Release and intestinal translocation of chemicals associated with microplastics in an in vitro human gastrointestinal digestion model

Abstract The global production of plastic currently exceeds 300 million tonnes per year. The extensive use of plastics and bad waste management has resulted in the presence of microplastics at different levels in the food production chain. From a chemical perspective, these microplastics are complex mixtures that contain multiple additives, such as plasticizers, flame retardants, stabilizers and pigments. Also other chemicals can be present in microplastics, including unreacted monomers, starting substances, and non-intentionally added substances. Finally, the microplastics may have adsorbed environmental contaminants. In this study we have used several types of microplastics, either from grinded beach litter or from frequently used food packing materials and pre-production samples. We quantified the chemical and metal release from these microplastics in worst case and physiological scenarios. We use a chemical extraction as worst case, and for the physiological scenarios we used an in vitro model of the human digestion and an in vitro model of the human intestinal epithelium. Subsequently all samples were analysed with sensitive ICP-MS, GCMS methods. We quantified 68 chemicals and 29 metals associated with a diversity of microplastics, some of these chemicals were also released in the luminal content of the human digestive tract under physiological conditions simulated in vitro. Only 22 chemicals reached the basolateral compartment of an in vitro intestinal epithelial model. From the ToxCast dataset we extracted 18 AOPs that were associated with the chemicals, that included AOPs associated with endocrine disruption. For a risk assessment of chemicals associated with microplastics more detailed data on oral microplastics exposure is needed, as well as more detailed toxicological studies on the hazards of both the individual and complex mixtures of the quantified chemicals.