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Multigenerational Exposure of the Estuarine Sheepshead Minnow (Cyprinodon variegatus) to 17β-estradiol. I. Organism-Level Effects Over Three GenerationsLife Cycles
Citation:
CRIPE, G. M., BECKY L. HEMMER, L. R. GOODMAN, J. W. FOURNIE, S. RAIMONDO, J. VENNARI, R. L. DANNER, K. SMITH, B. R. MANFREDONIA, D. H. KULAW, AND M. J. HEMMER. Multigenerational Exposure of the Estuarine Sheepshead Minnow (Cyprinodon variegatus) to 17β-estradiol. I. Organism-Level Effects Over Three GenerationsLife Cycles. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 28(11):2397-2408, (2009).
Impact/Purpose:
The Agency is developing Tier II testing protocols for multiple generation exposures of a variety of taxa to endocrine disrupting chemicals to evaluate dose-response and latent or cumulative adverse effects. This study measured traditional life-cycle endpoints in this first exposure of fishes through two full generations to the estrogen, 17f3-estradiol (E2). The results were compared among generations to identify early indicators of long-term effects or changes in sensitivity with exposure duration.
Description:
This study reports the effects of 17β-estradiol (E2) on reproductive processes through two complete generations of the sheepshead minnow, Cyprinodon variegatus, and determined the need for multiple generation exposure testing for assessing the risks of endocrine disrupting chemicals (EDCs). Adult F0 fish were continuously exposed to nominal concentrations of 0.01, 0.03, 0.08, 0.2 and 0.5 μg E2/L for 21 days, as was the F1 generation; the F2 generation was exposed to ≤ 0.2 μg E2/L during the 40-week test. A cumulative 21-day production of normal embryos was significantly reduced in the F0 generation at 0.5µg E2/L and in the F1 and F2 generations at > 0.08µg E2/L. However, analyses of the last 7 days of the 21-day egg production indicated that it was significantly reduced in all three generations at ≥ 0.08 μg E2/L. The proportion of infertile eggs increased significantly in F1 fish (0.03 μg E2/L) and F2 fish (≥ 0.08 μg E2/L). Changes in liver, kidney and gonadal tissues were seen in the F0 and F1 generation exposed to > 0.2µg E2/L. E2 affected the female gonadosomatic index at 0.5µg/L in the F0 and F1 generations, but not the hepatosomatic index in any treatment. All F1 fish in 0.5µg E2/L were phenotypically female. There was no significant treatment x generation effect on any non-lethal endpoint. However, exposure of fish to E2 throughout their life cycle (F1 and F2 generations) significantly decreased embryo production at concentrations lower than those affecting the F0 generation. Our results emphasize the importance of evaluating the impact of an estrogenic chemical on reproductive performance through a minimum of two sequential generations.