Risk ranking: investigating expert and public differences in evaluating food safety hazards.

The allocation of resources with respect to food safety issues requires that decision makers prioritize these issues, which may conflict with the public's opinions on these matters. The purpose of this study was to compare how Canadian expert and lay respondents rank different food hazards, with a view to better understanding their underlying rationales for making decisions on food safety. A Carnegie Mellon risk ranking model was adapted for use by individuals with different backgrounds to rank six food safety issues: bovine spongiform encephalopathy (BSE), Escherichia coli O157:H7, Salmonella, botulism, paralytic shellfish poisoning (PSP), and acrylamide. Focus groups were conducted using public (n=29) and expert (n=21) participants. Key themes were identified from the focus groups as reasons why issues were rated high or low. The most common themes for high rankings were prevalence (of an agent) and/or severity (of a disease) and knowledge and control of a food safety issue. For the lowest rankings, common themes included low prevalence and severity and personal control over an issue. Explanations for why choices were made included availability, affect, numeracy, and optimistic bias. The majority of the rationales used by all participants were similar with the exception of the high ranking given to acrylamide by the public participants. The effect of attribute framing seemed to be the most influential in a participant's choices. Understanding that comparable reasoning is used in food safety decisions by both experts and the public has important implications for developing productive risk communication dialogues about issues and priorities.