Co-occurrence of phthalic acid esters (PAEs) and cyclic volatile methylsiloxanes (cVMSs) in fine particulate matter (PM_0.5 and PM_0.1) collected from an industrial area in Vietnam

Distribution patterns of 10 phthalic acid diesters (PAEs) and four cyclic volatile methylsiloxanes (cVMSs) were investigated in fine particulate matter (PM_0.1 and PM_0.5) collected from Bac Ninh, an industrial province in Vietnam during September-October in 2021. Total concentrations of PAEs found in PM_0.1 and PM_0.5 were in the ranges of 1.76-372 (median: 34.0 ng/m³) and 2.23-895 ng/m³ (median: 15.4 ng/m³), respectively. Among PAEs, di-n-butyl phthalate (DBP) was the most abundant compound found in PM_0.1, whereas, di-2-(ethyl)hexyl phthalate (DEHP) was measured at the highest concentration in PM_0.5. Total concentrations of cVMSs measured in PM_0.1 and PM_0.5 were in the ranges of method quantification limit (MQL)-203 (median: 2.10 ng/m³) and MQL-537 ng/m³ (median: 0.389 ng/m³), respectively. Among cVMSs, decamethylcyclopentasiloxane (D5) was found at the highest concentration in both PM_0.1 and PM_0.5 fractions of particulate matter. The concentration ratios between PAEs and cVMSs in PM_0.1/PM_0.5 were greater than 1 (except di-n-octyl phthalate: DnOP), suggesting that these chemicals tend to sorb to PM_0.1 more preferentially than PM_0.5. Among sampling locations, high concentrations of PAEs and cVMSs were found at traffic intersections (Que Vo district) and a craft village (Tu Son city). Relatively stronger correlations existed between cVMSs pairs in PM_0.1 and PM_0.5 (correlation coefficient: 0.73-1) than those of PAEs (-0.83-0.90). The human exposure doses to PAEs and cVMSs through inhalation of particulate matter were estimated based on the measured concentrations in PM_0.1 and PM_0.5 fractions. The estimated exposure doses of PAEs and cVMSs for infants (7.1 ng/kg-bw/d and 2.5 ng/kg-bw/d) were higher than those for adults (2.6 ng/kg-bw/d and 0.9 ng/kg-bw/d).