From period pants or ‘leakproof’ underwear to sportswear, socks - and even ‘recovery-boosting’ post-surgery bras sold by Britain’s biggest cancer charity - all sorts of clothing is sold nowadays containing a material claimed to kill germs, prevent odour and even prevent infections.

That material is silver. It’s woven as tiny particles into clothes as an anti-bacterial agent.

And silver-infused clothing is a lucrative market, now worth an estimated £10.5billion worldwide, according to analysts Research and Markets - and it is projected to more than double by 2030.

But growing scientific evidence suggests silver in clothes may actually cause serious harm, possibly risking damage to internal organs, disrupting hormones and making wearers more susceptible to bacterial infections.

Currently, a proposed new law is making its way through Parliament that could effectively ban silver from being incorporated into clothing - especially underwear.

Launching the proposed legislation two years ago, Baroness [Natalie] Bennett of Manor Castle described the use of silver in clothing, as well as cosmetics and personal care products, as an ‘urgent health threat’.

Silver in clothing can kill bacteria because, when in contact with bodily fluids, such as sweat, saliva or menstrual fluid, it releases tiny, charged particles that lethally damage bacterial cell walls and DNA.

However, new research shows silver particles may kill off beneficial bacteria while leaving more resilient infectious bugs unharmed - leading to increased risk of bacterial infections.

While silver-infused clothing is a lucrative market, research now shows the particles may kill off beneficial bacteria while leaving more resilient infectious bugs unharmed

Furthermore, silver particles in clothing can enter the body and, ultimately, migrate to the liver - where they could affect its functioning and disrupt the natural balance of hormones in our body, according to a study published in 2024 in the journal Environmental Science: Nano.

The study’s laboratory tests on cell cultures showed that the particles can then interfere with the liver’s ability to regulate hormone levels.

In particular, this liver disruption seemed to reduce activity in the thyroid system (which regulates energy and metabolism) and separately the androgen system (which plays vital roles in development, reproduction and overall health).

Such worrying research prompted the European Union last year to impose a ban on the use of silver additives in all cosmetic products (it’s long been used as a germ-killing preservative and also as a shiny pigment in lipsticks and eyeshadow). The ban came into force in May.

Baroness Bennett’s Bill would restrict silver use in clothing and cosmetics in the UK.

In fact, action is already being taken here against cosmetics.

In February, the Office for Product Safety and Standards said that due to mounting scientific evidence, the use of silver nanoparticles and larger silver particles would be banned in cosmetics - new products have not been allowed to contain silver since March, while existing products containing it must be withdrawn from sale by the end of next month.

However, it’s still permitted in clothing. Of particular concern to experts are silver-containing period pants, marketed as an alternative to sanitary pads and tampons.

Dr Katy Stokes, a research fellow in biomedical research and health policy at the University of Warwick, who wrote the policy briefing paper advising the new parliamentary Bill, told Good Health: ‘Silver is typically added as an antimicrobial agent to period pants to combat user concerns about smell and hygiene. But the risks outweigh the benefits.’

Dr Stokes cites research backed by the US Food and Drug Administration, published in the journal ACS Applied Materials & Interfaces in 2018, which found nanosilver (silver in tiny particles measuring no bigger than 100 nanometres - by comparison a human hair is up to 100,000 nanometres wide) can kill protective healthy bacteria in the vagina.

‘This could potentially lead to increased incidence of bacterial infections among wearers,’ she says.

Indeed, the study found that nanosilver can kill helpful vaginal bacteria such as Lactobacillus very effectively. Worse, infectious bacteria such as Staphylococcus aureus that can colonise the area are so resilient they can shrug off attacks by nanosilver, researchers from the University of Memphis in the US, and Soochow University in China, found.

Another concern is the potential damage beyond women’s reproductive organs.

In 2024, scientists at the US National Centre for Toxicological Research said their research on female rats showed that vaginal exposure to nanosilver promptly caused tissue inflammation and disrupted the healthy balance of bacteria.

Furthermore, the nanosilver found its way into the bloodstream, where it migrated to other organs of the body and throughout the digestive system.

Thiago Verano-Braga, an associate professor of physiology and biophysics at the Federal University of Minas Gerais in Brazil, who has studied silver nanoparticles’ effects for years, has declared that ‘manufacturers absolutely shouldn’t be using silver nanoparticles in pants before there is a critical assessment of potential risks’.

Professor Verano-Braga supported a scientific study by the UK consumer body Which? and the Italian consumer organisation Altroconsumo in 2023, that tested a range of period pants and found ‘unnecessary high levels of silver which could have unknown health implications for wearers and damage the environment’. (If particles leach into waterways they can be harmful to aquatic life.)

There are no legal limits in the UK about how much silver can be added to period pants. Nor do clothing manufacturers have to declare the presence of silver on the packaging or website.

Consumers might find several types of silver in clothing, including nanosilver, silver copper zeolite, silver zinc zeolite, silver chloride, or Agion (a branded product made with silver zeolite).

Which? and Altroconsumo’s tests were not able to determine which type of silver was present, but said they had safety concerns regardless of the type used.

Their analysis found Intima by Bodyform and Marks & Spencer’s period pants contained the highest amount of silver of all the UK-marketed brands tested, at 126.7mg/kg and 57.8mg/kg respectively.

A spokeswoman for M&S told Good Health that the company’s period-pant products still contain the same amount of silver as in the 2023 tests.

She added: ‘Silver chloride is approved under UK regulations for use on textile products.

‘We, like many brands, use a trace amount of silver chloride in the middle part of the gusset - away from the skin - which is perfectly safe and designed to combat odour.’ Silver-containing period pants are also still sold by other major brands such as Victoria’s Secret and Next.

However, a spokesman for Bodyform told Good Health: ‘Since 2023, Bodyform has switched suppliers for its range of washable absorbent underwear and the new product range - including any products launched in the last two and a half years - do not contain silver.’

Dr Stokes’s briefing paper highlighted concerns about a ‘healing bra’ containing silver that is marketed by Cancer Research UK and ‘designed for use after any type of breast or chest surgery’.

On its website, the cancer charity describes its Royce post-surgery bra - which sells for £37.50 - as being ‘developed from anti-bacterial, anti-odour, thermo-regulating X-STATIC silver fibre (which contains a silver alloy) to aid the healing process’.

But Dr Stokes is highly concerned about this product and its marketing. ‘As well as an example of inherent exposure risk, this can also be seen as exemplifying the worrying trend of the unnecessary incorporation of additives,’ her paper says.

A spokeswoman for Cancer Research UK told Good Health it believed the type of silver used in the bra was not harmful to wearers, but that the maker, Royce, should be contacted for a definitive comment.

Royce, however, has not responded to Good Health’s questions.

The website of arc.com, which markets the X-STATIC silver fabric yarn, states: ‘Disclaimer: Products containing X-STATIC are not intended to be used in the diagnosis, cure, or treatment of human infection.

‘They are solely intended to protect the finished product itself from microbial growth. We make no public health claim.’

Dr Stokes told Good Health: ‘I would also be concerned the bra might be used outside of doctors’ advice on wound care, or for prolonged periods, whereby antimicrobial properties may cause microbiome or hormone disruption.’

On top of such concerns is evidence suggesting that adding silver to clothes may not be very effective against odour-causing strains of bacteria anyway.

For a study published in the International Journal of Clothing Science and Technology in 2014, scientists led by Rachel McQueen, a professor of human ecology at the University of Alberta, Canada, analysed textiles coated in a silver compound after they had been worn.

They found the textiles were not as good at preventing micro-organisms from surviving in real life as the makers’ original lab tests had suggested.

According to Dr Stokes, old-fashioned textiles may offer more effective alternatives.

‘For instance, natural fibres like merino wool offer inherent anti-odour properties, thanks to their ability to wick moisture and naturally inhibit bacterial growth,’ she says.

‘Their use is not only potentially more sustainable but also safer for consumers.’