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ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

ROYAL OAKS COMMUNITY
EDGEWATER, VOLUSIA COUNTY, FLORIDA
EPA ID No. FLN000407257

October 5, 2004

1.0 Summary

The Royal Oaks community hazardous waste site is a residential community (manufactured housing) of about24-acres with 31 residents, including six children aged 10 to 15 years. The property is west of Mango Tree Drive, just south of West Park Avenue in Edgewater, Volusia County, Florida. From December 2000 until July 2002, metal drums and pails believed to have contained paint, solvents, and paint-related products were excavated, stockpiled, or disposed of, along with contaminated soil and water associated with the buried waste in the Royal Oaks community. As a result of these activities, exposures to contaminants in the air, soil, and water might have occurred in the past.

The U.S. Environmental Protection Agency (EPA) asked the Florida Department of Health (DOH) if chemicals from the Royal Oaks community excavation presented a public health threat. Florida DOH evaluated this threat during excavation and removal activities in 2000 and 2001. Residents were concerned about potential cancer in the Royal Oaks community and possible exposure to arsenic- and lead-contaminated dust and to contaminated drinking water. Levels of metals, especially arsenic and lead, were below health-based screening levels and were not likely to present a health hazard. None of the identified contaminants of concern in the Royal Oaks community are known human carcinogens.

Based on the available data, Florida DOH selected four chemicals as contaminants of concern: ethylbenzene, toluene, trimethylbenzene, and xylene. Levels of these volatile organic compounds (VOCs) were above health-based screening levels in the excavation during cleanup activities. Between December 2000 and July 2001, while excavation and removal actions were underway, community residents might have been exposed to airborne VOCs and to contaminated sediment in the form of dust. Exposure to dust could have been by inhalation and, secondarily, by accidental ingestion (i.e., touching dusty surfaces and then incidentally ingesting the dust).

People who inhaled airborne VOCs near the excavation pit are unlikely to experience any noncancerous health effects at the level measured by the EPA in October 2001 after excavation ceased. However, residents might have been exposed to higher concentrations of VOCs during excavation. Because no air monitoring took place during excavation, Florida DOH cannot determine the public health risk that was present at that time.

Little available data exists concerning human health effects (including cancer) after oral or dermal exposure to ethylbenzene, toluene, trimethylbenzene, and xylene. More health effects are known from long-term, low-level exposure to these chemicals from inhalation (breathing). However, because no air monitoring was performed during excavation, the public health risk from inhaling these chemicals during excavation and removal activities cannot be adequately determined. Therefore, this site has been identified as an Indeterminate Public Health Hazard for past exposures, and as a No Apparent Public Health Hazard for current and future exposures.

2.0 Purpose and Health Issues

The EPA asked the Florida DOH whether chemicals from the Royal Oaks community excavation presented a public health threat. The EPA based its request on residents' concerns and the possibility that contamination existed beneath some of the residences. The Florida DOH Bureau of Community Environmental Health prepared this report to respond to the EPA request. This public health assessment is the first evaluation of the site by either Florida DOH or the federal Agency for Toxic Substances and Disease Registry (ATSDR).

In this report, Florida DOH evaluates the past, current, and future potential for exposures to chemicals at and near the Royal Oaks community site. The likelihood of these exposures to cause illnesses is then discussed, as is the need for additional actions to protect public health.

The Florida DOH conducted this public health assessment under a cooperative agreement with and funding from ATSDR. The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, or Superfund) authorizes ATSDR to conduct public health assessments at hazardous waste sites. Headquartered in Atlanta, ATSDR is a federal agency within the U.S. Department of Health and Human Services.

3.0 Background

3.1 Site History

The Royal Oaks community site is at 210 Mango Tree Drive in Edgewater, Volusia County, Florida (Figure 1). This 24-acre residential community consisted of 18 mobile homes, cleared lots, and undeveloped property (Figure 2). Approximately 31 persons lived in this community, including six children aged 10 years to 15 years old.

From 1962 to 1999, Hanson and McCallister, Inc. owned this site. The company had excavated large quantities of sand, creating a large borrow pit. The EPA reported that the pit was filled with land-clearing debris, tree stumps, and possibly construction debris.

In December 2000, utility workers installing underground lines discovered several 55-gallon metal drums and several 1-gallon paint cans buried under the southeastern portion of the site. The property owner's contractors uncovered more drums in extremely poor condition, containing sludge, solvents, and other paint-related chemicals (EPA 2001b). The Florida Department of Environmental Protection (DEP) tested the sludge from these drums and found that it contained lead and volatile organic compounds (VOCs).

In February 2001, the Florida DEP requested assistance from the EPA. In March 2001, the EPA conducted a geophysical survey to identify where additional drums might be buried. The EPA identified two locations. One location was on the southeast part of the site near where the drums were originally discovered. The other location was near the entrance to the site on Mango Tree Drive and consisted of nonhazardous buried debris.

In April and May 2001, the property owner's contractors excavated more soil on the southeast side of the site and underneath the driveway at a property on Towering Oaks Drive. They found additional 55-gallon drums and 1-gallon paint cans. Most of these drums were empty or rusted to the point of decomposition. Some of the drums appeared to be burned. The contractors also found paint chips in the soil and intact, empty drums. They placed the drums and cans in an enclosed roll-off dumpster and fenced the area (Remediation Technologies Inc. 2001a).

In July 2001, the EPA assumed regulatory responsibility for site activities. The water-filled excavation pit bordered by Towering Oaks Way and Treaty Oak Way was several feet deep. Five manufactured homes were immediately adjacent to the excavated area. Some homes were less than 20 feet from the excavation. According to the EPA, other homes in the neighborhood could also have drums buried beneath them. The EPA reported residents were at risk of exposure to contaminants by inhalation, ingestion, and direct contact (EPA 2001b).

In September 2001, a resident reported flooding and a broken sewer line in the neighborhood. The site owner buried the broken sewer pipe. Three weeks later, the EPA notified the Florida DOH, which in turn notified the Volusia County Health Department (CHD).

In October 2001, residents reported odors, burning eyes, nausea, vomiting, headache, dizziness, and skin problems before and after excavation activities to the Florida DOH . Residents also reported cancer and cancer deaths. Residents reported vapors entered their homes during the excavation. They were concerned that their children were exposed to arsenic- and lead-contaminated dust. Residents reported that during excavation, dust covered their homes and cars and that they had tracked this dust indoors. During the Florida DOH site visit, a boat repair facility and aromatic vapors were noticed to the north of the site.

In October 2001, the EPA tested ambient air at the site for volatile organic compounds (VOCs). Water, soil, and sediment from the excavation pit were also tested. The EPA found elevated levels of the following VOCs in some of the buried waste: ethylbenzene, toluene, xylene, and 1,2,4-trimethylbenzene.

Residents were relocated between October 2001 and May 2002 by the U.S. Army Corps of Engineers, after the EPA became involved with the cleanup. Prior to EPA's involvement, the property owner's contractor performed some excavation activities until residents reported symptoms they believed to be associated with vapors from the excavation.

In 2001 and 2002, Florida DOH evaluated chemical contaminants on site and environmental samples from off the site. A Health Consultation was released in the Fall of 2002, and Florida DOH held a public meeting to discuss the findings and record community concerns.

In September 2002, the EPA issued its final pollution report (Final POLREP #5). This report detailed the removal and proper disposal of all known contaminated soil and groundwater from the site, as well as backfilling of the excavation pit with clean soil and reseeding with grass.

On September 3, 2003, Florida DEP issued a No Further Action Approval letter to the property owner, releasing the property owner from any further obligation to conduct corrective actions (cleanup). This letter does not certify that the entire site is clean, but states that no contamination above state standards is known to exist on the site (Appendix E).

In December 2003, Florida DOH prepared the final Public Health Assessment for this site. A site chronology is included in Appendix A.

3.2 Site Description

The 24-acre Royal Oaks community had 18 single-family, manufactured houses. Approximately 31 residents, including at least six children aged 10 years to 15 years, were located on Mighty Oak Circle, Towering Oaks Way, and Treaty Oak Way in Edgewater, Volusia County, Florida (Figure 2). Some residents had young relatives and grandchildren who visited the property. The surrounding population was on commercial, manufacturing, and undeveloped land, and additional residences were located to the southwest along Carol Ann Drive.

Demographics. The area within 1 mile of the site encompasses parts of six Census Bureau block groups in Volusia County. In 2000, approximately 3,700 people lived within 1 mile of the site. About 25% were younger than 18 years of age, and 22% were older than 65 years. Of the total population, 1% were black, 96% were white, 2% were Hispanic, and 1% were American Indians, Asians, and other racial/ethnic groups (U.S. Bureau of the Census 2000).

Land Use. The site is in a mixed-use area of Edgewater, Florida. Several midsized commercial and manufacturing facilities are adjacent to the property to the north and east. Land to the west consists of a community park and single-family residences on Carol Ann Drive. Land to the south is mostly undeveloped. Railroad tracks and U.S. Highway 1 are east of the property.

Natural Resource Use. The Royal Oaks community drinking water is supplied by 19 wells operated by the Utilities Commission, City of New Smyrna Beach (UCNSB). Seven wells are located at the Glencoe Road Water Treatment Plant site. Six additional wells are located west of the Glencoe Plant along S.R. 44. The remaining six wells are located on S.R. 44, 12.5 miles inland. Well depths range from 183 feet to 364 feet, with an average depth of 240 feet.

3.3 Site Visit

Beth Copeland, Community Involvement Coordinator with the Florida DOH Bureau of Community Environmental Health, visited the site on October 4 and 5, 2001. Her findings are included in the Community Health Concerns section (5.0) of this report. On November 8, 2001, Shaun Crawford and Randy Merchant, also with the Bureau of Community Environmental Health, visited the site and the surrounding area and conducted a walking survey of the site and the surrounding area. Jeff Sulzbach of the Volusia County Health Department was present. The Florida DOH Bureau of Community Environmental Health, Health Assessment Team, also visited the site during a public meeting held in September 2002.

According to EPA estimates, 31 residents lived near the site in 18 manufactured homes. One resident was displaced by cleanup activities in 2001, and one other moved after excavation began. Six children lived at the Royal Oaks community site.

In January and September 2002, the excavation site was surrounded by a chain link fence with locked gates and some wind screening. Large mounds of excavated soil and sediment were stockpiled within the fenced area and partially covered with tarpaulins. At least two roll-off containers were within the fenced area. No excavation or remedial action occurred on the days of the site visits. According to local health department representatives and the EPA, the former excavation pit has been filled with clean soil.

4.0 Discussion

In this section, Florida DOH reviews the available site information (air, water, and soil data), including information on the chemical concentrations present in the air, soil, and water. Florida DOH determines whether the chemicals could affect people's health.

The public health assessment process has inherent uncertainties because, as discussed in New Jersey Department of Environment Protection 1990:

Science is never 100% certain;
The risk assessment process is inexact;
Information on the site and on actions (and interactions) of chemicals is never complete; and
Opinions differ on the implications of known information.

Florida DOH addresses these uncertainties in public health assessments by using health-protective assumptions when estimating or interpreting health risks. Florida DOH also uses wide safety margins when setting health-related threshold values. The assumptions, interpretations, and recommendations made throughout this public health assessment are conservative in the direction of protecting public health.

4.1 Environmental Contamination

This section examines environmental data collected at and near the site, sampling adequacy, and contaminants of concern. The maximum concentration and detection frequency for the contaminants of concern in the various media are also listed. Contaminants of concern are selected by considering the following factors:

Contaminant concentrations on and off the site. Contaminants are eliminated from further consideration when both the background and onsite concentrations are below health-based comparison values. Background concentrations are useful in determining if contaminants are site-related. This approach is necessary for assessing the public health risk of all contaminants detected, whether site-related or not.

Field data quality, laboratory data quality, and sample design.

Community health concerns.

Comparison of maximum concentrations with published ATSDR standard comparison values to provide complete and potential exposure pathways. The ATSDR's published standard comparison values are media-specific concentrations used to select contaminants for further evaluation. They are not used to predict health effects or to set cleanup levels. When ATSDR standard comparison values are absent, other regulatory guidelines can be used.

Comparison of maximum concentrations with toxicological information published in ATSDR toxicological profile documents to provide complete and potential exposure pathways. These chemical-specific profiles summarize toxicological information found in scientific literature.

The following standard comparison values (ATSDR 2001 and Florida DEP 1999) were used to select contaminants of concern, in order of priority:

Environmental Media Evaluation Guides (EMEGs). The ATSDR derives EMEGs from their Minimal Risk Levels (MRLs) by using standard exposure assumptions, such as ingestion of 2 liters of water per day and body weight of 70 kg spell out first time used for adults. MRLs are estimates of daily human exposure, generally for 1 year or longer, to a chemical likely to be without an appreciable risk of noncancerous illnesses.

Reference Dose Media Evaluation Guides (RMEGs). The ATSDR derives RMEGs from the EPA's Reference Dose (RfD), using standard exposure assumptions. RfDs are estimates of daily human exposure to a chemical not likely to have an appreciable risk of noncancerous illness. Exposure estimates are generally for 1 year or longer.

Cleanup Target Levels (CTLs). CTLs are the Florida DEP's minimum allowable concentrations of contaminants in soil (SCTLs) and groundwater (GCTLs). Florida DEP CTLs are enforceable and are required to be equal to or lower than federal standards. Florida DEP CTLs were used because the ATSDR does not have a standard for lead, mercury, butylbenzene, isopropyltoluene, and trimethylbenzenes in soil or water.

Using the components and criteria listed above, four chemicals were selected as contaminants of concern: ethylbenzene, toluene, trimethylbenzene, and xylene. Only the ATSDR values and other standard comparison values, such as DEP CTLs, were used to select contaminants of concern for further consideration. Identification of a contaminant of concern in this section does not necessarily mean that exposure will cause illness. Rather, identification serves to narrow the focus of the public health assessment to those contaminants most important to public health. The contaminants of concern are evaluated in subsequent sections and determined whether exposure is likely to cause illness.

This public health assessment first discusses the contamination that exists on the site and then the contamination that occurs off the site. "Onsite" is the area within the Royal Oaks community property boundary, including the fenced excavation pit, and "offsite" is the area outside the Royal Oaks community property boundary, as shown in Figure 2, Appendix B.

4.1.1 Onsite Contamination: 4.1.1.1 Onsite Groundwater (Pit Water). No onsite groundwater wells existed at the time of this public health assessment. For the purpose of this report, the water samples collected by EPA and Remtech from the excavation pit are referred to as groundwater samples. Pit water is the closest representative media for shallow groundwater beneath the site. Pit-water sample results are summarized in Table 1, Appendix C. For this public health assessment, the onsite groundwater (pit) samples are sufficient to characterize the onsite groundwater.; 4.1.1.2 Onsite Soil/Sediment. EPA and Remtech tested surface soil, excavation stockpile soil, and sediment from the bottom of the excavation pit.

The results for onsite soil analyses are summarized in Table 2, Appendix C. Although measured contaminant levels in the excavation pit sediments are above comparison values (Table 3, Appendix C), residents are not exposed to onsite sediment contamination at the bottom of the excavation pit because public access is restricted. Public access to the pit was also restricted during cleanup activities. Although neither Florida DEP or EPA certify that all contaminated soil has been removed from the site, both agencies have declared that no further action or removal is necessary at this time. According to agency documents, all contaminated soil identified as associated with drum removal and disposal has been properly removed and disposed. For this public health assessment, soil samples have been adequately characterized.; 4.1.1.3 Onsite Drinking Water. In November and December 2001, the Volusia County Health Department (CHD) tested onsite tap-water samples from six residences. The residential drinking water is supplied by the city of Edgewater and is presumably safe. Nevertheless, the Volusia CHD tested drinking-water samples because of a history of broken and rerouted water lines in the subdivision (due to contaminant excavation) and the demonstrated ability of volatile organic compounds (VOCs) to infiltrate pressurized water lines.

Analyses of samples from the public drinking water supply did not show the presence of site-related contaminants. Thus, Florida DOH concludes that for this public health assessment, onsite drinking water has been adequately tested. The lead level in water collected from outside hose spigots at two homes on the site was slightly above the drinking- water standards. The source of the lead was most likely the brass fittings inside the spigot. The testing of drinking water from inside these homes detected no lead.; 4.1.1.4 Ambient Air. In October 2001, EPA tested ambient air around the onsite excavation pit using a portable air-monitoring instrument.

The results for ambient-air analyses are summarized in Table 4, Appendix C. Because the portable air-monitoring instrument is not accurate for all chemicals and because air-sampling data are absent for the period when active excavation occurred, past ambient air quality was not adequately characterized for this public health assessment.
4.1.2 Offsite Contamination: 4.1.2.1 Offsite Groundwater. Most of the area surrounding the site is supplied with municipal water. In November 2001, the Volusia CHD sampled six private wells on Carol Ann Drive to the west and southwest of the site. The Florida DOH Laboratory analyzed these samples for volatile organic compounds (VOCs) and metals.

Analyses of samples from these wells did not show the presence of site-related contaminants. A lack of onsite and offsite shallow groundwater samples at the time of this public health assessment prevented adequate characterization of offsite groundwater. However, for this public health assessment, offsite groundwater contamination has been adequately characterized. After additional groundwater sampling, EPA and Florida DEP released the site from additional testing.
4.1.3 Quality Assurance and Quality Control. Existing environmental data have been used to prepare this public health assessment. These data are assumed valid because government consultants or consultants overseen by government agencies collected and analyzed the environmental samples. It is further assumed that consultants who collected and analyzed these samples followed adequate quality-assurance and quality-control measures concerning chain-of-custody, laboratory procedures, and data reporting.

The completeness and reliability of the referenced information determine the validity of the analyses and conclusions drawn for this public health assessment. In each of the preceding onsite and offsite contamination subsections, the adequacy of the data was evaluated to estimate exposures. The estimated data and presumptive data were assumed valid because of the qualifications of the sampling agency and the analytical laboratory. This assumption is protective of public health by assuming that a contaminant exists when in fact it might not exist.

4.2 Physical Hazards

During the November 2001 site visit, DOH staff noted that the water-filled excavation pit could be a drowning hazard if the pit was accessible. The excavation pit and related materials were enclosed by a chain-link fence with locked gates. Since that time, the excavation pit was filled and the fence removed.

4.3 Pathways Analyses

Chemical contaminants in the environment can harm people's health, but only if people have contact with those contaminants at a high enough concentration (dose) to cause a health effect. Knowing or estimating the frequency with which people could have contact with hazardous substances is essential to assessing the public health importance of these contaminants.

To decide if people can contact contaminants at or near a site, DOH looks at the human exposure pathways. An exposure pathway has five parts. These parts are:

a source of contaminants;

an environmental medium that can hold or move the contamination, such as, air, water, or soil;

a point at which people can come in contact with a contaminated medium, such as, in drinking water or in garden soil;

an exposure route, such as, drinking contaminated water from a well or eating contaminated soil on homegrown vegetables; and

a population who could come in contact with the contaminants.

An exposure pathway is eliminated if at least one of the five parts is missing and will not occur in the future. Exposure pathways are not eliminated if they are either completed or potential. For completed pathways, all five pathway parts exist and exposure to a contaminant has occurred, is occurring, or will occur. For potential pathways, at least one of the five parts is missing, but could exist. Also for potential pathways, exposure to a contaminant could have occurred, could be occurring, or could occur in the future.

4.3.1 Completed Exposure Pathways. No known past, present, or future completed exposure pathways exist for the Royal Oaks community.

4.3.2 Potential Exposure Pathways. The following human exposure pathways are considered to be potential (Table 5, Appendix C):: 4.3.2.1 Airborne Contaminants. Between December 2000 and July 2001, residents could have inhaled VOCs in the air during excavation and removal activities.; 4.3.2.2 Airborne Dust. Between December 2000 and July 2001, while excavation and removal actions were taken, community residents might have been exposed to sediment in the form of dust. Exposure might have been by inhalation and, secondarily, ingestion (touching dusty surfaces and incidentally ingesting the dust).; 4.3.2.3 Groundwater (Pit Water). Although no groundwater data existed for the site, water-sample collection and analyses from the excavation pit supported the assumption that groundwater contamination existed. Exposure to contaminated groundwater by ingestion and dermal contact could have been a potential future exposure pathway if drinking water wells were installed in areas of groundwater contamination or if contaminated groundwater reached public or private water supply wells. However, the EPA and Florida DEP have determined that no further groundwater monitoring is necessary, due to cleanup activities and the lack of identified contamination. No evidence exists of past exposures to groundwater contamination at the Royal Oaks community site.

4.4 Public Health Implications

People who inhaled airborne ethylbenzene or toluene near the excavation pit are unlikely to experience any noncancerous health effects at the level measured by the EPA in October 2001 after excavation ceased. However, residents might have been exposed to higher concentrations of VOCs during excavation. Because no air monitoring took place during excavation, Florida DOH cannot determine the public health risk.

Few data are available concerning human health effects, including cancer, after oral or dermal exposure to ethylbenzene, toluene, trimethylbenzene, and xylene. More information is known about the likely health effects from long-term, low-level exposure to these chemicals from inhalation (breathing). However, because no air monitoring took place during excavation, the public health risk from inhaling these chemicals during excavation and removal activities cannot be adequately determined.

4.4.1 Toxicological Evaluation. In this subsection, exposure levels and the health effects that might occur in people who are exposed to the contaminants of concern are discussed. Also in this subsection, general ideas such as the risk of illness, dose response and thresholds, and uncertainty in public health assessments are discussed.

Evaluation of exposure requires estimation of the daily dose of each contaminant of concern found at the site. Kamrin (1988) explains a dose in this manner:

"...all chemicals, no matter what their characteristics, are toxic in large enough quantities. Thus the amount of a chemical a person is exposed to is crucial in deciding the extent of toxicity that will occur. In attempting to place an exact number on the amount of a particular compound that is harmful, scientists recognize they must consider the size of an organism. It is unlikely, for example, that the same amount of a particular chemical that will cause toxic effects in a 1-pound rat will also cause toxicity in a 1-ton elephant.

"Thus instead of using the amount that is administered or to which an organism is exposed, it is more realistic to use the amount per weight of the organism. Thus 1 ounce administered to a 1-pound rat is equivalent to 2000 ounces to a 2000-pound (1-ton) elephant. In each case, the amount per weight is the same: 1 ounce for each pound of animal. This amount per weight is the dose. We use dose in toxicology to compare the toxicity of different chemicals in different animals."

Milligrams of contaminant per kilogram of body weight per day (mg/kg/day) were used to express the daily dose. A milligram is about the weight of a raisin or a paper clip, and a kilogram is about 2 pounds.

Standard assumptions about body weight, ingestion and inhalation rates, exposure time length, and other factors needed for dose calculation were used to calculate the daily dose of each contaminant (ATSDR 1992). The calculation of the dose assumed that people are exposed to the maximum concentration measured for each contaminant in each medium (Appendix C; Table 7). Florida DOH uses the maximum concentration of each contaminant until sufficient data are available to calculate a mean, median, mode, or other measure of central tendency.

To estimate exposure from incidental ingestion of contaminated soil, Florida DOH made the following assumptions: (1) children between the ages of 1 year and 6 years ingest an average of 200 milligrams (mg) of soil per day, (2) adults ingest an average of 100 milligrams of soil per day, (3) children weigh an average of 15 kilograms (kg), (4) adults weigh an average of 70 kg, and (5) children and adults ingest soil at the maximum concentration measured for each contaminant.

To estimate possible future exposure from drinking contaminated groundwater, Florida DOH made the following assumptions: (1) children between the ages of 1 year and 6 years ingest an average of 1 liter of water per day, (2) adults ingest an average of 2 liters of water per day, (3) children weigh an average of 15 kilograms (kg), (4) adults weigh an average of 70 kg, and (5) children and adults ingest contaminated groundwater at the maximum concentration measured for each contaminant.

To evaluate health effects, the ATSDR has developed Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous waste sites. An MRL is an estimate of daily human exposure to a contaminant below which noncancerous, adverse health effects are unlikely to occur. The ATSDR might develop MRLs for each route of exposure, such as ingestion and inhalation. The ATSDR also develops MRLs for the length of exposure, such as acute (less than 14 days), intermediate (15-364 days), and chronic (greater than 365 days). The ATSDR includes these MRLs in Toxicological Profiles. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status.: 4.4.1.1 Ethylbenzene. People who inhaled ethylbenzene vapors near the excavation pit are unlikely to experience any noncancerous health effects at the level measured by the EPA in October 2001 after excavation ceased. Residents might have been exposed to higher ethylbenzene concentrations during excavation. Because no air monitoring took place during excavation, the public health risk during excavation and removal activities cannot be determined.

Insufficient evidence exists to suggest whether ethylbenzene is a carcinogen in humans (ATSDR 1999).; 4.4.1.2 Toluene. People who inhaled toluene vapors near the excavation pit are unlikely to experience any noncancerous health effects at the level measured by the EPA in October 2001 after excavation ceased. Residents might have been exposed to higher toluene concentrations during excavation. Because no air monitoring took place during excavation, the public health risk during excavation and removal activities cannot be determined.

Toluene was not detected in water samples. For children exposed by ingestion or dermal contact to drum sediment containing toluene, no increased risk would exist for noncancerous health effects. The exposure level was below the Lowest Observed Adverse Effect Level (LOAEL) for acute and intermediate exposures for animals.

There is insufficient evidence to suggest whether exposure to toluene vapors can cause cancer in animals. No studies were located regarding carcinogenic effects in humans after oral or dermal exposures to toluene (ATSDR 2000).; 4.4.1.3 Trimethylbenzene (TMB). For the purpose of this public health assessment, only 1,2,4-trimethylbenzene (1,2,4-TMB) is evaluated for potential health effects because 1,2,4-TMB occurs at this site in greater concentrations than 1,3,5-TMB. Also, 1,2,4-TMB is more toxic than 1,3,5-TMB, and most of the health research is based on 1,2,4-TMB.

Insufficient toxicological research exists to permit determination of whether the levels of 1,2,4-trimethylbenzene found at this site are likely to cause illness. Similarly, insufficient evidence exists to suggest whether exposure to trimethylbenzene by inhalation, ingestion, or dermal contact can cause cancer in humans.; 4.4.1.4 Xylene. It is unknown if people inhaled xylene vapors near the excavation pit before excavation ceased. The EPA in October 2001 found no xylene vapors in air samples collected after excavation ceased. Because no air monitoring took place during excavation, the public health risk cannot be determined.

According to ATSDR, no studies were located regarding carcinogenic effects in humans after inhalation and oral exposures to mixed xylenes. Only limited evidence suggests that xylene could be a promoter for skin cancer and could also act as an initiator or carcinogen by dermal exposure (ATSDR 1995).

4.4.2 Risk of Illness, Dose Response/Threshold and Uncertainty. Appendix D discusses limitations on estimating the risk of illness, the theory of dose response, and the concept of thresholds. Also, Appendix D discusses the sources of uncertainty inherent in public health assessments.

4.5 Children and Other Unusually Susceptible Populations

4.5.1 Children. Before birth, children are forming body organs that need to last a lifetime. Because some contaminants cross the placental barrier, the mother's exposure to chemicals can cause the fetus to be exposed. During fetal growth, exposure could lead to injury or illness, causing malformation of organs (teratogenesis), disruption of function, or premature death.

After birth, the developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Children could be at greater risk than adults from exposure to hazardous substances emitted from waste sites. Children are more likely to be exposed because they play outdoors, and because they can bring food into contaminated areas. Children are shorter than adults and can breathe dust, soil, and heavy vapors close to the ground. Pound for pound of body weight, children drink more water, eat more food, and breathe more air than do adults. Therefore, children can have much greater "doses" than adults of contaminants that are present in soil, water, and air (ATSDR 1998). Some contaminants at the Royal Oaks site that could have affected children include:

Ethylbenzene	Gaseous ethylbenzene is heavier than air, and children generally spend more time on the floor or ground than do adults. Whether children would be different from adults in their weight-adjusted intake of ethylbenzene is currently unknown;
Toluene	Gaseous toluene is heavier than air, and because young children are closer to the ground or floor because of their height, they can breathe more toluene than adults during accidental exposures. Older children and adolescents could be exposed to toluene if they breathe household products containing toluene to obtain a so-called "high;"
Xylene	Xylene exposure symptoms for children are expected to be similar to those for adults. Ingestion of aspirin is likely to speed up the adverse effects of xylene in both the expectant mother and the fetus;
TMB	Too little is known about TMB (trimethylbenzene) to determine whether children are any more susceptible to exposure than are adults.

For children who lived on the site, exposure to these chemicals could have occurred by exposure to airborne contaminants and dust during excavation activities. However, since air monitoring was not conducted during excavation and removal activities, it is not known if any of these contaminants were present at levels that could have caused adverse health effects. Air monitoring after the excavation and removal activities were completed did not indicate these contaminants were present at levels where adverse health effects could have been likely.

The children living at Royal Oaks have been tested for lead in their blood, and no elevated blood lead levels were found. The results of this blood lead testing are given in a separate health consultation produced by the Florida DOH (2003).

4.5.2 Other Unusually Susceptible Populations. A susceptible population has different or enhanced responses to a toxic chemical than most people exposed to the same levels of that chemical in the environment. Reasons include genetic makeup, age, health, nutritional status, and exposure to other toxic substances (i.e., cigarette smoke or alcohol). These factors can limit the ability to detoxify or excrete harmful chemicals or could increase the effects of damage to organs or systems in the body. The following is not an exhaustive list, and it only reflects currently available data:

Ethylbenzene	Ethylbenzene exposure of individuals with impaired pulmonary function has been shown to worsen symptoms. Individuals with liver or kidney disease might be more susceptible to ethylbenzene toxicity, as would persons taking medications or other drugs that are known hepatoxins. Persons with dermatitis or other skin diseases could be at greater risk because ethylbenzene is a defatting agent that could aggravate these symptoms.
Toluene	Toluene metabolism can be affected by environmental and genetic factors. Chronic consumers of alcohol or people taking medications that interfere with toluene metabolism could be more susceptible. Ethnic variations in enzyme efficiency are known to exist. Individuals with pre-existing defects in heart rhythm, asthma, or other respiratory difficulty might be at an increased risk from toluene exposure.
Xylene	Xylene exposure of individuals with subclinical and clinical epilepsy, renal, hepatic, or cardiac disease could be more susceptible to the effects of xylene. People with respiratory diseases, such as asthma, could potentially be at risk after inhalation exposure. The bioavailability of dermally absorbed xylene adsorbed to clay soils is greater than the bioavailability of dermally absorbed pure xylene. For females, toxicokinetic studies have shown that the bioavailability of xylene absorbed to soil is greater than when xylene is ingested alone.
TMB	Little dose/response information exists regarding TMB (trimethylbenzene). For the purpose of this public health assessment, it is assumed that persons with compromised respiratory, renal, hepatic, and cardiac systems will be more susceptible to TMB exposure than those in the general population.

Because air monitoring was not conducted during excavation and removal activities, it is not known if any of these contaminants were present at levels where adverse health effects may have been likely. Air monitoring after the excavation and removal activities were complete did not indicate these contaminants were present at levels where adverse health effects could have been likely.

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