Partition of phthalates among air, PM 2 .5 , house dust and skin in residential indoor environments

As a group of typical endocrine disrupters, phthalates are simultaneously present in a variety of environmental media and enter human body through multiple exposure pathways. In this study, field monitoring data were used to characterize the skin-air (Klg), dust-air (Kd), and PM2.5-air (Kp) partition coefficients of DiBP, DnBP, and DEHP. The median values of log(Klg) in the summer and winter were 7.654 and 7.932, 7.265 and 7.902, 9.419 and 9.015 for DiBP, DnBP, and DEHP, respectively, and Klg was significantly higher in the winter. The median Kd (m3/mg) in the summer (0.036–0.151 for DiBP, 0.021–0.036 for DnBP and 1.479–4.069 for DEHP) were significantly higher than the counterparts in the winter (0.027–0.065 for DiBP, 0.022–0.245 for DnBP, and 0.140–3.250 for DEHP). In addition, Kd was associated with material of surface and residence time of dust. The Kp values (m3/μg) of DiBP, DnBP, and DEHP in the summer (0.053, 0.015, and 0.021) were also significantly higher than the counterparts in the winter (0.011, 0.004, and 0.025). The partition of phthalates was influenced by built environment, such as temperature, humidity, ventilation, indoor chemistry, smoking, and building age. Except Klg, there was substantial discrepancy between the estimates of K with empirical equations and the values of K based on field monitoring data in our study.