A growing number of sports bras, shirts and leggings brands found with high levels of toxic chemical, watchdog warns

An increasing number of sports bra and athletic wear brands have been found with high levels of BPA in them, a chemical compound that's used to make certain types of plastic and can lead to harmful health effects such as asthma, cardiovascular disease and obesity, a watchdog group said on Wednesday.

After warning customers in October about BPA in athletic clothes, the Center for Environmental Health (CEH) said it sent legal notices to eight more brands whose leggings, shorts, sports bras, and athletic shirts after testing showed the clothing could expose wearers to up to 40 times the safe limit of BPA, based on standards set in California, which has some of the most protective health laws around chemicals in the United States.

Under California law — specifically Proposition 65, enacted in 1986 — the maximum allowable dose level for BPA via skin exposure is 3 micrograms per day.

Most BPA exposure, however, has been studied in the context of ingestion, and skin absorption has been studied mostly through receipts produced by a heat-generated printer, rather than through clothes. BPA is eliminated from the body within a few days, although some experts believe ongoing exposure from multiple sources raises some concern.

Ana Soto, professor of immunology with Tufts University School of Medicine said the research community has established the danger of BPA exposure both through ingestion and dermal absorption (or through the skin) into the body.

"We know about absorption of BPA by handling thermal paper used for store receipts," said Soto, who has researched endocrine-disrupting chemicals, including BPA, for over 25 years. "The danger of dermal absorption of BPA has been known for a while, too," she said. "When you are exposed to a little dose orally and a little dose transdermally, they will together make a large dose. I’ve studied the effects of low doses of BPA during fetal development and found that these low exposure levels increase the risk of obesity, diabetes, behavioral issues and cancer."

Meanwhile, the American Chemistry Council, an industry trade group, maintains that BPA "is the most thoroughly tested chemicals in use today and has a safety track record of more than 50 years."

In a press release in February, the ACC wrote that in 2018, the US Food and Drug Administration published findings from "the largest study ever conducted to study the full range of potential health effects from exposure to BPA. This study along with many others confirmed that BPA is safe at the very low levels to which consumers are exposed."

California-based CEH, which conducted the testing, was founded in 1996 as a nonprofit consumer advocacy group. It has raised alarm bells over chemicals in furniture, carpets, and flooring as well as lead and cadmium in children's jewelry. It advises universities, companies and hospitals on potential chemical dangers in products.

The newly tested athletic wear brands and their products include leggings from Athleta, Champion, Kohl's, Nike and Patagonia, sports bras from Sweaty Betty, athletic shirts from Fabletics and shorts from Adidas, Champion and Nike. CNN has reached out to the companies for comment.

A spokesperson for Athleta said in a statement Wednesday that, "As a certified B-Corp, Athleta is deeply committed to ensuring all our products are made to applicable safety standards. We believe the CEH claims have no merit and stand by our products and practices."

Previously, the CEH warned consumers in October that sports bras from Athleta, PINK, Asics, The North Face, Brooks, All in Motion, Nike, and FILA that were tested for BPA over a six months period showed the clothing could expose wearers to up to 22 times the safe limit of BPA, based on standards set in California.

The group had also tested athletic shirts in October from brands that included The North Face, Brooks, Mizuno, Athleta, New Balance, and Reebok and found similar results.

The CEH had sent legal notices to the companies last year, giving them 60 days to work with the center to remedy the violations before the group filed a complaint in California state court requiring them to do so. The group said it subsequently initiated lawsuits in February against the companies.

To date, the watchdog said its investigations have found BPA only in polyester-based clothing containing spandex. "We want brands to reformulate their products to remove all bisphenols including BPA. In the interim, we recommend limiting the time you spend in your activewear by changing after your workout," the group said.

Athleta, Nike, Reebok, The North Face and Victoria's Secret (which owns PINK) did not provide a comment to CNN at the time.

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BPA (Bisphenol A) is found in a large number of everyday products, from water bottles and canned foods to toys and flooring. In adults, exposure to BPA has been linked to diabetes, heart disease, cancer, obesity and erectile dysfunction.

Premature death was also associated with BPA exposure, a 2020 study found. More recently, BPA has also been linked to asthma in school-age girls.

"People are exposed to BPA through ingestion, from eating food or drinking water from containers that have leached BPA, or by absorption through skin," Kaya Allan Sugerman, CEH's illegal toxic threats program director, said in a statement.

"Studies have shown that BPA can be absorbed through skin and end up in the bloodstream after handling receipt paper for seconds or a few minutes at a time. Sports bras and athletic shirts are worn for hours at a time, and you are meant to sweat in them, so it is concerning to be finding such high levels of BPA in our clothing," Allan Sugerman said.

Over the past year, the CEH has asked more than 90 companies, including Walgreens and socks and sleepwear brand Hypnotic Hats, to reformulate their products to remove all bisphenols, including BPA. Some have already agreed to do so.

"Even low levels of exposure [to BPA] during pregnancy have been associated with a variety of health problems in offspring," said Dr. Jimena Díaz Leiva, science director with CEH.

"Consumers can also be exposed to BPA through personal care products like skin lotions or dental sealant," said Pam Factor-Litvak, professor of epidemiology at Columbia Mailman School of Public Health. With fabric found to have BPA, she said BPA is chemically bonded to fabric but can come off easily.

"The chemical bonds in BPA are not strong so it can could get on from plastic that contained the clothing or through a chemical that was used to make fabric stretchy," she said. "Manufacturers have found it to be a useful chemical because it can make fabric soft and malleable."

Although CEH litigates under California's Clean Drinking Water and Toxics Enforcement Act of 1986, it says the repercussions of its settlements extend beyond California "as it is most often economically infeasible for companies to reformulate for just the California market."

"Our legal action has been successful in pushing entire industries to remove certain chemicals from products like children's candy or toys," the group said in a statement to CNN Business in October. "These cases not only serve to protect California consumers but also consumers throughout the country."

Update: This story has been updated to add context about BPA exposure, including that skin exposure studies are limited and California's regulations are the most stringent in the United States.

CNN's Brenda Goodman contributed to this report.