In evidence‐based scientific assessments, evidence synthesis is the step that occurs after collecting the data relevant to a clearly formulated research question and appraising the validity of the studies selected for the assessment, according to structured and pre‐defined approaches. When studies are readily comparable, evidence synthesis is usually carried out through meta‐analysis. In hazard assessment in chemical risk assessment (CRA), the process for combining evidence, ‘evidence integration’, is a recognised challenge as the underlying evidence bases are very diverse and not readily comparable (owing e.g. to varying degrees of validity and precision, diverse data types, different populations and species, models, end‐points, routes of exposure, and evidence streams ‐ human observational studies, experimental animal studies, in vitro and computational models data).
The European Food Safety Authority (EFSA) and the Evidence‐Based Toxicology Collaboration (EBTC) organised a Colloquium to develop a multistakeholder understanding of the best practices, challenges and research needs for evidence integration in CRA, with a focus on hazard identification and on combining multiple studies and end‐points for dose–response modelling. The methods discussed included: qualitative methods for integrating evidence within‐ and across evidence streams; bias‐adjusted meta‐analysis; quantitative approaches to combine evidence across evidence streams; and quantitative approaches for combining multiple end‐points and multiple studies for dose–response modelling.
All these methods showed advantages and needs for further development, testing, validation and effective implementation. Support to this could be provided by: more published primary toxicological and epidemiological data; optimisation of study design; a shared primary data repository; the establishment of a community of knowledge of toxicologists, epidemiologists and statisticians. Equally, to be conducted soundly, evidence integration in CRA should be undertaken by multidisciplinary groups (toxicologists and methodologists knowledgeable of the various integration techniques). EFSA and EBTC will continue the collaboration towards the development, testing and validation of best practices for evidence‐based CRA.
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