Chemical profile and toxicity of the leachates from aged plastics under simulated conditions

Marine organisms are prone to be exposed to leachates from aged plastics. However, the ecological risk of leachates from aged plastics remains elusive. In this study, the chemical profile and toxicity of leachates from aged plastics under simulated seawater (SW) and fish digest (FD) conditions were respectively investigated by chemical analyses and bioassays. Overall, 371 additives were identified in the leachates from 15 aged plastics, with the FD leachates containing nearly half as many identified additives as the SW leachates. In terms of toxicity, 20% of the FD leachates inhibited the bioluminescence of the recombinant Escherichia coli, while 16.7% of the SW leachates stimulated the bioluminescence. Besides, the heart rate of marine medaka (Oryzias melastigma) embryos was significantly accelerated by 66.7% of the FD leachates and 53.3% of the SW leachates. In general, the FD leachates had fewer identified additives and lower concentrations but elicited higher toxicity than the SW leachates. Furthermore, the leachates induced higher genotoxicity in O. melastigma embryos than in larvae. Compared with the virgin plastics, the aging process potentially promoted the leaching of additives, but exerted relatively lower toxicity on E. coli and O. melastigma larvae. This study has offered a comprehensive understanding of the chemical profile and toxicity of the leachates from plastics under virgin and aged status, which facilitates the risk assessment of marine plastic pollution.