Helen Lynn Senior Consultant and Research Fellow at Wen shares her thoughts on new testing from Which? showing PFAS and biocidal silver in period pants.

About the testing 

In a follow up to their 2023 testing Which? has tested a range of period pants for fit, comfort and absorbency. They also carried out independent chemical testing to see if they contain chemicals of concern. Once again, levels of PFAS (a forever chemical) and biocidal silver were found. Which? notes, they didn’t test all the period pants they reviewed; only the pants that scored highly on comfort, absorbency and claimed their products did not contain PFAS or biocidal silver. 

The results reveal only one of the three products that chemical testing was performed on had no detectable silver and the PFAS’s tested for either not present or below limits set out by EU REACH regulation.  Some of the pants reviewed are certified by Oeko Tex, which certifies that the products are tested for the presence of harmful substances.  

While an Oeko Tex certification explicitly prohibits the intentional use of PFAS and biocides, Which? found there is potential for trace contamination during manufacturing or from packaging. This is worrying as products which avoid the use of harmful substances like PFAS and biocidal silver are at risk of contamination during the manufacturing processes. 

This matters because the vagina is such an absorbent part of the human body and because of the regular exposure from period products. 

While Which? is concerned about levels of PFAS and silver in period products and the top-scoring period pant had no detectable silver and passed its PFAS test, it still scores products highly where PFAS and biocidal silver were found. In the EU

In the EU, Which? confirms, menstrual underwear is subject to REACH obligations and so can be subject to REACH restrictions of chemicals, they are considered consumer textiles and included under TULAC (textiles, upholstery, leather, apparel and carpets). Although Wen acknowledges this is  progress in the last couple of years, period products are not like any other consumer product. We still believe there are no safe levels of PFAS and it definitely should not be added intentionally to period products.

Règles Élémentaires report on Better Regulating Menstrual Products: why does it matter, outlines the issues with the REACH regulation of period products.

Harmful and untested substances have no place in period products, the only solution is specific regulation and supply chain monitoring.  

PFAS in period pants

Although there are about 10,000 PFAS substances in the PFAS ‘family’, we only have health and safety information on a handful. Widely used for its stick, stain and waterproof properties, it is increasingly being cited as very hazardous to human health and the ecosystem. 

PFAS is linked to adverse effects on the menstrual cycle, cancer, reproductive health and development. 

A recent European report concluded that if the current levels of PFAS pollution continue until 2050, it is projected the cost to society will reach €440 billion over that period. But it’s worth noting the EU did not consider period products or vagina absorption in its analysis. 

PFAS is added intentionally to period pants as a waterproof agent, but, as Which? points out, lower levels can also result from contamination during processing.

It has been found in period pants on a number of occasions, as well as in other period products sold on the UK market. Research has also found levels in product packaging. 

Banned in cosmetics because of the concerns about dermal safety and absorption, no such consideration has been given to PFAS presence in period products. Even though the vagina is up to 80% more absorbent than the skin on the rest of the body. 

As with the many toxic chemicals, pesticides and heavy metals discovered in period products, we know there are no safe levels of exposure. PFAS remains untested for its effects when used in period products and the health effects from vaginal absorption. Yet it has been found in period products at the same levels that are used in waterproof rain jackets. 

While the EU is progressing a group wide PFAS ban under EU REACH, this will be no mean feat due to the the complexity of the issue and because they are used so widely in consumer products. It is unclear if this ban will extend to period products or pants, as period pants are classified as technical textiles and may have a derogation. 

The Environmental Audit Committee (EAC) report to the UK government concluded the harm to human health from exposure to PFAS. It also highlighted that voluntary action on PFAS and self-regulation by industry are not sufficient to ensure transparency, accountability or reduce PFAS emissions.

Biocidal silver  

In 2023, Which? found levels of biocidal silver in some period pants at “unnecessary high levels of silver which could have unknown health implications for wearers and damage the environment”. 

Biocidal silver is used as an antimicrobial but is untested for use in period pants and other applications. Added purely to alleviate concerns about ‘menstrual odour’, up to 72% washes out after the first 10 washes. It is also toxic to aquatic life. 

Which ? testers were also asked about odour from using the pants. It is also unclear what type of ‘odour’ they were asked to detect? For example blood itself has a slightly metallic smell as do new textiles or textiles treated with additives? Given menstrual odour is an age-old construct, Wen asks, does this question perpetuate the myth of menstrual odour?

Which? itself says about the silver additive: “while the risk is minimal, there’s no need for it to be included, and brands should be transparent about what treatments are on their products, so consumers can make an informed choice.”

The drive to make period pants cheaper has led to the greater use of synthetic materials, like polyester, which tends to hold onto odours more than cotton fabric. This facilitates the need for an additive to reduce any concerns about potential odours. It’s worth noting that Which? testers noticed no discernible difference in odour between pants with added anti-odour treatments and those without. 

Because period products are unregulated, we find many additives like Biocidal Silver used purely as a selling point used to market the product.

A government response to a question from Wen about regulating additives like silver in period products stated: “A number of silver active substances are currently waiting to be assessed for safety and efficacy as biocides. While this is the case they can be legally used in treated articles including period products”. So, from the horse’s mouth, period products contain untested additives. 

Oeko Tex

Several of the products tested hold Oeko tex certification, which certifies all the materials used. Some of the levels of PFAS found suggest contamination during production. But it’s hard to know where many period products are produced, as often there is no information on the packet as to the source of raw materials or the country of origin. 

Workers are also exposed to PFAS daily, through sewing fabrics treated with PFAS and biocidal silver, although little research has been conducted on potential health impacts.

So, what’s next?

These results from Which? are the latest in the line of many tests finding harmful chemicals and substances in period products. Wen believes it is unacceptable that we find harmful chemicals, heavy metals and pesticides in our period products. 

The point about complying with UK regulation, is a moot point, there is no UK regulation for period products.

Let’s remember this is an industry worth between £24 and £40 billion. Our blood is their profit. 

The existing system based on self policing has not worked – if it did, we would not be finding levels of harmful chemicals in period products going back decades. Proposed voluntary codes like the International Standards Organisation (ISO) standard on menstrual products will just deliver more of the same. 

We are sick of voluntary codes, reassurances and placation – we want action, we want regulation and we want it now.

What we want the government to introduce:

• Regulation for all period products. 
• Mandatory ingredients labelling and material disclosure, both for intentional and unintentionally found restudies.
• Publicly accessible product safety information with a regularly updated list of assessed and prohibited ingredients akin to the European cosmetics regulation. 
• Transparency is essential for informed consumer choice and public trust.
• A precautionary approach to toxic chemicals in period products.

What you can do:

In the absence of proper regulation for period products, the consumer needs to turn detective.

Avoid any period products advertised as antimicrobial, anti-odour, using freshness technology, silver zeolite, silver, or suggesting stain resistant or water repellent properties. And check any trademarked ™  additives. If in doubt, contact the company. 

Ask the UK government to regulate all period products properly. We need to be sure what we are purchasing is as safe as possible. 

Read the Which? article. 

Sign Wen’s petition calling for regulation of period products.

If you are a clinician or academic, sign our sign up letter.