Are Penises Really Shrinking? Here's What the Science Says

One epidemiologist took a look at the research—and she's sounding the alarm.

Environmental scientists have warned for years that pollution can impact all aspects of health. Now, a new book has a memorable warning: Industrial chemicals are making penises shrink—and impacting fertility. The book, Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race, is written by Shanna H. Swan, MD, a professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York City.

Dr. Swan is a respected researcher who has worked for more than 25 years to try to understand the impact chemicals have on our environment and our health. So when she says penises are shrinking due to pollution, it's worth paying attention to.

While plenty of people are cracking shrinking penis jokes on social media about this, Swan's book is based in science—and it has real world implications. "I have been speaking to scientists and scientific organizations and publishing research about these environmental- and reproductive-health effects for many years," Dr. Swan tells Health. "My goal with this book is to reach as many people as possible and bring their attention to the current crises in reproductive health as well as the chemicals in our environment and lifestyle factors that are driving these changes."

Here's what the science says, and why it matters.

OK, are penises really shrinking?

Yep, and it starts in the womb. "When a pregnant woman has higher body concentrations of chemicals like phthalates, which lower testosterone levels, the development of her baby boy's genitals is disturbed," Dr. Swam explains. "This results in what has been named the 'phthalate syndrome,' which includes smaller penis size."

Dr. Swan published data on this back in 2005. Her work, which appeared in the journal Environmental Health Perspectives, linked phthalates—man-made chemicals widely used in toys, detergents, nail polish, soaps, and more—to physical changes in young boys. Those born to mothers with higher concentrations of phthalates in their bodies were more likely to have a smaller penis size at their 12-month checkup and testicles that hadn't fully descended. Additional research has found similar results.

Are Penises Really Shrinking? Here's What the Science Says
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What is happening with fertility?

There is something called the "1% effect," which has reproductive issues in men increasing at a rate of about 1% each year in Western countries. This includes decreased testosterone levels and declining sperm counts, which can impact fertility. Worth noting: fertility in the world is dropping by a rate of about 1% each year, according to data from The World Bank.

Women are affected, too. Rates of miscarriage in the US are increasing by about 1% each year as well.

Dr. Swan calls the change in sperm counts and other negative measures of reproductive health "alarming," adding, "these changes are driven by a combination of poor lifestyle choices and the hundreds of chemicals that people are exposed to on a daily basis throughout the world."

Other experts agree this is a problem

"There is certainly a growing body of medical literature suggesting that there may be a decline in sperm counts over time," Joshua A. Halpern, MD, assistant professor of urology at Northwestern University Feinberg School of Medicine in Illinois, tells Health. But the research isn't perfect, he says, noting that it's "very difficult to look back and compare different groups of men over time."

"The studies certainly raise significant concern, but we need better research to determine what is really going on and why," he says.

Women's health specialist Jennifer Wider, MD, tells Health that this information is important to pay attention to. "This is a well-researched book written by a respected expert in the field—shedding light on the fact that chemicals in our environment can have a detrimental effect on reproduction and our hormones," she says.

OK, so what can you do about it?

Count Down specifically breaks down things you can do on a personal level to reduce your exposure to hormone-altering chemicals and make lifestyle changes that will support healthy reproductive development. "One easy strategy is to swap out plastic food-storage containers and bottles in your kitchen for glass, ceramics, or metal ones," Dr. Swan says. "This will help reduce exposure to hormone-altering chemicals, which is not only important for pregnant women and couples planning a pregnancy, but for everyone because these chemical exposures can have long-term ripple effects on your health."

Dr. Wider recommends that you "pay attention" to what you're exposed to. "Phthalates, chemicals used in plastic production, and other endocrine-disrupting chemicals should be limited in everyday products, and we should all demand change from governing bodies and stronger policies to protect children, and men and women," she says.

If you're planning to have kids, you can also do other things to try to boost your fertility. "Most things that are good for overall health are also good for fertility," Dr. Halpern says. "Healthy diet, regular exercise, and stress reduction are key. And while it may be difficult to avoid some of the toxins found in the products we use every day, people should try to stay away from clearly harmful exposures, such as cigarette smoking and noxious chemicals."

Swan's website also has a resources section with info about and links to more than a dozen different organizations that offer guidance on reducing your exposure to toxic chemicals.

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