Leaching of di-2-ethylhexyl phthalate from biodegradable and conventional microplastics and the potential risks

There has been a growing concern about plastic pollution, both from a health and ecological perspective. One of the major concerns with plastic debris, especially microplastics (MPs) relates to their strong potential for releasing additives and chemicals. Di-2-ethylhexyl phthalate (DEHP) is a common plastic additive widely used as plasticizer in plastic products, and is of global concern due to its widespread contamination in the environment. In this study, two conventional nondegradable plastics (polyethylene (PE) bags and PE mulch) and two biodegradable plastics (poly(butylene adipate co-terephtalate)-starch-based-polylactic acid bags (PBAT/PLA bags) and PLA mulch) were selected to investigate the release of DEHP to seawater. The results showed that leaching potentials of DEHP from different types of MPs varied. Among the four selected MPs, PE mulch had the highest leaching potential (6.88 μg/g), followed by PE bags (4.24 μg/g), PLA mulch (1.10 μg/g) and PBAT/PLA bags (0.89 μg/g). The DEHP leaching kinetic curves of the four MPs were all in line with the pseudo first order model. The potential risk of environmental and human exposure to the leached DEHP was assessed using the average Phthalate Pollution Index (PPI). The calculated PPI indicated low pollution risks of DEHP released by the four MPs in seawater.