Umbrella Review: Impact of plastic-associated chemical exposure on human health.

What is the impact of plastic-associated chemical exposure on human health? Large-scale plastic production began in the 1950s and has since outpaced any other manufacturedmaterial (Geyer et al., 2017). Plastic is the signature material of our age which has transformed oureveryday lives via, for example, food packaging, construction materials, household and personalgoods, transport and medical applications (Landrigan et al., 2023). Plastic contamination of theenvironment, including air, water and soil, is ubiquitous, with plastics representing ‘a singularuncontrolled experiment on a global scale’ (Geyer et al., 2017) that are predicted to exceed planetaryboundaries, defined as a ‘safe operating space for humanity’ (Persson et al., 2022). During use, and once released into the environment, plastic fragments into smaller and smallerparticles called micro- and nanoplastics (World Health Organization (WHO), 2022a). These plasticparticles are beginning to be detected in human biospecimens (Kannan and Vimalkumar, 2021;Sripada et al., 2022). In addition, chemicals in plastics leach out of products during use anddegradation, reflecting the complex nature of plastic materials (Hahladakis et al., 2018). Indeed, thereare thousands of different known plastic-associated chemicals used to manufacture the polymermatrix of plastics, as well as added to the polymer matrix to give properties like flexibility (plasticisers)or fire resistance (flame retardants)(UNEP, 2023; Wagner et al., 2024; Wiesinger et al., 2021), withadditional chemicals that are inadvertently included in the manufacture of plastics, or formed andreleased during the degradation of plastics (Kato and Conte-Junior, 2021). Only a limited number ofthese chemicals have been looked for in human research or bio-surveillance programs, but of these,there are some common plastic-associated chemicals that have routinely detected in many humanstudies over several decades (Woodruff et al., 2011) although we are, in fact, exposed to mixtures ofmultiple chemicals (Wang et al., 2021). As part of its mission to eliminate the harmful effects of plastic on people and the planet, MinderooFoundation formed a partnership with the JBI to examine the published evidence for the impacts ofplastic exposure on human health. Evidence syntheses, such as pooled analyses and systematicreviews with meta-analysis, review the scientific literature both systematically and quantitatively, andprovide a rigorous and transparent evaluation of the published evidence (Curtin University LibraryServices, 2022). Here, we undertook an umbrella review to systematically evaluate this synthesised evidence.Umbrella reviews represent one of the highest levels of evidence synthesis currently available and arebecoming increasingly influential for translating research into best practice as well as policy (Fusar-Poli and Radua, 2018).KEY FINDINGS OF UMBRELLA REVIEW • There are no systematic reviews with meta-analyses of the health effects of plasticpolymers, micro- and nanoplastics. • We are exposed to plastic-associated chemicals from preconception onwards. • Despite a multitude of plastic-associated chemicals in use, only a fraction has beenresearched more than once, and subsequently meta-analysed, to assess health effects inhumans. • Exposure to plastic-associated chemicals is linked to a wide range of adverse healthoutcomes from before birth (miscarriage), at birth (weight, genital development andappearance), in children (neurodevelopment, obesity, blood pressure, asthma andbronchitis, precocious puberty in girls, i.e. onset before eight years), and in adultsUmbrella Review: Plastic-associated chemicals and human health. Part 1: Executive Summary 5(endometriosis, sperm concentration and quality, type 2 diabetes and insulin resistance,thyroid function, polycystic ovary syndrome, obesity, cardiovascular disease, hypertension,and cancer). • None of the plastic-associated chemicals examined can be considered safe, with multipleharmful health effects linked to each chemical class.