Plasticizers released from PVC microplastics in aquaculture environments: leaching behaviors and ecological implications

Contamination of microplastics (MPs) and their associated plastic additives in the marine environment is a global concern due to their widespread distribution and toxicity to aquatic life. Although polyvinyl chloride (PVC) materials are commonly used in aquaculture environments, the potential risks of PVC MPs and the release of their additives in aquatic environments and organisms remain largely unknown. In this study, we investigated the leaching behaviors of phthalate esters (PAEs), including the mass and composition of PAEs in PVC MPs and their leaching kinetics, and evaluated the environmental risks of using PVC canvas in aquaculture activities. It was found that diethyl phthalate (DEP) was the most dominant PAE compound leached from PVC MPs (44.70±7.87 ng/g), followed by dimethyl phthalate (DMP, 24.40±1.56 ng/g). The Elovich model was applied to simulate the leaching kinetics, and the simulated curves showed similar logarithmic trends that PAEs rapidly migrated from MPs to the water column at first and followed by a gradual increase over time. The different leaching kinetics of PAEs can be explained by their chemical properties, such as water solubility, molecular weight, and octanol-water partition coefficient. Compounds with lower solubility showed higher leaching coefficients, which are the constants of different PAEs in Elovich equation. Considering the potential joint toxicity of PVC leachates and the importance of food security, it is recommended to use PVC products responsibly and manage plastic waste properly.