Current methods for estimating human health risks from exposure to threshold-acting toxicants in water or food, such as those established by the U.S. EPA, the FDA, the NAS, the WHO and the FAO, consider only chronic or lifetime exposure to individual chemicals. These methods generally estimate a single, constant daily intake rate which is low enough to be considered safe or acceptable. The intake rate is termed the acceptable daily intake (ADI). Two problems with the approach have been recognized. The first problem is that the method does not readily account for the number of animals used to determine the appropriate 'no-observed-effect-level' (NOEL). The second problem with the current approach is that the slope of the dose-response curve of the critical toxic effect is generally ignored in estimating the ADI. The report illustrates both a revised approach to estimate ADIs with all toxicity data which includes methods for partial lifetime assessment, and novel methods for ADI estimation with quantal or continuous toxicity data. The latter method addresses to a degree the common problems with the current approach.