From dermal exposure to internal dose

Exposure scenarios form an essential basis for chemical risk assessment reports under the new EU chemicals regulation REACH (Registration, Evaluation, Authorisation and restriction of Chemicals). In case the dermal route of exposure is predominant, information on both exposure and dermal bioavailability is necessary for a proper risk assessment. Various methodologies exist to measure dermal exposure, providing quantitative or semiquantitative information. Although these studies may provide very specific and relevant information, it should be realized that case by case in-depth exposure assessment would be a very expensive process. Dermal bioavailability data are most often obtained from in vitro studies or animal experiments. For the design of studies, which generate data relevant for chemical risk assessment, detailed information on the exposure conditions is crucial (skin surface exposed, exposure duration, dose and physical state of the chemical). Results from non-testing methods for skin absorption, such as (Q)SARs, have been used only to a very limited extent for regulatory purposes. Suggestions are made in order to extend the use these methods to dermal risk assessment of chemical substances, thereby improving the practicability of REACH.