The<unk> <unk>  denotes the<unk>  of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant increase in the frequency or severity of any<unk><unk> s of the tested protocol. In drug<unk> opment, the<unk>  of a new drug is assessed in laboratory animals, such as mice, prior to initiation of human trials in order to establish a safe clinical starting dose in humans. The OECD publishes guidelines for Preclinical Safety Assessments, in order to help scientists discover the<unk> .
No-observed-adverse-effect level
Lowest-observed-adverse-effect level
Safety pharmacology
Relative biological effectiveness
Clinical endpoint
Risk–benefit ratio
Number needed to harm
Appropriate use criteria