. "Appendix B: Options for Dealing with Uncertainties." Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients. Washington, DC: The National Academies Press, 1998.
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TABLE B. Approaches for Dealing with Uncertainties in a Risk-Assessment Program
Program Model
Advantages
Disadvantages
Case-by-case judgments by experts
Flexibility
High potential to maximize use of most relevant scientific information bearing on specific issues
Potential for inconsistent treatment of different issues
Difficulty in achieving consensus
Need to agree on defaults
Written guidelines specifying defaults for data and model uncertainties (with allowance for departures in specific cases)
Consistent treatment of different issues
Maximizes transparency of process
Allows resolution of scientific disagreements by resorting to defaults
May be difficult
to justify departure
to achieve consensus among scientists that departures are justified in specific cases
Danger that uncertainties will be overlooked
Assessors asked to present full array of estimates, using all scientifically plausible models
Maximizes use of scientific information
Reasonably reliable portrayal of true state of scientific understanding
Highly complex characterization of risk, with no easy way to discriminate among estimates
Size of required effort may not be commensurate with utility of the outcome
References
EPA (U.S. Environmental Protection Agency). 1986. Guidelines for carcinogen risk assessment. Federal Register 51:33992–34003.
NRC (National Research Council). 1983. Risk Assessment in the Federal Government: Managing the Process. Washington, DC: National Academy Press.
NRC (National Research Council). 1994. Science and Judgment in Risk Assessment. Committee on Risk Assessment of Hazardous Air Pollutants. Board on Environmental Studies and Toxicology. Washington, DC: National Academy Press.
