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Discovering Causes of Feminized Fish

August 08, 2018 8:59 AM | Anonymous

Since the 1990s there have been widespread reports throughout the world of male fish from different water bodies that exhibit female traits. This "feminization", which includes changes to the appearance and reproductive ability of the males, has often been associated with exposure of the fish to chemicals in runoff from animal feedlots and discharges from wastewater treatment plants. Chemicals responsible for feminization are collectively referred to as endocrine disruptors, because of their ability to "mimic" the effects of estradiol, a natural estrogenic hormone that controls endocrine systems involved in reproduction in female animals and humans.

A significant amount of research has been focused on the identity of the estrogenic chemicals causing endocrine disruption, so that their release to the environment might be controlled. A recent paper authored by EPA researchers, "Re-evaluating the Significance of Estrone as an Environmental Estrogen", showed that the hormone estrone may be a very important cause of feminization of male fish. Estrone is produced naturally by livestock and humans, and is excreted from the body in waste. It has been known for some time that estrone can be present at high concentrations in wastewater discharges, but it has not been thought to be particularly important in causing feminization because it is a weak estrogenic chemical. However, the EPA scientists found that estrone can be changed by male fish to the much stronger estradiol, to a degree sufficient to cause their feminization. This indicates that estrone could be a much more important estrogenic endocrine disruptor than previously supposed.  

The paper describing this work is featured on the cover of the May 16th issue of Environmental Science & Technology and was recently selected by The American Chemical Society as an Editor’s Choice article. 

Sent by: Dennis Riecke, 2016 SDAFS Past President

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