Biometric Evaluation of the ATC Method for the Determination of the Acute Dermal Toxicity of Chemicals

Abstract

The new dermal acute toxic class (ATC) method is presented for one specific classification system for chemicals (released by the European Union) according to acute dermal toxicity. It is a stepwise procedure using three animals of one sex per step. Three starting doses are possible. Assuming a Probit model for the dose response relationship probabilities of a correct, of a less and of a more stringent classification are calculated. It is shown that these probabilities depend only weakly on the starting dose. Also, the expected numbers of used and of dead animals are derived in dependence on the LD50 and on the dose response slope β, as well as the starting doses minimizing the expected animal number are proposed. The results demonstrate that the dermal ATC method is a reliable alternative to the classical LD50 test with the use of significantly fewer animals.