Birth control for humans has dropped fertility in fish

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Many fish in the US are now taking birth control, most of them without consulting their gynaecologist.

A study done by the US Geological Survey found that fish all across the US are being exposed to a synthetic hormone called 17a-ethinylestradiol, also called EE2, which is one of the main ingredients in oral birth control pills, according to a report from the Washington Post.

The chemical is getting into waterways through human waste and by unused pills being washed down the drain.

Once exposed, fish produced offspring that had trouble fertilising eggs, the study found. The grandchildren of the fish originally exposed to the drug had a 30 per cent drop in their fertilisation rate.

“If those trends continued, the potential for declines in overall population numbers might be expected in future generations,” said Ramji Bhandari, a visiting scientist at USGS. “These adverse outcomes, if shown in natural populations, could have negative impacts on fish inhabiting contaminated aquatic.”

In fish, EE2 – along with the chemical BPA, often found in plastics – is thought to have caused some male smallmouth and largemouth bass to switch to the female sex by growing ovaries where the testes are supposed to be, the study said.

Up to 68 per cent of a dose of EE2 is released in human waste after taking oral birth control pills and a full dose is released when the pills are flushed. The study said that EE2 survives after being treated in wastewater.

The scientists are not sure how exactly the sex-changing is happening, but said that it appears to be spreading, threatening future fish populations.

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