The committee will review information on the land application of sludge and evaluate the methods used by the U.S. EPA to assess risks from chemical pollutants and pathogens in sludge. Specifically, the committee will:
1. Review the risk-assessment methods and data used to establish concentration limits for chemical pollutants in sludge to determine whether they are the most appropriate approaches. The committee will also consider the NRC's previous (1996) review and determine whether that report's recommendations have been appropriately addressed. Issues to consider include: (a) how the relevant chemical pollutants were identified; (b) whether all relevant exposure pathways were identified; (c) whether exposure analyses, particularly from indirect exposures, are realistic; (d) whether the default assumptions used in the risk assessments are appropriate; and (e) whether the calculations used to set pollutant limits are appropriate.
2. Review the current standards for pathogen elimination in sludge and their adequacy for protecting public health. The committee will consider: (a) whether all appropriate pathogens were considered in establishing the standards; (b) whether enough information on infectious dose and environmental persistence exists to support current control approaches for pathogens; (c) risks from exposure to pathogens found in Class B sludge; and (d) new approaches for assessing risks to human health from pathogens in sludge.
3. Explore whether approaches for conducting pathogen risk-assessment can be integrated with those for chemical risk-assessment. If appropriate, the committee will recommend approaches for integrating pathogen and chemical pollutant risk-assessments.
Sponsor: U.S. Environmental Protection Agency
