Assessing the Risks Associated With Exposure to Waterborne Pathogens: An Expert Panel's Report on Risk Assessment ^†

The resurgence of outbreaks of waterborne diseases in the United States underscores the need for quantitative methods for assessing the human health risks associated with various types of waterborne pathogens in diverse environments (e.g., drinking water, waste water, recreational water) under different exposure scenarios (e.g., ingestion, inhalation from aerosols). An expert panel developed a three-stage general framework for conducting risk assessments of waterborne pathogens. An initial problem formulation stage involving all stakeholders identifies the purpose of the risk assessment, the critical issues to be addressed, and how the results might be used to protect public health. The analysis characterizes both the exposure and the health effects. This compilation of quantitative and qualitative data, expert opinion, and other information yields a host/pathogen profile that explicitly identifies the assumptions and uncertainties associated with the profile. The final stage, risk characterization, states the likelihood and types and magnitude of effects likely to be observed in the exposed population under the expected exposure scenario, including all the inherent assumptions and uncertainties. This characterization will be used by risk managers and policy makers to reduce human health risks and by risk communication specialists to inform the public.