application can be updated or developed to ensure consistent attainment of target pathogen concentrations. To conduct QMRAs, a conceptual site model should be used to identify all potential routes of exposure; additional input data (e.g., dose-response and pathogen-survival data) should be collected; and consideration should be given to potential secondary transmission of infectious disease. QMRAs also can be used to analyze sensitivity and to ascertain what critical information is needed to reduce uncertainty about the risks from exposure to pathogens in biosolids. The pathogen standards should be reevaluated and updated periodically to ensure that they are supported by the best available scientific data and methods and to ensure that anecdotal information is not being used for the predication of past, current, or future regulations.
EPA should foster development of standardized methods for measuring pathogens in biosolids and bioaerosols.
EPA should promote research that uses improved pathogen detection technology to better establish the reliability of its prescribed pathogen treatment processes and biosolids-use controls to achieve and maintain minimal exposure over time. In setting pathogen treatment requirements, it might be useful to establish metrics for typical (mean) treatment performance and concentrations not to be exceeded.
Research should be conducted to assess whether other indicator organisms, such as Clostridium perfringens, could be used in regulation of biosolids. Such indicators, along with traditional indicators and operational parameters, may be suitable for monitoring day-to-day regulatory compliance.