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PRELIMINARY PUBLIC HEALTH ASSESSMENT

PLYMOUTH AVENUE LANDFILL
DELAND, VOLUSIA COUNTY, FLORIDA


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

In this section, we review the environmental data collected at this landfill. Specifically, weevaluate the adequacy of the environmental data, select contaminants of concern, and list theirmaximum concentration and frequency of detection. We then compare the maximumconcentrations found to background levels and to standard comparison values. In the data tables,we use the following comparison values:

    1. EMEGs--Environmental Media Evaluation Guides--are derived from theATSDR's Minimal Risk Levels (MRLs) and provide a measure of the toxicity of achemical. They are the ATSDR's estimate of daily human exposure to a chemical that islikely to be without an appreciable risk of adverse effects. EMEGs are usually based onexposure for a year or longer.

    2. LTHAs--Lifetime Health Advisories for Drinking Water--are the EPA's estimateof drinking water contaminant concentrations at which adverse health effects are unlikelyover lifetime exposure. LTHAs provide a safety margin to protect sensitive members ofthe population.

    3. MCLs--Maximum Contaminant Levels--are contaminant concentrations that theEPA considers protective of public health. They assume ingestion of 2 liters of water perday for 70-years. MCLs are regulatory concentrations.

    4. RMEGs--Media Evaluation Guides--are derived from the EPA's reference dose. RMEGs are an estimate of daily human exposure to a chemical that is likely to be withoutan appreciable risk of adverse effects. They are usually based on exposure for a year orlonger. RMEGS are similar to the EMEGs above.

    5. SMCLs--Secondary Maximum Contaminant Levels--are the EPA's estimate of theconcentration above which water is not aesthetically acceptable (primarily due to tasteand/or odor). SMCLs are regulatory concentrations in Florida.

We reviewed the environmental sampling data collected at this landfill and selected the following chemicals as contaminants of concern:

bariumiron
chromium (total)nitrate
1,2-dichloroethenesulfate
(cis & trans isomers)vinyl chloride

We selected these contaminants based on the following factors:

  1. Concentrations of contaminants on and off the site.
  2. Field data quality, laboratory data quality, and sample design.
  3. Comparison of on-site and off-site concentrations with health assessment comparison values for (1) noncarcinogenic endpoints and (2) carcinogenic endpoints.
  4. Community health concerns.

Identification of a contaminant of concern in this section does not necessarily mean that exposurewill cause adverse health effects. Identification serves to narrow the focus of this healthassessment to those contaminants most important to public health. When selected as acontaminant of concern in one medium, we also reported the concentration of that contaminant inall other media. We evaluate these contaminants in subsequent sections and decide whetherexposure has public health significance.

To identify industrial facilities that could contribute to the contamination near this landfill, wesearched the EPA Toxic Chemical Release Inventory (TRI) data base. The EPA developed TRIfrom the chemical release information (air, water, and soil) provided by certain industries. TheTRI data base covers releases between 1987 and 1991. We found one industrial facility in the32720 ZIP code that includes the Plymouth Avenue Landfill. Ardmore Farms estimates itreleased 20,000 pounds of ammonia into the air between 1987 and 1991. Ardmore Farms is anorange juice processing facility at 1915 N. Woodland Boulevard, about 2.5 miles northeast of thelandfill. Because of the distance, we do not expect that ammonia from this facility has affectedthe health of people living near the landfill.

In this assessment, we discuss the contamination that exists on the landfill first, separately fromthe contamination that occurs off the landfill.

A. On-site Contamination

The Environmental Protection Agency has proposed adding the three (3) sludge cells on theeastern edge of the landfill to the National Priorities List of Superfund hazardous waste sites. Inthis assessment we consider the entire 131-acre landfill. We define "on-site" as the landfillproperty boundary as shown in Figure 2 (Appendix A). We compiled data in this subsectionfrom the files of the Volusia County DSWM (VCDSWM 1994) and Florida Department ofEnvironmental Protection (DEP 1994). We also compiled data in this subsection from reports byBriley, Wild and Associates (BWA 1981, 1992) and the NUS Corporation (NUS 1990).

On-Site Waste Material

From June 1978 to October 1980, the landfill reportedly received 4,500 gallons per week ofnitric acid process waste slurry (pH 0-1) from the nearby Brunswick Corporation. This wastecontained up to 90,000 milligrams per liter (mg/L) of nitrate. The Volusia County DSWMspread the waste over an undisturbed area in the southeast corner of the landfill or deposited itinto shallow trenches also in the southeast corner of the landfill (BWA 1992). Table 1, below,summarizes the contaminants-of-concern maximum concentrations in this waste.



Table 1.

Maximum Concentrations in 1978 Nitric Acid Waste
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium NA --- --- None ---
Chromium
(total)
1 1/1 --- None ---
c+t-1,2-Di-
chloroethene
NA --- --- None ___
Iron17,500 1/1 --- None ---
Nitrate20,500 1/1 --- None ---
Sulfate NA --- --- None ---
Vinyl Chloride NA --- --- None ---

NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Source: Russell 1978

On-Site Surface Soil

There have been no surface soil samples (0-3 inches deep). We do not recommend the VolusiaCounty DSWM collect any on-site surface soil samples since it is unlikely that cover soil iscontaminated. In 1990, the NUS Corporation, under contract with the EPA, did collect onebackground surface soil sample (0-6 inches deep) from the northwest corner of the site (Figure 3,Appendix A). They found 0.034 milligrams per kilogram (mg/kg) of toluene, a component ofgasoline. Toluene in this surface soil sample is likely due to runoff from nearby Grand Avenue. They did not find any significant concentrations of metals, other organic chemicals, or pesticidesin this background sample (NUS 1990). Table 2, below, summarizes the contaminants-of-concern maximum concentrations in the on-site surface soil (0-3 inches deep).



Table 2.

Maximum Concentrations in On-Site Surface Soil (0-3 inches deep)
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground*
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium NA ---<1050,000 RMEG
Chromium
(total)
NA --- 3.3 4,000 RMEG
c+t-1,2-Di-
chloroethene
NA --- <0.00510,000 RMEG
Iron NA ---690 None None
Nitrate NA --- 2.1 106 RMEG
Sulfate NA --- NA --- ---
Vinyl Chloride NA --- <0.011 10 EMEG

* - EPA background surface soil sample 0-6 inches deep
NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Source: NUS 1990

On-Site Subsurface Soil (1-75 feet deep)

In 1989, NUS collected three subsurface soil samples (four to 5 feet deep) in and around thedisposal cells on the east side of the site (Figure 3, Appendix A). They analyzed these samplesfor metals, volatile organic chemicals, nonvolatile organic chemicals, pesticides, nitrate, andcyanide. They found elevated concentrations of chromium, iron, and nitrate in the samples fromthe disposal cells (NUS 1990). We consider sample PL-SB-01 as representative of backgroundsubsurface soil quality.

In 1991, Briley, Wild and Associates, consultants for the Volusia County DSWM, collected 212subsurface soil samples. They collected these samples (1 to 75 feet deep) from 22 spots near thedisposal cells (Figure 4, Appendix A). They analyzed these samples for nitrate and sulfate andfound elevated concentrations around the southern most disposal cell (BWA 1992).

Table 3, below, summarizes the contaminants-of-concern maximum concentrations in on-sitesubsurface soils (1 to 75 feet deep). For this public health assessment, these samples areadequate to characterize the subsurface soil quality. This is especially true for nitrate on the eastside of the landfill.



Table 3.

Maximum Concentrations in On-Site Subsurface Soil (1 to 75 feet deep)
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium <40 0/3 <550,000 RMEG
Chromium
(total)
58 0/3 <1 4,000 RMEG
c+t-1,2-Di-
chloroethene
<0.006 0/3<0.00510,000 RMEG
Iron 5,900 3/3 510 None ---
Nitrate 18083/215 4.2 106 RMEG
Sulfate19,200 7/7 NA None ---
Vinyl Chloride<0.012 0/3 <0.011 10 EMEG
NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Sources: NUS 1990, BWA 1992.

On-Site Surface Water

In 1987 and 1988, the Volusia County DSWM sampled and analyzed water from the largedepression in the center of the landfill. They and found elevated concentrations of iron(maximum 13.9 mg/L). There is no other water body on or near the site with which to comparesurface water concentrations. For this public health assessment, two samples are adequate tocharacterize the on-site surface water quality. Table 4, below, summarizes the contaminants-of-concern maximum concentrations in on-site surface water.



Table 4.

Maximum Concentration in On-Site Surface Water
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/L)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/L)
Comparison
Value
(mg/L)Source
Barium NA --- NA 0.7 RMEG
Chromium
(total)
0.01 1/1 NA 0.1 LTHA
c+t-1,2-Di-
chloroethene
<0.001 0/1 NA 0.1 LTHA
Iron 13.9 1/1 NA 0.03 SMCL
Nitrate <0.5 0/1 NA 10 MCL
Sulfate NA --- NA 400 MCL
Vinyl Chloride<0.001 0/1 NA0.0002 EMEG
NA - not analyzed mg/L - milligrams per liter
MCL - Maximum Contaminant Level
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
SMCL - Secondary Maximum Contaminant Level
Source: VCDSWM 1994

On-Site Sediments

In 1989, NUS collected one sediment grab sample from the large depression in the center of thelandfill (Figure 3, Appendix A). They analyzed this sample for metals, volatile organicchemicals, nonvolatile organic chemicals, pesticides, nitrate, and cyanide. They found elevatedconcentrations of barium, chromium, iron, and nitrate (NUS 1990). There is no other water bodyon or near the site with which to compare sediment concentrations. For this public healthassessment, one sample is adequate to characterize the on-site sediment quality. Table 5, below,summarizes the contaminants-of-concern maximum concentrations in on-site sediments.



Table 5.

Maximum Concentration in On-Site Sediments
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium 330 1/1 NA50,000 RMEG
Chromium
(total)
71 1/1 NA 4,000 RMEG
c+t-1,2-Di-
chloroethene
<0.011 0/1 NA10,000 RMEG
Iron13,000 0/1 NA None ---
Nitrate 6.7 1/1 NA 106 RMEG
Sulfate NA --- NA --- ---
Vinyl Chloride<0.021 0/1 NA 10 EMEG
NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Source: NUS 1990

On-Site Ground Water

For this assessment we have combined ground-water quality data from the surficial and Floridanaquifers. Three hydrogeological studies have documented a connection between the two aquifersat this site (USGS 1977, BWA 1981, BWA 1992).

The Volusia County DSWM has monitored ground-water quality at this landfill since 1981. In1983, they noticed the concentrations of nitrate in monitor wells M05 and M11 along the eastlandfill (Figure 5, Appendix A) boundary began to rise. The concentration of nitrate in monitorwell M11 peaked at 963 mg/L in March 1984. By 1992, the nitrate concentration in these wellshad fallen to between 40 and 80 mg/L (VCDSWM).

The Volusia County DSWM also found that the concentration of barium in monitor wells M05and M11 occasionally exceeded the drinking-water standard of 2 mg/L (VCDSWM 1994).

In 1990, the NUS Corporation sampled eight existing on-site monitor wells for the EPA (Figure3, Appendix A). They found approximately 100 mg/L of nitrate in two wells along the eastlandfill boundary: PL-MW-02 and PL-MW-03 (NUS 1990). Previous reports referred to monitorwells PL-MW-02 and PL-MW-03 as "M05" and "M11."

From 1989 to 1991, Briley, Wild and Associates conducted a contamination assessment for theVolusia County DSWM. This assessment focused on the extent of nitrate ground-watercontamination along the eastern landfill boundary. They found nitrate contamination in theground water under the eastern part of the site and for a short distance off site. They found thesurficial and the upper 30 feet of the Floridan aquifers were contaminated with nitrate atconcentrations as high as 170 mg/L (BWA 1992).

We consider monitor well M14 (also called PL-MW-01) representative of background ground-water quality. For this public health assessment, the existing data adequately characterize the on-site ground-water quality. Table 6, below, summarizes the contaminants-of-concern maximum concentrations in the on-site monitor wells.



Table 6.

Maximum Concentration in On-Site Monitor Wells
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/L)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/L)
Comparison
Value
(mg/L)Source
Barium 2.9 54/72<0.07 0.7 RMEG
Chromium
(total)
0.09 28/101<0.005 0.1 LTHA
c+t-1,2-Di-
chloroethene
<0.005 0/7<0.005 0.1 LTHA
Iron 18.5 42/51 1 0.3 SMCL
Nitrate963 95/107 0.1 10 MCL
Sulfate150 34/36 NA400 MCL
Vinyl Chloride <0.01 0/7<0.01 0.0002 EMEG
Sources: VCDSWM 1994, NUS 1990, BWA 1992.

B. Off-site Contamination

For the purposes of this evaluation, we define "off-site" as the area outside the landfill propertyboundary as shown in Figure 2 (Appendix A). We compiled data in this subsection from thefiles of the Volusia County DSWM (VCDSWM 1994) and Volusia CPHU (VCPHU 1994). We also compiled data in this subsection from reports by Briley, Wild and Associates (BWA 1992)and the NUS Corporation (NUS 1990).

Off-Site Surface Soil (0-6 inches deep)

In 1990, the NUS Corporation, under contract with the EPA, collected two surface soil samples(0-6 inches deep) 200-300 feet east of the landfill (Figure 3, Appendix A). They did not find anysignificant concentrations of metals, solvents, organic chemicals, or pesticides (NUS 1990). Since there is little stormwater run-off from the site, we do not recommend any additional off-site surface soil sampling. Table 7, below, summarizes the maximum concentrations ofcontaminants of concern in off-site surface soil (0-6 inches deep) in 1990.



Table 7.

Maximum Concentrations in Off-Site Surface Soil(0-6 inches deep)
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium <9 0/2 NA50,000 RMEG
Chromium
(total)
<3 0/2 NA 4,000 RMEG
c+t-1,2-Di-
chloroethene
<0.005 0/2 NA10,000 RMEG
Iron540 2/2 NA None None
Nitrate 2.4 2/2 NA 106 RMEG
Sulfate NA --- NA --- ---
Vinyl Chloride<0.011 0/2 NA 10 EMEG
NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Source: NUS 1990

Off-Site Subsurface Soil (1-75 feet deep)

In 1989, the EPA collected two subsurface soil samples (four to 5 feet deep) 200-300 feet east ofthe landfill (Figure 3, Appendix A). They analyzed these samples for metals, volatile organicchemicals, nonvolatile organic chemicals, pesticides, nitrate, and cyanide but did not find anyelevated concentrations (NUS 1990).

In 1991, Briley, Wild and Associates collected 88 subsurface soil samples (1 to 75 feet deep)from 13 locations east of the landfill (Figure 4, Appendix A). They analyzed these samples fornitrate and found elevated concentrations (maximum 11 mg/kg) in two samples (BWA 1992).

For this public health assessment, these samples are adequate to characterize the off-sitesubsurface soil quality. We consider sample PL-SB-01 (Figure 3, Appendix A) as representativeof background subsurface soil quality. Table 8, below, summarizes the contaminants-of-concernmaximum concentrations for off-site subsurface soil (1-75 feet deep).



Table 8.

Maximum Concentrations in Off-Site Subsurface Soil (1-75 feet deep)
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/kg)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Barium <3 0/2 <550,000 RMEG
Chromium
(total)
<2 0/2 <1 4,000 RMEG
c+t-1,2-Di-
chloroethene
<0.005 0/2 <0.00510,000 RMEG
Iron 250 2/2 510 None ---
Nitrate 11 9/90 4.2 106 RMEG
Sulfate NA --- NA --- ---
Vinyl Chloride<0.01 0/2 <0.011 10 EMEG
NA - not analyzed mg/kg - milligrams per kilogram
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
Sources: NUS 1990, BWA 1992.

Off-site Ground Water

In this section, we discuss the ground-water quality in the nearby private drinking-water wellsand the ground-water quality in off-site monitor wells. The Volusia County DSWM and theVolusia CPHU sampled most of the nearby private drinking-water wells between 1987 and 1989(Table 9). Between 1989 and 1992, the Volusia County DSWM installed and sampled the off-site monitor wells (Table 10). We used on-site monitor well M14 (also called PL-MW-01) asrepresentative of background ground-water quality.

The predominate ground-water contaminant associated with this landfill is nitrate. Since 1987,the Volusia County DSWM, the Volusia CPHU, and the NUS Corporation together havesampled about 40 nearby private drinking-water wells. This includes about 20 private drinking-water wells within 0.25 mile of the landfill (Figure 6, Appendix A). They found elevated nitrateconcentrations (>0.5 mg/L) in about half these wells (VCDSWM 1994, VCPHU 1994, NUS1990). Monthly between 1987 and 1989, the Volusia County DSWM resampled six of thesewells east and south of the landfill and found nitrate concentrations greater than 5 mg/L. Twohad nitrate concentrations between 10 and 15 mg/L; a third had concentrations as high as 20mg/L. Table 9, below, summarizes the contaminants-of-concern maximum concentrations foroff-site private drinking-water wells.

Although over 40 nearby private drinking-water wells have been sampled, we do not know thepast extent of the nitrate contamination. It is likely that before 1987, ground water nitrateconcentrations were higher and contamination was more widespread. Most of the approximately20 nearby private drinking-water wells that had less than 5 mg/L nitrate in 1987 have not beenresampled. Due to the karst (cavernous) geology of the area, ground water concentrations canchange rapidly. The lack of follow-up analysis for nitrate in these wells is a significant data gap. We recommend the Volusia County Department of Solid Waste Management resample thesenearby private drinking-water wells and analyze for nitrate.

In 1989, the Volusia CPHU sampled and analyzed ten nearby private drinking-water wells aspart of the underground petroleum storage tank program. They found low levels of 1,2-dichloroethene and vinyl chloride in the Volusia County Humane Society private drinking-waterwell (VCPHU 1994). Ground water sampling was inadequate, however, to determine the fullarea of contamination. We recommend the Volusia County Department of Solid WasteManagement sample all of the nearby private drinking-water wells and analyze for vinylchloride.



Table 9.

Maximum Concentration in Off-Site Private Drinking-Water Wells
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/L)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/L)
Comparison
Value
(mg/L)Source
Barium <0.1 0/22<0.07 0.7 RMEG
Chromium
(total)
<0.005 0/10<0.005 0.1 LTHA
c+t-1,2-Di-
chloroethene
0.006 3/10<0.005 0.1 LTHA
Iron 0.74 4/10 1 None ---
Nitrate 20118/147 0.1 10 MCL
Sulfate 7.3 1/1 NA400 MCL
Vinyl Chloride0.002 3/10<0.01 0.0002 EMEG
NA - not analyzed mg/L - milligrams per liter
LTHA - Lifetime Health Advisory MCL - Maximum Contaminant Level
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
SMCL - Secondary Maximum Contaminant Level
Sources: VCDSWM 1994, VCPHU 1994, NUS 1990.

Between 1989 and 1991, Briley, Wild and Associates installed and sampled five monitor wellseast of the landfill (Figure 4, Appendix A). For these monitor wells, we have combined ground-water quality data from the surficial and Floridan aquifers. Hydrogeological studies have showna connection between these two aquifers at this landfill (USGS 1977, BWA 1981, BWA 1992). They found elevated concentrations of nitrate, iron, and sulfate. Figure 7 (Appendix A) showsthe current (1992) extent of ground water with more than 10 mg/L of nitrate. Ground water withmore than 10 mg/L of nitrate extends about 200 feet east of the southeast side of the landfill(BWA 1992). We do not know how far ground water with more than 0.5 mg/L nitrate currentlyextends. Table 10, below, summarizes the contaminants-of-concern maximum concentrationsfor off-site monitor wells.

Only four off-site monitor wells and one private drinking-water well were tested for sulfate. Fivesamples are inadequate to characterize levels of sulfate in the off-site ground water. Sulfateconcentrations in these five wells, however, were below state drinking water standards. Since thelandfill stopped accepting the Brunswick Corporation sulfuric acid waste in 1980, it is likelysulfate concentrations will continue to decline. Therefore, we do not recommend additionalsampling for sulfate.



Table 10.

Maximum Concentration in Off-Site Monitor Wells
Contaminants
of
Concern
Maximum
Concen-
tration
(mg/L)
Total #
positive--------
Total #
samples
Back-
ground
Concen-
tration
(mg/L)
Comparison
Value
(mg/L)Source
Barium 0.3 6/23<0.07 0.7 RMEG
Chromium
(total)
0.02 3/23<0.005 0.1 LTHA
c+t-1,2-Di-
chloroethene
NA ---<0.005 0.1 LTHA
Iron 6.4 7/23 1 0.3 SMCL
Nitrate 1.3 4/23 0.1 10 MCL
Sulfate 48 4/4 NA400 MCL
Vinyl Chloride NA ---<0.01 0.0002 EMEG
NA - not analyzed mg/L - milligrams per liter
LTHA - Lifetime Health Advisory MCL - Maximum Contaminant Level
EMEG - Environmental Media Evaluation Guide based on the ATSDR minimal risk level.
RMEG - Media Evaluation Guide based on EPA reference dose.
SMCL - Secondary Maximum Contaminant Level
Source: BWA 1992

C. Quality Assurance and Quality Control

In preparing this public health assessment, we relied on the environmental data provided by theVolusia County DSWM, the Volusia CPHU, the Florida DEP and the EPA. We assume theseagencies followed adequate quality assurance and quality control measures concerning chain-of-custody, laboratory procedures, and data reporting. The completeness and reliability of thereferenced information determine the validity of the analysis and conclusions drawn for thispublic health assessment. We assume the data we reviewed for this assessment are valid sincethe environmental samples were collected and analyzed by governmental agencies or their contractors.

In each of the preceding On- and Off-Site Contamination subsections, we evaluated the adequacyof the data to estimate exposures. We assumed that estimated data (J) and presumptive data (N)were valid. This second assumption errs on the side of public health by assuming that acontaminant exists when actually it may not exist.

D. Physical and Other Hazards

The Volusia County DSWM has monitored the soil gases at the landfill borders but has notdetected significant quantities of methane or other gases. Since the cover soil at this landfill isporous sand, accumulation of dangerous concentrations of gases is unlikely. The Volusia CountyDSWM is currently expanding its soil gas monitoring program (HRS 1994).

If the landfill were not secured, the water-filled depression in the center could be a drowninghazard for young children. The landfill is, however, surrounded by an 8-foot chain-link fence andsupervised during the day. We did not see any other potential physical hazards during our visit.

PATHWAYS ANALYSES

In this section, we evaluated the environmental and human components of exposure pathways. Exposure pathways consist of five elements: a source of contamination, transport through anenvironmental medium, a point of exposure, a route of human exposure, and an exposedpopulation.

We eliminate exposure pathways if at least one of the five elements is missing and will never bepresent. We categorize exposure pathways that we can not eliminate as either completed orpotential. For completed pathways, all five elements exist and exposure to a contaminant hasoccurred, is occurring, or will occur. At least one of the five elements is missing, but could existin potential pathways. For potential pathways, exposure to a contaminant could have occurred,could be occurring, or could occur in the future.

A. Completed Exposure Pathways

Ground Water Pathway

The hydrogeology underlying this landfill is complex. The uppermost 70 to 80 feet is mostlysand. This sand contains the unconfined surficial aquifer. Compared to the rest of the county,the unsaturated zone under this landfill is unusually thick. Depth to the top of the surficialaquifer is between 15 and 45 feet below the land surface. Below the sands of the surficial aquiferare discontinuous layers of clay of the Hawthorne formation. Although these clays slow thedownward movement of water, they readily allow for recharge of the underlying semiconfinedFloridan aquifer; the surficial and Floridan aquifers under this landfill are hydraulicallyconnected. Water travels from the land surface to the Floridan aquifer in as little as six years. Karst (cavernous) limestone of the Avon Park formation contains the Floridan aquifer (BWA 1992; NUS 1990).

Rainfall at this landfill seeps rapidly into the sand and percolates down to the top of the surficialaquifer. High porosity of these sands does not allow for significant surface water run-off. According to 1982 water level measurements, flow was to the southwest, south, and southeast. Measurements in 1986 showed flow was to the south and southeast (BWA 1988). Because of thecomplex topography and geology, the direction of ground-water flow in the surficial aquifer islargely undefined. The surficial aquifer serves as a source of recharge to the deeper Floridanaquifer.

Regionally, ground-water flow in the Floridan aquifer is west toward discharge to the St. JohnsRiver and south toward discharge to Blue Springs. A 1977 U.S. Geological Survey investigationdecided that ground-water flow in the Floridan aquifer under this landfill is to the east, south, andwest (USGS 1977). A more recent investigation found flow in the Floridan aquifer under thislandfill is predominantly to the southeast (BWA 1992).

Ingestion of contaminated ground water is a past completed exposure pathway (Table 10). Except for the Humane Society well, nitrate is the only contaminant to which we know peoplehave been exposed. Analyses for sulfate have been inadequate. Solid or liquid waste disposed ofat the landfill is a likely source of nitrate. Other possible sources of nitrate include:malfunctioning septic tanks, improper fertilizer disposal (ferneries), and improper animal wastedisposal (commercial chicken farm). Although over 40 nearby private drinking-water wells havebeen sampled at one time or another, we do not know the past extent of the nitrate ground-watercontamination. It is likely that in the past, ground-water nitrate concentrations were higher andcontamination was more widespread. Between 1987 and 1989, elevated nitrate concentrations(<0.5 mg/L) were found in about 20 nearby private drinking-water wells. Although there areother possible sources of this nitrate contamination, we assume that at least some has migratedfrom the landfill. Ingestion is the route of exposure. Between 40 and 60 people may have beenexposed in the past. More people may be exposed in the future if the appropriate agency doesnot clean-up the ground water.

B. Potential Exposure Pathways

Air Pathway

Inhalation of contaminated dust is a past potential exposure pathway (Table 11). Contaminatedsurface soil could have been the source. Air could have been the medium and nearby residentsthe points of exposure. Inhalation could have been the route of exposure. We categorize thisexposure route as potential since there are insufficient data to confirm that either the surface soilor air was contaminated.

C. Eliminated Pathways

We eliminated incidental soil ingestion and surface water ingestion as exposure pathways. Although this landfill is open for use by the public during the day, it is fenced, access ismonitored by Volusia County DSWM personnel, and there are no signs of trespass.

We eliminated inhalation of solvents released from ground water during showering and otherdomestic uses as an exposure pathway. This is not a significant exposure pathway at this sitesince the Humane Society Well was the only well with any solvents. The concentrations ofsolvents in the Humane Society well were low and the inhalation dose insignificant since thiswater was not used for showering.

Also, we eliminated inhalation of methane and other landfill gases as an exposure pathway. TheVolusia County DSWM has monitored the soil gases at the landfill borders but has not detectedsignificant quantities of methane or other gases. Since the cover soil at this landfill is poroussand, accumulation of dangerous gas concentrations is unlikely.



Table 10.

Completed Exposure Pathways
PATHWAY
NAME
EXPOSURE PATHWAY ELEMENTSTIME
SOURCEENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
EXPOSED
POPULATION
Ground
Water
LandfillGround WaterDrinking-
Water
Wells
Ingestion40-60
Nearby
Residents
Past
&
Future


Table 11.

Potential Exposure Pathways
PATHWAY
NAME
EXPOSURE PATHWAY ELEMENTS TIME
SOURCE ENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
EXPOSED
POPULATION
Contam-
inated
Dust
Landfill
Surface
Soil
Air On and Off
Site
Inhalation Unknown Past



PUBLIC HEALTH IMPLICATIONS

In this section we discuss potential health effects on persons exposed to specific contaminantsand address specific community health concerns.

A. Toxicological Evaluation

Introduction

To evaluate health effects, the ATSDR developed a Minimal Risk Levels (MRLs) forcontaminants commonly found at hazardous waste sites. An MRL is an estimate of daily humanexposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. The ATSDR developed MRLs for each route of exposure, such as ingestion and inhalation, andfor the length of exposure. The ATSDR categorizes length of exposure as acute (less than 14days), intermediate (15 to 364 days), or chromic (greater than 365 days). The ATSDR presentsthese MRLs in Toxicological Profiles. These chemical-specific profiles provide information onhealth effects, environmental transport, human exposure, and regulatory status.

In this section, we use standard assumptions to estimate human exposure from ingestion ofcontaminated ground water. We assume the average adult ingests 2 liters of water per day andweighs 70 kilograms. Since there are no data for the concentrations of contaminants in on-sitesurface soil or air, we cannot evaluate the public health threat from these potential exposurepathways.

Barium

It is unlikely the concentrations of barium in the off-site ground water have caused illnesses. Thevarious governmental agencies did not detect barium in any of the private drinking-water wellsamples. They detected barium in only 6 of the 23 off-site monitor well samples. The ATSDRhas not established a Minimal Risk Level for barium. The estimated maximum dose fromingestion of the ground water in the monitor wells is less, however, than the lowest dose that didnot cause an effect in laboratory animals (ATSDR 1992). Therefore, it is unlikely that barium inthe ground water has caused any illnesses.

Chromium (total)

It is unlikely the concentrations of chromium (total) in the off-site ground water have causedillnesses. Since not all of the analyses for chromium differentiated between the different forms,we have considered the total of all of the forms. The various governmental agencies did notdetect chromium in any of the private drinking-water well samples. They detected chromium inonly 3 of the 23 off-site monitor well samples.

The ATSDR has not established a Minimal Risk Level for chromium. The estimated maximumdose from ingestion of ground water in the monitor wells is less, however, than the lowest dosethat did not cause an effect in laboratory animals (ATSDR 1993a). Therefore, it is unlikely thatchromium in the ground water has caused any illnesses.

cis and trans-1,2-Dichloroethene

It is unlikely the concentrations of 1,2-dichloroethene in the off-site ground water have causedillnesses. 1,2-Dichloroethene (total cis and trans isomers) was found in 3 out of 10 privatedrinking-water well samples. The estimated maximum dose from ingestion is less than both theacute and intermediate ATSDR MRLs. The ATSDR has not established a chronic MRL sincescientists do not know the long-term human health effects of exposure to 1,2-dichloroethene. Scientists have not reported birth defects, reproductive effects, or cancer in humans or animalsexposed to 1,2-dichloroethene (ATSDR 1990). The maximum concentration of 1,2-dichloroethene in these drinking-water wells was also less than the EPA Maximum ContaminantLevel (MCL) for drinking water.

Iron

Concentrations of iron found in the ground water in both the drinking-water and off-site monitorwells are unlikely to cause illnesses. These concentrations, however, may give the water anastringent or metallic taste. In many places in Florida, natural ground water quality does notmeet the secondary drinking water standard of 0.3 mg/L for iron. The EPA bases this secondarydrinking water standard on iron's taste and staining threshold. There is no ATSDR toxicologicalprofile for iron.

Nitrate

Maximum concentration of nitrate in the drinking-water wells could have causedmethemoglobinemia in bottle fed infants less than six months old. These nitrate concentrationsare unlikely, however, to cause any illnesses in infants older than six months, children, or adults. Methemoglobinemia is a condition where the blood is unable to transport oxygen to the tissuesproperly. We commonly refer to methemoglobinemia in infants as "blue baby syndrome."

When the Volusia CPHU found drinking-water wells with >10 mg/L nitrate, they advised theowner not to use this water to prepare infant formula. They also notified the Volusia CPHUmedical director. Since there were no infants in these homes, we do not expect there were anycases of methemoglobinemia or "blue baby syndrome." There have been no reports ofmethemoglobinemia in this area.

Bacteria in the stomach, particularly of infants less than six months old, metabolize nitrate tonitrite. Nitrite reacts with hemoglobin, and markedly decreases the ability of blood to carryoxygen to the tissues. Bottle-fed infants less than six months old have a high stomach pH. Bacteria that reduce nitrate to nitrite may proliferate in the stomach at a high pH, leading to anincreased formation of nitrite. Nitrite then reacts with the hemoglobin (the molecule in the bloodthat transports oxygen) to form methemoglobin. Methemoglobin is unable to transport oxygenresulting in methemoglobinemia (NAS 1977a).

The EPA bases its Maximum Contaminant Level (MCL) for nitrate in drinking water (10 mg/L)on epidemiological studies of infants with methemoglobinemia. There is little margin of safetyin this value, however (NAS 1977a). There is no ATSDR toxicological profile for nitrate.

Sulfate

Because of the lack of sampling data, we cannot assess the public health threat of sulfate in theground water. As noted above, the various governmental agencies only tested one drinking-water well for sulfate. One sample is inadequate to characterize levels of sulfate in the drinking-water wells. Sulfate concentrations four to five times higher than found in the off-site monitorwells could have a laxative effect (cause diarrhea) in sensitive individuals (NAS 1977b). Thereis no ATSDR toxicological profile for sulfate.

Vinyl Chloride

Concentrations of vinyl chloride found in the private drinking-water wells are unlikely to causeillnesses. Ground water sampling was inadequate, however, to determine the full area ofcontamination. The estimated maximum dose of vinyl chloride in one drinking-water well wasslightly above the chronic oral ATSDR Minimal Risk Level (MRL). This MRL, however,includes a one thousand fold safety factor. The ATSDR bases this MRL on changes in liver cellsof rats fed vinyl chloride in their diet daily for almost three years (ATSDR 1993b).

The Department of Health and Human Services has decided that vinyl chloride is a knowncarcinogen. Similarly, the International Agency for Research on Cancer and EPA have decidedthat vinyl chloride is carcinogenic to humans. Rats fed high levels of vinyl chloride daily for oneto two years developed liver cancer (ATSDR 1993b). Concentrations in drinking-water wellsnear this landfill are so low, however, there is no apparent increased risk of cancer to humans.

B. Health Outcome Data Evaluation

We did not evaluate community health outcome data. Although the concentrations of nitrate in afew nearby private drinking-water wells exceeded the standard, it is unlikely a search of state-wide health outcome data would detect an effect in such a small group. Therefore, there is littlejustification or community demand for an evaluation of health outcome data at this time. Iffuture environmental investigations find other contaminants or more widespread contamination,we will evaluate health outcome data as appropriate.

C. Community Health Concerns Evaluation

We have addressed each community health concern as follows:

1. In 1988, one nearby resident complained of digestive problems. This resident saidthat other nearby residents had (unspecified) health problems that lasted until they ceaseddrinking water from their wells.

    "Digestive problems" cover a wide range of medical conditions. Without a medicaldiagnosis or a more specific description of the symptoms, it is difficult to assess thisconcern. Diarrhea could be considered a "digestive problem." Although theenvironmental data are insufficient to establish a link to this landfill, ingestion of highconcentrations of sulfate is one possible cause of diarrhea. The Brunswick Corporationdisposed of high sulfur content waste at the landfill. Only four off-site monitor wells andone private drinking-water well were tested for sulfate. Sulfate concentrations in thesefive wells, however, were below state drinking water standards. Since the landfillstopped accepting the high sulfur content Brunswick Corporation waste in 1980, it islikely sulfate concentrations will continue to decline. Therefore, we do not recommendadditional sampling for sulfate.

    Without further information, we cannot assess other (unspecified) health problems.

2. In 1994, one nearby resident complained that although their health has not beenaffected, their horses have failed to breed as expected.

    In 1989, the Volusia CPHU sampled the well that both this resident and their horses use. They analyzed for gasoline related contaminants but did not find any. We suggest thisresident contact a county agricultural extension agent to discuss the failure of their horsesto breed. Also, we suggest this resident have their well analyzed for nitrates. Theenlarged cecum and colon of horses provide a location for the microbial reduction ofnitrate to nitrite (NAS 1977).

3. In 1994, one nearby resident complained that she and her husband experienceddiarrhea for over six months when drinking the water from their well. She said that theirphysician was unable to diagnose the cause but their symptoms ceased when they switched to bottled water.

    Although the environmental data are insufficient to establish a link to this landfill,ingestion of high concentrations of sulfate is one possible cause of diarrhea. TheBrunswick Corporation disposed of high sulfur content waste at the landfill. Only fouroff-site monitor wells and one private drinking-water well were tested for sulfate. Sulfateconcentrations in these five wells, however, were below state drinking water standards. Since the landfill stopped accepting the high sulfur content Brunswick Corporation wastein 1980, it is likely sulfate concentrations will continue to decline. Therefore, we do notrecommend additional sampling for sulfate.

    Another possible cause of diarrhea is giardia. Laboratories do not commonly analyze forthis protozoan in drinking-water wells. It could have, however, traveled from the landfillto nearby drinking-water wells though the karst (cavernous) limestone. It could also haveinfiltrated from contaminated surface water to ground water along poorly constructed ordeteriorated drinking-water wells. If nearby residents experience diarrhea again, werecommend the Volusia CPHU sample their wells and analyze for coliform bacteria and if funds are available, for giardia.

4. In 1994, one nearby resident mentioned that her husband had died of cancer(melanoma) and she had been treated successfully for breast cancer. She was unsure if thelandfill caused her family's health problems.

    Melanoma, a form of skin cancer, is associated with excessive sun exposure. The causesof breast cancer are less well known. None of the chemicals found at this landfill to dateare associated with melanoma or breast cancer. Contaminated ground water from the landfill is not known to extend in the direction of this resident.

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