After months of trying to get pregnant, Kirstie Phillips threw out all her scented candles. She also trashed her body wash, moisturizer and the scented plug-ins she used in her Suffield, Conn., home.
Phillips, a 30-year-old nurse anesthetist, had always taken for granted that she would conceive easily. She was active, she ate healthy and she came from a family with no history of infertility. Her husband had no known health issues either.
But when doctors discovered that her ovaries weren’t functioning properly, Phillips became convinced by chatter on a Facebook group—and scientific papers she subsequently looked up—that synthetic chemicals found in everyday consumer products were to blame.
Two years after reducing her exposure to chemicals, Phillips, with the help of artificial insemination, gave birth to a son. Ten months later, she was pregnant again, this time naturally. In October of last year she gave birth to a daughter. She is certain her lifestyle change made the difference.
“I don’t have proof but I can’t think of anything else,” she said.
Fertility rates around the world are declining, including in the U.S., where the total fertility rate last year fell to the lowest on record.
Many scientists believe chemicals found in everyday products could be a factor, with a growing body of research showing potential negative effects for male and female reproductive systems, from exposure even in tiny amounts.
“The power of these chemicals to impact fertility is mind boggling,” says Patricia Hunt, a professor at the School of Molecular Biosciences at Washington State University who has studied chromosomally abnormal human eggs for several decades. “We have all sorts of evidence that indicates: ‘Whoa, we’re in serious trouble here.’”
The scrutiny runs parallel to rising skepticism about traditional explanations for various health-related quandaries—perhaps most prominently embodied in Robert F. Kennedy’s nomination to run the U.S. Department of Health and Human Services.
Kennedy’s most controversial positions have been around vaccines and fluoride, but he has for years contended that man-made chemicals are affecting fertility. He has also gone well beyond the established science on the issue, saying he thinks chemicals are leading to gender confusion in children.
The chemicals Hunt and other scientists are concerned about are called endocrine disrupters because they mimic or block the hormones responsible for many of the body’s essential functions, including reproduction. They can be found in everything from plastic packaging and toys to sofa covers and cosmetics.
On Wednesday, the state of Texas cited adverse reproductive effects in a lawsuit against several manufacturers, alleging they falsely advertised their chemical products as safe for ordinary household products.
Even as the links between chemicals and fertility issues are more widely acknowledged, pitched debates continue about what levels of exposure are dangerous.
The chemical industry disputes that its products, at the levels humans are typically exposed to, are linked to adverse health outcomes. The American Chemistry Council, a U.S. trade body, says fertility is influenced by multiple factors and that its members “undertake extensive scientific analyses to evaluate the potential risk of their chemicals, from development through use and safe disposal.”
Given the ubiquity and volume of such chemicals, some scientists say they could interact with one another in the human body in ways that could have dramatic effects. Some chemicals build up over time, while others leave the body after a few hours but are so commonly used that people are continually exposed anyway.
The U.S. Environmental Protection Agency lists “interference with reproduction” as one of the possible adverse effects from exposure to chemicals that disrupt the endocrine system. The agency also notes that current testing methods make it difficult to assess the extent of the risks.
There are a number of factors involved in declining fertility, researchers say, including women choosing to have babies later in life and more couples choosing not to have children at all.
In research published in 2021, Melissa Kearney, an economist at the University of Maryland specializing in demographics, along with two co-authors, looked for possible explanations for the continued drop in U.S. birthrates. They found that “broad societal changes that are hard to measure or quantify” were likely behind the shift, and that state-level differences in factors including unemployment, abortion laws, housing costs and contraceptive usage could explain almost none of the decline.
Kearney says she’s seen research that links environmental factors to global sperm count declines, which have been connected to a decline in fertility.
“I have seen nothing that makes me doubt the validity of that research, and I find it intriguing (and troubling),” she wrote in an email. “The various sets of factors are all likely playing a role.”
Among the chemical classes researchers have linked to lower fertility are PFAS—found in everything from drinking water and nonstick cookware to takeout containers and waterproof clothing—and nicknamed “forever chemicals ” for their tendency to hang around.
Last year, Mount Sinai researchers concluded that higher blood concentrations of certain PFAS were associated with a significant reduction in the likelihood of pregnancy and live births.
Other studies have shown that certain PFAS can disrupt reproductive hormones and delay puberty and have been linked with increased risks for polycystic ovary syndrome—the condition Phillips had—and endometriosis, a condition in which tissue irregularly grows outside the uterus, such as in the ovaries and fallopian tubes.
Bisphenol-A—a chemical widely used to line drinks cans—has also been linked to fertility issues in women. In men, studies have linked BPA to poor semen quality, undescended testicles and testicular cancer. The U.S. and many other countries no longer allow BPA in baby bottles and sippy cups.
In the U.S. BPA has been found in over 90% of the general population via urine samples.
In 2023, Europe’s top food regulator formally proposed slashing what it calls “the tolerable daily intake” for BPA by 20,000 times. The move—if approved by the European Parliament—would effectively ban the use of BPA in everything that comes into contact with food. Among the concerns the regulator raised was the link between BPA and reproductive toxicity.
The U.S. Food and Drug Administration has said it is considering a petition from some U.S. scientists to follow suit. It pointed The Wall Street Journal to its 2014 safety assessment that concluded that BPA “is safe at the levels occurring in foods.” When it comes to PFAS, the FDA says it is currently working to better understand how exposed Americans are to the chemicals in food.
Another class of chemicals are phthalates, found in scented products of the kind Kirstie Phillips threw away, and in certain plastics. Studies have linked phthalates to lower egg yields in women. They have also been linked to a shorter ano-genital distance in men, which in turn has been correlated with a lower sperm count.
Shanna Swan, a professor of public health at the Icahn School of Medicine at Mount Sinai in New York City, has spent decades researching the impact of phthalates and other endocrine disrupters.
In 2017 she published a sperm-count analysis that showed a nearly 60% decline in human sperm counts across the developed world between 1973 and 2011.
While some scientists have argued that lower sperm counts aren’t neatly tied to declining fertility, Swan is convinced that her research supports the contention that endocrine-disrupting chemicals are making it harder for humans to have babies.
Swan points to studies showing that dogs and horses are suffering from a decline in fertility.
“There is no question that they are exposed to the same chemicals we are,” says Swan. “There is also no question that these animals are not voluntarily delaying child bearing.”
Write to Saabira Chaudhuri at Saabira.Chaudhuri@wsj.com
