Recycled Polyester: Production and Composition
Recycled polyester is a synthetic fiber created from plastic waste, primarily polyethylene terephthalate (PET) bottles and, increasingly, post-consumer textile waste. This process diverts discarded plastics from landfills, reducing the demand for new petroleum-based resources. There are two main methods for producing rPET: mechanical recycling and chemical recycling.
Mechanical recycling involves collecting, sorting, washing, and melting plastic waste into flakes or pellets. These are then extruded into yarn. This method can result in shorter fiber lengths, potentially reducing material strength over multiple recycling cycles.
Chemical recycling breaks down PET into its molecular components. These purified monomers are then re-polymerized to form new polyester, yielding material comparable to virgin polyester. While more expensive and energy-intensive, this method offers a closed-loop system where polyester can be recycled indefinitely. Source material and recycling processes can introduce variability or residual substances.
Chemicals of Concern in Recycled Materials
Chemicals in recycled polyester can stem from the original plastic source or be introduced during the recycling process. Antimony trioxide, a catalyst used in virgin polyester production, can persist in rPET. Studies indicate antimony can leach from recycled plastic.
Phthalates and Bisphenol A (BPA), often found in original plastics like bottles, are another concern. These endocrine disruptors can remain in the recycled material and have been linked to developmental and reproductive problems. Research on rPET bottles shows leachable BPA concentrations can increase with higher recycled content.
Per- and polyfluoroalkyl substances (PFAS), or “forever chemicals,” are used in textiles for water and stain resistance. If recycled textiles containing PFAS are used, these substances can transfer to new rPET products. PFAS are persistent in the environment and associated with health concerns like immune system disorders, liver damage, and increased cancer risk.
Heavy metals like lead, chromium, and cobalt can also be present, often from dyes or contaminants in the waste stream. Residual dyes and processing chemicals from original garments or recycling steps may remain, including formaldehyde and azo dyes, which are known skin irritants or allergens.
Assessing Potential Health Impacts
Chemicals in recycled polyester can affect human health through various exposure pathways. Dermal contact is a primary route, where chemicals may leach from fabric onto the skin, especially with prolonged contact or sweating. Studies show chemicals like benzothiazole and heavy metals can migrate from textiles to the skin and be absorbed.
Inhalation is another pathway, particularly concerning microplastic fibers and volatile organic compounds (VOCs) off-gassing from textiles. Synthetic fabrics, including polyester, shed microfibers during wear, washing, and drying, which can become airborne and inhaled. Research indicates microplastics have been found in lung tissue, and textile workers exposed to polyester fibers have experienced respiratory issues.
Accidental ingestion of microplastics is also possible, especially for children who may put objects or fabrics in their mouths. Microplastics have been found in various food and water sources, leading to estimates of significant weekly ingestion. While research on direct human health impacts of microplastic ingestion is ongoing, their ability to absorb other pollutants and associated chemicals raises concerns.
Current scientific understanding suggests that while chemicals are present, levels in consumer rPET products are generally low. Direct human studies on long-term exposure to rPET contaminants are still developing. However, cumulative exposure from multiple sources over time remains an area of scientific inquiry.
Regulatory Oversight and Consumer Considerations
Various regulatory and certification standards exist to mitigate concerns about harmful substances in textiles. The OEKO-TEX Standard 100 tests finished textile products, including recycled materials, for over 1,000 harmful substances. This certification aims to ensure product safety for human contact, with stricter requirements for items with more intensive skin contact, such as baby products.
The Global Recycled Standard (GRS) is an international, voluntary standard setting requirements for recycled content, as well as social, environmental, and chemical practices throughout the supply chain. GRS includes strict limitations on hazardous chemicals to protect human health and the environment during production. While both certifications help ensure a safer product, they do not guarantee the complete absence of all chemicals.
Consumers concerned about chemical exposure from rPET products can take several practical steps. Washing new garments before wearing them is often recommended to remove residual processing chemicals, dyes, and other irritants. This action can reduce substances like formaldehyde and excess dyes that may cause skin irritation.
Choosing products with recognized certifications like OEKO-TEX Standard 100 or GRS assures textiles have been tested for harmful substances. For certain applications, such as next-to-skin clothing, consumers might consider natural fibers if chemical sensitivities are a concern. Proper disposal of rPET items is important to prevent further environmental impact from microplastic shedding.