Quaternary Ammonium Compounds (QACs) in Textiles and Laundry Wastewater: Occurrence and Environmental Risk Assessment

Quaternary ammonium compounds (QACs) have been used as antimicrobial additives in textiles, but information on the environmental occurrence of QACs in textiles and their ecological impacts from laundry wastewater is scarce. In this study, we purchased 119 textile samples from Chinese online vendors, with the product types including face masks, socks, towels, sportswear, underwear, clothing, quilts, and medical textiles. These samples were analyzed for traditional and emerging QACs using target and suspect screening approaches with high-resolution mass spectrometry. The total concentrations of 18 traditional QACs ranged from 7.34 to 145000 ng/g, with a median of 176 ng/g. Additionally, 16 emerging QACs were identified, with total concentrations ranging from 5.45 to 349000 ng/g and a median concentration of 346 ng/g. Under laboratory conditions, the leaching rates of QACs from underwear, towels, and socks to wash water reached 77%, 55%, and 81%, respectively. In real-life simulated laundry experiments, hand-wash released higher ΣQACs concentrations compared to machine-wash (medians: 42.1 vs. 22.4 ng/g, respectively), suggesting that manual laundering may lead to greater QAC release. The toxicity evaluation by whole-effluent toxicity approaches showed that laundry wastewater and equivalent QACs solution both caused immobilization of Daphnia magna in a dose-response relationship, with wastewater exhibiting lower toxicity than the standard solution. Furthermore, risk quotients derived from bioassay results and environmental dilution factors across 150 countries indicated that 10% of regions face high risk (RQ > 1) when laundry wastewater is discharged after WWTP treatment, whereas 51% of regions show high risk when laundry wastewater is directly discharged together with sewage, highlighting that the ecological risks of QACs released from textiles in laundry wastewater should not be overlooked.