How your workout clothes might be undermining your health

Working out and moving your body to feel good is an essential part of physical wellness - but what if the clothing you wear to the gym is actually making you sick?

While reports concerning the use of PFAS (per and polyfluoroalkyl substances) and PFCs, better known as ‘forever chemicals’ used to coat textiles that are hazardous to both humans and the environment, is nothing new, a recent study has highlighted another group of chemical substances commonly found in sportswear could be potentially harmful to us.

Although stretch, breathability, and sweat-wicking abilities are several of the key physical properties consumers look for in sportswear, many of us are not concerned with the fabrication of our workout clothes. However, synthetic fabrics such as Spandex, polyester, and nylon, commonly used in sports bras and leggings, are essentially plastics derived from petrochemicals.

Unfortunately, to achieve many of these properties, these materials frequently contain chemical additives, including phthalates and bisphenols, which can be extracted by sweat and then absorbed through our skin. Known as brominated flame retardants (BFR), this group of chemicals used in various products to inhibit burning are associated with health risks like thyroid disorders, hormonal imbalances, and neurological problems.

According to the study 'Novel Insights into the Dermal Bioaccessibility and Human Exposure to Brominated Flame Retardant Additives in Microplastics' published by the American Chemical Society, human sweat, which contains natural oil, promotes the dissolution and diffusion of chemicals from plastics due to oil's lipophilic properties. This process results in the body’s extraction of chemicals from plastics upon contact with the skin.

The more you sweat, the more chemicals your body may absorb

Researchers at the University of Birmingham carried out several tests that focused on flame retardants found in fabrics that looked at the interaction between sweat and plastic during typical home activities. Although the researchers noted that further studies were needed to determine the specific chemicals and their amounts absorbed through synthetic workout clothing and gym environments by individuals engaged in strenuous exercise, the overall results indicate the more you sweat, the more chemicals your body may absorb.

The study, published in July, also indicates the potential for other plastic additives, such as bisphenols, phthalates, and PFAS, to leach into sweat and be absorbed through the skin. Notably, bisphenols have been detected at levels up to 40 times above the safe limit in some sportswear. The research builds on previous studies into the effect of harmful chemicals in plastics, which can bioaccumulate in the body, leading to elevated internal concentrations due to repeated and varied exposures and pose potential health risks.

This is not the first study to outline the potential harmful effects of chemicals absorbed by the skin found in sportswear. Earlier this year, tests by the Center for Environmental Health (CEH) found elevated levels of BPA, a harmful plastic compound, in various sports bras and athletic wear from several brands, including Nike, Adidas, Patagonia, and Athleta. These levels exceed California's strict safety standards, as set by Proposition 65, by up to 40 times.

While most BPA studies focus on ingestion, its skin absorption through athletic clothing raised several legitimate concerns, especially given BPA's links to health issues like asthma and cardiovascular disease. Continuous exposure from multiple sources, despite BPA's short-term bodily presence, is a growing health concern.

In October 2022, the Center for Environmental Health alerted consumers about excessive BPA levels in sports bras from brands like PINK, Nike, Fila, The North Face, and Asics, exceeding the maximum limit by over 22 times. Similar findings were reported for athletic shirts from Reebok, New Balance, The North Face, and Mizuno. The organization provided a 60-day period for these companies to address the violations before initiating lawsuits in February this year.

Phasing out these chemicals, along with BFRs and PFAS, a group of over 4,700 man-made chemicals used beyond the fashion industry, remains challenging, as these chemicals remain prevalent in various sectors, including packaging, cookware, and cosmetics. Those looking to minimize any potential exposure to these chemicals can opt for sportswear made from organic, minimally processed natural fibers like organic cotton, hemp, or merino wool.