Background: Use of divergent methods to identify health risks posed by environmental hazards may hinder the goal of transparency and reduce the level of confidence the public may have in the recommendations made. There is no international standard for best practice in conducting hazard identification or risk assessment of environmental hazards.

Objectives: To describe the processes and methods used by national and international organizations that conduct hazard identification and/or risk assessment of environmental hazards, including; how they define eligible types of evidence; search for evidence; assess quality at the individual study level and the overall body of evidence; and make final recommendations.

Methods: We searched the websites of 19 organizations and extracted data from all relevant publicly available written guidance documents that described the methods and processes used in hazard identification and/or risk assessment of environmental hazards.

Results: Seventeen of the 19 organizations had publicly available documents describing the methods and processes used in hazard identification and/or risk assessment; 15 organizations described the process for how the substances to be assessed were selected; 1 organization used full systematic review methods; 11 organizations assessed the scientific quality of the included studies, but only five named the tool/s they used to assess quality; seven conducted a formal assessment of the quality of the overall body of evidence using clear criteria; nine organizations described the process for making the final hazard identification or risk assessment conclusions/recommendations; eight rated the strength of the final conclusions/recommendations; and 11 organizations had a disclosure statement regarding conflicts of interest of working/review group members.

Conclusions: This work highlights the need for more standardized tools and processes used in the evaluation and synthesis of evidence, and methods employed to formulate recommendations when conducting hazard identification and/or risk assessment of environmental hazards, with the goal of increasing both transparency and comparability between organizations.

Patient or healthcare consumer involvement: Each organisation was given the opportunity to provide additional information and review the data we collected on the methods they employ.