ABSTRACT
The rate-determining step for human risk assessment is bioavailability, that amount of chemical in the environment which gets into the human body. If the exposure includes skin, then skin permeability becomes a rate-determining step. Various methods are available to assess skin permeability. These include in vivo, in vitro, and computer model methods. Cost/benefit would favor the in vitro system (this is assumed) and certainly the computer calculated permeability is cost friendly (not to mention manpower friendly). The downside is that errors can cost money and human suffering. This presentation gives examples of the different methodologies, showing when they work and where validation points out method shortcomings.
