Endocrine-disruptors come from a variety of man made sources, such as pesticides, plastics, pharmaceuticals, ordinary household chemicals, and industrial chemicals. They alter the hormonal functions of various species by acting as sex hormones, which prevent normal hormonal binding and breakdown of natural hormones (Colborn et al. 1993). Specific effects found in wildlife and laboratory studies on mammals, reptiles, amphibians and fish include abnormal blood hormone levels, reduced fertility, altered sexual behavior, modified immune system, masculinization of females, feminization of males, undescended testicles, reduced penis size and testis, altered bone density and structure, cancers of the male and female reproductive tract, and lastly, malformed fallopian tubes, uterus and cervix. The
fact that these man made endocrine-disruptors have a long half life in the environment and can accumulate within an organism
poses a potential threat to the survival and fitness of most amniotic species (Stone 1994). This broad effect results from a homology shared among amniotes.
If other non-endocrine environmental influences are involved in increased extinction rates, then particular, endocrine-related patterns of morphological or developmental changes should not be observed. These patterns would include
masculinization of females, feminization of males, reduced penis
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