Contraceptive pills flushed down the toilet are turning male fish transgender. Estrogen present in the pills creates female characteristics in the male fish. These pills are affecting one out of every five male river fish. It reduces sperm production and triggers the production of eggs.
Experts from the University of Exeter, United Kingdom, found that 20 percent of freshwater fish at 50 different sites showed high feminine characteristics. They also found that offspring of these fish showed higher chances of getting affected by chemicals and undergo a transformation.
The chemicals which affect fish are present in contraceptive pills, by-products of cleaning agents, plastics, and cosmetics. Anti-depressants too are altering the natural orientation of the fishes. Estrogen-like substances from sewage plants are a factor, too.
Other than making them transgender, the other alterations seen in the fish are less aggressive and competitive behavior, which means fewer chances of finding a mate and breeding. Consumption of these fishes by humans can have possible adverse effects, such as PCOS (Polycystic Ovary Syndrome) in women, and hormonal disturbance in both males and females.
Professor Charles Tyler from the University of Exeter said that these chemicals might have wider health effects on fish than expected. In the laboratory, Tyler created a transgenic fish to study the effects of chemicals in the bodies of fish in real-time. It was found that estrogen from plastic waste affects the valves of the heart.
Research done in 2010 in Potomac Conservancy in Washington DC showed that 80 percent of male bass in the Potomac River exhibited female characteristics. Eggs were found in their testes because of toxic stew consumption.
Professor Tyler added that other research has shown that many chemicals that are discharged via the sewage such as antidepressants reduce the natural shyness of certain fish species, including how they react to predators.
Tyler presented his reports in the opening lecture of the 50th Anniversary Symposium of the Fisheries Society in the British Isles on July 3. The symposium was held at the University of Exeter and ends on July 7.