The definition and observation of clear-cut adverse health effects for
continuous (quantitative) responses, such as altered body weights or
organ weights, are difficult propositions. Thus, methods of risk asses
sment commonly used for binary (quantal) toxic responses such as cance
r are not directly applicable. In this paper, two methods for calculat
ing upper confidence limits on excess risk for quantitative toxic effe
cts are proposed, based on a particular definition of an adverse quant
itative response. The methods are illustrated with data from a dose-re
sponse study, and their performance is evaluated with a Monte Carlo si
mulation study.