Transgender Fish: Contraceptive Pills Flushed Down Water Drains Cause Male Fish To Mutate Into Females

Chemicals found in contraceptives and household products that are flushed down the drains are giving rise to transgender fish in rivers. Researchers said that male river fish now turn into females because of chemicals that pollute the water.

Male Roach Fish Turn Into Females

Charles Tyler, of the University of Exeter in Britain, and colleagues said that the males of the roach fish now display more feminine traits.

Some male river fish were found to have reduced sperm quality, and show less aggressive and competitive behavior which can reduce their odds of breeding successfully. Some fish were even found to be producing eggs, which makes them less able to reproduce.

The researchers found that 20 percent of the freshwater fish at 50 different sites show higher feminine characteristics, and they attribute this to ingredients present in birth control pills and by-products of plastic, cleaning agents and cosmetics.

Other Effects Of Chemicals In Water

The effects also appear to impact the offspring of these transgender fish, which were found to be more susceptible to chemical alteration.

Tyler and colleagues said that chemicals discharged through sewage treatment, such as those from antidepressant drugs, can also reduce the natural shyness of some species of fish, which include the way they react to predators.

"They don't just affect reproduction and they don't just induce things like transgender," Tyler said. "They can also affect things like the way the fish behave, the immune system of the fish and how things like bones develop as well."

Scientists have been concerned of the effects of chemicals on the gender of fish. In 2010, The Potomac Conservancy in Washington, D.C. made a call for further studies after it was discovered that over 80 percent of male bass fish in the Potomoc River showed female traits, which was likely caused by toxic chemicals polluting the water.

Effects On Humans

Exposure of fish to potentially harmful chemicals poses danger to humans as well. Studies indicate that the chemical polychlorinated biphenyl (PCB) that builds up in the fatty tissues of fish may pose health risks to people who often eat contaminated fish. Fetuses and young children are particularly susceptible to the effects of these chemicals on their nervous system.

The findings of Tyler and colleagues are set to be presented at the 50th Anniversary Symposium of the Fisheries Society in the British Isles, which will be held at Exeter University from July 3 to July 7.

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