An evaluation of neurobehavioral tests used to assess the neurodevelopmental effects of early ammonium perchlorate exposure.

Perchlorate is an anion known to interfere with normal production of thyroid hormones that are integrally involved in the development of the central nervous system and neurobehavioral capacities. Given the identification of drinking water contamination with perchlorate, there are efforts to investigate the effects of exposure in developing fetuses and children in order to guide the establishment of regulatory standards. Systematic neurobehavioral investigations in animal models have been completed to evaluate neurodevelopmental consequences of exposures at different concentrations in drinking water. However, these investigations have not directly addressed the public concern for increased incidences of childhood attention deficit disorders, autism, and lowered IQs of children in areas with known contamination. Although epidemiological data suggest there is not a relationship between drinking-water perchlorate exposure and these childhood disorders, it may be prudent to use animal models to systematically assess the potential for such problems. Given the behavioral complexity of these problems, an appropriate evaluation will require the use of nontraditional neurobehavioral tests such as operant conditioning tasks of varying levels of complexity, and juvenile rat play. Such tests will provide a more direct evaluation of the potential for attention deficits, autism, and lowered IQ scores related to thyroid hormone disruption due to early perchlorate exposure.