Earth Protect Blog

By Nicholas Kristof

© The New York Times Co.

Something alarming is happening between our legs. Sperm counts have been dropping; infant boys are developing more genital abnormalities; more girls are experiencing early puberty; and adult women appear to be suffering declining egg quality and more miscarriages.

It’s not just humans. Scientists report genital anomalies in a range of species, including unusually small penises in alligators, otters and minks. In some areas, significant numbers of fish, frogs and turtles have exhibited both male and female organs.

Four years ago, a leading scholar of reproductive health, Shanna H. Swan, calculated that from 1973 to 2011, the sperm count of average men in Western countries had fallen by 59%. Inevitably, there were headlines about “Spermageddon” and the risk that humans would disappear, but then we moved on.

Now Swan, a public health researcher at Mount Sinai Medical Center in New York, has written a book, “Count Down,” and sounds a warning bell. Her subtitle is blunt: “How our modern world is threatening sperm counts, altering male and female reproductive development, and imperiling the future of the human race.”

Swan and other experts say the problem is a class of chemicals called endocrine disrupters, which mimic the body’s hormones and thus fool our cells. This is a particular problem for fetuses as they sexually differentiate early in pregnancy. Endocrine disrupters can wreak reproductive havoc.

These endocrine disrupters are everywhere: plastics, shampoos, cosmetics, cushions, pesticides, canned foods and ATM receipts. They often aren’t on labels and can be difficult to avoid.

Chemical companies are as reckless as tobacco companies were a generation ago, or as opioid manufacturers were a decade ago. They lobby against even safety testing of endocrine disrupters so that we have little idea if products we use each day are damaging our bodies or our children. We’re all guinea pigs.

Aside from the decline in sperm counts, growing numbers of sperm appear defective — there’s a boom in two-headed sperm — while others loll aimlessly in circles rather than furiously swimming in pursuit of an egg. And infants who have had greater exposures to a kind of endocrine disrupter called phthalates have smaller penises, Swan found.

Uncertainty remains, research sometimes conflicts. There are competing theories about whether the sperm count decline is real and what might cause it and about why girls appear to be reaching puberty earlier, and it’s sometimes unclear whether an increase in male genital abnormalities reflects actual rising numbers or just better reporting.

Still, the Endocrine Society, the Pediatric Endocrine Society, the President’s Cancer Panel and the World Health Organization have all warned about endocrine disrupters, and Europe and Canada have moved to regulate them. But in the United States, Congress and the Trump administration seemed to listen more to industry lobbyists than to scientists.

Patricia Ann Hunt, a reproductive geneticist at Washington State University, has conducted experiments on mice showing that the impact of endocrine disrupters is cumulative, generation after generation. When infant mice were exposed for just a few days to endocrine-disrupting chemicals, their testes as adults produced fewer sperm, and this incapacity was transmitted to their offspring. While findings from animal studies can’t necessarily be extended to humans, after three generations of these exposures, one-fifth of the male mice were infertile.

What, if anything, does all this mean for the future of humanity?

“I do not see humans becoming extinct, but I do see family lines ending for a subset of people who are infertile,” Andrea Gore, a professor of neuroendocrinology at the University of Texas at Austin, told me.

More research is necessary, and government regulation and corporate responsibility are crucial to manage risks, but Swan offers practical suggestions for daily life for those with the resources. Store food in glass containers, not plastic. Above all, don’t microwave foods in plastic or with plastic wrap on top. Avoid pesticides. Buy organic produce if possible. Avoid tobacco or marijuana. Use a cotton or linen shower curtain, not one made of vinyl. Don’t use air fresheners. Prevent dust buildup. Vet consumer products you use with an online guide like that of the Environmental Working Group.

Many issues in headlines today won’t much matter in a decade, let alone in a century. Climate change is one exception, and another may be the risks to our capacity to reproduce.