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PUBLIC HEALTH ASSESSMENT

BROWARD COUNTY-21ST MANOR DUMP
FT. LAUDERDALE, BROWARD COUNTY, FLORIDA


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

In this section, we will review the environmental data collected at this site. We will evaluate theadequacy of the sampling that has been conducted, select contaminants of concern, and list themaximum concentration and frequency of detection of the contaminants found in various media. The maximum concentrations found will then be compared to background levels and to standardcomparison values. The following comparison values are used in the data tables:

    1. CREG--Cancer Risk Evaluation Guide--calculated from EPA's cancer slope factors, is thecontaminant concentration that is estimated to result in one excess cancer in a million personsexposed over a lifetime.

    2. EMEG--Environmental Media Evaluation Guide--derived from ATSDR's Minimal Risk Level(MRL), which provides a measure of the toxicity of a chemical, is the estimate of daily humanexposure to a chemical that is likely to be without an appreciable risk of adverse effects, generallyfor a period of a year or longer.

    3. LTHA--Lifetime Health Advisory for Drinking Water--is EPA's estimate of the concentrationof a contaminant in drinking water at which adverse health effects would not be anticipated tooccur over a lifetime of exposure. LTHAs provide a safety margin to protect sensitive membersof the population.

    4. MCL--Maximum Contaminant Level--is the contaminant concentration that EPA considersprotective of public health over a 70 year lifetime at an exposure rate of 2 liters of water per day. MCLs are regulatory concentrations.

    5. Chronic RfD--Reference Dose--is EPA's estimate of the daily exposure to a contaminant that isunlikely to cause adverse health effects.

We have reviewed the environmental sampling data and selected the following chemicals as contaminants of concern:

Arsenic
Vanadium
1,2-Dichloroethene
Dieldrin
Chromium
Chloroform
Trichloroethene
Lead
1,1-Dichloroethene
Vinyl chloride

For chromium, the analysis reports did not specify whether chromium metal (chromium 0),trivalent chromium (chromium III) or hexavalent chromium (chromium VI) was detected. Sincechromium VI is the most toxic form of the metal, we feel it is most protective of public health toassume the presence of chromium VI and have used the appropriate comparison valuesthroughout this assessment.

We selected these contaminants based on the following factors:

  1. Concentrations of contaminants on- and off-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.

In addition, twenty other chemicals were detected in various media at this site. There areToxicological Profiles available for eight of these chemicals. For these eight, there is insufficienthuman health data available to determine their public health significance. These chemicals arelisted in Appendix B. For the remaining twelve chemicals, there are no toxicological dataavailable upon which to base an assessment of their public health significance. These chemicalsare listed in Appendix C.

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 the public healthassessment to those contaminants most important to public health. When selected as a contaminant of concern in one medium, we have also reported that contaminant in all other media. We will evaluate these contaminants in subsequent sections and determine whether exposure haspublic health significance.

To identify industrial facilities that could contribute to the contamination near the 21st ManorDump site, we searched the 1987, 1988, and 1989 EPA Toxic Release Inventory (TRI) data base. EPA developed TRI from the chemical release information (air, water, and soil) provided bycertain industries. The TRI search revealed the presence of one industrial facility in the 33317 zipcode area, which includes the site, that had reported releases between 1987 and 1989. EricksonIndustries (now Lilly-Ram Industries, Erickson Div.) is located at 2355 SW 66th Terrace in Davieapproximately two miles west of the site. They estimated the release of 37,803 pounds of styreneinto the air between 1987 and 1989 and 2,666 pounds of methyl methacrylate into the air between1988 and 1989. Because of the distance from the site and the direction of the prevailing winds,which are generally from the east and southeast, releases from this facility are unlikely to haveproduced any contamination on or around the 21st Manor Dump site.

In this assessment, the contamination that exists on the site will be discussed first, separately fromthe contamination that occurs off the site.

A. On-site Contamination

For the purposes of this evaluation, "on-site" will be defined as the area within the original dump. This area is entirely within the property owned by the Broward County School Board andincludes a major portion of the road, 21st Manor, and a limited area within the southern part ofthe Meadowbrook Elementary School yard (Fig. 4, Appendix A)

We compiled data in this subsection from the following EPA reports: the 1988 site screeninginvestigation, the 1989 soil sampling study, and the 1990 listing site inspection (6, 7, 8). Additional data were compiled from a 1988 report by the Florida Department of EnvironmentalRegulation (FDER) of the Peele-Dixie Wellfield contamination in Broward County (3).

On-Site Surface Soil

EPA has not collected any surface soil samples (0 - 3 inches) from this site. Since no surface soildata exist on the site, a significant data gap exists in assessing the site's public health implications.

On-Site Subsurface Soil

As part of the reports listed above, EPA contractor NUS Corporation collected a total of 28subsurface (1.5 to 30 feet deep) samples from various locations on the site (Fig. 5, Appendix A). On-site concentrations of arsenic and chromium were at levels below background samples. Dieldrin in on-site samples was found above the levels found in background soil samples and at aconcentration exceeding the Cancer Risk Evaluation Guide (CREG).


Table 1.

Maximum Concentrations in On-Site Subsurface Soil
Contaminants
of
Concern
Maximum
Concentration
(mg/kg)
Total #
positive*
--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Arsenic 1.5 0/5 10 15 RfD
Chromium 13 0/28 27 250 RfD
Lead130 0/28 10 NONE ----
Vanadium 4.7 0/19 2.8 NONE ----
1,1-Dichloro-
ethene
ND 0/5 ND .058 CREG
1,2-Dichloro-ethene ND 0/5 ND ---- ----
Chloroform NA ---- ---- ---- ----
Trichloro-
ethene
ND 0/5 ND ---- ----
Vinyl chloride NA ---- ---- ---- ----
Dieldrin .065 2/12 ND .044 CREG

NA - not analyzed
ND - not detected
mg/kg - milligrams per kilogram
* - concentration exceeds at least one health-based comparison value
RfD - Reference Dose
CREG - ATSDR Cancer Risk Evaluation Guide
Sources: 1988 EPA Site Screening Investigation (6)
1990 EPA Listing Site Inspection (8)

On-Site Shallow Groundwater

As part of the site screening investigation and listing site inspection, EPA contractor NUSCorporation sampled the shallow groundwater (20-30 feet deep) from a total of ten temporarywells on the site (Fig. 6, Appendix A). Three off-site temporary wells were sampled to establishbackground conditions. The Florida Department of Environmental Regulation (FDER) analyzedtwo samples from an on-site monitoring well as part of their 1988 Peele-Dixie Wellfieldcontamination investigation. On-site shallow groundwater was contaminated with arsenic,chromium, lead and vanadium. Lead concentrations in both background and on-site samplesexceeded the Florida MCL for drinking water. Concentrations of arsenic, chromium andvanadium were above the background in all samples in which they were detected.



Table 2.

Maximum Concentration in On-Site Shallow Groundwater
Contaminants
of
Concern
Maximum
Concentration
(ug/L)
Total #
positive*
--------
Total #
samples
Back-
ground
Concen-
tration
(ug/L)
Comparison
Value
(ug/L)Source
Arsenic 29 2/11 ND 3 RfD
Chromium 300 3/11 ND 50 RfD
Lead 120 8/11 39 15 FL MCL
Vanadium 120 2/11 ND 20 LTHA
1,1-Dichloro-ethene ND 0/13 ND .058 CREG
1,2-Dichloro-ethene ND 0/14 ND 70 LTHA/
MCL
Chloroform ND 0/8 ND 5.7 CREG
Trichloro-
ethene
ND 0/14 ND 5 MCL
Vinyl chloride ND 0/4 ND 0.2 EMEG
Dieldrin NA ---- ---- ---- ----

NA - not analyzed
ND - not detected
ug/L - micrograms per liter
* - concentration exceeds at least one health-based comparison value
LTHA - EPA Lifetime Health Advisory
CREG - ATSDR Cancer Risk Evaluation Guide
EMEG - ATSDR Environmental Media Evaluation Guide
RfD - EPA Reference Dose
MCL - EPA Maximum Contaminant Level
FL MCL - Florida Maximum Contaminant Level
Sources: 1988 EPA Site Screening Investigation (6)
1988 FDER Peele-Dixie Wellfield Contamination (3)
1990 EPA Listing Site Inspection (8)

On-Site Deep Groundwater

EPA has not collected any deep groundwater (>60 feet) samples from the site. Since no deepgroundwater data exist on the site, a significant data gap exists in assessing the site's public healthimplications.

B. Off-site Contamination

For this assessment, "off-site" will be defined as the area outside of the dump itself, including theremainder of the Meadowbrook Elementary School property (Fig. 4, Appendix A). We compileddata in this subsection from the following EPA reports: the 1988 site screening investigation, the1989 soil sampling study, and the 1990 listing site inspection (6, 7, 8). Data were also compiledfrom the 1988 Florida DER Peele-Dixie Wellfield Contamination study and the results of privatewell sampling conducted by the Broward CPHU from 1987 to 1991 (3, 4).

During the site visit, we observed several small businesses in the area, notably a tool and diecompany. Mr. Commiskey and Mr. Galbreath provided anecdotal information concerning theexistence of backyard automobile and motorcycle repair businesses in the neighborhoodsurrounding the site. Although these and other activities may have contributed to thegroundwater contamination in the area, it is not possible to confirm or quantify any contaminationoriginating from these sources.

Chloroform, trichloroethene, 1,1-dichloroethene, vinyl chloride, and 1,2-dichloroethene occur inoff-site groundwater. The drinking water aquifer in the area surrounding the site is sufficientlycontaminated that many of the municipal supply wells in the South Peele-Dixie Wellfield andseveral private wells in an area north of the site have been closed or condemned (Fig 7, AppendixA).

Off-Site Surface Soil

EPA has not collected any surface soil samples (0 - 3 inches) from around this site. Since no off-site surface soil data exist, a significant data gap exists in assessing the site's public healthimplications.

Off-Site Subsurface Soil

As part of its 1990 listing site inspection, EPA contractor NUS Corporation collected ninesubsurface (1.5-30 feet deep) soil samples from the area immediately surrounding the dump site(8) (Fig. 8, Appendix A). Analysis of these samples included dieldrin, lead, chromium andvanadium. All concentrations were below levels of concern.

Table 3. Maximum Concentrations in Off-Site Subsurface Soil

Table 1.

Human Health Effects at Various Hydrogen Sulfide Concentrations in Air
Contaminants
of
Concern
Maximum
Concentration
(mg/kg)
Total #
positive*
--------
Total #
samples
Back-
ground
Concen-
tration
(mg/kg)
Comparison
Value
(mg/kg)Source
Arsenic NA ---- ---- ---- ----
Chromium 4.6 0/5 27 250 RfD
Lead 19 0/5 10 NONE ----
Vanadium 3.5 0/2 2.8 NONE ----
1,1-Dichloro-ethene NA ---- ---- ---- ----
1,2-Dichloro-ethene NA ---- ---- ---- ----
Chloroform NA ---- ---- ---- ----
Trichloro-ethene NA ---- ---- ---- ----
Vinyl chloride NA ---- ---- ---- ----
Dieldrin .0011 0/2 ND .044 CREG

NA - not analyzed
ND - not detected
mg/kg - milligrams per kilogram
* - concentration exceeds at least one health-based comparison value
RfD - EPA Reference Dose
CREG - ATSDR Cancer Risk Evaluation Guide
Sources: 1990 EPA Listing Site Inspection (8)

Off-Site Groundwater

For its December 1988 wellfield contamination study, the Florida Department of EnvironmentalRegulation sampled 21 monitoring, 1 public and 38 private wells located within a radius of 1 mileof the dump site (3). Fourteen of these wells were screened in the shallow groundwater (<60feet) and the rest were screened in the deep groundwater (>60 feet). Also, between 1987 and1991, the Broward CPHU monitored nine private drinking water wells along SW 44th Terrace,which is within one-half mile north of the site (4). All of these wells were screened in the deepgroundwater. Not all wells were analyzed for all contaminants and some wells were sampledmore than once (Fig. 9, Appendix A).

Concentrations of 1,1-dichloroethene and 1,2-dichloroethene above comparison values weredetected in two of the fourteen shallow wells and thirteen of the forty-six deep wells analyzed byFDER. In addition, seven of the nine deep drinking water wells along SW 44th Terrace, whichwere analyzed by the Broward CPHU, contained concentrations of 1,1-dichloroethene and vinylchloride above comparison values. Background concentrations of these contaminants in both theshallow and deep groundwater samples were below detection limits.


Table 4.

Maximum Concentration in Off-Site Shallow Groundwater
Contaminants
of
Concern
Maximum
Concentration
(ug/L)
Total #
positive*
--------
Total #
samples
Back-
ground
Concen-
tration
(ug/L)
Comparison
Value
(ug/L)Source
Arsenic ND 0/5 ND 3 RfD
Chromium 1 0/6 ND 50 RfD
Lead 7 0/6 39 15 FL MCL
Vanadium 12 0/6 ND 20 LTHA
1,1-Dichloro-ethene 68 3/19 ND .058 CREG
1,2-Dichloro-ethene 310 2/31 ND 70 LTHA
Chloroform 16 1/29 ND 5.7 CREG
Trichloro-ethene 6 1/30 ND 5 MCL
Vinyl chloride 25 1/6 ND .2 EMEG
Dieldrin NA ---- ---- ---- ----

NA - not analyzed
ND - not detected
ug/L - micrograms per liter
* - concentration exceeds at least one health-based comparison value
FL MCL - Florida Maximum Contaminant Level
Sources: 1988 FDER Peele-Dixie Wellfield Contamination (3)
1990 EPA Listing Site Inspection (8)


Table 5.

Maximum Concentration in Off-Site Deep Groundwater
Contaminants
of
Concern
Maximum
Concentration
(ug/L)
Total #
positive*
--------
Total #
samples
Back-
ground
Concen-
tration
(ug/L)
Comparison
Value
(ug/L)Source
Arsenic ND 0/6 ND 3 RfD
Chromium ND 0/6 ND 50 RfD
Lead ND 0/6 ND 15 FL MCL
Vanadium ND 0/6 ND 20 LTHA
1,1-Dichloro-ethene 24 79/140 ND .058 CREG
1,2-Dichloro-ethene 252 23/143 ND 70 LTHA
Chloroform 110.7 2/87 ND 5.7 CREG
Trichloro-ethene 9 1/130 ND 5 MCL
Vinyl chloride 4.9 10/29 ND .2 EMEG
Dieldrin NA ---- ---- ---- ----

NA - not analyzed
ND - not detected
ug/L - micrograms per liter
* - concentration exceeds at least one health-based comparison value
LTHA - EPA Lifetime Health Advisory
CREG - ATSDR Cancer Risk Evaluation Guide
EMEG - ATSDR Environmental Media Evaluation Guide
RfD - EPA Reference Dose
FL MCL - Florida Maximum Contaminant Level
Sources: 1988 FDER Peele-Dixie Wellfield Contamination (3)
1987-1991 Broward CPHU Private Well Monitoring (4)

C. Quality Assurance and Quality Control

We requested, but were unable to obtain, a data review summary from EPA. We assume thesedata are valid, however, since the environmental samples were collected and analyzed bygovernmental agencies or their contractors. In preparing this public health assessment, we reliedon the information provided by these agencies and assumed that adequate quality assurance andquality control measures were followed with regard to chain-of-custody, laboratory procedures,and data reporting. The validity of the analysis and conclusions drawn for this public healthassessment are determined by the completeness and reliability of the referenced information.

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 errors on the side of public health by assuming that acontaminant exists when actually it may not exist.

Although quality assurance and quality control information is unavailable for the Broward CPHUprivate well sampling data, there are no indications that these data are not reliable. Samplescollected and analyzed for all other referenced studies in this public health assessment wereperformed according to the Engineering Support Branch Standard Operating Procedures andQuality Assurance Manual, U.S. Environmental Protection Agency, Region IV, EnvironmentalServices Division, April 1, 1986.

D. Physical and other Hazards

No physical hazards were observed during the site visit and none were mentioned in any of thesite-related documents reviewed for this public health assessment.

PATHWAYS ANALYSES

To determine whether nearby residents are exposed to contaminants migrating from the site, weevaluated the environmental and human components of exposure pathways. Exposure pathwaysconsist of five elements: a source of contamination, transport through an environmental medium,a point of exposure, a route of human exposure, and an exposed population.

An exposure pathway can be eliminated if at least one of the five elements is missing and willnever be present. We categorize exposure pathways that are not eliminated as either completedor potential. For completed pathways, all five elements exist and exposure to a contaminant hasoccurred, is occurring, or will occur. For potential pathways, at least one of the five elements ismissing, but could exist. For potential pathways, exposure to a contaminant could have occurred,could be occurring, or could occur in the future.

A. Completed Exposure Pathway

Private Well Pathway

Past and current exposure pathways are possible from contaminated groundwater present inprivate wells. Approximately 74 residences within one-half mile north of the site use private wellsas their source of drinking water. The only completed exposure pathway involves those residentswho use private well water for drinking, cooking and other domestic purposes.

The contaminants present in these wells do not occur in the shallow groundwater on-site and arenot believed to be site-related. Seven of the nine wells sampled by the Broward CPHU between1987 and 1991 contained contaminants such as 1,1-dichloroethene and vinyl chloride. Althoughthe Broward CPHU provided alternate sources of drinking water, contaminated water was stillused for other purposes, such as showering and laundering.

We do not know how many of the remaining 65 private wells are contaminated. However, sincemunicipal supply wells within a few hundred feet of these private wells are contaminated and theyall draw on the same aquifer, it appears likely that other private wells are contaminated. Therefore, until we have better data, we will assume that all private wells are contaminated.

We do not know how many persons use private wells. However, these persons would be exposedto 1,1-dichloroethene and vinyl chloride through ingestion, inhalation and skin contact. 1,1-Dichloroethene and vinyl chloride both evaporate into the air from contaminated water duringshowers and baths so that persons may be exposed as they breathe the air in their homes (9, 10). In addition, 1,1-dichloroethene may absorb across the skin during showers and baths thusincreasing exposure (10).

The Broward CPHU issued its first bottled water notice in May, 1988 to inform residents usingprivate wells of the contamination in their well water and of the availability of alternate sources ofdrinking water. Although well water probably was used for various domestic purposes, includingdrinking, all residences having condemned wells and most of the remaining households wereconnected to a municipal water supply by May, 1992 (pers. comm., Willard Galbreath, May1992). Thus, these residents would have had a maximum exposure period of about four years.


Table 6.

Completed Exposure Pathway
EXPOSURE PATHWAY ELEMENTS
PATHWAY
NAME
SOURCEENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
EXPOSED
POPULATION
TIME
Private
Wells
UnknownGroundwaterResidence
(taps)
Ingestion
Inhalation
Skin
Absorption
Residents
Using
Private
Wells
Past

B. Potential Exposure Pathways

Surface Soil Pathway

Since no surface soil (0 - 3 inches) samples have been analyzed, we do not know whatcontaminants may be present. Dieldrin is present in the subsurface soil (1.5-30 feet) and there isthe possibility that this and other contaminants may also be present in the surface soil both on- andoff-site. There is the potential for exposure via incidental ingestion to children at theMeadowbrook school. However, until we receive surface soil data, we cannot assess theimportance of this exposure pathway and no further evaluation of this pathway will be made inthis public health assessment.

Municipal Well Pathway

Monitoring of municipal supply wells in 1984 by the Ft. Lauderdale Public Utilities Departmentdetected no contamination. In December 1986, 1,1-dichloroethene was detected in one municipalsupply well which was immediately taken off line. Discovery of more widespread contaminationled to immediate closing of all affected municipal wells. Thus, there is very little likelihood ofcurrent or future contamination from this source. It is currently unknown if data exist for theperiod between 1984 and 1986 and until this information becomes available, we cannot assess theimportance of this exposure pathway and no further evaluation of this pathway will be made inthis public health assessment.

On-Site Subsurface Soil Pathway

The subsurface soil within the dump site is contaminated with dieldrin. During the approximatelytwenty year period when the dump was open, access to the area was unrestricted. Individualsusing the dump, children or other trespassers would have had the potential for exposure to thesecontaminants through incidental ingestion. However, no information is available concerning thenumber of children or other trespassers on the site, the frequency and duration of their visits ortheir identity. Because this information is not available and is not likely to ever be available, wecannot fully assess the importance of this exposure pathway.

On-Site Shallow Groundwater Pathway

The shallow groundwater on-site is contaminated with lead, arsenic, vanadium and chromium,that have not been detected in the groundwater off-site. Since this contamination is not present inthe groundwater off-site and residences that had obtained drinking water from private wells arenow supplied by municipal water, current and future exposure by this pathway is unlikely. Duringthe period when the dump was open, this groundwater was exposed at the surface, allowing thepotential for exposure to these contaminants through incidental ingestion if swimming occurred. However, no information is available concerning the persons who may have been on the site. Because this information is not available and is not likely to ever be available, we cannot fullyassess the importance of this exposure pathway.


Table 7.

Potential Exposure Pathways
EXPOSURE PATHWAY ELEMENTS
PATHWAY
NAME
SOURCEENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
EXPOSED
POPULATION
TIME
Surface
Soil
Dump siteSurface soilSchool yardIngestionSchool childrenPast
Present
Future
Municipal
Wells
UnknownGroundwaterResidence(taps)IngestionInhalation SkinAbsorptionResidentsPast
Sub-
surface
Soil
Dump siteSubsurface soilDump siteIngestion ChildrenTrespassersPast
Shallow
Ground-
water
Dump siteGroundwaterDump siteIngestionChildrenTrespassersPast

PUBLIC HEALTH IMPLICATIONS

In this section we will discuss the health effects for persons exposed to specific contaminants,evaluate state and local health databases, and address specific community health concerns.

A. Toxicological Evaluation

Introduction

To evaluate health effects, ATSDR has developed Minimal Risk Levels (MRLs) for contaminantscommonly found at hazardous waste sites. MRLs are an estimate of daily human exposure to acontaminant below which non-cancer, adverse health effects are unlikely to occur. ATSDRdeveloped MRLs for each route of exposure, such as ingestion and inhalation, and for the lengthof exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greaterthan 365 days). ATSDR presents these MRLs in Toxicological Profiles. These chemical-specificprofiles provide information on health effects, environmental transport, human exposure, andregulatory status. In the following discussion, we used ATSDR Toxicological Profiles for thefollowing chemicals:

Arsenic
Vanadium
1,2-Dichloroethene
Dieldrin
Chromium
Chloroform
Trichloroethene
Lead
1,1-Dichloroethene
Vinyl chloride

In this section, we used standard assumptions to estimate human exposure from ingestion of soiland groundwater. To estimate exposure from incidental ingestion of contaminated soil, we madethe following assumptions: 1) children between the ages of 6 and 18 ingest an average of 200milligrams (mg) of soil per day, 2) these children weigh about 35 kilograms (kg), and 3) theyingested soil on the site at the maximum concentration measured for each contaminant. Toestimate exposure from ingestion of contaminated drinking water, we made the followingassumptions: 1) adults drink 2 liters of water each day and weigh 70 kg, 2) children drink 1 literof water each day and weigh 10 kg, and 3) they ingested water at the maximum concentrationmeasured for each contaminant.

During the period when the dump was open, the shallow groundwater on-site was exposed at thesurface. Although there are no reports that this water was used for swimming, this possibilitycannot be ruled out. In order to estimate potential past exposure from this source, we made thefollowing assumptions: 1) children between the ages of 6 and 18 ingest an average of 0.05 L ofwater per hour during swimming, 2) each swimming event lasts 1 hour, 3) they swim 72 times peryear (3 times/week and 24 weeks/year), 4) these children weigh about 35 kg, and 5) they wereexposed to the maximum concentration measured for each contaminant.

ARSENIC

When the dump was open, trespassers on the site may have been exposed to arsenic via incidentalingestion of contaminated water when swimming. These exposures, however, are unlikely tohave caused adverse health effects.

The estimated daily dose of arsenic from incidental ingestion of contaminated water (duringswimming) is less than the ATSDR chronic Minimal Risk Level (MRL) (11). Arsenic is classifiedas a human carcinogen by inhalation exposure and has been shown to increase cancer incidence inhumans when ingested in water. However, exposure to arsenic at the concentrations found in thewater on-site when the dump was open would result in no apparent increase in the risk ofdeveloping cancer. Arsenic may also enter the body through the skin, but this is not usually animportant consideration.

EPA did not analyze for arsenic in off-site subsurface soil. Arsenic was analyzed for, but notdetected, in off-site groundwater.

CHROMIUM

When the dump was open, trespassers on the site may have been exposed to chromium viaincidental ingestion of contaminated water when swimming. These exposures, however, areunlikely to have caused adverse health effects.

Since the analysis reports did not specify which of the three major forms of chromium waspresent, we have assumed the presence of chromium (VI), the most toxic form. The estimateddaily dose of chromium (VI) from incidental ingestion of contaminated water (during swimming)is less than the ATSDR chronic Minimal Risk Level (MRL) (12). Exposure to chromium at theconcentrations found in the water on site when the dump was open would not have been likely tocause any adverse health effects. Dermal contact with chromium (VI) may result in skinsensitivity. However, information on the doses of chromium (VI) required to produce thissensitization are not available.

Chromium was analyzed for but not detected in off-site deep groundwater.

LEAD

When the dump was open, trespassers on the site may have been exposed to lead via incidentalingestion of contaminated water when swimming. Although ATSDR and EPA have no leadexposure guidelines (MRLs or RfDs) for comparison (13), we estimate that the maximumconcentrations in the on-site water are unlikely to have caused adverse health effects.

Although the maximum concentration of lead in the water on site (120 ug/L) is eight times greaterthan the Florida drinking water standard (15 ug/L), we estimate the annual volume of water thatcould have been ingested while swimming would have been about 100 times less than the annualvolume of water ingested from drinking water sources. Therefore, we estimate that the dose oflead from incidental ingestion during swimming would have been about 12 times less than thedose from drinking water at the Florida standard.

Lead was analyzed for but not detected in off-site deep groundwater.

VANADIUM

When the dump was open, trespassers on the site may have been exposed to vanadium viaincidental ingestion of contaminated water when swimming. These exposures, however, areunlikely to have caused adverse health effects.

The estimated daily dose of vanadium from incidental ingestion of contaminated water (duringswimming) is less than the draft ATSDR intermediate Minimal Risk Level (MRL) (14). A chronicMRL is unavailable. Vanadium has not been identified as causing cancer. Therefore, incidentalingestion of vanadium-containing water when swimming would be unlikely to cause adversehealth effects. Since vanadium does not pass readily through the skin, adverse health effects fromskin exposure are also unlikely.

Vanadium was analyzed for but not detected in off-site deep groundwater.

CHLOROFORM

Residents of the 74 homes north of the site who obtained their drinking water from private wellshave been exposed to chloroform by ingestion in drinking water. Exposure has also probablyoccurred through skin absorption and inhalation of evaporated chloroform during showering orbathing. The maximum concentration detected, however, is unlikely to cause adverse healtheffects.

The estimated daily dose of chloroform from ingestion is less than the estimated chronic MinimalRisk Level (MRL) (9). Although exposure has probably also occurred through inhalation andskin absorption, there is no information available to enable us to estimate the possible adversehealth effects from exposure via these routes. Chloroform is a probable human carcinogen basedon animal exposure studies. At the maximum concentration detected, however, there would beno apparent increase in the risk of developing cancer.

EPA did not detect chloroform in on-site shallow groundwater and did not analyze for chloroformin on-site or off-site subsurface soil.

1,1-DICHLOROETHENE

Residents who obtained their drinking water from private wells have been exposed to 1,1-dichloroethene by ingestion. Exposure has also probably occurred through skin absorption andinhalation of evaporated 1,1-dichloroethene during showering or bathing. The maximumconcentration detected, however, is unlikely to cause adverse health effects.

The estimated daily dose of 1,1-dichloroethene from ingestion is less than the estimated chronicMinimal Risk Level (MRL) (15). Exposure has probably also occurred through inhalation andskin absorption. However, there is no information available to enable us to estimate the possibleadverse health effects from exposure via these routes. Although animal studies indicate that 1,1-dichloroethene can adversely affect the liver, kidneys, lungs, heart and blood, there is insufficientinformation from human exposure studies to estimate what the health effects may be in humans. 1,1-Dichloroethene is a possible human carcinogen based on limited animal exposure studies. Lifetime exposure to 1,1-dichloroethene at the maximum concentration detected would result in alow increase in the risk of developing cancer. Because the maximum duration of exposure to 1,1-dichloroethene for residents using private well water is four years, however, the actual risk isconsidered to be negligible.

EPA did not detect 1,1-dichloroethene in on-site subsurface soil or shallow groundwater and didnot analyze for 1,1-dichloroethene in off-site subsurface soil.

1,2-DICHLOROETHENE

Residents who obtained their drinking water from private wells have been exposed to 1,2-dichloroethene by ingestion. Exposure has also probably occurred through skin absorption andinhalation of evaporated 1,2-dichloroethene during showering or bathing. The maximumconcentration detected, however, is unlikely to cause adverse health effects.

The estimated daily dose of 1,2-dichloroethene from ingestion is less than the estimatedintermediate Minimal Risk Level (MRL) (10). A chronic MRL is not available. Exposure hasprobably also occurred through inhalation and skin absorption. However, there is no informationavailable to enable us to estimate the possible adverse health effects from exposure via theseroutes. Although animal studies indicate that 1,2-dichloroethene can adversely affect the liver,lungs and heart, these effects have not been observed in studies involving humans.

EPA did not detect 1,2-dichloroethene in on-site subsurface soil or shallow groundwater and didnot analyze for 1,2-dichloroethene in off-site subsurface soil.

TRICHLOROETHENE

Residents who obtained their drinking water from private wells have been exposed totrichloroethene by ingestion. Exposure has also probably occurred through skin absorption andinhalation of evaporated trichloroethene during showering or bathing. The maximumconcentration detected, however, is unlikely to cause adverse health effects.

The estimated daily dose of trichloroethene from ingestion is less than the estimated intermediateMinimal Risk Level (MRL) (16). A chronic MRL is not available. Exposure has probably alsooccurred through inhalation and skin absorption. However, there is no information available toenable us to estimate the possible adverse health effects from exposure via these routes. Trichloroethene is a suspected human carcinogen. However, its potential as a human carcinogenis currently under review by EPA. Based on estimates from animal studies and because themaximum duration of exposure to trichloroethene for residents using private well water is fouryears, the risk of developing cancer at the maximum concentration detected is negligible.

EPA did not detect trichloroethene in on-site subsurface soil or shallow groundwater and did notanalyze for trichloroethene in off-site subsurface soil.

VINYL CHLORIDE

Residents who obtained their drinking water from private wells have been exposed to vinylchloride by ingestion. Exposure has also probably occurred through inhalation of evaporatedvinyl chloride during showering or bathing. The maximum concentration detected, however, isunlikely to cause adverse health effects.

The estimated daily dose of vinyl chloride from ingestion is less than the estimated chronicMinimal Risk Level (MRL) (17). Exposure has probably also occurred through inhalation. However, there is no information available to enable us to estimate the possible adverse healtheffects from exposure via this route. Although animal studies have indicated that vinyl chloridecan adversely affect the liver, there is no information available from which we can estimate thepossible adverse human health effects from exposure to vinyl chloride at the concentrations foundat this site. Vinyl chloride is a definite human carcinogen based on both animal and humanexposure studies. A lifetime of exposure at the maximum concentration detected would result in alow increase in the risk of developing cancer. However, because the maximum duration ofexposure to vinyl chloride for residents using private well water is four years, the actual risk isconsidered to be negligible.

EPA did not detect vinyl chloride in on-site shallow groundwater and did not analyze for vinylchloride in on-site or off-site subsurface soil.

DIELDRIN

When the dump was open, trespassers on the site may have been exposed to dieldrin via incidentalingestion of contaminated soil. These exposures, however, are unlikely to have caused adversehealth effects.

The estimated daily dose of dieldrin from incidental ingestion of contaminated soil exceeds thedraft ATSDR chronic Minimal Risk Level (MRL) (18). However, the dump was open for a maximum of 20 years and trespassers, such as children, would have been unlikely to visit thedump on a daily basis, Therefore, we estimate that the actual health risks from exposure todieldrin on the site are negligible. Dieldrin is classified as a probable human carcinogen based onanimal studies. Although there is no evidence of dieldrin causing cancer in humans, estimatesfrom these animal studies indicate that there may be a moderately increased risk of developingcancer for an individual exposed for a lifetime to the maximum dieldrin concentration found in theon-site subsurface soil. Again, since lifetime exposure on a daily basis is not possible at this site,we consider the actual risk of developing cancer to be negligible. Adverse health effects fromexposure to dieldrin in these soils via skin absorption is unlikely since skin absorption isinsignificant compared to ingestion.

EPA did not analyze for dieldrin in on-site or off-site groundwater.

B. Health Outcome Data Evaluation

Guided by community health concerns in the population living near the site, Florida HRSepidemiologists conducted an evaluation of cancer and birth defect incidence in this area. Theyfound that the rates of cancer and birth defects in the 33317 zip code, which includes the 21stManor Dump site, are not unusual (19).

The Broward CPHU discontinued sampling of the private wells along SW 44th Terrace afterthese residences were connected to municipal supply water, and has not conducted anyindependent health studies or investigations. Although there is no systematic, ongoing healthmonitoring program being conducted, Broward County School Board safety officials have notnoticed any pattern of illnesses among children at the Meadowbrook Elementary School thatcould be linked to exposure at this site. School medical personnel may be able to discern achange in the level or type of illnesses exhibited by the children. However, they may not associatethis change with possible exposure to site contaminants.

C. Community Health Concerns Evaluation

We have addressed the community health concern as follows:

  1. Residents of the neighborhood around the site who have obtained their drinking waterfrom private wells are concerned about possible unspecified health effects to themselvesand their children from drinking contaminated water.

Although the off-site private well contamination does not appear to be site-related, seven privatewells located just north of the site were condemned by the Broward CPHU when their monitoringprogram detected 1,1-dichloroethene and vinyl chloride at levels exceeding Florida's primarydrinking water standards. Two other private wells in the area also showed traces of these samecontaminants.

Monitoring of these wells has been conducted on a regular basis since 1987 and elevatedcontaminant levels occurred beginning in late 1988. As elevated contaminant levels appeared, theBroward CPHU provided alternate drinking water sources to the affected community members. All residences having condemned wells and the majority of the remaining households have beenconnected to a municipal water supply.

Based on established comparison values for the contaminants detected in the private well water,the health risk from drinking this water is considered to be low. Further, because the BrowardCPHU removed the contaminated wells from use before any significant exposure could occur, weconsider the actual health risk to residents on private wells to be negligible.

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