Health risks of residential indoor and outdoor exposure to fine particle-bound phthalates

We performed residential indoor fine particle (PM2.5) measurement from 26 homes and three outdoor monitoring locations. Six PM2.5-bound phthalate easters (PAEs) — including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP) — were measured using a thermal desorption-gas chromatography/mass spectrometer method. Average concentrations of summation of six PAEs (Σ6PAEs) in residential indoors (646.9 ng/m3) were slightly lower than the outdoor levels. DEHP was the most abundant PAE congener (80.3%) and was found at the highest levels, followed by BBP, DnBP, and DnOP. Strong correlations were observed between indoor DEHP with DnBP (rs: 0.88; p < 0.01), BBP (rs: 0.83; p < 0.01), and DnOP (rs: 0.87; p < 0.01). However, no apparent inter-correlations were shown for PAE congeners. Principal component analysis affirmed heterogeneous distribution and notable variations in PAE sources between residential indoor and ambient exposure. The results provide critical information for mitigation strategies, suggesting that PAEs from indoor and outdoor sources should be considered when exploring the inhalation risks of PAEs exposure.