This Chemical Can Impair Fertility, But It’s Hard to Avoid

This Chemical Can Impair Fertility, But It’s Hard to Avoid

Hormone-disrupting phthalates can be found in everything from plastics and household goods to personal care products. Studies have shown they may be harmful to women’s reproductive systems.

Phthalates dangers: Hormone-disrupting phthalates can be found in everything from plastics and household goods to personal care products. Studies have shown they may be harmful to women’s reproductive systems.

Kaci Aitchison Boyle always thought getting pregnant would be easy: just plan some romantic evenings and let nature take its course. So when Boyle and her husband decided to start a family in 2011, she expected to be snuggling a newborn by year’s end.

Boyle, then 32, ditched the birth control pills she had started taking as a teenager to regulate her “incredibly irregular” and painful periods, thinking it might take a while to start menstruating again. Instead, her wildly erratic schedule returned. She tried every ovulation test she could find to predict fertile days, but none worked for her.

Phthalates dangers

Phthalates dangers: It’s a chemical that can impair fertility, but hard to avoid | (Yukai Du/The New York Times)

After about eight months without a positive pregnancy test, Boyle sought help from her doctor. She learned she had polycystic ovary syndrome (PCOS), the most common cause of female infertility. A healthy woman has about a 1 in 5 chance of getting pregnant every month until age 32, when the odds begin to decline. PCOS, a health condition marked by excess androgen hormones and irregular menstrual cycles, reduces those odds by impairing ovaries’ ability to release eggs. That meant Boyle would likely have a harder time getting pregnant than other women her age.

Clearly, a woman can’t get pregnant naturally with her own eggs if she doesn’t ovulate, but what’s less clear is what causes PCOS and other conditions that reduce fertility. However, mounting research implicates prenatal exposures to synthetic chemicals that affect hormonal activity. And few have received more attention than phthalates, which are industrial chemicals with a history of reproductive toxicity found in hundreds of products, from plastics to cosmetics.

Phthalates are well-known hormone-disrupting chemicals, said Jodi Flaws, Ph.D., a professor of comparative biosciences and the director of the Interdisciplinary Environmental Toxicology Program at the University of Illinois. “They can interfere with the production, elimination or binding of any hormones in the body. And the reproductive system in particular is extremely sensitive to these compounds.”

Phthalates are added to a dizzying array of plastics, household goods, drugs, cleansers and personal care products to make them flexible, durable and fragrant. They easily escape from these products as vapors or particles, and are found in the urine of nearly every American, as well as in blood, sweat, breast milk, semen and ovarian fluids.

phthalates dangers

Image source: iStock

We consume phthalates that leach from food and beverage processing and packaging materials and that coat drugs. Our skin absorbs the compounds via lotions, makeup and shampoos and we even inhale particles that off-gas from blinds, shower curtains and linoleum floors.

“Here’s a class of chemicals we have a problem with and they’re ubiquitous,” said Tracey Woodruff, Ph.D., who directs the Program on Reproductive Health and the Environment at the University of California, San Francisco. “They’re used everywhere.”

Hormone-disrupting chemicals like phthalates change how reproductive organs develop in the womb in animal studies, with harmful effects that play out over a lifetime and even across generations. Scientists think prenatal exposures to phthalates and other toxics may set the stage for gynaecological disorders like PCOS and may make women more sensitive to other chemicals that impair fertility.

Studies by Dr. Flaws and her colleagues over the past few years have shown that female mice exposed in the womb to the same phthalate mixtures detected in pregnant women are born with fertility problems that they pass on to their female offspring. “Some problems will be evident at birth and some might not show up until puberty or later in life,” Dr. Flaws said. “We’re starting to think the same thing happens in humans.”

Scientists don’t have long-term human data on phthalates yet, Dr. Flaws said. But they know from the tragic consequences of giving pregnant women diethylstilbestrol, or DES — a synthetic estrogen prescribed to prevent miscarriage — that a mother’s exposures to hormone disrupters can harm her baby’s development with repercussions that span generations.

Millions of women took DES until 1971, when doctors realised it caused a rare vaginal cancer and the Food and Drug Administration advised against its use. Since then, scientists have learned that DES caused several reproductive problems, including infertility, in both boys and girls. “When the ones who could get pregnant had kids, their children had some of the same problems,” Dr. Flaws said.

The children you carry in your womb carry the seeds of their future children, Dr. Woodruff said. “So if you expose my future daughter or son, you’re also exposing their future daughter or son,” she said. “If the machinery that guides development gets mucked up, once you change it, it’s really hard to change it back.”

A history of neglecting research on women

Unlike some toxics that build up in fat cells, phthalates quickly pass through the body. But, since they are constantly replaced by other phthalates in our plastics and personal care products, scientists call them “pseudo-persistent.” Studies show that women have higher levels of phthalates than men, which they link to products like perfumes, hair spray and cosmetics, all tools of the trade for on-air broadcast journalists like Boyle.

Yet scientists understand less about how phthalates disrupt reproduction in females. That’s partly because it requires special imaging techniques to study women. And while problems like undescended testicles are visible in males at birth, problems with ovaries often aren’t apparent until puberty or later.

Nearly two decades ago, scientists showed that exposing pregnant rats to phthalates disrupts testosterone in their male offspring, leaving them with a suite of genital deformities and semen problems, dubbed “phthalate syndrome.”

“The whole process of making eggs and sperm is completely controlled by hormones,” said Patricia Hunt, Ph.D., a reproductive biologist at Washington State University. “In experiments, we can screw things up really, really badly with toxic exposures in developing males and females and permanently change an animal’s reproduction.”

Studies of phthalates’ effects on women have found problems. A 2018 study, for example, found an association between phthalate exposure and poor egg and embryo quality in women undergoing fertility treatments. But generally, the field of women’s health research is underfunded, Dr. Woodruff said.

Early clues to phthalates’ reproductive risks to women surfaced in 1975, when researchers found that Russian factory workers who were exposed to high phthalate levels on the job had fewer pregnancies and more miscarriages than unexposed women. In a study nearly two decades later, scientists found that phthalate exposures in rats targeted the ovaries, the primary regulator of reproduction and fertility in women.

Phthalates dangers: Reducing exposures

Couples, like the Boyles, don’t usually read studies about rat infertility before trying to start a family. And Boyle wasn’t thinking about hormone-disrupting chemicals during her 20s, when she worked at radio stations in Seattle or when she landed a job as co-host for a TV morning show at the age of 31. It wasn’t until she went through several rounds of in vitro fertilisation transfers that she started wondering if environmental chemicals, like those in the foundation and eye makeup she wore on camera, could affect fertility.

Boyle’s fertility doctor at Pacific NW Fertility clinic, Lora Shahine, M.D., had always told her patients to focus on exercising and eating well to boost fertility. She started advising them to reduce their exposures to phthalates and other hormone-disrupting chemicals after she read about “overwhelming evidence” linking them to gynaecological and pregnancy problems when researching the 2015 book she co-wrote, “Planting the Seeds of Pregnancy.”

Doctors typically can’t know for sure whether phthalates are causing an individual’s fertility problems, but they can point to a growing body of research that links higher levels of the chemicals to a higher miscarriage risk, lower fertility and difficulty conceiving. “This is not something that was taught in medical school,” Dr. Shahine said.

IVF treatment in Singapore, phthalates dangers

Image source: Shutterstock


It’s challenging to study women with fertility problems, Dr. Woodruff said, because it’s hard to disentangle chemical exposures from other potential contributors, including gynaecological conditions. And doctors are taught to think about immediate causes of disease, like infection, not chemical exposures that cause chronic conditions, she said.

“We’re one of the first medical schools to have a lecture on environmental reproductive health for medical students,” Dr. Woodruff said. “Most medical schools don’t have that.”

It wasn’t until 2013 that the American College of Obstetricians and Gynaecologists, working with the University of California, San Francisco, issued a statement urging clinicians to identify and reduce patients’ exposure to toxic environmental chemicals, based on “sufficiently robust” evidence linking them to adverse reproductive and developmental health outcomes.

Studies over the past several years have linked higher phthalate levels to lower levels of successful IVF outcomes and increased miscarriage risk with and without IVF. In April, researchers warned that mothers’ phthalate exposures before conception may be an overlooked risk factor for adverse pregnancy outcomes.

Fertility clinics don’t test for phthalates so Boyle didn’t know her levels. And she couldn’t always tell which products contained phthalates because companies can avoid disclosing them by citing proprietary claims and simply listing “fragrance.” But many cosmetics sold in the United States contain phthalates that are banned in the European Union. And she worried that the makeup she slathered on her face for TV was seeping into her skin and possibly getting into her lungs.

Dr. Shahine advised Boyle to make changes bit by bit. It’s possible to reduce exposures by choosing “phthalate-free” personal care products and avoiding scented soaps, air fresheners, fabric softeners and other cleansers. And it’s best to choose “fragrance free” rather than “unscented,” Dr. Woodruff said, because companies can use other chemicals to hide scent.

Cutting down on takeout food can also reduce exposures. “If you eat a higher diet of food prepared outside the home, you’re going to have higher exposure to phthalates,” Dr. Woodruff said. A 2018 study by Dr. Woodruff and a team of researchers found that eating more takeout or restaurant food, especially cheeseburgers, was associated with higher phthalate exposures than eating at home. It’s not clear whether the chemicals are leaching from processing equipment, packaging materials or food-handling gloves, she added, “but it’s better to eat fresh fruits and vegetables prepared in your home.”

Still, it’s hard for an individual to stop all their phthalate exposures because they’re so pervasive. Dr. Woodruff advocates for government policies that switch from toxic to safer alternatives. “Otherwise you’re really at the mercy of the industry.”

Nearly three years ago, after enduring several more rounds of IVF transfers and two painful miscarriages, Boyle gave birth to her daughter, Scarlett. She’ll never know why her body had so much trouble ovulating and holding onto her pregnancies. And there’s no way of knowing whether her efforts at avoiding products with phthalates and other toxic chemicals helped her get pregnant.

Then, out of the blue, she learned some other news this year. “We’re expecting in September, and I’ll be 41 in October. This was a complete surprise.”

This Chemical Can Impair Fertility, but It’s Hard to Avoid” by Liza Gross © 2020 The New York Times Company

Liza Gross is a science and health journalist and author of “The Science Writers’ Investigative Reporting Handbook.”

This story was originally published on 25 August 2020 in NYT Parenting.  

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