Thinx aren't the only menstrual products that allegedly contain toxic chemicals. Here are the other period products that may contain them, according to a report.

• Thinx settled a lawsuit claiming its period product contained harmful chemicals called PFAS. 
• The company denied the claim. It is paying up to $5 million in reimbursements to customers.
• Other products have reportedly tested positive for a chemical that suggests PFAS may be present.

People who wear period-proof underwear made by Thinx might be questioning what's in their menstrual products. The company just settled a class-action lawsuit that alleged the underwear contained long-lasting and potentially toxic chemicals called PFAS. Thinx has denied the claims, though the company has committed to paying up to $5 million in reimbursements to customers. 

But finding an unquestionably chemical-free replacement menstrual product may not be so easy. Some pads, tampons and other brands of period underwear may contain the same chemicals allegedly found in Thinx underwear, exposing an already sensitive area of the body to potential toxins. 

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PFAS are chemicals that have been linked to cancer and pregnancy complications

Research has linked the presence of PFAS in the body to various health harms, including an increased risk of some cancers, high blood pressure, complications during pregnancy, and low birth weight.

Some customers who wore Thinx claimed they developed other health problems affecting the area that came in contact with Thinx underwear: irregular menstrual cycles, urinary tract and yeast infections, and unexplained infertility, according to the class-action suit filed in California.

In a statement to Insider, Felicia Macdonald, vice president of strategic communications and public affairs for Thinx wrote, "We can confirm that PFAS have never been part of our product design. We will continue to take measures to help ensure that PFAS are not added to our products." Macdonald added that the company denies the allegations made in the lawsuit.

PFAS indicators have allegedly been detected in some popular pad and tampon brands

The same chemicals allegedly found in Thinx underwear may be present in other sanitary pads, tampons and incontinence pads, according to reports by Mamavation and Environmental Health News that were published last year. Menstrual cups were not studied in the reports. 

The consumer studies, conducted at labs certified by the US Environment Protection Agency, tested 23 types of tampons and 46 pad products for fluorine, an indicator of PFAS. 

Five popular tampon brands and 22 types of pads — even some advertised as organic — were found to detectable levels of fluorine between 11 and 154 parts per million, which strongly suggests that PFAS are present, according to the report. However the Mamavation report pointed out that this does not mean PFAS were added deliberately to the products; sometimes PFAS can be introduced to a commercial product accidentally in the supply chain.

Insider could not independently verify these reports. 

Some of the pads and tampons that reportedly included indications of PFAS include:

• Playtex SPORT Regular & Super Tampons
• Tampax Cardboard Applicator Unscented Tampons
• Up & Up Regular Tampons
• Always No Feel Protection Thin Liners
• Amazon Basics Daily Pantiliners Long Length

A past Mamavation investigation also looked at PFAS indicators in period underwear and found that in addition to Thinx, underwear from the brands Knix and Proof also contained fluorine. 

A representative of Knix wrote in an email to Insider: "We conduct regular testing for PFAS, and we have never intentionally added them to our products." The makers of the other period products mentioned above did not respond to Insider's requests for comment.

Some period products might be safer to use than others

There are more than 9,000 types of PFAS, so it is impossible to say with certainty if any period product is truly PFAS-free.

However, there were some brands that were found to have non-detectable levels of fluorine in the Mamavation consumer report. These included:

• Live Better Organic Cotton Pantiliners
• Lola Ultra Thin Liners Made with 100% Organic Cotton
• o.b. Organic 100% Organic cotton – regular
• Seventh Generation Organic Cotton Tampons
• Natracare Organic Tampons with applicator

Vaginas can be extra sensitive to chemicals

It's still not entirely clear how much exposure to PFAS via the skin affects our health, and women's health advocates are calling for more research regarding PFAS in period products specifically.

Period products are classified as medical devices by the US Food and Drug Administration, meaning that they are not as heavily regulated as medications. However new laws in New York and California aim to increase transparency around what ingredients are used in pads, tampons, and other menstrual products.

"We already know that PFAS has the ability to impact almost every organ of the body," Linda Birnbaum, former director of the National Institute of Environmental Health Sciences, told Mamavation. "The vagina is an incredibly vascular area and dermal exposure is often higher there than in other places of the body."

That's because it's not just PFAS that can affect your health. Period products containing fragrances, synthetic fibers, and other chemicals are also on the market, and have the potential to cause health issues.