RESUMO
Polymers are the main building blocks of plastic, with the annual global production volume of fossil carbon-based polymers reaching over 457 million metric tons in 2019 and this figure is anticipated to triple by 2060. There is potential for environmental harm and adverse human health impacts associated with plastic, its constituent polymers and the chemicals therein, at all stages of the plastic life cycle, from extraction of raw materials, production and manufacturing, consumption, through to ultimate disposal and waste management. While there have been considerable research and policy efforts in identifying and mitigating the impacts associated with problematic plastic products such as single-use plastics and hazardous chemicals in plastics, with national and/or international regulations to phase out their use, plastic polymers are often overlooked. In this review, the polymer dimension of the current knowledge on environmental release, human exposure and health impacts of plastic is discussed across the plastic life cycle, including chemicals used in production and additives commonly used to achieve the properties needed for applications for which the polymers are generally used. This review focuses on polycarbonate, polystyrene, polyvinyl chloride, and polybutadiene, four common plastic polymers made from the hazardous monomers, bisphenol, styrene, vinyl chloride and 1,3-butadiene, respectively. Potential alternative polymers, chemicals, and products are considered. Our findings emphasise the need for a whole system approach to be undertaken for effective regulation of plastics whereby the impacts of plastics are assessed with respect to their constituent polymers, chemicals, and applications and across their entire life cycle.
RESUMO
BACKGROUND: Global plastic production has increased exponentially since the 1960s, with more than 6300 million metric tons of plastic waste generated to date. Studies have found a range of human health outcomes associated with exposure to plastic chemicals. However, only a fraction of plastic chemicals used have been studied in vivo, and then often in animals, for acute toxicological effects. With many questions still unanswered about how long-term exposure to plastic impacts human health, there is an urgent need to map human in vivo research conducted to date, casting a broad net by searching terms for a comprehensive suite of plastic chemical exposures and the widest range of health domains. METHODS: This protocol describes a scoping review that will follow the recommended framework outlined in the 2017 Guidance for the Conduct of Joanna Briggs Institute (JBI) Scoping Reviews, to be reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist. A literature search of primary clinical studies in English from 1960 onwards will be conducted in MEDLINE (Ovid) and EMBASE (Ovid) databases. References eligible for inclusion will be identified through a quality-controlled, multi-level screening process. Extracted data will be presented in diagrammatic and tabular form, with a narrative summary addressing the review questions. DISCUSSION: This scoping review will comprehensively map the primary research undertaken to date on plastic exposure and human health. Secondary outputs will include extensive databases on plastic chemicals and human health outcomes/impacts. SYSTEMATIC REVIEW REGISTRATION: Open Science Framework (OSF)-Standard Pre-Data Collection Registration, https://archive.org/details/osf-registrations-gbxps-v1 , https://doi.org/10.17605/OSF.IO/GBXPS.
