Dietary exposure experiments on the migration of chemical pollutants from microplastics to bivalves.

Plastics can contain two types of organic contaminants; absorbed from ambient water, and already contained as additives. To investigate the bioaccumulation of these substances, we conducted two types of exposure experiments using mussels and polyethylene microplastics with absorbed PCBs and containing four types of additives (BDE209, DBDPE, UV327 and UV234). After dietary exposure for 15 days, significantly higher concentrations of total PCBs, UV327 and UV234 were detected in the gonad of exposed groups than in the control groups, respectively. However, no significant differences in BDE209 or DBDPE levels were observed between the control and exposure groups. Although a higher transfer ratio was shown for PCB congeners with octanol-water partition coefficients (logK) below 7, the ratio was lower for higher-hydrophobic PCBs with logK above 7. This suggests that higher hydrophobic compounds (not only highly chlorinated PCBs, but also BDE209 and DBDPE) tend not to desorb or leach from plastics.