Fish reproduction as an indicator of endocrine disruption by chemical compounds

Concern over changes in the health and fecundity of both wildlife species and humans, which may be associated with the disruption of hormonal systems by endocrine-disrupting chemical compounds in the environment, has been increasing. A large number of compounds are suspected of having endocrine-disrupting activity and, therefore, convenient but relevant assay methods are desired. Studies on endocrine disruptants are briefly reviewed, and protocols to evaluate their effects on fish reproduction are introduced. Reproductive defects have been observed in wildlife species, e.g., American alligators (Lake Apopka, USA), white suckers (Lake Superior, Canada), bald eagles (Great Lake, USA). 1–3) Some agents called endocrine-disrupting compounds are suspected for these observations. Endocrinedisrupting compounds are natural or man-made agents present in the environment that interfere with the normal endocrine function. This diverse group of chemicals includes environmental estrogens. And, a number of industrial, municipal, agricultural, and natural compounds have been shown or are suspected to be estrogenic. 4–8) Such compounds include biodegradation products of alkylphenol polyethoxylates (octylphenol, nonylphenol, bentylphenol, butylbenzyl phthalate, dibutyl phthalate, and bisphenol A), polychlorinated biphenyls (PCBs), and conventional pesticides (dichlorodiphenyltrichloroethane [DDT], chlordecone, methoxychlor, kelthane, endosulfan, methoxychlor), as well as natural and synthetic estrogens (17β-estradiol, estrone, genistein, coumestrol, diethylstilbesterol, and ethinyl estra