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PUBLIC HEALTH ASSESSMENT

POMONA OAKS WELL CONTAMINATION
GALLOWAY TOWNSHIP, ATLANTIC COUNTY, NEW JERSEY


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

To identify possible facilities that could contribute to contamination of environmental media near the Pomona Oaks Well Contamination site, the ATSDR and the NJDOH searched the 1987, 1988, and 1989 Toxic Chemical Release Inventory (TRI). TRI is developed by the USEPA from chemical release (air, water, and soil) information provided by certain industries. Upon review and evaluation, TRI was not found to contain information on toxic chemical release in Galloway Township which was pertinent to the contaminants and pathways of concern at the Pomona Oaks Well Contamination site.

The tables in this section list the contaminants of concern for the Pomona Oaks Wells site. These contaminants are evaluated in subsequent sections of the Public Health Assessment to determine whether exposure to them has public health significance. ATSDR selects and discusses these contaminants based upon 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 background concentrations, if available.


  4. Comparison of on-site and off-site concentrations with health assessment comparison values for carcinogenic and noncarcinogenic endpoints.


  5. Community Health concerns.

In the data tables that follow under the On-site Contamination subsection and the Off-site Contamination subsection, the listed contaminant does not mean that it will cause adverse health effects from exposures. Instead, the list indicates which contaminants will be evaluated further in the Public Health Assessment. When selected as a contaminant of concern in one medium, that contaminant will be reported in all media.

The data table may include one or more of the following acronyms:

* CREG = ATSDR Cancer Risk Evaluation Guide
* EMEG = ATSDR Environmental Media Evaluation Guide
* MCLG = EPA Maximum Contaminant Level Goal
* MCL = EPA Maximum Contaminant Level
* PMCLG = EPA Proposed Maximum Contaminant Level Goal
* ppm = Parts per million
* ppb = Parts per billion
* RfD = EPA Reference Dose
* RfC = EPA Reference Concentration

Comparison values for public health assessments are contaminant concentrations in specific media that are used to select contaminants for further evaluation. These values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. CREGs are estimated contaminant concentrations based on a one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from USEPA's cancer slope factors. USEPA's Maximum Contaminant Level Goal (MCLG) ia a drinking water health goal. USEPA believes that the MCLG represents a level that no known or anticipated adverse effect on the health of persons should occur which allows an adequate margin of safety. Proposed Maximum Contaminant Level Goals (PMCLGs) are MCLGs which are being proposed. Maximum Contaminant Levels (MCLs) represent contaminant concentrations that USEPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime of 70 years at an exposure rate of 2 liters of water per day. While MCLs are regulatory concentrations, PMCLGs and MCLGs are not. USEPA's reference dose (RfD) and Reference Concentration (RfC) are estimates of the daily exposure to a contaminant that is unlikely to cause health effects.

A. On-Site Contamination

The field work for the Pomona Oaks Remedial Investigation was performed from October 1988 to March 1989. Activities included a soil gas survey, deep subsurface soil sampling, sediment sampling, and groundwater sampling (domestic and monitoring wells). Air and shallow soil sampling was not conducted as part of the remedial investigation.

Groundwater; Residential wells

From 1982 to 1985, the domestic wells of the Pomona Oaks subdivision were sampled by the Atlantic County Health Department, the U.S. Environmental Protection Agency, the New Jersey Department of Health, and the New Jersey Department of Environmental Protection and Energy. Concentrations of VOC's exceeding N.J. drinking water criteria were detected in 50 wells. Contaminants of concern exceeding ATSDR comparison values which were detected in domestic wells are presented in Table 1.

Table 1 - Contaminants of concern detected in Pomona Oaks subdivision private wells; 1982 - 1985.

Compound Maximum Concentration
Detected (ppb)
Comparison Value
ppb Source
Benzene 2,060.0 1.2 CREG
Chloroform 31.0 5.7 CREG
1,2-Dichloroethane 880.0 0.38 CREG
1,1-Dichloroethane 60.0 NA NA
1,1-Dichloroethylene 4.4 0.058 CREG
1,1,2-Trichloroethane 46.0 0.61 CREG
NA = Not Available
Data from Pomona Oaks Subdivision Record of Decision: Sept 1990.

Residential wells were sampled as part of the Remedial Investigation in November and December 1988. Additionally USEPA's Emergency Response Team (ERT) conducted residential well sampling in August 1989. No contaminants were detected above ATSDR comparison values during these sampling events. The results of the Remedial Investigation have shown that the groundwater contamination previously identified at the Pomona Oaks site no longer exists at levels of public health concern. The report concluded that the source of the previously identified contamination was a singular event, with the resultant contamination dissipated via volatilization and natural attenuation.

Groundwater; Monitoring Wells

Groundwater samples from 19 monitoring wells were collected in February 1989 as part of the Remedial Investigation. Contaminants detected above ATSDR comparison values are presented in Table 2.

Table 2 - Contaminants of concern detected in Pomona Oaks Subdivision monitoring wells; February 1989.

Compound Frequency
of
Detection
Conc.
(ppb)
Monitoring
Well
Comparison Value
ppb Source
Benzene 1 of 20 8.0 MW-1S* 1.2 CREG
1,2-Dichloroethane 1 of 20 2.0 MW-6I** 0.38 CREG
Chloroform 2 of 20 2 - 6 MW-6S** 5.7 CREG
* = Well downgradient of Pomona Garage.
** = Well down gradient of Pomona Oaks Subdivision.
Data from Final Remedial Investigation report; May 1990.

Monitoring well MW-1S is adjacent to a gasoline station and its level of benzene is reported as an anomaly resulting from a spill. Likewise, while monitoring wells MW-6I and MW-6S each show a VOC above the ATSDR comparison value, these results are considered anomalous and not indicative of the presence of a contamination plume.

Soil Gas Survey

A soil gas survey was conducted as part of the Remedial Investigation to attempt to identify areas of shallow soil and groundwater contamination, as well as identify potential sources of contaminants. The soil gas survey included 142 locations. Generally soil gas concentrations of VOC's were highest in the vicinity of the Pomona Plaza area where commercial gasoline stations are located. Contaminants detected (i.e. benzene, toluene, ethylbenzene) are consistent with compounds associated with petroleum products. A soil gas contour map for total VOC concentration is presented in Figure 4.

Deep Soil Sampling

As part of the remedial investigation, deep soil samples were collected during installation of on-site monitoring wells. No contaminants of concern found in groundwater samples were detected.

Sediment Sampling

As part of the remedial investigation, three sediment samples were collected from a dry drainage basin within the Pomona Oaks subdivision. No contaminants of concern found in groundwater samples were detected.

Exposure Assessment

An exposure assessment of residents of the Pomona Oaks subdivision was conducted by the NJDOH in January 1983. This exposure assessment quantified exposure to benzene volatilizing from contaminated groundwater by sampling bathroom breathing zone air in the showers of residents. All samples exceeded the ATSDR air EMEG for acute exposure of 2 ppb for benzene. Additionally, all samples exceeded the ATSDR inhalation cancer risk concentration of 0.1 ug/m3 for benzene.

Table 3 - Benzene Levels in Residential Shower Air and Well Water; Pomona Oaks Well Contamination Site.



Household



Season/Year

Breathing Zone
Shower Air



Well Water
Concentration
(ppb)

Concentration*
ppb
mg/m3

A

Winter 1984
Spring 1984

73.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.237
45.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.146

33.0
31.0

B

Summer 1983
Winter 1984
Spring 1984

1,170.0 &nbsp &nbsp &nbsp &nbsp 3.814
201.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.655
184.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.599

210.0
90.0
56.0

C

Fall 1983
Winter 1984
Spring 1984

347.0 &nbsp &nbsp &nbsp &nbsp &nbsp 1.131
237.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.772
1,500.0 &nbsp &nbsp &nbsp &nbsp &nbsp 4.89

76.0
80.0
700.0

D

Winter 1984
Spring 1984

620.0 &nbsp &nbsp &nbsp &nbsp &nbsp 2.02
33.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.107

113.0
48.0

E

Fall 1983
Winter 1984
Spring 1984

620.0 &nbsp &nbsp &nbsp &nbsp &nbsp 2.02
55.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.179
502.0 &nbsp &nbsp &nbsp &nbsp &nbsp 1.636

370.0
49.0
550.0

F

Fall 1983

91.0 &nbsp &nbsp &nbsp &nbsp &nbsp 0.296

27.0

Data from: "Pomona Oaks Exposure Assessment"; NJDOH, October 1984.
* 1 ppm = 3.26mg/m3 at 20 degrees C.

B. Off-Site Contamination

Off-site sampling at the Pomona Oaks Wells site has been limited to groundwater investigation in an attempt to determine whether a plume of contamination exists, determine its extent, and ascertain whether down-gradient groundwater quality has been impacted by the site.

As part of the RI, USEPA sampled residential wells (winter 1988, summer 1989) in the nearby Pinehurst area located to the south-east of the Pomona Oaks subdivision. Data from these sampling events indicate that groundwater quality in the Pinehurst area is not being impacted by the Pomona Oaks site. Off-site contamination associated with the Pomona Oaks site has not been identified in groundwater or any other environmental media.

C. Quality Assurance And Quality Control

In preparing this public health assessment, the ATSDR and the NJDOH rely on the information provided in the referenced documents and assumes that adequate quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of analysis and conclusions drawn for this public health assessment is determined by the availability and reliability of the referenced information.

Data utilized in formulation of this public health assessment were subject to level 4 data quality objectives which require the greatest amount of analytical documentation and quality control/quality assurance methods. All sample results generated by a Contract Laboratory Program (CLP) laboratory underwent data validation by EBASCO according to USEPA Region II criteria.

D. Physical And Other Hazards

The Pomona Oaks Well Contamination site presents no apparent physical hazards. Since the contamination at the Pomona Oaks Well Contamination site is associated with subsurface groundwater, there is no discernable evidence of site-related contaminants. As a viable residential neighborhood, there are no physical site boundaries or restrictions.

PATHWAYS ANALYSIS

To determine whether nearby residents are exposed to contaminants associated with the site, ATSDR evaluates the environmental and human components that lead to human exposure. This pathways analysis consists 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.

ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. In completed pathways, all five elements exist and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential pathways, however, have at least one of the five elements missing, but could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present.

A. Completed Exposure Pathways

Completed exposure pathways at the Pomona Oaks site are limited to those pathways associated with the domestic use of contaminated groundwater for a period of approximately 3 years (1982-1985) prior to the availability of a public water supply.

Residents of Pomona Oaks first filed complaints with the ACHD regarding foul tasting well water in June 1982. In January 1983, the ACHD advised sixteen households to discontinue use of groundwater for drinking and cooking, and began to provide bottled water to affected households. The wells in the households selected to receive bottled water exhibited total VOC's concentrations > 100 ug/l (or > 50 ug/l for a single contaminant). In addition to the 16 homes provided with bottled water, 34 homes exhibited well contamination above N.J. drinking water standards (MCL's) but less than the 100 ug/l total VOC's cutoff level. It is possible that residents ingested contaminated water prior to June 1982, since it is not known when the presumed contamination event occurred. It is likely that residents of approximately 50 identified households ingested contaminated groundwater prior to the time when the ACHD provided bottled water (a duration of approximately six months), although individual consumption practices and durations may have varied.

After the advisory by the ACHD to limit ingestion of well water, it is likely that residents with contaminated wells continued to utilize groundwater for non-potable domestic purposes (e.g.: showering/bathing, irrigation, laundry) for approximately three years until the public water supply was available. Sampling data from the 1983 NJDOH exposure assessment has demonstrated significant exposure to VOC's during showering activities probably occurred in households with contaminated wells. Similarly, it would be expected that other domestic activities such as laundering clothes and running dishwashers would also liberate VOC's into the residences of Pomona Oaks, although air data are limited to the breathing zone of residential showers. Table 4 summarizes the completed exposure pathways at the Pomona Oaks Wells site.

Table 4 - Completed Exposure Pathways

Name Source Media Point of
Exposure
Route of Exposure Exposed Population Time
Potable
Water
PORW* GroundWater Residence Ingestion Residents Past
Showers PORW* GroundWater Residence Inhalation Residents Past
* Pomona Oaks Residential Wells

By August 1985, connection of 193 homes within the subdivision to the Absecon water supply was completed. Current information indicates there are no residences presently utilizing domestic wells for any purpose.

B. Potential Exposure Pathways

Based upon current conditions, there are no potential exposure pathways associated with the Pomona Oaks site. Current site data indicate groundwater in the area of the site does not exhibit contamination above ATSDR comparison values or New Jersey drinking water standards. The availability of a public water supply for the Pomona Oaks sub-development has eliminated dependence upon domestic wells for potable water.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

The toxicological evaluation of completed exposure pathways at the Pomona Oaks site is based upon the assumption of an exposure duration of one year for the ingestion pathway, and three years for the inhalation pathway associated with showering. A period of approximately six months elapsed between the time the contaminated water was reported to the ACHD and the initiation of supplying bottled water to affected (sampled) residences. It is impossible to accurately determine when groundwater first exhibited contamination above health based criteria, or exactly when all individuals began to utilize an alternate potable water supply. The use of a one year duration for the ingestion route is intended to compensate for these uncertainties. Additionally, although residents were advised by the NJDOH to shower in alternate water supplies if possible, it is realistic to assume that residents utilized contaminated wells for domestic purposes (particularly showering) for the period between the first report of contamination and the availability of a public water supply.

The toxicological effects of the contaminants detected in potable wells at the Pomona Oaks subdivision have been considered singly. The cumulative or synergistic effects of mixtures of contaminants may serve to enhance their public health significance. Additionally, individual or mixtures of contaminants may have the ability to produce greater adverse health effects in children as compared to adults. This situation depends upon the specific chemical being ingested or inhaled, its pharmacokinetics in children and adults, and its toxicity in children and adults.

Benzene

Site data indicate that exposure to benzene occurred in residences of the Pomona oaks subdivision through the ingestion and inhalation pathways. For a period of approximately one year, as many as fifty households were exposed daily to low doses of benzene by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink 2 liters of well water per day and individuals took, on the average, two fifteen minute showers per day.

Based upon maximum levels of benzene detected in potable wells at the site, exposure dosages approached and perhaps exceeded the "no observed adverse effect level" (NOAEL) for ingestion exposure of intermediate duration cited in the ATSDR Toxicological Profile for benzene. At such concentrations, there are animal data (human data are limited) which indicate hematological, immunological, and neurological effects are possible. Based upon the levels of benzene detected in shower stall air samples at the site, concentrations approached and perhaps exceeded the lowest observed adverse effect level (LOAEL) cited for acute inhalation exposure cited in the ATSDR toxicological profile for benzene. At such concentrations, there are animal data (human data are limited) which indicate hematological, immunological, neurological, developmental, and reproductive effects are possible.

Benzene is classified by the USEPA as a Class A (known human) carcinogen. The lifetime excess cancer risk (LECR) associated with the oral exposure route for benzene at the site would present no apparent increased risk of cancer. Levels of benzene detected in on site showers exceeded the ATSDR inhalation cancer risk concentration. Projected LECRs for the inhalation pathway associated with showering show a cancer risk ranging from no apparent increased risk to insignificant or no increased risk.

The cancer risk associated with benzene exposure at the site may be interpreted by the following scenario. If 100,000 persons were exposed through ingestion for one year to the maximum concentration of benzene detected in potable wells, or exposed through inhalation for three years to the maximum concentration of benzene detected in showers at the site, at most an additional 4 cases of cancer may occur in 70 years. For the approximately 200 persons in the Pomona Oaks subdivision exposed to benzene in their contaminated well-water, it is therefore unlikely that they will develop cancer as a result of their exposure. Nevertheless, because of this theoretical increase in the rate of cancer, ATSDR considers this exposure unacceptable.

Chloroform

Site data indicate that exposure to chloroform occurred in some residences of the Pomona Oaks subdivision through the ingestion pathway. There are no data describing chloroform concentrations in residential showers. For a period of approximately one year, as many as fifty households were exposed daily to low doses of chloroform by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink two liters of water per day.

Based upon maximum levels of chloroform detected in potable wells at the site, exposure doses were below the "no observed adverse effect level" (NOAEL) for ingestion exposures of intermediate duration cited in the ATSDR Toxicological Profile for chloroform. At such concentrations adverse health effects are not likely to occur.

Chloroform is classified by the USEPA as a Class B2 (suspected human) carcinogen. However, the lifetime excess cancer risk (LECR) associated with the oral exposure route for chloroform at the site would present an insignificant or no increased risk of cancer.

1,2-Dichloroethane

Site data indicate that exposure to 1,2-dichloroethane occurred in some residences of the Pomona Oaks subdivision through the ingestion pathway. There are no data describing 1,2-dichloroethane concentrations in residential showers. For a period of approximately one year, as many as fifty households were exposed daily to low doses of 1,2-dichloroethane by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink two liters of water a day.

Based upon maximum levels of 1,2-dichloroethane detected in potable wells at the site, exposure dosages were below the "no observed adverse effect level" for ingestion exposure of intermediate duration cited in the ATSDR Toxicological Profile for 1,2-dichloroethane. At such concentrations, adverse health effects are not likely to occur.

1,2-dichloroethane is classified by the USEPA as a Class B2 (suspected human) carcinogen. The lifetime excess cancer risk (LECR) associated with the oral exposure route for 1,2-dichloroethane at the site would present no apparent increased risk of cancer.

The cancer risk associated with 1,2-dichloroethane at the site may be interpreted by the following scenario. If 100,000 persons were exposed through ingestion for one year to the maximum levels of 1,2-dichloroethane detected in potable wells at the site, at most an additional four cases of cancer may occur in 70 years. For the approximately 200 persons of the Pomona Oaks subdivision exposed to 1,2-dichloroethane in their well-water, it is therefore unlikely that they will develop cancer from their exposure. Nevertheless, because of this theoretical increase in cancer, ATSDR considers this exposure unacceptable.

1,1-Dichloroethane

Site data indicate that exposure to 1,1-dichloroethane occurred in some residences of the Pomona Oaks subdivision through the ingestion pathway. There are no data describing 1,1-dichloroethane concentrations in residential showers. For a period of approximately one year, as many as fifty households were exposed daily to low doses of 1,1-dichloroethane by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink two liters of water per day.

Based upon maximum levels of 1,2-dichloroethane detected in potable wells at the site, exposure dosages were below the "no observed adverse effect level' (NOAEL) for ingestion exposure of intermediate duration cited in the ATSDR Toxicological Profile for 1,1-dichloroethane. At such levels, adverse health effects are not likely to occur.

1,1-dichloroethane is classified by the USEPA as a Class C (inconclusive human evidence) carcinogen. There is presently no ATSDR CREG for 1,1-dichloroethane against which site data for the compound may be compared. The LECR associated with the oral exposure route for 1,1-dichloroethane was not estimated.

1,1-Dichloroethylene

Site data indicate that exposure to 1,1-dichloroethylene occurred in some of the residences of the Pomona Oaks subdivision through the ingestion pathway. There are no data describing 1,1-dichloroethylene concentrations in residential showers. For a period of approximately one year, as many as fifty households were exposed daily to low doses of 1,1-dichloroethylene by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink two liters of water per day.

Based upon maximum levels of 1,1-dichloroethylene detected in potable wells at the site, exposure dosages were below the "no observed adverse effect level" (NOAEL) for ingestion exposure of intermediate duration cited in the ATSDR Toxicological Profile for 1,1-dichloroethylene. At such concentrations, adverse health effects are not likely to occur.

1,1-dichloroethylene is classified as a Class C (inconclusive human evidence) carcinogen. The lifetime excess cancer risk (LECR) associated with the oral exposure route for 1,1-dichloroethylene at the site would present insignificant or no increased risk of cancer.

1,1,2-Trichloroethane

Site data indicate that exposure to 1,1,2-trichloroethylene occurred in some of the residences of the Pomona Oaks subdivision through the ingestion pathway. There were no data describing 1,1,2-trichloroethane concentrations in residential showers. For a period of approximately one year, as many as fifty households were exposed daily to low levels of 1,1,2-trichloroethane by using contaminated groundwater for drinking and other domestic purposes. Exposure dose assessment assumes that adults drink two liters of water per day.

Based upon maximum levels of 1,1,2-trichloroethane detected in potable wells, exposure doses were below the "no observed adverse effect level" for ingestion exposure of intermediate duration cited in the ATSDR Toxicological Profile for 1,1,2-trichloroethane. At such concentrations, adverse health effects are not likely to occur.

1,1,2-trichloroethane is classified by the USEPA as a Class C (inconclusive human evidence) carcinogen. The lifetime excess cancer risk (LECR) associated with the oral exposure route for 1,1,2-trichloroethane at the site would present insignificant or no increased risk of cancer.

B. Health Outcome Data Evaluation

Because of the completed exposure pathways which existed at the site, and the community concern regarding the possibility of adverse health outcomes among households which experienced well contamination, review of appropriate health outcome data for this site was initiated.

The New Jersey Cancer Registry (NJCR) was used for the ascertainment of cancer cases. The Cancer Registry, operated by the New Jersey Department of Health, is a population based cancer incidence registry including the entire State of New Jersey. By law, all individuals with newly diagnosed cancers are reportable to the registry. In addition, the registry has reporting agreements with neighboring states, (New York, Pennsylvania, and Delaware) where information on New Jersey residents which is diagnosed in those states will be supplied to the NJCR. The NJCR has been operational since October 1, 1978.

The study period for this investigation was January 1, 1979 through December 31, 1988. A "case" was defined as an individual who resided in Galloway Township, New Jersey, and was diagnosed with a new primary malignant cancer during the study period. The information for each newly diagnosed case available from the NJCR is limited. The basic source is documented information from the patient's medical record. The collected information includes demographic data regarding each patient and medical data on each cancer. Variables used to analyze the incidence of cancer in the study area include: name, address at time of diagnosis, state municipality code, census tract code, primary cancer site, histology type, date of diagnosis, age at diagnosis, date of birth, race, sex, and NJDOH registry identification number.

Information on other risk factors such as occupational exposures or personal lifestyle habits are not available in the abstracted medical information used in this evaluation. The potential risk factors that cannot be accounted for in the study design may vary significantly within the study area, or relative to the State as a whole.

Cancer analysis was completed for select cancer types within the study area. These types included bladder, brain and CNS, colon, pancreatic, lung, leukemia, lymphoma, rectal, stomach, kidney, female breast, and prostate. These cancer types were selected for review since State age-specific rates were available and published by the NJCR. Males and females were evaluated separately. All races were combined in the analysis.

Analysis of the cancer incidence was completed using standardized incidence ratios (SIRs). The SIR is calculated by dividing the observed number of cancer cases by the number of cases expected. The expected number of cases are determined on the presumption that the incidence rates for the entire state of New jersey would prevail in the population surveyed. The study area age/sex specific population data was determined from the 1980 U.S. Census.

Evaluation of the observed and expected numbers is accomplished by interpreting the ratio of these numbers. If the observed number of cases equals the expected number of cases, the SIR will equal one (1.0). When the SIR is less than one it is concluded that fewer cases were observed than expected. Should the SIR be greater than one, it is concluded that more cases than expected were observed. Statistical significance in this investigation was evaluated using a 95% confidence interval (CI).

Table 5 presents the findings of the health outcome data (SIR) analysis. The observed number of total cancer cases in Galloway Twp. was not found to be elevated in comparison to the number of cases expected for this population based upon average incidence rates for the State. Limitations of SIR analysis for cancer incidence may include masking of the small potentially affected population by the greater overall population of Buena. However, the data indicate an overall status of incidence rates for the municipality. The lower than expected rates indicate that it is probable that incidence rates are at or below normal for the potentially affected population.

Table 5 - Geographic Cancer Analysis; Galloway Township, New Jersey, Using 1982 New Jersey State Rates. Period: 1979-1988.

All Females All Males
Age Range
Years
Population
N=6027
Incidence Rate
Per 100,000
Age Range
Years
Population
N=6149
Incidence Rate
Per 100,000
0-4
5-9
10-14
15-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70-74
75-79
80-84
85+
444
409
441
732
637
500
483
377
301
277
267
297
267
227
132
121
76
39
24.53
11.14
8.00
18.03
60.77
130.47
169.01
233.7
324.15
442.45
577.97
779.41
1048.05
1335.29
1619.13
1769.95
2012.69
1973.85
0-4
5-9
10-14
15-19
20-2
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70-74
75-79
80-84
85+
450
467
460
804
720
480
504
410
290
274
315
267
215
207
121
84
40
41
17.51
8.77
10.90
16.83
29.52
47.58
54.93
105.80
144.86
253.11
487.32
821.37
1398.47
2009.73
2917.90
3570.18
4053.44
4110.16
Cases
Expected
Cases
Observed
SIR 95 % CI Cases
Expected
Cases Observed SIR 95 % CI
Lower Upper Lower Upper
215.26 109.00 0.51 0.47 0.61 233.01 87.00 0.37 0.30 0.46

C. Community Health Concerns Evaluation

The residents of the Pomona Oaks subdivision have expressed concern over the length of time that the community may have been exposed to contaminated groundwater prior to the initial complaint filed with the ACHD in 1982. Since the subdivision contains approximately 200 homes which all employed wells for potable water supply, and the contamination is thought to be the result of a singular spill or release event, it is likely that the groundwater contamination would have been noticed by residents fairly soon after entering the subdivision wellfield. However, its detection would depend upon the contaminants reaching a concentration which could be detected by an individuals odor and/or taste threshold. In addition, groundwater in the area is moving at a relatively fast rate. Although it is impossible to accurately determine when contamination first occurred, conditions at the site support the assumptions that long term low level contamination (prior to the initial report filed with ACHD) was possible although not probable, and that high level, long term contamination was not probable.

The communities concern regarding the potential for long term (carcinogenic) health effects were addressed by the review of the NJCR data. Cancer incidence was not found to be elevated and was found to be less than State averages. However, the susceptibility for a carcinogenic response may vary widely among individuals, and individual cases may not be apparent through statistical analysis of incidence data. Individual residents expressing concern regarding cancer will be extended the opportunity to discuss their concerns with NJDOH and the ATSDR on an individual basis (refer to the Public Health Actions section of the Health Assessment).

The communities concern regarding possible adverse pregnancy outcomes has been addressed in the Toxicological Evaluation Sub-section. Only for the household which experienced the maximum concentration of volatilized benzene would exposure doses approach those concentrations where adverse pregnancy outcomes might be possible.

At the time this public health assessment was completed, ATSDR and NJDOH do not have a program of routine medical monitoring. However, for those residents who may be concerned regarding benzene exposure in the past, it is recommended that they receive periodic blood counts. This is an effective method for early detection of Leukemia which is a possible outcome of exposure to benzene. If personal physicians have questions regarding the health effects of benzene exposure, Medical representatives of ATSDR will provide additional information.

Public Comment Period

The New Jersey Department of Health conducted a public comment period for the Public Health Assessment of the Pomona Oaks Well Contamination site from March 28, through April 29, 1994. The Public Health Assessment was placed in local repositories to facilitate written commentary and reaction from the public at large. In addition, the document was circulated to the Atlantic County Health Department for the purpose of soliciting commentary by local Health Officials.

A summary of the commentary received by the NJDOH and associated responses is presented in Appendix 1.

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