Fish feminization is widespread in Great Britain and in the US. The causes now appear to be a mixture of chemicals, including excreted byproducts of birth control pills and industrial chemicals. In Our Stolen Future we discussed the case of feminized fish in Great Britain's rivers and presented the evidence available to date that sewage treatment plants were releasing something that acted like estrogen. In a series of studies, John Sumpter and his colleagues examined, but rejected at the time, that the substance might be a form of estrogen excreted by women in their urine after taking oral contraceptives. They showed that other substances, especially nonylphenol, were both capable of causing feminization and present in the water at levels sufficient to cause the problem. At the time, Sumpter said: "We don't know if the mixture is related to alkylphenol polyethoxylates. It could be a single family of chemicals or a mixture of detergents, pesticides and plasticizers." It appeared likely that "a range of chemicals" were contributing to the effect. This story has developed significantly since OSF's publication, and it appears that indeed the urinary byproduct of oral contraceptives is involved in some cases, but not all. Scientists are also discovering that fish in US rivers have been affected, as well as salt-water fish inhabiting estuaries around Britain's coasts.
|
|||||