Considering evidence: The approach taken by the Hazardous Substances Advisory Committee in the UK.

The Hazardous Substances Advisory Committee (HSAC) provides expert advice to UK officials, Ministers and other relevant bodies on the protection of the environment, and human health via the environment, from potentially hazardous substances and articles. Hazardous substances are often the subject of controversy, on which individuals, and different groups in society, hold divergent views. This paper details the approach taken by HSAC when considering the evidence to provide advice on hazardous substances. Firstly HSAC reviews the range of evidence and determines its quality considering: transparency of aims, the methodology and results, completeness, independent review and accessibility. HSAC does not follow one explicit methodology as the wide range of hazardous substances we consider means they need to be addressed on a case by case basis. Most notably HSAC considers the evidence in the wider context, being aware of factors that influence individuals in their decision making when receiving a HSAC opinion e.g. trust in the source of the evidence, defensibility, conformity to a ‘world view’ and framing. HSACs also reflect on its own perspectives with the aim of addressing bias by the diversity of its membership. The Committee's intention, in adopting this rounded approach, is to reach opinions that are robust, relevant and defensible.