Bioavailability and organ-specific impacts of polyethylene-adsorbed bisphenol A compared to free bisphenol A in rats

Abstract

Introduction: Microplastics (MP) are emerging contaminants ubiquitously present in the food chain. Increasing evidence indicates that MP can be absorbed and accumulated in organs. Plastic additives of MP raise as a major health concern. Objective: To analyze the bioavailability and health impact of polyethylene (PE)-adsorbed bisphenol A (BPA-PE) and free BPA. Experimental design: In the study I, rats were gavaged with 2 mg/kg free BPA, BPA-PE (0.67 g PE/kg), or their respective vehicles. In the study II, rats were gavaged with 0,67 mg/kg free BPA, BPA-PE (0.22 g PE/kg), pristine PE, or the combined vehicles. All rats were sacrificed 24 h after administration. Results: Plasma glucuronidated BPA (gBPA) was detected in BPA-PE rats of both studies. In the study I, only free BPA administration induced (P<0.05) the activity of hepatic antioxidant proteins (GPx, SOD). Conversely, only BPA-PE administration altered (P<0.05) the activity of lung antioxidant enzymes (GRd, SOD). Moreover, only BPA-PE increased the expression of genes involved in oxidative stress (Mn- Sod, iNos) in the liver, adipose tissue (AT), and lung; in lung repair (Tgfb, Col1a1); and in AT lipogenesis (Srepb1c, leptin). In the study II, gBPA levels from BPA-PE group were not different from those found in the free BPA group. In the gut, both free BPA and BPA-PE increased (P<0.05) the activity of a prooxidant enzyme (MPO), a phase II detoxification enzyme (GST), and the expression of Mrd1, involved in the protection from toxics. Both pristine PE and BPA-PE induced (P<0.05) Tgfb mRNA levels in the lung. Conclusions: The bioavailability of MP-adsorbed BPA is similar to that of free BPA. However, the body distribution of BPA-PE appears to differ from that of free BPA, affecting organs such as the lung.