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Endocrine Disruptors

Once upon a time, scientists firmly believed that “the dose makes the poison.” That is, if something was bad for you, lots of it would be very bad for you, but just a little bit of it might not be too bad at all.

Over the past decade, however, researchers have shown this isn’t always the case. In fact, some toxicants do more damage in small doses, studies show, than they do in large doses. And those small doses can be most harmful when they are very, very tiny indeed.

Such is the case with a class of chemicals known as endocrine disruptors, or estrogen mimickers, so named because they mimic hormonal activity in the body that can disrupt the reproductive development of a growing fetus. They have also managed to stir up large amounts of controversy, since it’s difficult to pinpoint the impact of individual chemicals upon humans.

Much of what we know to be true about endocrine disruptors we know from exposing laboratory mice to chemicals at critical stages of fetal development. From these studies we know that synthetic chemicals can cross the placenta and wreak havoc upon animals growing in utero. While the pregnant mother may appear to be unaffected, her children – and even her children’s children – will suffer reproductive problems, such as chromosomally abnormal eggs or infertility.

The best-known example of such consequences in humans is what happened to the offspring of women who took the drug DES to prevent miscarriages during the 1940s to 1970s. The mothers were fine, but their daughters suffered high rates of reproductive problems, such as fibroid tumors and endometriosis.

That drug was taken off the market, but countless other common household products and cosmetics made up of potentially dangerous toxicants remain on the market today. Women are exposed to a host of products (from laundry detergents to kids’ shampoos) containing ingredients that cause problems for laboratory animals when they are exposed to them at very low doses. The chemicals are known endocrine disruptors, but nobody knows for sure what they are doing to human embryos exposed during critical stages of development.

Which raises another tricky issue: Should manufacturers be forced to prove these products are safe before putting them on the market? Or should we allow them to be sold to the public until someone can prove they are doing more harm than good?

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To read more about this and other environmental health issues, go to: www.environmentalhealthnews.org, www.ourstolenfuture.org, or www.healthandenvironment.org