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BACKGROUND: Environmental estrogens in wastewater treatment work (WwTW) effluents are well established as the principal cause of reproductive disruption in wild fish populations, but their possible role in the wider health effects of effluents has not been established.
OBJECTIVES: We assessed the contribution of estrogens to adverse health effects induced in a model fish species by exposure to WwTW effluents and compared effects of an estrogen alone and as part of a complex mixture (i.e., spiked into effluent).
METHODS: Growth, genotoxic, immunotoxic, metabolic, and endocrine (feminized) responses were compared in fathead minnows (Pimephales promelas) exposed for 21 days to a potent estrogenic effluent, a weakly estrogenic effluent before and after spiking with a steroidal estrogen [17α-ethinylestradiol (EE^sub 2^)], and to EE^sub 2^ alone.
RESULTS: In addition to endocrine disruption, effluent exposure induced genotoxic damage, modulated immune function, and altered metabolism; many of these effects were elicited in a sex-specific manner and were proportional to the estrogenic potencies of the effluents. A key finding was that some of the responses to EE^sub 2^ were modified when it was present in a complex mixture (i.e., spiked into effluent), suggesting that mixture effects may not be easily modeled for effluent discharges or when the chemicals impact on a diverse array of biological axes.
CONCLUSION: These data reveal a clear link between estrogens present in effluents and diverse, adverse, and sex-related health impacts. Our findings also highlight the need for an improved understanding of interactive effects of chemical toxicants on biological systems for understanding health effects of environmental mixtures.
KEY WORDS: 17α-ethinylestradiol, environmental estrogen, fish, genotoxicity, health, immunotoxicity, metabolism, mixture effect, wastewater treatment works effluent. Environ Health Perspect 115:1704-1710 (2007). doi:10.1289/ehp. 10443 available via http://dx.doi.org/ [Online 30 August 2007]
There is heightened concern worldwide about the impacts of endocrine-disrupting chemicals present in the aquatic environment that can alter physiological function in wildlife and humans (reviewed by Tyler et al. 1998). Effluents from wastewater treatment works (WwTWs) are a major point source of endocrine-disrupting chemicals into water-courses, and exposure has been associated with a range of reproductive impacts, particularly in fish, including the induction of intersex (Jobling et al. 1998), lowered hormone levels (Folmar et al. 1996), and reduced gamete production and fertilization capability (Jobling et al. 2002a, 2002b).