Chemical testing strategies for predicting health hazards to children

Abstract

The United States Environmental Protection Agency has proposed the development of a Children’s Health Test Program under the Toxic Substances Control Act. The Environmental Protection Agency’s proposal for the children’s health test battery has 12 different assays including general toxicity, genotoxicity, carcinogenicity, neurotoxicity, and developmental and reproductive toxicity. The current Environmental Protection Agency testing proposal is an “all or nothing” test battery. An alternative and preferable approach would be to use a science-based, tiered testing scheme. It is proposed that the Screening Information Dataset program, currently used by the Organization for Economic Co-operation and Development (OECD) for the Screening Information Dataset-High Production Volume test battery, or equivalent, be considered for the first step. Step 1 would include acute and repeat dose toxicity testing, developmental toxicity testing (first species OECD 414 or OECD 422), reproductive toxicity screening (OECD 415 or 422), and genetic toxicity testing. For this step, the rat would be the initial and only species tested unless the mouse was used for in vivo genetic toxicity. Step 2 of the proposed children’s health test battery would include developmental testing (second species OECD 414) or special mode of action studies performed for those chemicals that proved to be developmental toxicants in Step 1. Those chemicals that tested positive as reproductive toxicants in Step 1 would be tested in a two-generation reproduction study (OECD 416) or a special mode of action study. Steps 1 and 2 provide information on whether oncogenicity or developmental neurotoxicity testing is useful. Step 3 would include chronic toxicity/oncogenicity testing for those chemicals that tested positive for genetic toxicity in Step 1, and positive for developmental concerns in Step 2. In this step, chemicals would also be tested for developmental neurotoxicity if they showed evidence of neuropathy, behavioral effects, or neurotoxic potential in earlier studies. This stepwise approach would conserve resources and answer scientific questions in a logical, orderly, timely, and cost-effective manner.