Male fish mutating into females because of waste chemicals, expert warns

Expert calls for stronger stance on chemicals and drugs that are likely to have ‘sub-lethal’ effects on wildlife

Ian Johnston Environment Correspondent

Monday 3 July 2017 13:00 BST

Tougher controls should be considered on chemicals that can feminise male fish and cause other “sub-lethal” effects, a leading ecotoxicologist has said.

Nearly 10 years after he helped reveal how significant an impact human drugs were having on wildlife, Professor Charles Tyler has warned that scientists are becoming increasingly concerned about the consequences of thousands of waste substances.

Some are from industrial processes, but others are drugs taken by people that then pass through them and into the sewers or are simply flushed directly into the toilet.

Professor Tyler, of Exeter University, will talk about the issue in a speech at the 50th Anniversary Symposium of the Fisheries Society in the British Isles.

He took part in a major study in 2008 that found nearly a quarter of male roach fish taken from 51 sites on English rivers showed signs of becoming female, such as having eggs in their testicles.

In some rivers, all the male roach were found to have been feminised to a degree because of high levels of oestrogen, which is used along with progestin in birth-control pills to prevent ovulation and is also present in other drugs.

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