‘Grey literature’ in systematic reviews and evidence syntheses on Environmental Health & Toxicology topics: a survey protocol

Background Systematic reviews and other types of evidence syntheses use rigorous methods to identify and synthesise all of the relevant evidence to answer a question. A robust search strategy is crucial to conducting a high quality evidence synthesis, as an inadequate search may miss relevant evidence and produce biased findings. Methodological recommendations endorse searching for ‘grey literature’, i.e., reports published outside of traditional commercial publishing. However, there is currently a lack of clarity about what is considered to be the relevant types of grey literature and how to deal with it. Objectives This survey will aim to answer three questions: (1) How do those conducting evidence syntheses on environmental health and toxicology (EHT) topics understand ‘grey literature’; (2) Where do they search for grey literature?; (3) How do they deal with included grey literature evidence? Methods Participants will be individuals who conduct systematic reviews and evidence syntheses in EHT, without restrictions on: previous experience in conducting evidence synthesis, age, gender or geographic location. Survey will be disseminated via relevant professional organisations, systematic review and evidence synthesis organisations, and social media. It will consist of a mix of demographic and content questions. Descriptive statistics will be reported as frequencies and percentages; free-text responses will be analysed thematically. Ethics The survey was exempted from a requirement to undergo ethics review. The first page of the survey will provide the respondents with information about the project and ethics approval; respondents will provide consent by clicking on a button to advance to the survey.