Water Health Assessment<BR>(Dover Township) Toms River, New Jersey

Case-Control Study of Childhood Cancers in Dover Township, December 2001
(Dover Township) Toms River, New Jersey

Volume 1: Summary of the Final Technical Report

Continued.........

Results for Public Water Well Fields:

Exposure to neither unadjusted Holly Street well field water, nor time-specific Holly Street well field water appeared to be associated with any childhood cancer groupings in either the Birth Records or Interview Studies. However, it should be noted that the exposure pathway was interrupted early in the study period, so only a limited number of study subjects were potentially exposed.

Exposure to unadjusted or time-specific Parkway well field water did not appear to be associated with any of the childhood cancer groupings when males and females were analyzed together. However, when exposure to time-specific Parkway well field water was analyzed separately by sex, a noticeable pattern of elevated odds ratios was found in the Interview Study. For the prenatal time specific Parkway well field water high exposure category, a five-fold increased risk was found for females diagnosed with leukemia (OR=5.0; 95% CI-0.8, 31). Also for females diagnosed with leukemia, the prenatal time-specific Parkway well field water source/consumption high exposure category was significantly elevated (OR=6.0; 95% Cl=l.1, 32). While the addition of tap water consumption to the unadjusted Parkway well field water source variable only modestly increased the odds ratio (see Figure 1), the time adjustment noticeably increased both the unadjusted water source and the unadjusted water source/consumption variables.

Because of the uncertainty when contaminated groundwater reached the Parkway well field, odds ratios were recalculated using alternate temporal adjustments regarding the year the well field became contaminated. The original time specific Parkway well field variable assumed an exposure period of 1982 through 1996. Eight annual incremental adjustments were made to calculate alternate prenatal time-specific Parkway well field variables assuming a contaminant transit time of as little as six years to as long as 14 years. The eight new contaminant time windows include 1978-1996, 1979-1996, 1980-1996, 1981-1996, 1983-1996, 1984-1996, 1985-1996, and 1986-1996. During the prenatal period, the odds ratios remained elevated for all of the high exposure categories of the alternate time-specific Parkway well field water variable for females diagnosed with leukemia, with the 1984-1996 exposure period displaying the highest odds ratio (OR= 15; 95% CI=0.8, 274). Of note, female leukemia cases in the high prenatal Parkway well field exposure category were all born after 1983.

Although no associations were detected in analyses of the overall study population, a statistically significant association and consistency in multiple measures of association were seen between prenatal exposure to time-specific Parkway well field water (1982-1996) and leukemia in female children. These findings are consistent with one of the study's a priori hypothesis that exposure to Parkway well field water during this interval was a risk factor for childhood leukemia.

The high exposure category for time-specific Parkway well field during tile postnatal period did not display a similar pattern for female children with leukemia. None of the unadjusted or time-specific Parkway well field indices for leukemia in males or the unadjusted or time-specific Parkway well field indices for brain and central nervous system cancers displayed any pattern or consistency. The results from the Birth Records Study analysis did not display any pattern or consistency of association with any childhood cancer groups evaluated.

Although there were no known exposure pathways associated with the eight other public water supply well fields (Anchorage, Berkeley, Brookside, Indian Head, Route 70, Silver Bay, South Toms River, and Windsor), analyses were conducted. Odds ratios for these other well fields fluctuated above and below 1.0 in both the Interview and Birth Records Study with no consistent pattern detected. Many of these well fields supplied only small amounts of water to a limited number of study residences.

Results for Private Well Water:

For both the Interview and Birth Records Study, few study children ever lived in a household with a private well in any of the 11 groundwater regions that had a history of groundwater contamination. In general, no elevation of risk or consistent pattern was found for childhood cancer and exposure to private wells in a potentially contaminated groundwater region. However, in the Interview Study the odds ratios for ever using a private well in a residence in any of these 11 groundwater regions during the total time and postnatal time were both over 5.0 for leukemia (males and females combined). The elevated odds ratios were based on two case children (1 male and 1 female) both with leukemia, whose residence used a private well, but were in two separate groundwater regions. The prenatal leukemia odds ratio could not be calculated since there were two cases but no controls with private well usage in any of these groundwater regions during that time period.

Exposure to Air Pollution from Point Sources:

Computer modeling was used to derive monthly estimates of potential exposure at each study residence to ambient air emissions from two facilities in the Dover Township area: Ciba-Geigy and Oyster Creek Nuclear Generating Station, from 1962 through 1996 (see Volume IV, Appendix F). Data from this modeled effort provided the average amount of ambient air emissions from each facility and was used to calculate an exposure index for each study subject using residential information.

As with the water distribution system modeling, this was the most objective method available to estimate the past exposure. However, the quality of input data for the air models was not considered to be as high quality as in the water modeling. This was particularly true for the Ciba-Geigy models where actual emission data was unavailable and weather data used was from a station fifty miles away. In an effort to address the missing emission data, annual production information for the Ciba-Geigy facility was used to modify the monthly exposure estimates used in the exposure assessment. Additionally, EOHSI conducted sensitivity analyses using weather data available for a portion of the study period from a closer weather station and also used a different model to calculate estimates for comparison. In general, both the use of a different model and the use of closer weather data produced higher exposure estimates than the data used for the exposure assessments. Exposure estimates for Oyster Creek were considered better since they were generated using actual emission data and on-site weather information.

Manufacturing operations at the Ciba-Geigy facility began in 1952 and ceased in 1996. Over the years, the facility produced anthraquinone-based dyes, azo dyes, epoxy resins, and other specialty chemicals. Ciba-Geigy was the only industrial facility in the Dover Township area which met the New Jersey Department of Environmental Protection's definition of a major emitter of hazardous air pollutants, including carcinogenic materials. Very limited historic emissions data for the facility were available to adequately characterize potential exposure to the Community. Modeled Ciba-Geigy ambient air emission estimates were closely correlated with modeled ambient particulate levels and are likely a surrogate of exposure to both gaseous and particulate air pollution arising from the site.

Exposure indices were created for Interview Study subjects for three time periods: the total study time period (from one year prior to birth until the date of diagnosis); the prenatal time period; and the postnatal time period. For the Birth Records Study, only exposures at the birth residence were evaluated for the prenatal period, since no other exposure data were available. Three exposure categories were calculated for the air pollution indices: low, medium, and high. These categories were determined using the 50th and 75 th exposure percentile values within the control population.

Results for Air Pollution Sources:

Exposure to Ciba-Geigy ambient air emissions did not appear to be associated with childhood cancers when both sexes were evaluated together. However, when evaluated separately, females with leukemia displayed a noticeable pattern. In the Interview Study, elevated odds ratios were found for the high and medium prenatal exposure categories for Ciba-Geigy ambient air emissions in females with leukemia diagnosed prior to age five (high exposure category OR=19, 95% Cl=0.9, 397; medium exposure category OR=5.2, 95% Cl=0.5, 57). Five of the seven female leukemia cases under age five were in the medium or high Ciba-Geigy exposure categories while only nine of 27 controls were in those categories. When the medium and high Ciba-Geigy prenatal exposure categories were collapsed into a single exposure category, the new odds ratio for leukemia in females diagnosed prior to age five was elevated (OR= 7.5; 95% Cl=0.8, 71) relative to the low exposed group.

For the Birth Records Study, only the prenatal period was evaluated and it was assumed that the residence at birth was also the residence throughout the pregnancy. As in the Interview Study, elevated odds ratios were found in the Birth Records Study for the high and medium exposure categories of Ciba-Geigy ambient air emissions for prenatal exposure in females diagnosed with leukemia prior to age five (high exposure category OR=7.8, 95% Cl=0.8, 77; medium exposure category OR=2.0, 95% Cl=0.1, 35).

Although no associations were detected in analyses of the overall study population, a consistent elevation in the odds ratios and an apparent dose response effect was seen in both the Interview and Birth Records Studies (see Figure 2) between prenatal exposure to Ciba-Geigy ambient air and leukemia in female children diagnosed prior to age five. These findings are consistent with one of the study's a priori hypothesis that exposure to Ciba-Geigy ambient air emissions was a risk factor for childhood leukemia.

In the Interview Study, the postnatal high exposure category was also elevated for Ciba-Geigy ambient air emissions (OR=5.5, 95% Cl=0.3, 122) for females diagnosed with leukemia prior to age five.

In general, all of the estimated Oyster Creek ambient exposures were far below the limit of detection of 70fCi/ml3 for iodine131. A lifetime cancer risk from the exposure levels estimated by the computer modeling is extremely low, on the order of about one in a billion. Exposure to Oyster Greek ambient air emissions did not appear to be associated with any childhood cancer groups evaluated in either the Interview or Birth Records Studies.

Residential Proximity to Sites of Concern

Residential distance within one-half mile of a site of concern was also evaluated as a risk factor. Because relatively few study children ever lived within one-half mile of a site of concern, an index of ever/never having lived near a site was used, rather than the percent of time a child lived near the site. For the Interview Study, exposure indices for ever having lived within one-half mile of a site of concern were created for three time periods: the total study time period (from one year prior to birth until the date of diagnosis); the prenatal time period; and the postnatal time period. For the Birth Records Study, only the birth residence was evaluated for the prenatal time period, and it was assumed that the mother's residence at the time of the child's birth was the mother's residence throughout the pregnancy period.

Residential proximity to a site was not specific to an exposure pathway, as were the air and water distribution modeling or groundwater plume shapes. Residential proximity was evaluated because it might capture other routes of exposure that could not be accounted for in the more sophisticated assessments, such as potential exposure through contact with the site. In general, the indices developed using proximity to sites of concern should be considered to be a less accurate estimate of potential exposure than indices derived using the computer model estimates.

Results for Residential Proximity to Sites of Concern:

In the Interview Study, the only site of concern displaying any pattern or consistency in elevated odds ratios was ever having lived within one-half mile of the Ciba-Geigy pipeline (during the total study time, prenatal, and postnatal periods) among females diagnosed with leukemia (ORs ranging between 5.1 and 17). Because residential distance to the entire pipeline was a fairly crude estimate of exposure, a more refined index was developed in an attempt to better define the potential exposure pathway of the pipeline. The new index evaluated residential proximity to three known breaks in the pipeline (after the breaks occurred). When residential proximity to one of the three known breaks in the pipeline was taken into consideration, few of the total study population (5 cases and 14 controls) were ever exposed, and the odds ratios diminished.

As noted above, for the Birth Records Study, only odds ratios for the prenatal period were evaluated. There was no pattern or consistency in the odds ratios for proximity to the pipeline or any other site of concern in the Birth Records Study. The index for proximity to the Ciba-Geigy pipeline was statistically significantly correlated with the time-specific Parkway index in the Interview Study(r=0.30), but no statistically significant correlation was found in the Birth Records Study. It is important to note that no completed exposure pathways associated with the Ciba Geigy pipe line were identified in the Ciba-Geigy Public Health Assessment.

Other Factors

The etiologic factors for childhood cancer are not well understood. Numerous studies have been conducted to evaluate a variety of factors which might be associated with an increased risk of childhood cancer. With the exception of q few factors that have been consistently identified in the literature (certain genetic diseases and prenatal exposures to ionizing radiation) there is an absence of consistency for most other potential risk factors examined to date. For a more detailed discussion on the etiology of childhood cancers, see Volume IV, Appendix B, In addition to the distinct environmental factors evaluated in this study, information on a wide variety of other factors was collected. These factors were included because they have been suggested in other studies to be associated with childhood cancer, or may be potential confounders to the environmental factors of interest.

In general, most of the other factors displayed no differences between the cases and controls. Study findings related to the other factors were found to be generally consistent with the published literature, with the exception of consumption of cured meat which displayed a protective effect, in contradiction to the published reports that suggest cured meats are a risk factor for some childhood cancers.

Conclusions

As the final part of the investigation of the incidence of childhood cancer in Dover Township, Ocean County, the New Jersey Department of Health and Senior Services (NJDHSS) and the federal Agency for Toxic Substances and Disease Registry (ATSDR) conducted an epidemiologic case control study to evaluate distinctive environmental exposure pathways identified in this community during earlier phases of the Public Health Response Plan. Association of selected childhood cancer with these environmental pathways represent the study's primary hypotheses.

Highlights of the study findings are presented in Table 1. The results in this Final Report should be interpreted carefully and in conjunction with existing biological and epidemiologic knowledge. Due to the relatively small number of study subjects, the analyses are sensitive to random fluctuations in numbers, which can result in substantial imprecision in the odds ratios (reflected by wide confidence intervals). Based on a combination of evaluation criteria for determination of risk factor and cancer causal associations, NJDHSS and ATSDR have concluded the following:

* No single risk factor evaluated appears to be solely responsible for the overall elevation of childhood cancer incidence in Dover Township.
*Although no associations were detected in analyses of the overall study population, a statistically significant association and consistency in multiple measures of association were seen between prenatal exposure to time-specific Parkway well field water (1982-1996) and leukemia in female children of all ages. This finding seems to support the hypothesis that prenatal exposure to Parkway well field water during this interval was a risk factor for childhood leukemia in females. However, it is important to note that there is considerable uncertainty in the findings.
*Although no associations were detected in analyses of the overall study population, a consistent elevation in the odds ratios and an apparent close response effect was seen in both the Interview and Birth Records Studies between prenatal exposure to Ciba-Geigy ambient air and leukemia in female children diagnosed prior to age five. This finding seems to support the hypothesis that exposure to Ciba-Geigy air emissions was a risk factor for childhood leukemia in females. As noted above, there is considerable uncertainty in the findings.
*No associations were seen between exposure to Holly Street well field water prior to 1976 and any of the cancer groupings evaluated. However, because few children had any study time before 1976, the ability to examine this factor was limited in this study.
*The use of a private well for drinking water within any region that had a history of groundwater contamination was rare in this study. Odds ratios for leukemia were elevated in the Interview Study for ever living in a residence with a private well in any of these groundwater regions during the postnatal time period, but could not be calculated for the prenatal period.
*An association was observed during the prenatal and postnatal time periods for residential distance from the Ciba-Geigy pipeline .and leukemia in female children, but the association diminished when documented Ciba-Geigy pipeline breaks were taken into consideration. No completed exposure pathways associated with the Ciba-Geigy pipeline were identified in the Ciba-Geigy Public Health Assessment.
*No consistent patterns of association were seen between the other environmental factors and any of the cancer groupings evaluated.
*Study findings related to the other factors evaluated were found to be generally consistent with the published literature, with the exception of the consumption of cured meat variables.
*The ability to adjust for confounding in this study was limited due to the relatively small number of study subjects.

Recommendations

1. The NJDHSS should update the Childhood Cancer Incidence Health Consultation when an additional five years of cancer incidence data (1996-2000) are available from the New Jersey State Cancer Registry in order to determine if there are any changes in childhood cancer incidence rates or time trends in Dover Township.

2. Effort should be continued to cease or reduce exposure to hazardous substances, including;

*The effort to ensure that the Reich Farm groundwater pollution does not cause contamination of additional Parkway well field wells should be continued in order to guarantee that this exposure pathway is not completed. Periodic groundwater sampling of the Reich Farm plume should continue in order to ensure that the plume is accurately delineated and does not affect currently unaffected public supply wells. In addition, monitoring of the effectiveness of treatment systems now in place is necessary to ensure that contaminants are not reintroduced into the community water distribution system.
*All private well restriction zones in Dover Township should be maintained in order to ensure that this potential exposure pathway is not completed.
*Continued efforts should be made by the United States Environmental Protection Agency and Ciba Specialty Chemicals to contain and remove contaminants in the affected aquifer associated with the Ciba-Geigy site. The restrictions on the use and construction of private wells in areas known to be affected by the Ciba-Geigy site should be maintained. The remediation of the Ciba-Geigy property should continue in order to reduce the threat of further contamination of groundwater and prevent future exposures to hazardous chemicals.

3. Because of the complexity of issues in Dover Township, it would be beneficial to continue educational efforts on cancer, Such as providing study-specific information and environmental health information to teachers and children in the schools, to health care providers, and to the community at large.

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