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Declining Male Fertility -- Urban Myth Or Alarming Trend?

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An endocrine disruptor is a natural or synthetic substance that disrupts some aspect of the endocrine system, which governs our hormones. It can be a prescription drug, a naturally occurring chemical, or an industrial or environmental pollutant.

The endocrine disruptors that concern some scientists most are those that have an estrogen-like effect, meaning that they can attach themselves to estrogen receptors in the body and cause different and unknown effects, including hormonal imbalances.

A lot of chemical pollutants may get into the body during a lifetime of eating and drinking polluted or contaminated water, says Joshua Barzilay, MD. "A lot of the chemicals that are in the water do have an estrogen-like effect," says Barzilay, who is an endocrinologist at Kaiser Permanente of Georgia, and also author of the book The Water We Drink.

Barzilay says that many of the worrisome endocrine disruptors are chemicals that result from the breakdown of items that have made our lives easier in the last 25 years, such as plastics and computer chips. And while they are not terribly poisonous per se, the molecules take a long time to break down, and they are accumulated in our bodies and stored in places such as fat tissue.

Drinking bottled water won't help either, says Barzilay. "It is not just the water itself: it is the fish that live in the water, the animals that we eat that drink from the water," he says, adding that it is also the incineration of items, such as plastics, that then return to the water via precipitation.

"It is all interconnected, one with the other."

These endocrine disruptors are of concern not only because they enter a person's body but also because they can alter the development of a growing fetus. "The development of the fetus in utero is in part governed by the estrogen and testosterone environment," says Barzilay. "A lot of these chemicals are released into the bloodstream during gestation, and they have an estrogen-like effect and may suppress development of testicles in utero."

Suppressing the development of testicles in utero could lead to infertility 20 years down the road. It also could lead to other problems, such as testicular cancer and hypospadias, a small but correctable malformation of the penis, both of which have been on the rise.

Barzilay says studies have found behavioral and physiological abnormalities in animals exposed in utero to too much estrogen at the wrong time. "But to do studies like that in humans is kind of tough," and even if researchers found the same effect, they may not be able to prove estrogen exposure was the cause.

Lindsay agrees that this argument is plausible, but he isn't convinced that is what is going on. "You can take small bits of hard data and you can try to link them all together into a global idea -- that is where the science begins to break down," he says. "It is very easy to overinterpret some of the harder science -- some of which has given us declining sperm counts, some not. So then coming up with a theory of why there might be declining sperm counts, you might argue, is premature because we haven't even shown that they are."

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