since it is the minimum concentration classified as R38 (‘‘irritating to skin’’)
under the Dangerous Substances Directive of the European Communities (EEC, 1992). Hence, by definition, any chemical (or formulation) showing equal or greater skin irritation than 20% SDS (by statistical analysis), should be classified as irritating to skin under the acute exposure conditions used. Using the conve- nient calculation of TR50 (time of exposure required for 50% of subjects to show positive skin irritation response), it has been reported that the range of response for 20% SDS across multiple studies is approx- imately 1.5–3 h (Robinson et al., 1998). Testing under