Harmful "Forever" Chemicals Are Linked to Delayed Puberty in Girls

Chemicals called PFAS (aka per- and polyfluoroalkyl substances) made news a few years ago when they were allegedly found in popular brands of period underwear, including Thinx, via independent testing. Now the harmful substances are making waves once again, as a recent study from researchers at the University of Cincinnati found that PFAS may delay puberty in girls.

Over 820 girls between ages 6 and 8 from Cincinnati and the San Francisco Bay Area were originally enrolled in the study, published last month in Environmental Health Perspectives. The researchers then followed up with them for years, tracking signs of puberty, such as breast development and pubic hair, and taking blood samples to measure their hormones and PFAS levels.

The researchers found that, across both geographic groups, about 85 percent of the participants had “measurable levels of PFAS,” according to a university press release. They also found that participants’ hormone levels decreased with PFAS exposure in a way that was “consistent with findings of the delay of the onset of puberty.”

Delayed onset of puberty in girls can lead to negative long-term health issues, corresponding author Susan Pinney, PhD, a professor of environmental and public health sciences at the University of Cincinnati’s College of Medicine, said in the press release. Those can include “a higher incidence of breast cancer, renal disease, and thyroid disease.”

The study found that girls who were exposed to PFAS had their puberty delayed by an average of five or six months, but Dr. Pinney stressed that that was an average figure. “There will be some girls where it’s delayed a lot more and others that it wasn’t delayed at all,” she said. “We are especially concerned about the girls at the top end of the spectrum where it’s delayed more.”

Another issue the study found: between the two groups, over 99 percent of participants had “measurable levels of PFOA,” aka perfluorooctanoic acid, a chemical described as “one of the most important” PFAS. PFOA, like other PFAS, “persists in the environment and does not break down,” the CDC notes. (PFAs are often called “forever chemicals” because of how long they can take to degrade.) It’s been found in bodies of water, which Dr. Pinney speculates may be a source of contamination leading to the results of her study; a chemical plant released PFAS into the Ohio River, the main source of drinking water in the area, for decades.

PFAS are used to make fluoropolymer coatings, which are used in a wide variety of products, including food, furniture, food packaging, and products that resist heat, oil, stains, grease, and water, according to the CDC. Independent lab testing in 2020 found evidence of PFAS in the moisture-wicking layer of Thinx period underwear, the part that lies directly against the vagina.

While Thinx ultimately settled a class action lawsuit for $5 million over the allegations of PFAS, the headlines made by the news have led to a greater awareness of these harmful chemicals and just how prevalent they are in products we use every day. Follow-up studies on period and incontinence products, in particular, found that many were contaminated (though often in lower amounts that suggested the contamination was unintentional).

With this new study revealing a connection between PFAS, hormones, and delayed puberty, it’s clear that tighter regulations and further research into these chemicals is necessary.

Before you go, check out our favorite skincare brands for teens: