Ecological effects - trdoer40212

humans and other animals. The epoxides may be further biotransformed to

dihydrols, which can be conjugated and excreted in the (Klaassen, Amdur, and

Doull 1986). Biliary and fecal excretion of the cyclodiene insecticides also

occur. Lindane has been metabolized in rats by progressive dehydrochlorination,

glutathione conjugation, and aromatic hydroxylation. Primary excretion of the

metabolites occurs in the urine (Klaassen, Amdur, and Doull 1986).

Ecological effects

As a result of the bioconcentration of organochlorine insecticides in

ecosystems, organisms at the top of natural food chains may sustain injury due to

the gradual accumulations of residues in organisms that make up their food

sources. Reproductive success of certain species of wild birds is adversely

affected by exposure to DDT or its metabolites (Klaassen, Amdur, and Doull

1986). Eggshell thinning has been demonstrated following ingestion of DDT and

related chlorinated hydrocarbon insecticides. In addition, the ability of DDT to

enhance the metabolism of estrogen may impact reproductive success in birds by

creating an endocrine imbalance affecting egg laying and nesting cycles

(Klaassen, Amdur, and Doull 1986). Fish and some lower aquatic organisms are

extremely sensitive to the acute toxicity of DDT.

Significant evidence of endocrine disruption exists for the following groups

of organisms: snails, oysters, fish, alligators and other reptiles, and birds, such as

gulls and eagles (USEPA 1997). Significant population declines as a result of

exposure to endocrine-disrupting chemicals have been reported for alligators in

Central Florida and some populations of marine invertebrate species.

References

Briggs, S. A., and Council, Rachel Carson. (1992). Basic guide to pesticides:

Their characteristics and hazards. Taylor & Francis, Washington, DC.

Klaassen, C. D., Amdur, M. O., and Doull, J. (1986). Casarett and Doull's

toxicology: The basic science of poisons. 3rd ed., Macmillan, New York.

Hazardous Substances Database (HSDB). (1997). On-line database.

Integrated Risk Information System (IRIS). (1997). On-line database.

U.S. Environmental Protection Agency. (1997). "Fact sheet: EPA special report

on endocrine disruption," Office of Research and Development, Washington,

DC.

D60

Appendix D Toxicological Profiles