Troubled waters

Pollutants alter sexual characteristics of wild fish

 
Last Updated: Saturday 04 July 2015

Hormones leaking into streams from cattle ranches are altering the sexual characteristics of wild fish. This alarming fact was revealed during a study conducted by researchers from the us-based St Mary's College of Maryland. The findings once again put a question mark on the validity of using hormones to stimulate growth in cattle. According to a 1999 survey by the us department of agriculture, about 99 per cent of the nation's biggest cattle ranches use the hormones on a large scale.

The researchers examined minnows in three streams that flow into the Elkhorn river, and found "significant alterations in the reproductive biology" of the wild fish. The males had one-third less testosterone (male sex hormone) and their testes were about half as big as those of the unexposed fish. The female fish had about 20 per cent less estrogen (female sex hormone) as compared to minnows from uncontaminated streams. According to the researchers, it is unknown whether the hormones affect human beings similarly when they enter the human foodchain via fish. "We do hope that human exposure is minimal, given that only trace amounts of these synthetic hormones remain in the meat. But the findings are reasons enough to be alarmed, at least for the aquatic life," says Edward Orlando, the lead researcher.

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