The leading role and responsibility of the international scientific community in test development.

The possibility that one or more environmental factors may be affecting adversely the endocrine systems of humans and wildlife has been the subject of international study for the past 7 years. Irrespective of which factors are the most important contributors to the perceived problem; the decision has been taken to evaluate synthetic chemicals for such chemical toxicities. This decision requires access to reliable and relevant endocrine disruption (ED) assays. However, few such tests currently exist, albeit many candidate assays are currently under development. Faced with this situation, the US Environmental Protection Agency has taken the lead in supporting the development and validation of appropriate ED assays. Two of these assays, the rodent uterotrophic assay and the Hershberger anti-androgen assay, are in the final stages of validation, a project conducted under the auspices of the Organisation for Economic and Commercial Development. This article describes the particular scientific issues associated with the validation of these two assays and alerts to the continuing need to consider new assay protocols as they become available.