A recent investigation by consumer group Which? found that period pants by some of the UK’s leading brands contain high levels of silver. It claimed that the element not only has serious implications for the environment, but also our health. If you’re a period pants devotee, you may be shocked to find that out – particularly if you’ve swapped tampons and pads for period underwear in a bid to be more eco-friendly.  

But what exactly does this mean for our gynaecological health, and are there any safer brands out there offering a greener, safer period?

The silver in period pants can exist in various forms: nanosilver (microscopic particles of silver), silver zeolite, silver copper zeolite, silver zinc zeolite or silver chloride. The long-term effect of silver on our health and the environment is unknown but some experts believe there is growing evidence to suggest it could be toxic.  

The US Food and Drug Administration found that nanosilver can kill lactobacillus, the healthy bacteria in your vagina which helps to fight off infection. The European Chemicals Agency has also declared nanosilver and silver zeolite toxic to aquatic wildlife. When washed, period pants containing these silver treatments might release harmful particles into the environment, posing as similar a threat to humans and wildlife as PFAs – AKA ‘forever chemicals’.

The period underwear market is booming. Mintel claims that almost a fifth of women in the UK have purchased period pants, and a third (rising to almost half of younger women aged 21-31) are interested in buying them in the future. It’s by far the most popular eco-friendly choice of sanitary product – only 10% of women buy reusable sanitary pads, 7% use menstrual cups and just 5% are fans of reusable tampons.

But the biggest barrier to more women buying reusable period products is concerns over hygiene, with six in 10 women believe disposable options are more hygienic. And it’s for this reason that you’ll find silver lurking in period underwear. 

Silver is typically used as an antimicrobial agent in products (such as period pants) where people may be concerned about odour or hygiene. However, previous textile testing by AltroConsumo, the Italian consumer organisation who partnered Which? in this latest investigation, has shown that this doesn’t always work – some products in testing even lost their silver content after just two washes. This has led some experts to believe its presence in period pants is unnecessary. 

Which? tested period pants for several chemicals, including chromium VI, cadmium and arsenic – all of which, you’ll be incredibly pleased to hear, were not found in any products. However, the presence of silver caused concern, although the tests could not determine the type of silver used.

Intima by Bodyform and period pants by Marks & Spencer contained notably more silver than other brands, at 126.7mg/kg and 57.8mg/kg respectively.

Thinx, Luna by Superdrug, and Modibodi contained 8.3mg/kg, 7.4mg/kg and 0.9mg/kg respectively. Airism by Uniqlo and Cool Period contained smaller amounts of 0.3mg/kg and 0.2mg/kg.

This isn’t the first time that Thinx has been in environmental trouble. It recently settled a $5 million lawsuit in the US after its ‘non-toxic’ branded products were allegedly found to contain PFAs.  

Those brands have been quick to defend their use of silver-based treatments for odour control, stating that all materials used have been deemed safe by regulators.

In response to the Which? investigation, Thinx said: “The odour controlling layers in Thinx products are treated with Agion®, an EU regulated treatment containing silver zeolite and silver copper zeolite. Agion® is widely used for odour resistance in textiles and deemed safe for consumers by the EU.”

A spokesperson for Essity (owner of Bodyform and Modibodi) told Strong Women: “We can say with absolute certainty that consumers can wear Bodyform and Modibodi period underwear with confidence because they are safe, sustainable and provide superior performance. Both sets of underwear tested contain silver copper zeolite to prevent odour when wearing the pants for up to 12 hours, which our research shows is a key concern for customers.

“All of our washable underwear is certified according to Oeko-Tex standard 100 which means that every single component has been tested for harmful substances and that the underwear has been designated as harmless for human health.” 

A spokesperson for Marks & Spencer said: “We do not use either nanosilver or silver zeolite and, like many brands, use a small amount of silver chloride in the middle part of the gusset away from the skin, which is perfectly safe, approved by the UK and EU, and designed to combat odour.”

And Uniqlo told Strong Women that they “adhere to the strictest safety standards in all our markets of operation. Silver is used in [our] period pant products to prevent the growth of odour-causing microorganisms, and is used in accordance with UK and EU regulations. We clearly state the purpose for using silver on the packaging of each product.”

Finally, Superdrug told us: “Superdrug Luna period pants uses Micro-Fresh technology [containing silver chloride], a commercially proven antimicrobial fabric treatment… [Our] policy is to avoid any harmful or hazardous materials in our products, and we hold certification to demonstrate non-migration of the material.” 

The Which? tests, which can detect any silver above 0.1mg/kg, did not detect any silver in Repeat, Wuka, Lovable (an Italian brand), Primark and Sloggi pants. However, Sloggi’s website states it does use a silver-based antimicrobial, and Primark says it uses Micro-Fresh.

Alongside the knowledge that Repeat, Wuka and Lovable all came out well from the investigation, other brands are giving women a silver-free choice. Essity stated that an entire Modibodi range free of silver-based antimicrobials will be available from 2024 onwards.

Natalie Hitchens, head of home products and services at Which?, said: “Those concerned about the possible side effects of silver in period pants should choose brands that don’t contain silver. Eco-conscious consumers could also consider other options such as menstrual cups, reusable applicators and reusable menstrual pads. 

“Which? believes brands should clearly state which products contain silver so shoppers can make informed decisions about what they are buying and the possible risks.”

There is currently no legal limit to the amount of silver companies can add to period products, and while some brands choose to, they don’t have to declare this use on packaging which can make silver-free selection a problem.  

1. Choose brands that clearly state they are ‘silver-free’.
2. Beware of mentions of silver-based, anti-odour, antibacterial or anti-microbial technology, which could mean silver or other biocides have been used.
3. Ask manufacturers directly if the products contain silver or anti-bacterial technology, to send a message to companies that people care about this.

Images: Getty