Microbial risk assessment frameworks, principles and approaches

Approaches for conducting microbial risk assessment (MRA) are rapidly evolving for decision-making about microbial pathogen-related health risks. The purposes of this project were to identify the similarities and differences of current MRA frameworks, describe key scientific challenges, compare diverse applications of the frameworks, and develop recommendations for advancing MRA. Online searches and contacts with experts were used to identify current frameworks and completed MRAs. The scope of the search was worldwide, but applications were limited to government-sponsored MRAs. Europe, Australia, Canada and the United States have published MRA policies, guidelines, and/or assessments. The most recent MRA completed by each government organization was compared to all others' MRAs to identify similarities and differences in approach, methods, analysis, and interpretation. Nearly all policies emphasized the importance of using sound science or weight-of-evidence methods in a clearly structured, documented and transparent process. Less often were iteration, documentation of assumptions, or health protection stated among fundamental MRA principles. While most government agencies relied on the four components of chemical risk assessment, several assessors noted the limitations of this approach. Some agencies have recognized the value of adding an initial problem formulation step, as in ecological risk assessment, and others have applied stochastic modeling methods to account for the dynamics in microbial pathogen scenarios. Finally, this presentation will provide recommendations for MRA and related decision-making improvements; such as including a systematic scoping and planning step, obtaining data needed to conduct MRAs, developing consistent modules for analytic purposes, and validating completed MRAs.