New research suggests that chemicals in synthetic workout clothing could be absorbed through the skin during exercise. The study, led by the University of Birmingham, focused on brominated flame retardants (BFRs), which are used in a wide range of consumer products including fabrics. These chemicals have been linked to health issues such as thyroid disease, hormonal disruption and neurological problems.
The researchers found that oily substances in sweat can leach chemical additives from plastic-based fabrics like Spandex, nylon and polyester. Dr Mohamed Abdallah, associate professor in environmental science at the University of Birmingham and principal investigator, explained that the oil in sweat helps 'bad chemicals' to come out of microplastic fibres and become available for human absorption. The findings suggest that as people sweat more, they could absorb higher levels of these chemicals.
Although the study focused on flame retardants, which are not commonly added to sportswear, Dr Abdallah noted that other plastic additives such as bisphenols, phthalates and PFAS may also leach into sweat. Bisphenols have been found at up to 40 times the safe limit of exposure in items from popular sportswear brands. The researchers say these findings can be 'logically extrapolated' to someone running and sweating intensely.
Previous research on plastic exposure has largely centred on diet, but this study highlights dermal absorption as a significant route. Harmful chemicals in plastics can bioaccumulate, building up in the body over time. A separate study published in August found increasing rates of cancer among Americans under 50, with experts suggesting that exposure to a wide range of pollutants and carcinogenic chemicals may be a contributing factor.
Alden Wicker, author of To Dye For: How Toxic Fashion is Making Us Sick, points out that workout wear marketed as 'sweat-wicking' or water-repellent often contains PFAS, the 'forever chemicals' known to be carcinogenic. She notes that polyester fabrics are typically coloured with disperse dyes, which are known skin irritants, particularly for children and those with sensitive skin.
