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Wen Zhang, Ph.D., P.E., BCEE
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Photo irradiation of BPA-free Baby Bottles could still leach out toxic chemicals such as microplastics and Bisphenol S
Dr. Wen Zhang’s group at New Jersey Institute of Technology and Dr. Yang Li’s group at Beijing Normal University published a collaborative research article in Envirommental Science and Technology showing that baby botttles derived polyethersulfone (PES) and polyphenylsulfone (PPSU) microplastics both released Bisphenol S under UV irradiation. These commericial plastics are now made of bisphenol A (BPA) free polymers as BPA is found to BPA is cause endocrine disruption of human body. However, since PES is a polyether polymerized only by bisphenol S (BPS) monomers, and PPSU is polymerized alternately by BPS and 4,4’-dihydroxybiphenyl (DHBP), they still have potential to leach out toxic chemicals such as plastic or poymer debrics (microplastics, nanoplastics and monomers). This study evidenced the release of BPS from PES and PPSU microplastics (MPs) derived from baby bottles under UV irradiation. Unfortunately, BPS also exhibits high estrogenic activity and interferes with the biological endocrine (hormonal) system, causing obesity, cancer and neurological diseases. Thus, the ecological and health risks of such commercial BPA-free plastic bottles are still concerning especially having UV exposure (e.g., sunlight irradiation).
A previous study reproted by Zhang’s group (https://doi.org/10.1021/acs.est.9b03428) indicates the risks of organometal release from Polyvinyl Chloride (PVC) Microplastics. Based on the knowledge (e.g., release kinetics model), this new study further streamlined the plastic aging pathways through experimental and computational appraoches. Finally, the collabortion team proposed a refined mechanitic kinetics model to predict the BPS release rate from MPs. This study provides groundwork that deepens our understanding of environmental aging and the chemical release of MPs. One of the chemical aging mechanisms could be that the photochemically generated hydroxyl radicals (•OH) attack results in the breakage of ether bonds and the formation of phenyl radicals (Ph•) and phenoxy radicals (Ph–O•). The •OH addition and hydrogen extractions further produce BPS from the decayed PES or PPSU MPs.
The study was supported by the Fund for National Key R&D Program of China (2017YFA0605001), the National Natural Science Foundation of China (Nos. 52170024 and 21677015), and the New Jersey Water Resources Research Institute (NJWRRI) Grant (Project Number: 2018NJ399B).