A sperm under the influence of an endocrine disrupting chemical in sunscreen. Because of chemicals like these, sperm have trouble swimming properly to deliver the goods.
Prof. Timo Strünker, Münster, Germany
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.
"There's been a decrease not only in sperm numbers, but also in their quality and swimming capacity, their ability to deliver the goods," said Shanna Swan, an epidemiologist at the Icahn School of Medicine at Mount Sinai, who notes that researchers have also linked semen problems to shorter life expectancy.
Perhaps you were expecting another column about political missteps in Washington, and instead you've been walloped with talk of bad swimmers. Yet 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 the 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). These problems are often found together and are labeled testicular dysgenesis syndrome.
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.
"The semen quality among young Chinese men has declined over a period of 15 years," concluded the study, which involved more than 30,000 men.
Perhaps even more alarming, Canadian scientists conducted a seven-year experiment on a lake in Ontario, adding endocrine disrupting chemicals and then observing the impact on fathead minnows. The chemicals had a devastating impact on males, often turning them into intersex fish, with characteristics of both sexes but incapable of reproducing.
The crisis for male reproductive health seems to begin in utero. Male and female fetuses start pretty much the same, and then hormones drive differentiation of males from females. The problem seems to be that endocrine disrupting chemicals mimic hormones and confuse this process, interfering with the biological process of becoming male.
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. Receipts from thermal printers, like at gas pumps and A.T.M.s, are also suspect. When in doubt, she consults guides at ewg.org/consumer-guides.
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. America 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. The industry's deceit marks a replay of Big Tobacco's battle against regulation of smoking.
If you doubt the stakes, look at the image with this column of a hapless sperm swimming in circles, and remember this: Our human future will only be as healthy as our sperm.
Michael Hall North Carolina
Many of the comments focus on the issue of overpopulation and how decreasing human fertility could be a good thing. This is really missing the point of how males are being damaged in-utero due to these chemicals. The testicular dygenesis syndromes discussed are only one issue that science has been able to link so far. It is aptly put that "endocrine disrupting chemicals...interfere with the biological process of becoming male." Malformed males, either overtly phenotypically or hormonally thus emotionally, should be a concern for everyone. This equals more human suffering, not to mention increased medical and societal costs. In addition the view that this may be a good thing to reduce population growth ignores the fact that the populations most at risk for this damage to male biology are in Western advanced countries, where fertility rates are already dropping due to couples having fewer children than in poor developing countries, so this is not the solution. The insanity of not more tightly regulating these chemicals after so many decades of evidence shows the corruption of our government and cultural choices where "jobs and economic prosperity" trumps protecting human health. As long as we worship money and convenience above all, this will continue.
WhiteMtnRider TX
Endocrine Disruptors have been causing breast cancer and other diseases in women for years, with NO regulation from US Govt (even while so many of these additives and pesticides are banned in European countries!). This article points the finger at a male's most prized possession - his reproductive organs. Maybe now the lawmakers and regulators will give a hooey.
Petey tonei Ma
My physician aunt who would have been almost 100 years old, would tell us back in the early 1990s that synthetic diapers wrapped tight around boys' loins, would eventually negatively impact sperm count and quality. She would insist we use loose cloth diapers for our boys.
sf ny
The hormones fed to our food supply may have a little something to do with it.
Hormones have changed the start of menses to younger and younger girls with each passing generation, where it's not uncommon to be 10 years old now. This is a most certain worry or concern in the human evolution process.
All of the chemicals in our environment have been messing with human physiology for decades now. Something that Rachel Carson knew all too well.
Can't say she, (and others) did not try to warn us. But as always greed prevails.
Greg Maguire
La Jolla, CA Endocrine disruptors are prevalent in our environment, including many of the skin and hair care products that are applied to and left on our bodies. Now emerging are esthetician groups and manufacturers who are aware of this problem and making and using products without endocrine disruptors. In the larger view, understanding our exposome is key to understanding our health. In my field of study, neurodegeneration, diseases such as amyotrophic lateral sclerosis (ALS) and Parkinsons are not genetic, herditary diseases, but are mutlifactorial, including a strong component of exposure to environmental toxins. Mr. Kristof's important article is one more example of why a strong EPA is needed more than ever before in our advancing industrial world full of more and new kinds of chemicals.
CAROL AVRIN CALIFORNIA
I read that fifty percent of the human conceptus are too flawed to be implanted. (When extremely impaired foetus are conceived,the religionists should butt out.)Some of chemicals leached into the environment mimic estrogen which inhibits androgen expression; hence intersex morphology. This messes up a lot of life on Earth. Therefore, when greed preempts science, we are progressing towards the destruction of all advanced life on this planet.
Cathy PA
I've been wondering lately if the rise of gender confused individuals, such as transexuals, might be due to the effects of endocrine disruptors in the environment. Certainly it's well known that when frogs and small fish grow up in waters with these chemicals it can effect their gender development. Though, I also think it's a case where overly gendered toys convince children that if they prefer the toys of the opposite gender they must really be the opposite gender.
Ed Homestead
The major influence on human reproduction is estrogen. Estrogen has become ubiquitous in the environment. The majority of estrogen in the environment comes from plastics. Plastic is the major component of manufacturing. The amount of estrogen in humans has risen exponentially since the invention of plastic. How this is ever going to be reversed is unclear, but fewer humans in the world is not a problem but a blessing. Fewer people, less plastics and other chemicals that contain estrogen. But it is an individual choice as to what we purchase and what we use in our everyday life. This requires a level of critical thinking that is absent in our culture. We have come to believe all the lies that corporations through their advertising mind control told us we must have to live a useful and happy life. Take a stroll around any big box store, grocery store, or the ubiquitous pharmacy, and the amount of useless and frivolous junk is mind blowing. Until we learn how to disconnect from the lies brought to us over the electronic medias and instead think for ourselves, the junk will always be with us, and so will the estrogen.
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