Bioaccumulation of legacy and emerging organophosphorus flame retardants and plasticizers in insects during metamorphosis

Seven insect taxa belonging to five different orders were collected from a former Chinese e-waste dumping site to investigate the occurrences of organophosphorus flame retardants (PFRs) and plasticizers. The total PFR and plasticizer concentrations were in the ranges of 2.3-91 ng/g ww (median: 20 ng/g ww) and 420-15600 ng/g ww (4040 ng/g ww), respectively. The contaminant patterns varied greatly among different insect taxa owing to their specific habitats and feeding habits. The larvae of litchi stinkbugs and grasshoppers exhibited significantly higher PFR concentrations than their adult counterparts. In contrast, the adults of butterflies, moths, and dragonflies exhibited significantly higher PFR concentrations than their larvae. Additionally, negative linear correlations were frequently observed between the ratios of PFR and plasticizer concentrations in adult to larva (A/L) and log KOW in the four studied insect taxa, which were different from those corresponding to persistent organic pollutants. Notably, the contaminant concentrations of dragonfly ecdysis were significantly higher than those of dragonfly larvae, indicating that ecdysis is an important pathway by which dragonflies remove PFRs and plasticizers.