Occurrence of Phthalate acid esters in new and used household curtains and their distribution patterns

Phthalate acid esters (PAEs) are widely used plasticizers that can be detected in indoor materials. In this study, the concentrations of six PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), and di-n-octyl phthalate (DNOP), were measured in new and used household curtains collected from Yazd, Iran. A total of 47 samples were analyzed, comprising 29 new curtains and 18 used ones. The mean log concentrations (µg/g) of DEP were significantly higher in used curtains compared to new ones (p < 0.05), whereas BBP showed higher values in new curtains. DEHP was the dominant compound in most samples, while BBP showed greater variability depending on curtain characteristics. Observed differences among the compounds may be attributable to intrinsic properties, including volatility and fiber affinity. In addition, factors such as curtain usage status, washing, and environmental conditions may contribute to the observed patterns. Multiple regression analysis showed that usage status (new vs. used) was more strongly associated with PAE concentrations than fabric type or color. After adjustment, the concentrations of DEP, DBP, and DEHP remained significantly higher in used curtains (p < 0.05). However, due to the cross-sectional design and differences in sample sources, the results should be interpreted as descriptive observations rather than causal relationships. Overall, this study provides baseline data on PAEs in household curtains and highlights the need for further investigations under controlled conditions.