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Public Health Assessment
Ciba-Geigy Corporation
(Dover Township) Toms River, New Jersey
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Pathway Analysis
To determine whether residents of Dover Township were or are exposed to contaminants from the CGC site, the ATSDR and the NJDHSS evaluate the environmental and human components that lead to exposure. An exposure pathway consists of five elements: (1) a source of contamination; (2) transport of the contaminants through an environmental medium; (3) a point of human exposure; (4) a route of human exposure; and (5) a receptor population.
The ATSDR and the NJDHSS classify exposure pathways into three groups: (1) completed pathways, that is, those in which it is likely that some persons in the receptor population were exposed, are being exposed, or will be exposed; (2) potential pathways, that is, those in which exposure might have occurred, may be occurring, or may yet occur; and (3) eliminated pathways, that is, those which can be eliminated from consideration because one of the five elements is missing and will never be present, or in which no contaminants of concern can be identified. Completed or potential pathways, discussed below, may be interrupted by remedial actions or public health interventions.
Completed Human Exposure Pathways
Holly Street Community Water Supply Wells
The ATSDR and the NJDHSS have determined that there was a completed human exposure pathway to CGC-related contaminants through ingestion of water from the community water supply wells of the Holly Street well field, as documented in 1965 and 1966. Although the full nature and magnitude of contamination is not known, there is evidence that certain Holly Street wells (# 13, # 14 and # 1 8) were contaminated with aniline-based dyes and nitrobenzene in those years. The source of the CGC cite-related contaminants appears to have been surface water from the Toms River drawn down into the ground and into the shallow Holly Street wells (TRCC, 1966b; CDM, 1994d).
The duration of exposure through this pathway cannot be determined, since data are lacking before 1965 and after 1966. The CGC began the process of discharging liquid chemical waste to the Toms River in 1952. Holly Street wells #13 and #14 were in operation beginning in 1946 and 1953, respectively. Holly Street well # 1 8 was installed in 1965. It is possible, therefore, that wells # 13 and # 14 may have been contaminated before 1965, depending on the nature of groundwater and surface water interaction in those years. Construction of the outfall pipeline in 1966 reduced the amount of pollutant discharge to the river, but, as noted previously, discharge to the river
continued from disposal areas at the CGC site. Holly Street well # 13 was sealed in 1967. Well # 14 was in operation until 1975 and was sealed in 1983. Well # 18 was in operation until 1980, and was also sealed in 1983.
The total number of persons associated with this exposure pathway in the past is difficult to determine. Exposure potential is dependent upon the dynamics of the water system during the period in question, and the location of potentially affected residences relative to the Holly Street point of entry within the water system. Overall, approximately 35,500 persons were receiving community water in 1965. Because the Holly Street well field was one of two operating in 1965 and 1966, the number of people receiving at least some of their water from this source is potentially large.
Private Wells: Cardinal Drive/Oak Ridge Parkway Area
The ATSDR and the NJDHSS have determined that there was a human exposure pathway associated with the use of private wells in the Cardinal Drive/Oak Ridge Parkway area. Private residential wells in this neighborhood that were found to be contaminated with VOCs were reported by the USEPA to be used for irrigation and/or non-potable domestic purposes at the time of sampling (1985 to 1988). Use of private well water for non-potable purposes may result in exposure through dermal contact and inhalation of volatile components, although the magnitude of exposure through use of wells for irrigation or other outdoor purposes is likely to be smaller than from the use of well water for household potable purposes.
It is possible that private wells in the Cardinal Drive/Oak Ridge Parkway area were used for potable and other household purposes prior to the sampling period, however, since hook-up to the community water supply was not mandatory. For these reasons, the ATSDR and the NJDHSS consider it likely that use of private wells in the past constituted a completed exposure pathway through inhalation, dermal, and possibly ingestion routes.
Between 1986 and 1991, and in accordance with the ROD, the CGC offered to compensate homeowners for costs associated with sealing affected wells, and 15 wells were eventually sealed, thereby interrupting this exposure pathway. The number of persons exposed in the past through this pathway cannot be determined.
A summary of the completed human exposure pathways associated the CGC site is presented in the following table.
Completed Human Exposure Pathways Associated
with the Ciba-Geigy Corporation Site
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Pathway
Name |
Source |
Environmental Media |
Point of
Exposure |
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Community
water supply
wells at
Holly
Street |
CGC Site |
Surface
Water
and
Groundwater |
Residences
and other
locations
served by
water
from the
Holly
Street
well field. |
|
Private Wells
Cardinal Drive/
Oak Ridge
Parkway area. |
CGC Site |
Groundwater |
Residences
with
private wells |
Table Continued......
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Pathway
Name |
Route of
Exposure |
Exposed
Population |
Contam-
inants
(Time
Documented |
|
Community
water supply
wells at
Holly
Street |
Ingestion,
inhalation,
dermal
contact. |
Residents receiving
community water
from Holly
Street well
field (Number
unknown) |
Dyes and
nitrobenzene
(1965-1966) |
|
Private Wells
Cardinal Drive/
Oak Ridge
Parkway area. |
Dermal
contact,
inhalation,
and possibly
ingestion |
Residents using
contaminated
private wells
(Number
unknown) |
VOCs
(1985-1988) |
Private Wells in Other Areas
Samples of some private residential wells in other areas near the site and along the outfall pipeline contained metals or low levels of VOCS. Although these contaminants are not CGC site-related, a completed human exposure pathway exists or existed in the past to these substances. Efforts to interrupt this pathway and to reduce exposure to lead and mercury were undertaken in the Coulter Street and other areas through well closures and provision of alternate sources of water. Residents participating in the NJDHSS/ATSDR private well sampling with elevated lead levels were provided informational material advising them on methods to reduce lead exposure.
Potential Pathways
Airborne Contaminants
In 1986, quantitative air monitoring was conducted in the vicinity of the marshland in the Winding River Park on the east bank of the Toms River (RADLKN, 1986). Several VOCs possibly related to the CGC site (benzene, chlorobenzene, chloroform, tetrachloroethylene, trichloroethylene, toluene) were detected, indicating the potential for exposure to airborne VOCs during recreational use of the park or in nearby residential areas.
Odor complaints were periodically received by the Dover Township Board of Health (and later the Ocean County Health Department) from residents east and south of CGC property. These complaints were typically investigated using standard instruments (flame ionization and photo ionization detectors); no evidence of significant airborne contamination was documented. However, since these survey instruments are relatively insensitive
(minimum detection limits are about I ppm for most VOCS), the potential inhalation pathway involving airborne emissions from CGC property may not have been fully characterized. Since CGC has been inactive since 1996, the likelihood of current exposure to any airborne contaminants emanating from the plant site appears minimal.
Contaminated Soils
There had been a potential for trespassers to be exposed to site-related contaminants through direct contact with contaminated soils on-site (ATSDR, 1988a). However, this potential pathway is likely to be interrupted through site security measures at the CGC site.
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