Effects of polyethylene and polystyrene microplastics on bioaccumulation and toxicity of dibutyl phthalate in...

Microplastics (MPs) are increasingly found alongside pollutants in marine environments, yet their effects on the behavior of these pollutants, such as phthalate esters (PAEs), remain largely unexplored. This study investigated the bioaccumulation and toxicity of dibutyl phthalate (DBP, a prevalent marine PAE) in Mytilisepta virgata (a common mussel in East Asia) in the absence and presence of MPs (polyethylene and polystyrene, in both pristine and naturally aged forms). Results from uptake kinetics revealed that DBP accumulation in mussels varied with the type of co-exposed MPs, likely influenced by their DBP adsorption capacity and density-mediated distribution pattern. Observations from depuration kinetics suggested that the accumulated DBP tended to persist in mussels after exposure to either DBP alone or a combination of DBP and MPs. Lipid peroxidation (LPO) analysis indicated that while MPs did not exacerbate DBP-induced lipid peroxidation with significant differences in LPO levels noted between MP types and aging forms, they could compromise the resilience of mussels to lipid peroxidation. Acute toxicity tests demonstrated that mussels maintained a survival rate of over 90 % at bioavailable levels of DBP, regardless of the presence of MPs. These findings imply that while mussels can thrive, they may risk substantial DBP accumulation and irreversible oxidative damage in marine environments where DBP and MPs coexist, potentially causing negative impacts on mussel population and higher trophic levels. This study provides insights into how MPs influence the fate of coexisting pollutants in marine environments, enhancing our understanding of the ecological risks posed by MPs.