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更新时间:2017-3-14 10:25:49 来源:纽约时报中文网 作者:佚名

Are 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.


“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.

“不仅精子数量下降,而且它们的质量、游泳能力以及完成任务的能力也有所下降,”西奈山伊坎医学院(Icahn School of Medicine at Mount Sinai)的流行病学家莎娜·斯旺(Shanna Swan)说。她还指出,研究者认为,精液问题与预期寿命缩短有关。

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.”

德克萨斯大学奥斯汀分校(University of Texas at Austin)的药理学教授、《内分泌》(Endocrinology)杂志的编辑安德烈·戈尔(Andrea Gore)这样对我说:“男性的精液质量和生育能力下降了。不是每个想繁殖后代的人都能实现愿望。男性功能紊乱对生活质量的影响以及给社会造成的经济负担是不可估量的。”

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.

人类和动物研究表明,罪魁祸首是塑料、化妆品、沙发、农药以及其他无数产品中常见的一种被统称为内分泌干扰物的化学物质。鉴于它与环境的关系,《纽约客》(The New Yorker)曾把这种危机文雅地称为“无声的精子”,25年来的无数研究最终导致了这种忧虑:这个世界的精子遇到了麻烦。

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.”

“我认为我们处在一个转折点上,”丹麦生育学者、这一领域的先驱尼尔斯·埃里克·斯卡克贝克(Niels Erik Skakkebaek)在接受采访时说。“这关乎我们能否持续存在下去。”

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.