A systematic evidence map protocol for mapping global exposure to bisphenols and their alternatives and social and environmental justice implications

Background: Bisphenol A (BPA) is one of the highest-volume chemicals produced worldwide, and human exposure to BPA is thought to be ubiquitous. Stricter regulations around the use of BPA have led many manufacturers to switch to other bisphenol chemicals with similar functions such as bisphenol S and F. Even though exposure to BPA, other bisphenol chemicals and bisphenol alternatives poses a health risk for humans, very little is known about the granular exposure levels of different populations around the world. Aim: This systematic evidence map (SEM) will identify human studies reporting concentrations of bisphenols and their alternatives measured in human bio-samples with the aim to chart the global human exposure levels by country and population characteristics to identify research gaps and discuss any social and environmental injustice implications. Search strategy and eligibility criteria: MEDLINE (R), Embase and Web of Science (WoS) databases as well as grey literature sources will be searched using predefined search strings. The database search results will be supplemented by backward and forward citation tracking on included studies. A scoping exercise conducted during planning identified 90 bisphenol chemicals and alternatives used in plastics. These include BPA, other bisphenol chemicals with/without similar functions to BPA as well as alternatives with similar functions to bisphenol chemicals. Eligible studies must measure concentrations of at least one relevant bisphenol chemical/alternative in human bio-samples. Study selection: Only primary studies published in English since 2010 will be considered. The title, abstract and keywords will be screened by the DistillerAI tool and two independent reviewers. Grey literature will be screened by two reviewers for inclusion and exclusion. The full text of the included studies will then be screened by two independent reviewers. Study appraisal: Study quality will not be evaluated in this SEM. Data extraction and coding: Data extraction and coding will be performed by two independent reviewers. Parameters of interest will include the following: study characteristics (e.g., year of publication, sampling timepoints and study design), population information (e.g., country, age, sex, ethnicity, number of participants) and exposure information (sources of exposure, bio-sample analyzed, chemical name, concentration, and detection frequencies). Synthesis and visualization: The results will be presented using a narrative summary, tables, bar plots and colorcoded maps. The interactive database will be available on a dedicated freely accessible website. Systematic map protocol registry and registration number: This protocol has been registered on Open Science Framework (OSF) and is available at https://doi.org/10.17605/OSF.IO/MNWTD.