Exposure to chemicals is a big concern for human health. Among all routes of exposure to chemical, topical route is important with different exposure scenarios.

Level of absorption to chemical topically applied is usually done with skin absorption study using human skin. Using validated analytical method, the amount of chemical penetrating the skin is quantified. Knowing chemical toxicity, a risk assessment can be done. For consumer exposure to cosmetics, Sccs guidelines provided define protocol.

Guidelines for pesticides are also well described. Nevertheless, many other scenarios cannot be easily defined. What should be the scenario of non-occupational exposure to polycyclic aromatic hydrocarbons in urban environment? How to evaluate a working day of a hairdresser submitted to repeated exposure?

Impact of the different experimental parameters of skin absorption studies on the level of chemical absorption and their consequences on risk assessment will be discussed.

Alternatives to in vitro human skin absorption study are possible to overcome such constraints. Monitoring the level of exposure can also be done through biomonitoring within plasma or urine. Of course, such monitoring can be done knowing metabolism profile. Thus, for Benzo[a]pyrene, the hydroxylated metabolite is quantified. Examples of biomonitoring of different chemicals topically applied will be presented.