Chapter 43 - Regulatory Considerations in Developmental Neurotoxicity of Organophosphorus and Carbamate Pesticides

Abstract

The assessment of chemical pollutants, including pesticides, for developmental neurotoxicity potential has been, and continues to be, an issue of intense scientific and public concern. Pesticide registration in the United States is conducted by the US Environmental Protection Agency (EPA) under the authority of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and the Federal Food Drug and Cosmetic Act. These regulations were both amended in 1996 with the promulgation of the Food Quality Protection Act (FQPA). It is believed that exposure to environmental agents contributes to adverse developmental outcomes. Many pesticides and classes of pesticides, including the organophosphorus (OP) and carbamate (CM) pesticides, are known to affect the nervous system, and there are concerns regarding the potential for developmental neurotoxicity following early life exposures to these substances. This is particularly important because the unique behaviors and activities of children place them at greater risk for increased exposure to pesticides by multiple routes. Health effect test guidelines, which are standardized protocols that describe the conduct of defined toxicology studies, have been published by the EPA and by a number of other regulatory agencies throughout the world. The developmental neurotoxicity (DNT) includes measurements that are not assessed in any other available guideline studies, particularly in relationship to the developing organism, and has been shown to be a sensitive indicator of developmental insult. Evaluation and interpretation of DNT and comparative cholinesterase study data are conducted in accordance with agency risk assessment guidelines for developmental toxicity, reproductive toxicity, and neurotoxicity.