Many estrogenic contaminants are produced for spe-
cific purposes and are used in pesticides, plastics, elec- trical transformers and other products (for review see, Ahlborg et al , 1995; Caldwell, 1985, Table 1) Other substances are generated as by-products during manu- facturing or are breakdown products of some other
chemical, and some, like 17�-ethinylestradiol and di-ethylstilbestrol (DES), are drugs