Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents (1997)
Chapter: USE OF CONFIDENCE LIMITS
as a factor of 10. Typically, uncertainty factors of 10 are used when extrapolating from animal-toxicity data to humans. The uncertainty of exposure and risk estimates should be estimated for critical biological effects.
Use of Confidence Limits
A shortcoming of the CDEPAT report is the failure to calculate confidence limits for the different exposures, such as ECt5 and ECt16. Point (best) estimates are needed to provide the best risk-benefit trade-offs, but the uncertainty of these estimates should be considered. Confidence intervals can be obtained for individual probit dose-response lines. The calculation of uncertainty becomes more complex when an average probit line is based on two or more sets of toxicity data. In that case, a central line might be chosen, as was done by CDEPAT for some of the estimates. If human data are not available, the line for the species most like humans may be selected. Various lines may be given more weight according to the quantity and quality of the data.
