Period underwear has become mainstream in the past few years, appealing to eco-conscious millennials who want to save money and the planet.
Their comfort factor has also made them popular to teens and young pubescent girls looking for a less invasive alternative to tampons.
But the evidence is beginning to emerge that up to two-thirds of period underwear contain toxic ‘forever chemicals’ linked to everything from kidney cancer to miscarriage and even infertility.
Thinx, the most popular brand of period underwear in the US, settled a three-year-long class-action lawsuit for $4million after Nicole Dickens, who previously used the products, accused the company of having forever chemicals in their underwear
Exactly how the toxic chemicals made their way into the underwear is unknown, but it is thought that it is the liquid-repellent outer layer that most likely contains PFAS. The forever chemicals can enter the bloodstream through pores in the skin. Once in the blood, they can travel anywhere in the body and could stay for many years. PFAS are associated with numerous health risks, including reduced fertility and a higher risk of miscarriage and kidney cancer
Independent third-party testing of Thinx’s underwear was alleged to show detectable levels of per- and poly-fluoroalkyl substances, known as PFAS.
They are a class of roughly 12,000 man-made chemicals which repel grease, water, stains and heat.
All PFAS contain carbon-fluorine bonds, one of the strongest known to man. They have been dubbed ‘forever chemicals’ because they take thousands of years to break down in the environment and body.
Dr Shruthi Mahalingaiah, an environmental health researcher at Harvard T.H. Chan School of Public Health, told DailyMail.com: ‘[PFAS] don’t break down or get metabolized in the body.
‘They are excreted in breast milk, menstrual blood, transfer to the fetus during pregnancy, and blood loss. A very small amount may be excreted via feces and urine.’
Dr Mahalingaiah bought a pair of period underwear for her daughter but was shocked to learn of their potential PFAS-content, especially because they are were marketed as a natural, organic product.
There has been speculation over exactly how and at what point in the manufacturing process the toxic chemicals make their way into the underwear.
It is thought that the stain- and water-resistant coating that is added to the fabric contains PFAS.
In its settlement, Thinx agreed to ensure PFAS are not ‘intentionally added’.
Consumer activist site Mamavation found 65 percent of period underwear it tested had detectable levels of fluorine in either the outer or inner crotch layer.
Mamavation sent 17 pairs of underwear from 14 brands to an Environmental Protection Agency-certified laboratory to calculate amounts of fluorine in the material over 10 ppm.
Eleven of the pairs had detectable fluorine in them.
Dr Ken Spaeth, chief of the division of occupational and environmental medicine at Northwell Health, told DailyMail.com the presence of PFAS ‘would typically be a manufacturing issue’.
He said: ‘PFAS has some use in settings where a barrier is intended to be created for blocking moisture, so that may be the issue.’
The health risks of PFAS are far-reaching but not fully understood. Links have been made to high blood pressure, some types of cancer, and even infertility.
Period underwear has become mainstream in the past few years, appealing to eco-conscious millennials who want to save money and the planet (file image)
The specific ways in which PFAS chemicals damage people’s health are unclear, but the fact that they affect a number of organ systems in the body is widely accepted.
Dr Spaeth said: ‘We don’t know the exact mechanisms, we just know the results of contamination.
‘The ability for these chemicals to disrupt the signaling is part of its endocrine disruption activities.
‘And it appears to be directly damaging of the cells of the liver and some of the other organ systems.
‘The cancer-causing pathways seem to relate to a number of different cell toxic pathways of inflammation and potential damage to genes.’
He added: ‘The full mechanism of injury is not fully known, but their ability to injure is certainly recognized nonetheless.’
PFAS in period underwear is particularly worrying, Dr Spaeth said.
He added: ‘In consideration of the fact that this is underwear, the genitalia are particularly susceptible to absorption. The skin in and around the vagina become potential areas of uptake.
‘Given some of the preliminary numbers, in terms of the levels that are found in some of these products, they would suggest that they’re quite high, so the potential for a substantial uptake has to be considered.’
Dr Spaeth said the evidence for PFAS’ effect on fertility is ‘mixed’.
He said: ‘There is certainly some evidence to suggest that [infertility] may be an issue… These chemicals are endocrine disrupting.
‘One of the ways that they are disturbing the endocrine system relates to the normal pathways and normal activities of hormone signaling, including estrogen and and some of the other hormones that are critical in reproductive health for women. So there’s certainly that potential, but it’s not clear exactly the extent to which that would impact fertility in particular.’
PFAS can also be dangerous during a number of stages of pregnancy, including to the developing fetus.
A study published in June found that middle-aged women with the highest amounts of PFAS in their blood were 71 percent more likely to develop high blood pressure than other women their age with lower levels of chemicals.
The study said that PFAS might be an ‘underappreciated contributing factor to women’s cardiovascular disease risk’.
One study in 2020 found that participants with the highest concentrations of PFAS in their blood were more than twice as likely to develop kidney cancer, compared to those with the lowest concentrations.
Humans already have a measurable level of PFAS chemicals in us already, which enter when we breathe air, eat food or drink contaminated water.
PFAS can also enter the body through the skin, as the particles are so small. Dr Spaeth said: ‘Once they’re in the body… they can travel in the bloodstream and therefore potentially reach anywhere in the body.’
Authors of a 2016 review said that half of the studies they looked at found that PFAS exposure led to increased time it took women to get pregnant.
A study in Minnesota in 2020 also found that removing PFAS-contaminated water supplies led to fewer premature births and fewer babies born with a low weight, plus an increased fertility rate.
In Sweden, researchers found that women with double the amount of PFAS in their blood compared to other participants were 50 percent more likely to suffer a miscarriage.
Dr Spaeth said: ‘It’s an additional exposure to a chemical that’s already in our bodies from a variety of sources. We’re all walking around with measurable levels of these PFAS chemicals in us already. Adding to that can only increase the risk of health effects. So in situations where one can identify additional exposures, it’s concerning for sure.’
There are ‘real potential ramifications’ from being exposed to PFAS, he said, due to endocrine disrupting chemicals which have a variety of health effects, including things like reproductive cycles.
Dr Spaeth added: ‘At the very least, these kinds of chemicals should not be in used in such ways that individuals are being exposed without some word of warning about it.’
