Are chemicals putting your sperm in trouble?

Let’s begin with sex.

As a couple finishes its business, millions of sperm begin theirs: rushing toward an egg to fertilize it. But these days, scientists say, an increasing proportion of sperm — now about 90 percent in a typical young man — are misshapen, sometimes with two heads or two tails.

Even when properly shaped, today’s sperm are often pathetic swimmers, veering like drunks or paddling crazily in circles. Sperm counts also appear to have dropped sharply in the last 75 years, in ways that affect our ability to reproduce.

This isn’t just a puzzling curiosity, but is rather an urgent concern that affects reproduction, possibly even our species’ future.

Andrea Gore, a professor of pharmacology at the University of Texas at Austin and editor of the journal Endocrinology, put it to me this way: “Semen quality and fertility in men have decreased. Not everyone who wants to reproduce will be able to. And the costs of male disorders to quality of life, and the economic burden to society, are inestimable.”

Human and animal studies suggest that a crucial culprit is a common class of chemical called endocrine disruptors, found in plastics, cosmetics, couches, pesticides and countless other products. Because of the environmental links, The New Yorker once elegantly referred to the crisis as “silent sperm,” and innumerable studies over 25 years add to the concern that the world’s sperm are in trouble.

And so are men and boys. Apparently related to the problem of declining semen quality is an increase in testicular cancer in many countries; in undescended testicles; and in a congenital malformation of the penis called hypospadias (in which the urethra exits the side or base of the penis instead of the tip).

There is still disagreement about the scale of the problem, and the data aren’t always reliable. But some scientists are beginning to ask, At some point, will we face a crisis in human reproduction? Might we do to ourselves what we did to bald eagles in the 1950s and 1960s?

“I think we are at a turning point,” Niels Erik Skakkebaek, a Danish fertility scholar and pioneer in this field, told me. “It is a matter of whether we can sustain ourselves.”

One recent study found that of sperm donor applicants in Hunan province, China, 56 percent qualified in 2001 because their sperm met standards of healthiness. By 2015, only 18 percent qualified.

How should we protect ourselves? Swan said she avoids plastics as much as possible, including food or drinks that have touched plastic or been heated in plastic. She recommends eating organic to avoid pesticide residues, and avoiding Tylenol and other painkillers during pregnancy. When in doubt, she consults guides at

Yet this isn’t just a matter of individual action, but is also a public policy issue that affects tens of millions of people, their capacity to reproduce and their health and life expectancy.

What’s needed above all is more aggressive regulation of endocrine disrupting chemicals. The United States has been much slower than Europe to regulate toxic chemicals, and most chemicals sold in the U.S. have never been tested for safety.

The larger question is why we allow the chemical industry — by spending $100,000 on lobbying per member of Congress — to buy its way out of effective regulation of endocrine disruptors.

If you doubt the stakes, remember this: Our human future will only be as healthy as our sperm.

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