Superfund Research Program
The Persistence of Polychlorinated Biphenyls in Hudson River Sediments
The Hudson River is heavily contaminated with polychlorinated biphenyls (PCBs) from Hudson Falls, New York, which is north of Albany, to the southern tip of Manhattan Island. Covering a distance of about 200 miles, this stretch of the Hudson was designated a Superfund site in 1983. The principal source of contamination was two electrical capacitor manufacturing plants, one in Hudson Falls and the other just downstream in the town of Fort Edward. Over a period of 30 years, the plants may have discharged as much as 1.3 million pounds of PCBs into the Hudson, contributing to the spread of these toxins throughout the river and the food chain it supports.
This PCB contamination is a considerable source of public health concern, especially for the rapidly developing unborn child. Epidemiological studies suggest that prenatal exposures to PCBs can delay the attainment of early developmental milestones in newborn children and infants. Concern exists that these early neurobehavioral deficits may persist lifelong. To protect newborns in New York against the deleterious effects of early PCB exposures, state and federal authorities have issued warnings to women of childbearing age to avoid consumption of fish from the Hudson River, as these fish bioaccumulate PCBs in their tissues.
A major unresolved question involves the extent to which PCBs in the Hudson decompose through a natural process termed reductive dechlorination. In this process, bacteria remove chlorine atoms from PCB molecules and replace them with hydrogen atoms. Preliminary laboratory data had suggested that such natural degradation would occur, and that dredging of the Hudson River might, therefore, prove unnecessary.
To assess the extent of reductive dechlorination occurring in the river, scientists from the Rensselaer Polytechnic Institute and the Lamont-Doherty Earth Observatory of Columbia University - partners in the Superfund Basic Research Program of the Mount Sinai School of Medicine - have been analyzing the chlorination patterns of PCBs extracted from Hudson River sediment samples representing several decades of accumulation. They have found that reductive dechlorination of PCBs in the Hudson River is not nearly as extensive as predicted from laboratory studies.
At a highly contaminated site in the river near one of the PCB sources, the scientists found that significant dechlorination of PCBs had occurred, but that the rate of dechlorination decreased dramatically after about a year. Even after years to decades of residence, dechlorination of the PCBs had not occurred to the extent observed in some laboratory incubations after only a few months. At a moderately contaminated site, only the initial stages of dechlorination had occurred, even after several decades.
These findings have major implications for the environment and for public health. The principal implication is that PCB contamination of the Hudson River will persist for decades and that consumption of fish from the river will, therefore, continue to be a source of significant public health concern. Because the findings relate directly to the rate and extent of the natural degradation process, they will play an important role in the ultimate selection of remedial action for the Hudson.
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To learn more about this research, please refer to the following sources:
- McNulty AK. 1997. In Situ Anaerobic Dechlorination of Polychlorinated Biphenyls in Hudson River Sediments. M.S. thesis, Rensselaer Polytechnic Institute.
- McNulty AK, Bopp RF, Estabrooks FD, Chillrud SN. 1996. In situ anaerobic dechlorination of PCBs in Hudson River sediments. In: Society of Environmental Toxicology and Chemistry (SETAC) Annual Meeting 1996. Washington, DC.
- Chillrud SN. 1995. Transport and Fate of Particle Associated Contaminants in the Hudson River Basin. Ph. D. thesis, Columbia University, New York.
- Bopp RF, Simpson HJ. 1989. Contamination of the Hudson River: The Sediment Record. In: Contaminated Marine Sediments Assessment and Remediation, National Research Council, NAS. NATIONAL ACADEMY PRESS, Washington, DC. pp.401-416.
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