Several consensus definitions of the term endocrine disrupter have appeared
recently, but all definitions include the important, though frequently imp
licit, stipulation that the animal is not distressed or in obvious discomfo
rt. Instead, a superficially healthy animal is experiencing alterations in
hormone synthesis, transport, receptor interaction, metabolism, excretion,
or feedback regulation. In addition, hormone disruption may occur during se
x differentiation, and its effects may not be manifested until after sexual
maturation. Many cases of chemically induced reproductive impairment have
been reported for both freshwater and marine species. However, reproductive
impairment may not necessarily result from hormone disruption and should b
e considered suggestive, but not conclusive, evidence of endocrine disrupti
on. A suite of in vivo and in vitro assays will more adequately assess whet
her a compound is truly endocrine disrupting. This review will cover basic
endocrinology of marine and estuarine invertebrates and vertebrates, method
s for detecting endocrine disruption, and examples of endocrine disruption
in various species.