Thinx Responds To Claims Toxic Chemicals Were Found In Period Underwear

Period underwear brand Thinx will ‘dramatically’ expand the list of chemicals it tests for after an Australian scientist claimed he found toxic chemicals in the crotch of some of the brand’s products.

The New York-based company has hit back at claims 'high levels' of per-and polyfluorinated substances (PFAS) were detected in its period underwear, saying it goes to great lengths to keep its products body-safe.

Thinx makes feminine hygiene products, including period underwear, to offer women a reusable alternative to pads and tampons. The products can be bought online in Australia.

Last week, a report claimed independent testing had found PFAS on two varieties of Thinx underwear. Thinx maintains that its own third-party testing has never detected any traces of PFAS.

Image: Thinx

PFAS are a group of manufactured chemicals that have been used for decades to make products that resist heat, stains, grease and water.

According to the Australian health department, PFAS might be present in furniture and carpets, food containers and makeup along with other personal care and cleaning products.

Studies in the U.S. have linked some PFAS to thyroid and kidney cancer, among other health issues. But the health department maintains there is no consistent evidence that exposure causes adverse health effects in humans.



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The U.S. report, published in Sierra, cited a small pool of findings collected by Australian-born nuclear scientist Dr Graham Peaslee, who now works in Chicago.

Sierra writer Jessian Choy wrote that she sent Peaslee unworn samples of Thinx's organic cotton underwear line, along with two varieties from European brand Lunapads.

Speaking to 10 daily, Peaslee confirmed he had been contacted by a woman to run tests on the underwear and that they had previously worked on a similar project about menstrual underwear together.

Peaslee said he used a form of nuclear reaction analysis called particle-induced gamma-ray emission (PIGE) to conduct fluorine measurements on the samples.

He said he found a layer of "fluorinated material" inside the crotch of all Thinx varieties supplied to him.

According to the Sierra report, the tests found 3,264 parts per million (ppm) PFAS in a sample of the My Thinx 'organic' brief and 2,053 ppm in the 'organic' BTWN Shorty underwear, made for teens.

Peaslee said copper and zinc were also present in the Thinx samples.

He said this is indicative of copper and zinc oxide nanoparticle treatments -- or antimicrobials -- which are used in some textiles.

The tested Lunapads underwear reportedly did not contain the chemicals that the Thinx underpants tested positive for.

Despite the findings, Peaslee acknowledged his sample size was "too small to say anything definitive" and that the results would not necessarily extend to samples in all countries.

"The results certainly need to be verified more broadly," he said, but added that he felt consumers "have the right to know".

Thinx has contested the Sierra report, telling 10 daily that its own third-party testing has never detected any harmful chemical levels, including PFAS.

“All Thinx and Thinx (BTWN) underwear undergo the most stringent product safety evaluations available," CEO Maria Molland said.

"While Thinx products comply with all legal safety standards in Europe and the U.S. we go beyond those requirements and are constantly working to improve our products and manufacturing processes to use the safest substances and materials available."

The company has publicly released its latest third-party lab tests from September 2019, which appear to show no evidence of PFAS.

The company claimed it had reached out to Sierra "to learn more about their testing process". 

Molland added Thinx will "dramatically" expand the list of chemicals it tests for to develop a "robust, safer chemical policy" across the brand.

"If any unregulated PFAS chemicals are ever found in our products, we will move swiftly to remove them," she said.

Another popular Australian brand of period underwear is Modibodi.

It was not involved in Peaslee's testing.

Modibodi CEO Kristy Chong told 10 daily its materials and treatments have been scientifically tested to ensure they comply with global standards and requirements.

"We do not use PFA or nanotechnology in our garments," Chong said.

Peaslee said he hopes his initial tests will encourage others to follow suit.

"Given the growing concern about using these chemicals only for essential uses because of their environmental and human health issues, I think we need to identify where they are being used and urge brands to avoid PFAS," he said.