Polyester (PET) is a synthetic polymer derived from petroleum that dominates the global textile market due to its low cost and durability. While the fiber itself is chemically inert, concerns surround residual chemicals from manufacturing and toxic additives applied during finishing. These substances can pose health risks not associated with natural fibers. This article explores the specific chemical components and exposure pathways contributing to polyester’s toxicity concerns.
Chemical Composition and Manufacturing Residues
Polyester fiber is synthesized through polymerization, a reaction involving terephthalic acid and ethylene glycol. This process requires a catalyst, most commonly Antimony Trioxide.
Antimony is a heavy metalloid categorized as a potential human carcinogen. Although the industry asserts that the antimony becomes chemically “locked” into the finished PET polymer, residual amounts remain in the fabric. Studies have shown that this residual antimony can leach out of the textile when exposed to heat or simulated sweat, creating a route for potential dermal exposure.
Finishing Treatments and Applied Toxins
The greatest potential for toxicity in polyester garments often comes not from the base fiber but from the numerous chemical treatments applied after the fiber is created. Disperse dyes, used to color the synthetic fibers, are a significant concern, especially the class of chemicals known as azo dyes. These dyes can cause allergic contact dermatitis and skin irritation in sensitive individuals, as they can remain in the fabric and leach out onto the skin.
To achieve functional properties, polyester is frequently treated with a cocktail of chemical finishes that include water repellents and flame retardants. Water- and stain-resistant garments are often treated with Per- and Polyfluoroalkyl Substances (PFAS), known as “forever chemicals” because they persist in the environment and the human body. PFAS exposure is linked to endocrine disruption, developmental issues, and an increased risk of certain cancers. Furthermore, flame retardants, such as organophosphate flame retardants (OPFRs) and brominated compounds, are added to reduce flammability, but some types have been associated with developmental and neurological effects.
Other common finishes include formaldehyde, used for wrinkle resistance, which is a known carcinogen that can cause allergic reactions and respiratory irritation. Recycled polyester (rPET) can introduce an additional concern, as Bisphenol A (BPA), an endocrine disruptor, has been detected in recycled materials at levels exceeding regulatory limits in some items. These finishing agents are often not chemically bound to the fiber, increasing their potential to transfer to the wearer through physical contact and sweat.
Biological Exposure Routes and Health Effects
Chemicals embedded in polyester fabrics can enter the human body through three primary routes: dermal absorption, inhalation, and ingestion. Dermal absorption, or skin contact, is a direct pathway, especially when the chemicals are in contact with sweat or heat, which increases the skin’s permeability. This contact can lead to localized effects like allergic sensitivity, contact dermatitis, and rashes. Tight-fitting sportswear, which is often polyester, exacerbates this issue by promoting friction and sweat, thereby increasing the absorption of residues like antimony and formaldehyde.
Inhalation is another route, primarily through the shedding of microfibers from the textile during wear and washing. Polyester fibers release microplastics, which are tiny plastic particles, into the air and environment. While the exact health effects of inhaled microplastics are still being studied, they have been detected in human tissues, and in vitro studies suggest they may induce inflammation and oxidative stress. New garments can also off-gas volatile organic compounds (VOCs), which may cause respiratory irritation or headaches.
Ingestion primarily occurs indirectly, as microplastics from textiles enter the environment and food chain. These particles have been found in various food sources, including sea salt, beer, and honey. The chemicals and microplastics entering the body through any of these routes can contribute to a long-term toxic load, with long-term exposure to endocrine-disrupting substances potentially interfering with reproductive and metabolic health.
Reducing Exposure and Consumer Guidance
Consumers can take several practical steps to minimize their exposure to the chemical residues in polyester clothing. Washing new garments before wearing them is highly recommended to help flush out surface-level finishing chemicals and residual dyes. Choosing clothes that are undyed or lightly colored may help reduce potential exposure to high concentrations of disperse dyes.
Seeking out textiles with recognized safety certifications, such as Oeko-Tex Standard 100, can provide assurance that the finished product has been tested for harmful substances. For items worn directly against the skin, such as underwear and activewear, considering alternatives like organic cotton, linen, or Tencel can significantly reduce chemical contact.