ISEE/ISEA 2006 Conference Abstracts Supplement: Symposium Abstracts: Abstracts
The National Children's Study (NCS) is a longitudinal birth cohort study initiated in the United States to evaluate the relationships between children's health and the environment. Plans are to follow 100,000 children from preconception or early pregnancy until adulthood. Among multiple health outcomes, the study is proposing to investigate whether pre- and/or postnatal exposures to nonpersistent pesticides increase the risk of poor performance on neurobehavioral and cognitive examinations during infancy and early childhood. We have reviewed measurements for exposure assessment and propose a sampling scheme that can be used to characterize exposures during pregnancy and early childhood. Characterization of exposures will be challenging. Nonpersistent pesticides include many chemicals with biologic half-lives on the order of hours or days. Exposures can occur through multiple pathways (eg, food and residential or agriculture pesticide use) and by multiple routes (inhalation, ingestion, and dermal). Effects may depend on the developmental stage when exposure occurs. Sequential sampling will be required and should involve a combination of environmental and biologic monitoring as well as collection of questionnaire data. Exposure dosimeters will likely include biologic markers, personal and indoor air sampling techniques, collection of dust, surface and dermal wipe samples, and dietary assessment tools. Criteria for sample selection include evaluation of the timeframe of exposure captured by the measurement in relationship to critical windows of susceptibility, the cost and validity of the measurements, participant burden and variability in exposure routes across populations and at different age periods. As part of the NIEHS/EPA Children's Environmental Health Center, we have been conducting longitudinal birth cohort studies to evaluate effects of prenatal exposure to nonpersistent pesticides on fetal growth and infant neurocognitive development. We have used a number of strategies to assess exposure, including measurements of pesticides in personal air and house dust samples collected during pregnancy and in maternal and child urine, maternal and umbilical cord blood, and meconium. Our research has shown significant associations between certain insecticides and adverse fetal growth and neurocognitive development. Lessons learned from this research are discussed.