Thinx, the period panty brand recently purchased by Kimberly-Clark, has settled a class action lawsuit that its products, which are marketed as a safer, more sustainable approach to menstrual hygiene — contain potentially harmful chemicals.

Plaintiffs say third-party testing on the underwear revealed the presence of short chain per-and polyfluoroalkyl substanes (PFAS), human-made chemicals that are found in many consumer and industrial products, do not easily break down and have been linked to adverse health effects.
 
“Through its uniform, widespread, nationwide advertising campaign, [Thinx] has led consumers to believe that Thinx Underwear is a safe, healthy and sustainable choice for women, and that it is free of harmful chemicals,” the complaint filed in May 2022 said. “In reality, Thinx Underwear contains harmful chemicals … which are a safety hazard to the female body and the environment.”
 
Thinx has denied these allegations saying that PFAS have never been part of its product design and that it will continue to take measures to ensure the chemicals are not added to its products. However, the lawsuit alleges that, despite the fact that PFAS and other environmental toxins are present in a wide range of consumer products, Thinx misled consumers, marketing itself as an “organic, sustainable and nontoxic” alternative to traditional one-use menstrual products, including pads and tampons. This comes at a time when a growing number of menstruating people are proactively seeking out safer, more environmentally friendly products.

The U.S. District Court for the Southern District of New York gave the settlement its preliminary approval in December, more than two years after the litigation began.

Class members were notified of the settlement this week. As part of it, Thinx has committed to paying up to $5 million to provide reimbursement as well as making some changes to its marketing and production processes.

Anyone who bought Thinx underwear between Nov. 12, 2016, and Nov. 28, 2022, can submit a claim online before mid-April to choose between cash reimbursement for up to three pairs of purchased underwear at $7 each or a voucher for 35% off a single purchase of up to $150 (for a maximum discount of $52.50).
 
Legals woes concerning the presence of PFAS are nothing new in feminine hygiene.  Last year, a report from Mamvation assessed 46 sanitary pads, panty liners and incontinence pads and found that 22 of them had detectable levels of fluorine, an indicator of the presene of PFAS.

EHN.org partially funded the testing and Pete Myers, chief scientist of Environmental Health Sciences, which publishes Environmental Health News, reviewed the findings. The report came just a month after Mamavation found PFAS evidence in several popular tampon brands.  A past investigation also looked at PFAS in period underwear and found 11 of 17 tested pairs had detectable levels of fluorine.

In addition to Thinx, period underwear brand Knix Wear,  is being sued two California women because of marketing claims they say are misleading. The underwear is “PFAS free” and “designed to be both safe and effective” – despite allegedly containing the chemicals, which have been proven to harm human health, according to the proposed class action lawsuit filed in the U.S. District Court for the Northern District of California.

PFAS can build up in the body for long periods and cause numerous health harms, including weakened childhood immunity, low birth weight, endocrine disruption, increased cholesterol levels, weight gain in children and dieting adults, and other health problems.