At the end of this lecture, students should be able to describe the roles of hazard identification (HI) and dose-response assessment (DRA) in health risk characterization (RC). They are expected to understand that both HI and DRA are now considered the two key parts of toxicity assessment (TA). And they should know that nowadays the key components of health risk assessment (RA) are TA, human exposure assessment (HEA), and RC.

In addition, students should be able to list and define the dozen or more measures that are currently used to denote directly or indirectly a health risk level as (in)significant. They are expected to know that an appreciation or application of any of these risk measures is meaningless, unless they can understand what (minimum) level of safety factor is needed in assessing the health risk in question. By definition, some of the risk measures used today already have a safety factor built in.

Last but not least, from this lecture, students should be able to outline and explain many of the major issues pertaining to the uncertainties inherent in RC. It is due to these uncertainties that a safety factor needs to be incorporated into the risk calculation. Students should know that both HEA and TA play an important role in RC, since the latter characterization component is basically an integrative process in which information from HEA is used to check against that from TA. Because the uncertainty issues in HEA and TA are enormous and overwhelming, so are those in RC.