A leading ecotoxicologist revealed that some chemicals can “feminize” male fish and cause “sub-lethal” effects.
Professor Charles Tyler is also known for his contributions in revealing almost 10 years ago how significant an impact human drugs were having on wildlife. Now he is warning that scientists are getting more concerned about the effects of thousands of waste substances.
Some of those substances are from industrial processes, others are drugs taken by people that then pass through them and into the sewers or are just flushed into the toilet.
Professor Tyler took part of a major study in 2008 that discovered nearly a quarter of male roach fish taken from 51 sites on English rivers had signs of becoming female, including having eggs in their testicles.
In some rivers, in fact, so huge is the effect that all the male roach were discovered to have been feminized to a degree due to high levels of oestrogen, which is used along with progestin in birth-control pills to prevent ovulation and is also present in other drugs.
Other chemicals can also have an impact on different parts of the fish anatomy, like the liver, heart and brain. Professor Tyler said:” If you look in terms of what gets into a fish’s liver or gonad, the analysis of the chemicals it contains is a bit of blueprint in terms of what’s flushed down the toilet.”
Tyler said that they are beginning to establish not just the chemicals’ effects on gender,but also their impact on the physiological processes in the fish as well.
Humans use thousands of chemicals, 200 of which have been shown to result in feminization. The trouble it brings is that this can prevent males from breeding successfully.
The effects do not kill the fish but can dangerously reduce their population over time, creating a need to study further what could be harmful chemicals to restrict their use in the future for the sake of wildlife preservation.