Quantitative Procedures for Neurotoxicology Risk Assessment
In this project, previously published information on biologically based dose-response model for brain development was used to quantitatively evaluate critical neurodevelopmental processes, and to assess potential chemical impacts on early brain development. This model has been extended using similar principles for early neocortical development has allowed the evaluation of both normal neocortical development as well as to simulate the assessment of chemically induced alterations in neurodevelopment. The underlying premise in these models is understanding the impact of chemical exposures, and the basic dynamic, cellular and molecular processes that control early embryo/fetal brain development. Chemicals with available robust data sets have been chosen to illustrate the above issues. However, some related compounds with limited information will be evaluated as well. This will improve our understanding of how these methods can be applied to a broader range of toxicants. The chemicals used in the present case studies are: Methylmercury, Ethanol, Chlorpyrifos and Benomyl. An external draft report on four case studies of selected chemicals was peer-reviewed by independent peer reviewers in July 2005, and is presently being revised per suggestions of the peer reviewers.