Voyaging of halogenated polycyclic aromatic hydrocarbons, an emerging group of pollutants, on micro-mesoplastics in the marine environment.

The limited existing research on the accumulation of hazardous chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs) in micro-mesoplastics (mMPs) motivated this investigation. We collected mMPs from the coastal environments of Sri Lanka and Japan. Out of 75 target compounds analyzed, 61 were detected, with total parent PAH concentrations reaching 16,300 and 1770 ng/g plastic in Sri Lanka and Japan, respectively. The total parent PAH concentrations in mMPs from the southern Sri Lankan coastline were relatively higher than those from the eastern coastline. Phenanthrene and naphthalene were the dominant parent PAH congeners in most mMP samples. Chlorinated pyrenes and brominated naphthalene were predominant among halogenated PAHs. The estimated toxic equivalency quotient (TEQ) ranged from 0.67 to 1057 ng-TEQ/g plastic, with the highest levels observed in polystyrene (PS) particles from the southern Sri Lankan coast. Benzo[a]pyrene and dibenzo[a,h]anthracene exhibited elevated TEQ for parent PAHs, whereas dichloropyrene, and dibromopyrene represented the highest TEQs for ClPAHs and BrPAHs, respectively. The data evidenced that several HPAH congeners can increase the PAH-like toxicity (∼86%) in mMPs. This study provides insights into the accumulation of parent and halogenated PAHs in mMPs, highlighting their potential combined implications in marine and terrestrial ecosystems.