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Some PAH metabolites are carcinogenic, mutagenic, or teratogenic to
organisms. Rather than enhancing detoxification, metabolism of some
carcinogenic PAHs in induced animals could result in a higher steady-state level
of toxic products (Steggeman 1981). Although studies with various carcinogens
have demonstrated that chemicals can cause cancer in aquatic species, most
attempts to demonstrate carcinogenesis by PAHs in aquatic species have
produced equivocal results (Pliss and Khudoley 1975). Although recently there
has been some evidence that PAHs can cause cancer in aquatic animals, there is
to date no direct evidence of a single specific PAH induction of carcinogenesis
in aquatic species (Neff 1979 and Steggeman 1981).
Studies in the Duwamish River, Boston Harbor, and Hudson River have
identified populations of Dover sole and Atlantic tomcod with very high
incidences of hepatocellular carcinoma (Varanasi 1989), and higher incidences
of similar diseases have been reported for other environments. Although the
etiology of such diseases in fish is uncertain, there is reason to suspect that the
chemical environment is responsible, and PAHs have not been exonerated
(Steggeman 1981). Bottom sediments in the areas that these fish populations
inhabited contained elevated levels of PAHs.
The impacts of concern in the terrestrial environment include both direct
toxicity and food-chain impacts. The toxic effects of PAHs in mammals can be
inferred from the extensive toxicity testing work performed on laboratory
animals. As with humans, the basic conclusion is that exposure to PAHs are only
slightly to moderately toxic by acute exposure, but longer exposures to certain
PAHs can result in cancer. Biomagnification in animal food chains is unlikely,
however, since PAHs are readily metabolized.
References
Lu, P. Y., Metcals, R. L., Plummer, N., and Mandel, D. (1987). Arch. Env.
Contam. Toxicol. 6:129-142.
Neff, J. M. (1979). Polycyclic aromatic hydrocarbons in the aquatic
environment. Applied Science Publishers, London.
Pliss, G. B., and Khudoley, V. V. (1975). J. Natl. Cancer Inst. 55:129.
Steggeman, J. J. (1981). "PAHs and their metabolism in the marine
environment." PAHs and Cancer. Vol 3, H.V. Gelboin and P. Tso, ed.
Academic Press, NY, 1-60.
U.S. Environmental Protection Agency. (1982). "An exposure and risk
assessment for benzo(a)pyrene and other polycyclic aromatic hydrocarbons,"
Volume IV, Final draft report, Washington, DC.
Varanasi, U. (1989). Metabolism of polycyclic aromatic hydrocarbons in the
aquatic environment. CRC Press, Cleveland, OH.
D67
Appendix D Toxicological Profiles
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