TestSmart and toxic ignorance

There are a number of national and international efforts designed to screen chemicals for toxicity. Although the emphasis in terms of the specific chemicals is different, e.g. endocrine disruptors, children's health, High Production Volume (HPV), the European Registration, Evaluation and Authorisation of Chemicals (REACH) programme, the purpose is the same. Each is intended to evaluate the potential toxicity of chemicals to humans and, in some cases, to the environment. How best can these tasks be accomplished? The first need is to provide a realistic prioritisation of which chemicals need to be evaluated. Once identified, a defined decision-tree approach with an emphasis on short-term in vitro assays and new genomic technologies offers the greatest promise. The more practical matter of screening the chemicals would be by using a tiered decision-tree approach. Common features of the approach would be the use of three tiers. The first tier would be a screening/prioritisation tier, the second would provide an initial characterisation of toxicity, and the third would discern mode of action/biological activity. The intent of this approach is to provide a concept that will allow decisions to be made as to which chemicals need to be tested, provide some idea as to their toxicity and finally mode of action, and at the same time, taking into account the Three Rs, reduction, refinement and replacement. Thus, specific batteries of tests are not discussed, as these would need to be tailored to the specific chemicals of concern, e.g. endocrine disruptors, HPV. Neither are regulatory requirements factored into the concept, but the data that would be gathered should consider the possibility of eventual submission of the data obtained by in vitro and other non-traditional approaches by regulatory authorities.