Accounting for the differences in oestrogenic responses in rainbow trout (Oncorrhynchus mykiss: Salmonidae) and roach (Rutilus rutilus) exposed to effluents from wastewater treatment works

Tyler, C R, Spary, C, Gibson, R, Santos, E M, Shears, J and Hill, E M (2005) Accounting for the differences in oestrogenic responses in rainbow trout (Oncorrhynchus mykiss: Salmonidae) and roach (Rutilus rutilus) exposed to effluents from wastewater treatment works. Environmental Science and Technology, 39 (8). pp. 2599-2607. ISSN 0013-936X

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Effluents from wastewater treatment works (WwTWs) contain estrogenic substances that induce feminizing effects in fish, including vitellogenin (VTG) synthesis and gonadal intersex. Fish vary in their responsiveness to estrogenic effluents, but the physiological basis for these differences are not known. In this study, uptake of estrogen from two WwTW effluents (measured in hydrolyzed bile) and estrogenic response (VTG induction) were compared in a salmonid (rainbow trout, Onchorhynchus mykiss) and a cyprinid fish (roach, Rutilus rutilus). Immature rainbow trout were more responsive than maturing roach to the estrogenic effluents. The more potent of the two estrogenic effluents (containing between 24.3 and 104.1 ng estradiol-17 equivalents/L [E2eq/L]) resulted in a 700-fold and 240-fold induction of plasma VTG in male and female trout, respectively, but only a 4-fold induction in roach (and in males only). The less potent effluent (varying between 4.1 and 6.8 ng E2eq/L) induced VTG in the trout only, with a 4-fold and 18-fold induction in males and females, respectively. In fish exposed to tap water, the estrogenicity of the hydrolyzed bile was 0.03 0.01 ng E2eq/L (for both sexes in trout), 0.18 0.04 ng E2eq/L in male roach, and 0.88 0.15 ng E2eq/L in female roach. The higher bile content of estrogen in control roach reflected their more advanced sexual status (and thus higher endogenous estrogen) compared with the immature female trout. In trout maintained in effluents, the bile content of estrogen was 100-fold and 30-fold higher than controls at WwTW A and B, respectively. Bioconcentration factors (BCFs) for estrogenic activity in bile were between 16 344 and 46 134 in trout and between 3543 and 60 192 in roach (no gender differences were apparent). There were strong correlations between VTG induction and the estrogenic activity of bile extracts for both trout and roach. The results confirm that estrogenic contaminants bioconcentrate to a high degree in fish bile and that the level (and nature) of this accumulation may account for responsiveness to the endocrine disruptive effects of estrogenic effluents. Immature fish were the more appropriate life stage for quantifying estrogen exposure and uptake in bile, as they contain little circulating endogenous oestrogen compared with sexual maturing fish. The nature of the estrogenic contaminants is detailed in an accompanying paper.

Item Type: Article
Additional Information: This is the first work to suggest mechanisms which could explain the different susceptibilites of fish to estrogenic effluents and has a potential impact on current methodologies for estimating environmental risk and impact. This work was funded by an EPSRC grant to me and I directed the research work.
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Depositing User: Elizabeth Hill
Date Deposited: 06 Feb 2012 19:58
Last Modified: 14 Jun 2012 11:35
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