children demand special emphasis in communities faced with the contamination of their environment. Children are at a greater risk than adults from certain kinds of exposure to hazardous substances emitted from waste sites. They are more likely to be exposed because they play outdoors and because they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. In addition, the developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most important, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care. The consideration of children regarding this site is important because children (1) may absorb metals (i.e., arsenic) from the intestine more efficiently than adults, (2) may be more sensitive to the toxicity of chlorinated solvents (i.e., tetrachlorotheylene) and (3) are the likely population to contact the sediments in the drainage ditch. Because of the small number of residences in the areas surrounding the site, Florida DOH does not anticipate a child population being exposed to ditch sediments or ground water.
The only known community health concerns were expressed in March 1997, when a neighbor reported that Queen's Auto Salvage discharged oil products and antifreeze into a sinkhole. The neighbor also charged that this dumping contaminated the private potable and irrigation wells. Based on the low contaminant concentrations and the absence of any MCL violations, Florida DOH does not anticipate ingestion of water from this private well to have caused illness in the past nor increased the risk of cancer from past exposures. Currently, this well is no longer used for potable purposes.
The site is categorized as an indeterminate public health hazard from past exposures. Because the length of time the on-site drinking water well was contaminated prior to 1997 is unknown, Florida DOH is unable to estimate the public health risk from using this well in the past. For current exposures, the site categorized as a no apparent public health hazard. The on-site drinking water well is equipped with a filter and use of off-site ground water is unlikely to cause illness. This site may be categorized as a public health hazard, however, in the future. Future use of on-site ground water without a filter may increase the risk of illness.
This section describes what ATSDR and/or Florida DOH plan to do at this site. The purpose of a Public Health Action Plan is to reduce any existing health hazards and to prevent any from occurring in the future. ATSDR and/or Florida DOH will do the following:
Florida Department of Health, Authors
Davis H. Daiker, Ph.D.
Bureau of Environmental Epidemiology
Division of Environmental Health
Randall Merchant
Manager
Bureau of Environmental Epidemiology
Division of Environmental Health
ATSDR Designated Reviewer
Debra Gable
Technical Project Officer
Division of Health Assessment and Consultation
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