Effect of Microplastic Types on the In Vivo Bioavailability of Polychlorinated Biphenyls

Thisstudy investigated the effect of MP type on the bioavailabilityof HOCs, providing insights into exposure from co-occurring HOCs andMPs. As MPs are released into the soil, various equilibriumstatusesare expected. MPs could play roles as a source, acleaner, or a sink of HOCs. Threetypes of MPs (LDPE, PLA, and PS) were selected to study their effecton polychlorinated biphenyl (PCBs) relative bioavailability (RBA)measured by a mouse model. As a source of HOCs, exposureto MP-sorbed PCBs resulted in their accumulation in adipose tissuewith PCB RBA as 101 & PLUSMN; 6.73% for LDPE, 76.2 & PLUSMN; 19.2% for PLA,and 9.22 & PLUSMN; 2.02% for PS. The addition of 10% MPs in PCB-contaminatedsoil led to a significant (p < 0.05) reductionin PCB RBA (52.2 & PLUSMN; 16.7%, 49.3 & PLUSMN; 4.85%, and 47.1 & PLUSMN;5.99% for LDPE, PLA, and PS) compared to control (75.0 & PLUSMN; 4.26%),implying MPs acted as cleaner by adsorbing PCBs fromthe digestive system and reducing PCB accumulation. MPs acted as asink for PCBs in contaminated soil after aging, butthe sink effect varied among MP types with more pronounced effectfor LDPE than PLA and PS. Therefore, the role played by MPs in bioavailabilityof HOCs closely depended on the MP types as well as the equilibriumstatus among MPs, soil, and HOCs.

Automated summary

This study examined the impact of different types of microplastics (MPs) on the bioavailability of hydrophobic organic contaminants (HOCs). MPs released into the soil can exhibit various equilibrium statuses and act as a source, cleaner, or sink for HOCs. Three types of MPs (LDPE, PLA, and PS) were studied for their effect on the relative bioavailability (RBA) of polychlorinated biphenyls (PCBs) using a mouse model. Exposure to MP-sorbed PCBs resulted in their accumulation in adipose tissue, with LDPE showing the highest RBA (101 ± 6.73%), followed by PLA (76.2 ± 19.2%) and PS (9.22 ± 2.02%). When added to PCB-contaminated soil, MPs led to a significant reduction in PCB RBA, particularly LDPE (52.2 ± 16.7%), PLA (49.3 ± 4.85%), and PS (47.1 ± 5.99%), compared to the control (75.0 ± 4.26%), suggesting that MPs act as cleaners by adsorbing PCBs and reducing their accumulation. MPs also acted as a sink for PCBs in aged contaminated soil, with LDPE showing a more pronounced effect than PLA and PS. Therefore, the role of MPs in HOCs' bioavailability depends on the MP types and equilibrium statuses among MPs, soil, and HOCs.