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Library: Letters: SENES | |||||||||||||||
Letter to COPAJanuary 29, 1998 Coalition Opposed to PCB Ash in Monroe County, Inc. (COPA) Dear COPA: This letter is being written as a result of the January 2000 deadline set by U.S. District Judge S. Hugh Dillin for the polychlorinated biphenyl (PCB) cleanup in the Bloomington, Indiana area. The extensive PCB contamination is a result of Westinghouse Bloomington Plant operations (production of capacitors) from 1958 until 1977. Because of the concern over potential effects, long persistence, and increasing residues in the environment, U.S. production was voluntarily restricted in 1970, and all non-closed uses were banned by the U.S. Environmental Protection Agency (USEPA) in 1978 (Peterle, 199 1). Even though PCB use at the Westinghouse Plant ceased in 1977, PCBs continue to leach into the environment. The many characteristics that have made PCBs desired by industry also make them persistent, stable, and available for bioaccumulation in the environment. Persistence refers both to the actual breakdown of the chemical and its disappearance; persistence infers that the compound or its metabolites are still present and that toxic properties are still present. PCBs have been found to be ubiquitous in the environment, and high concentrations have been found in predatory species and 'in aquatic systems where industrial contamination and aerial fallout has occurred. PCBs are poorly soluble in water and extremely soluble in oils as well as fats. Due to their chemical stability, PCBs are generally poorly metabolized by biological systems, and they tend to accumulate in tissues of aquatic organisms, primarily within organs that are rich in lipids. PCBs have a high potential for bioaccumulation in aquatic ecosystems; bioaccumulation is defined as the net accumulation of a chemical by an organism as a result of uptake from all routes of exposure. PCBs bioaccumulate in the food chain and often increase several orders of magnitude in concentration at each succeeding trophic level (D'Itri and Kamrin, 1983). A food chain is an often simplified, abstract representation of the links between consumers and consumed populations [i.e., plant-herbivore (organism that eats plants) -carnivore (organism that eats animals)]. A trophic level is defined as the position in the food chain assessed by the number of energy-transfer steps to reach that level. PCBs in water have been shown to bioaccumulate in fish and marine mammals, reaching levels thousands of times higher than the levels in the water. Therefore, even small releases of PCBs can significantly affect the environment. Sensitivity of wildlife species to PCBs is quite variable. Some fish species are killed by exposures as low as 0. 1 parts per billion (ppb), while other species can survive concentrations of over 1,000 ppb (Eisler, 1986). PCBs do transfer across the placenta and milk of mammals. The assessment of the impact of PCB on wildlife is difficult because most organisms analyzed for residues contain not only PCBs, but other chlorinated hydrocarbons as well. PCBs have also been shown to be contaminated with dibenzofurans, and this further complicates the assessment of toxicity related to carcinogenicity and teratogenicity. Residues in wildlife, both aquatic and terrestrial, are widespread (Task Force on PCB, 1976). PCBs have been shown to cause cancer in animals; in addition, chronic exposure of animals to PCBs can lead to disrupted hormone balances and reproductive failures. Animals that inhaled very high levels of PCBs have experienced liver and kidney damage, while animals that ingested food with large amounts of PCBs experienced mild liver damage. Animals that ingested food containing smaller amounts of PCBs experienced liver, stomach, and thyroid glad injuries, and problems with their reproductive systems. Exposure of PCBs to the skin of animals has resulted in liver, kidney, and skin damage. In order to protect human health, the USEPA has set a maximum contaminant level of 0.0005 milligrams of PCBs per liter of drinking water. In addition, the Food and Drug Administration (FDA) requires that milk, eggs, other dairy products, poultry fat, fish, shellfish, and infant food contain no more that 0.2-3 parts of PCBs per million parts of food. However, we would like to bring to your attention that these established concentration limits are not consistent with respect to the amount of health risk incurred by individuals consuming PCB-contaminated water and food. For example, the USEPA drinking water standard is based on a conservative cancer risk estimate of one chance in one million (10-6) over an individual's lifetime. In addition, for Aroclor- 1254/1260, the FDA limits would translate to lifetime cancer risks that would approach and possibly exceed one chance in ten thousand to one chance 'in one thousand. The FDA limits are therefore a factor of 100 to 1,000 times less restrictive than the standards developed by the USEPA for drinking water. PCBs that are associated with the fats of fish or animal flesh cannot be removed by washing and are only partially removed by cooking procedures (D'Itri and Kamrin, 1983). Therefore, contaminated fish constitute a dietary source of exposure of such magnitude that even occasional consumption provides a dose sufficient to elevate human concentrations above background levels in the human population (D'Itri and Kamrin, 1983). The PCB-contaminated sites in the Bloomington, Indiana area are located in an area with limestone formations, characteristic of karst terrain. Karst is defined as a landscape generally lacking in rivers, marked by sinkholes and caves, and formed because the underlying rock dissolves more easily than most rocks (Beck and Sinclair, 1986). Sinkholes, swallow holes, caves, and at least one sinking stream are present in the vicinity of the sites consistent with the karst geology of the region. Because of the karst terrain, capping a contaminated site will not stop the leaching of PCBs into the groundwater. A study of the contaminated sites is currently underway by a karst hydrogeologist. Because of the unique characteristics of karst topography, remedial decisions should not be made until the karst study has been completed. Because the sites and the contaminated off-site environments have not been adequately characterized, making remedial decisions will be extremely difficult. In addition, because baseline or preliminary ecological and human health risk assessments have not been performed to date, characterizing the ecological risks to human health and the environment resulting from the PCB contamination is not possible. If remediation decisions are made without adequate site characterizations and baseline risk assessments, the possibility exists of not adequately cleaning up the sites. In addition, money can be wasted by over-cleaning sites. Therefore, it is in the best interest of all parties involved that all sites be adequately characterized and baseline risk assessments be performed before any decisions are made regarding site remediation. Incineration of PCBs is often thought of as the "easy" way to breakdown PCBs. Incineration is a quick way of getting rid of the chemical, but it is also a very dangerous way of degrading PCBs. Incomplete combustion of PCBs could result in the formation of polychlorinated dibenzofurans, which are even more toxic to the environment than PCBs. Incineration also requires large amounts of heat, which can also be dangerous if not properly contained. A safer alternative which should be considered is the use of microorganisms. Over 20 new strains of bacteria have exhibited capabilities for the biodegradation of PCBs; several have shown exceptional degradative competence (Unterman et al., 1988). Unfortunately, even with complete remediation of all contaminated sites, PCBs will remain in the underground and off-site environment for many years. Because of their persistence and the extensive contamination, they will continue to present toxic problems to wildlife for many years. Sincerely,
References Beck, B.F. and Sinclair, W.C. 1986. Sinkholes in Florida: an introduction. Rep. 85-86-4. Sinkhole Research Institute, College of Engineering, University of Central Florida, in cooperation with the U.S. Geological Survey, Orlando, Florida. D'Itri, M.F. and Kamrin, M.A. 1983. PCBs: Human and Environmental Hazards Butterworth Publishers, Woburn, Massachusetts. Eisler, R. 1986. Polychlorinated biphenyl hazards to fish, wildlife and invertebrates: a synoptic review. Biological Report 85(1.7), U.S. Fish and Wildlife Service Contaminant Hazard Review Report No. 7. Peterle., T.J. 1991. Wildlife Toxicology Van Nostrand Reinhold, New York, New York. Unterman, R., Brennan, M.J., Brooks, R.E., and Johnson, C. 1988. Biological degradation of polychlorinated biphenyls. Biological Sciences Branch, General Electric Corporate Research and Development, Schenectady, New York. |
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