Monday, December 04, 2006

Hormone Interference

It has been known for several years now that pollution in local waterways, particularly the Potomac and Anacostia Rivers, has interfered with the hormone systems of the fish population. Male fish have been found bearing eggs, for example. There is finally some research being done to explore whether these pollutants are linked to human problems, mainly diabetes, birth defects, and infertility. Here are a few pollutants under scrutiny:

· Phthalates, a family of additives used to make vinyl plastic flexible and prevent perfume from evaporating, have been linked to lower sperm counts and other sexual problems in male rats, as well as to heightened allergic reactions in the animals. Chemical industry officials have said that these tests used unrealistically high doses and that the results are not likely to translate to humans.

· Bisphenol A, used as a building block for hard plastic goods like bottles and as a resin to line food cans, has been connected in some experiments to abnormal sexual development in male lab rodents, as well as a predilection for obesity. Officials from the chemical and pesticide industries have vigorously criticized these results, saying that other studies have shown the chemical to be harmless.

· Treated sewage, which carries human estrogen and birth-control pill components excreted in waste, has been linked to "feminized" male fish in waters around the world. In the St. Lawrence River in Canada, a recent study found that a third of male minnows had female characteristics. Another example might be the Potomac, though the cause of its problems has not been officially pinpointed. The EPA and sewage-plant officials have said they are working on ways to better clean the wastewater.
The linked article goes on to explain that proving the link with rigorous studies is difficult because of the ethical limitations involved in human research. However, the studies that have been done do show connections between the chemicals and human problems. Even if a link could be proven, decreasing exposure to these chemicals would be difficult because of their current ubiquity.

This echoes something I have noted before on this blog. There is a tendency sometimes to equate environmentalism with "nature" or animal rights - in other words, a peripheral concern. In reality, we humans are part of the environment ourselves, and changes - whether large-scale or subtle - ultimately affect us as well.

You'll know things have gotten worse in the river if you catch a fish with legs.