Legacy and novel brominated flame retardants in outdoor settled dusts and pine needles in a megacity of Eastern China: Interpretation of plant uptake.

Brominated flame retardants, considered emerging contaminants, are widespread and persist in the environment. This study investigated the contamination of legacy and novel brominated flame retardants in paired outdoor settled dusts and pine needles sampled from a megacity in the Eastern China. The measured total concentrations of PBDEs (∑PBDEs) in outdoor settled dusts and pine needles were in the range of 77.4-345.2 ng/g dw and 20.7-120.0 ng/g dw, respectively, and equivalent ranges for novel brominated flame retardants (∑NBFRs) were 25.7-1917.2 ng/g dw and 9.4-38.7 ng/g dw, respectively. BDE-209 and DBDPE dominated PBDEs and NBFRs profiles, respectively, in both dusts and pine needles. Outdoor settled dusts exhibited greater potentials to accumulate high-brominated PBDE homologues and EH-TBB while pine needles tended to accumulate low-brominated PBDE homologues, BTBPE and TBC. The plant uptake of BFRs was interpreted by McLachlan's framework on the assumption that the levels of BFRs in outdoor settled dusts and particle phase of air were positively correlated. The accumulation of PBDEs in pine needles was dominated by equilibrium partitioning between the vegetation and the gas phase when log K values <10 and by particle-bound deposition when log K values >13. However, NBFRs exhibited more complicated accumulation behavior. The predicted 50th percentile of the estimated daily intakes of ∑PBDEs via outdoor settled dusts exposure for adults and children were 3.5 × 10 and 1.4 × 10 ng/kg body weight (bw)/day, respectively, and equivalent values for ∑NBFRs were 1.6 × 10 ng/kg bw/day and 6.3 × 10 ng/kg bw/day, respectively. The calculated hazard index (HI) values were far <1, indicating exposure of BFRs via outdoor settled dust intake would not pose potential non-carcinogenic health risks to both adults and children.