Unseen Substances in rPET Clothing and Their Impact on Workers

1417 

Professional Poster 

H Chen¹

¹National Taiwan University, Taipei City, Taiwan

Hui-Yu Chen  
National Taiwan University

Recycled polyester (rPET) made from post-consumer PET bottles may see increasing application in workwear and uniforms as part of corporate sustainability efforts. Although rPET provides environmental advantages, its recycling process can introduce non-intentionally added substances (NIAS), including impurities, degradation products, and chemical residues that differ from those in virgin polyester. In addition, to enhance the performance of recycled materials, additional additives may be incorporated during the manufacturing process. These substances raise concerns for workers who wear such clothing for long periods (8–12 hours), often in conditions involving sweat and friction. Extended skin contact may allow chemicals to migrate from the fabric to the skin, presenting a potential but under-researched occupational exposure route. This research emphasizes the importance of identifying and evaluating NIAS and other chemicals of concern in rPET textiles, as well as assessing related health risks. By connecting sustainability objectives with occupational health, the study highlights the need for scientific data to ensure that environmentally friendly uniforms do not compromise worker safety.

The use of recycled polyester textiles in clothing may increase faster than the accumulation of toxicological data on wearer exposure. During the recycling and subsequent finishing processes, upstream contamination, cleaning agents, thermal degradation, and finishing treatments may result in the presence of NIAS and functional additives. Representative chemicals of concern include aromatic amines, benzothiazoles, phthalates, and bisphenols, many of which are linked to carcinogenicity, endocrine disruption, and skin sensitization. Occupational settings–marked by prolonged wear (8-12 hours) and sweating–may increase chemical migration compared to casual consumer use. Although voluntary and regulatory standards set limits for known substances, they rarely consider NIAS or actual workplace conditions. In addition, quantitative data on the occurrence and concentrations of chemicals in rPET garments remain limited. This gap leaves Environmental, Health, and Safety (EHS) teams without a solid framework to assess risks and inform purchasing decisions. Our study addresses this by combining NIAS-focused discovery and occupational exposure calculation to offer evidence-based recommendations for safer rPET uniforms.

The samples analyzed in this study comprised clothing items made from virgin and recycled polyester, including T-shirts, polos, and base layers. For each garment, measurements were recorded for weight, grams per square meter (GSM), color, country of manufacture, and declared recycled content. To investigate chemical content, extracts from 1-gram textile samples were examined using GC/MS/MS to detect volatile and semi-volatile compounds such as aromatic amines, phthalates, and organophosphate esters; less volatile substances like benzothiazoles and bisphenols were chemically modified for GC–MS analysis. Identification confidence followed Schymanski criteria, and semi-quantification was performed using surrogate standards for each chemical class. Method validation criteria included calibration coefficients (R²) of at least 0.995, method detection limits (MDL) below or equal to 1 ng/g, limits of quantification (LOQ) at or under 3 ng/g, recoveries between 70% and 130%, repeatability with relative standard deviation (RSD) under 20%, and batch blanks showing surrogate recoveries between 60% and 140%.

Daily dermal exposure dose (DED) was estimated using a simplified formula: DED = (C × d_cloth × A_skin × F_mig × F_contact × F_pen × t_contact) / BW, where C is the concentration of the chemicals in textiles, d_cloth is the density of the textile, A_skin represents 3,000 to 4,500 cm² of upper-body skin contact area, F_mig is the migration rate of chemicals to the skin per day, F_contact is the fraction of contact area for skin, F_pen is the penetration rate of chemicals into body, t_contact is 8 to 12 hours of daily wear time, and BW is body weight assumed to be 70 kg. This model offers a preliminary estimate of potential occupational exposure without the need for complex simulations.

NIAS were classified into risk categories based on Thresholds of Toxicological Concern (TTC) values (30, 9, and 1.5 µg/kg-day for Cramer classes I, II, and III, respectively), combined with structural alerts for electrophilic groups, aromatic amines, or organophosphate esters. Statistical analyses included detection frequencies, median values with interquartile ranges, effect size calculations, and comparisons across variables such as color, country of manufacture, and proportion of recycled content.

The results revealed that virgin and recycled polyester types contained NIAS, with recycled polyester generally exhibiting a greater variety of chemicals. The main classes identified included benzothiazoles, aromatic amines, phthalates, organophosphate esters, and bisphenols. In summary, the study showed that NIAS are common in polyester clothing and are more chemically complex in recycled PET. Presenting the data in terms of dose-relevant exposure offered better understanding of occupational risks, emphasizing the importance of procurement standards, supplier collaboration, and focused monitoring to ensure that adopting sustainable recycled PET uniforms does not compromise worker safety.

Chemical Sampling and Instrumental Analysis

Exposure Assessment