Toxicity Assessment Alternatives: Methods, Issues, Opportunities contains a broad array of critical surveys, contributed by active and respected investigators, describing their research and offering updates on toxicity assessment alternatives, directions determined by current and future grant programs, opportunities for mechanistically based test methods to detect endocrine disruptor activity, the use of alternatives in the Department of Defense hazard assessment initiatives, and the issues and opportunities for validation and regulatory acceptance. Several of these advances make use oftransgenic models that reduce the time and cost of carcinogenicity testing. Others use tissue cultures for the assessment of endocrine disrupting chemicals. Cultures of human epidermal keratinocytes are applicable as models for sulfur mustard lesions, and in vitro protein denaturation is used as a chemical test for assessing the ocular and dermal irritation potential of cosmetic prod- ucts. Molecular modeling is applied to explaining chemical toxicity. Commercially developed assay systems have undergone extensive evaluation by their manufacturers. Some of these await external valida- tion, and others await acceptance by North American and European regulatory agencies. Toxicity Assessment Alternatives: Methods, Issues, Opportunities provides information from members of the scientific and regulatory communities on what has been achieved and what has been accepted in alternatives to animal testing.