MULTIGENERATIONAL EXPOSURE OF THE ESTUARINE SHEEPSHEAD MINNOW (CYPRINODON VARIEGATUS) TO 17β-ESTRADIOL. I. ORGANISM-LEVEL EFFECTS OVER THREE GENERATIONS

A 280-d study examined the effects of 17 beta-estradiol (E2) on reproduction and development of the sheepshead minnow (Cyprinodon variegatus) exposed from the parental (F0) through three subsequent (F1, F2, and F3) generations and evaluated the need for multigenerational assessments of the risks of endocrine-disrupting chemicals. This first three-generation study exposed adult F0 and F1 fish to measured concentrations of 0.01, 0.04, 0.08, 0.2, and 0.3 mu g E2/L; the F2 and F3 generations were exposed to 0.2 mu g E2/ L or less. The cumulative 21-d production of normal embryos was significantly reduced in the F0 generation at 0.3 mu g E2/L and in the F1 and F2 generations at 0.08 mu g E2/L or more. The daily reproductive rate was significantly reduced in all three generations at 0.08 mu g E2/L or more during spawning days 8 to 14 and 15 to 21. The proportion of infertile eggs from F1 fish was significantly increased above that of the solvent controls at 0.04 and 0.2 mu g E2/L and from F2 fish at 0.04 mu g E2/L or more. Changes in liver, kidney, and gonadal tissues were seen in the F0 and F1 generations exposed to 0.2 mu g E2/L or more. The female gonadosomatic index was significantly decreased at 0.3 mu g E2/L in the F0 and F1 generations. Estradiol affected the hepatosomatic index only in female F1 fish, but not in a dose-dependent manner. All F1 fish in 0.3 mu g E2/L appeared to be phenotypically female. Our results indicate that life-cycle exposure to E2 significantly decreased embryo production by F1 and F2 fish at concentrations lower than those affecting the F0 generation, and they emphasize the importance of evaluating the impact of an estrogenic chemical on reproduction through a minimum of two (F0 and F1) generations.