CEFIC Workshop on methods to determine dermal permeation for human risk assessment

We report on a workshop, held with the support of CEFIC (European Chemical Industry Council), designed to bring together relevant expertise and to reach a consensus recommendation on a standardised protocol for in vitro determination of permeability coefficients. The proposed protocol is intended, in the first instance, for testing aqueous soluble chemicals only. The Workshop also proposed a strategy to extend the scope of the methodology to the full range of industrial chemicals, and made recommendations for the use of the permeability coefficients in risk assessment. The rationale for organising the workshop is the European Commission proposal known as REACH, which will require extensive risk assessments of all existing chemicals, including exposure via dermal contact. It is impractical to measure dermal permeation for the many thousands of industrial chemicals in use today. An alternative approach is to base predictions of permeation on statistically derived relationships between physical-chemical properties and the permeability coefficient of representative chemicals, relationships known as QSARs (quantitative structure- activity relationships). However, existing QSARs have been derived from data obtained by a variety of experimental methods, which makes the prediction less reliable. The reliability is to be improved by using a standardised widely-adopted experimental protocol.