[Use of semi-quantitative approaches in the evaluation and classification of potential teratogenicity of industrial...

To provide a consistent teratogenic risk assessment from animals' data, the system described here suggests an evaluation by stages. Based on the expert system from Mattison, the toxic responses of common species of experimental animals are scored. The scores are then multiplied by the ratio of the lowest adult 'toxic dose A, to the lowest developmental toxic dose D (A/D). The products form 3 categories. Based on the reversibility of the developmental effects, the categories are subdivided into classes A B C D. This system should permit an unbiased risk assessment and a comparison of industrial chemicals' prenatal toxicity.