Your gym clothes could be leaching toxic chemicals, new study reveals

A new study shows your workout wear could be leaching harmful chemicals. Photo / 123rf

Whether your preferred method of exercise is a brisk walk around the block, a challenging HIIT class, or an at-home yoga or pilates practice, chances are you’ve got a go-to workout outfit too.

When it comes to gym clothes, comfort, convenience and flexibility are key — but have you ever thought about what your favourite leggings or sports bra are made of?

The workout set you’ve carefully laid out or grabbed off the washing line is probably made of synthetics such as nylon, polyester or spandex, which are basically plastics made from petrochemicals along with harmful chemicals like bisphenols or pthalates.

Have you ever thought about what your activewear is made of? Photo / 123rf

Now, a new study has shown when you sweat in these materials, they could be leaching chemicals from those plastics that can then be absorbed by our skin, reports The Guardian UK.

The study’s findings

Research done by the University of Birmingham concentrated on a particular type of compound called brominated flame retardants (BFR), which are used in several products including fabrics to prevent burning.

They’re also thought to be a cause of hormonal disruption, thyroid disease and neurological issues.

The researchers found because sweat contains oil, and oil’s lipophilic chemical nature can cause the chemicals in plastic to dissolve, your body’s oils can leach chemicals from plastics you come into contact with.

In other words, the oil in our sweat “help[s] the bad chemicals to come out of the microplastic fibres and become available for human absorption”, according to the study’s principal investigator and associate professor in environmental science at the University of Birmingham, Dr Mohamed Abdallah.

They ran tests on flame retardants in fabrics to see how much sweat interacts with these plastics when people wear workout gear passively. Further studies are needed to see how many and what kind of chemicals someone would absorb from their clothing after a sweaty gym session.

But Abdallah notes that going by the implications of the study, it’s safe to say additives like bisphenols, PFAs and phthalates “may leach out into sweat and become available for dermal absorption” — so sweating more could mean you absorb more of these chemicals.

Your favourite workout gear might just be harming your health in the long term. Photo / Getty Images

What are the risks of these chemicals?

The harmful chemicals in plastics tend to accumulate slowly and stay in our bodies, and that can in turn lead to negative health effects.

A new study published in the Environmental Pollution journal last month found 25 flame retardants in 50 American mothers’ breast milk, while another study this year has found gastrointestinal, breast and endocrine cancer cases are on the rise in Americans under 50 — particularly in women.

The exact cause of this isn’t clear, but, according to experts, exposure to these harmful chemicals is a factor.

In her 2023 book To Dye For: How Toxic Fashion is Making Us Sick, Alden Wicker notes that workout clothes — particularly those marketed as water-repellent or sweat-wicking — usually contain “forever chemicals” or PFAs.

She adds polyesters’ bright hues usually come from disperse dyes, which are known skin irritants, particularly for those with conditions like dermatitis or eczema.

“Most fashion brands do not know who is dyeing and finishing and manufacturing their materials,” Wicker says.

“And those suppliers will be incentivised to do things as cheaply as possible, to get cheaper chemicals from uncertified sources that could be contaminated with heavy metals and other hazardous substances.”

Martin Wagner, a biologist at the Norwegian University of Science and Technology, says that research estimates there are “more than 13,000 plastic chemicals” in existence. He tells the Guardian that “since most of these are not investigated for their health or environmental impacts, there is an urgent need to improve the safety of plastics”.

What to look for on your activewear labels

When it comes to activewear, look for sustainably made natural textiles — organic hemp, cotton or merino.

Lycra or elastane is nearly impossible to avoid in stretchy clothing, but you can check whether clothing items are certified by the Global Organic Textile Standard or OEKO-TEX, and check brands’ websites to see who their suppliers are.

A recent survey in the US found 72 per cent of those surveyed would opt for plastic-free sports gear if it was easy to find.

But even Wicker admits that “it can be expensive to get rid of all your synthetics and overhaul your wardrobe”.

“I would say do it a little bit at a time unless you have chronic health issues, serious concerns or you react to some of these materials,” she adds.

As for Abdallah, he opts for natural fabrics like cotton to work out in and tries to have as few synthetic fabrics in his home as possible, saying “Why be exposed to these chemicals at even low levels?

“Why not avoid the risks?”