ISEE/ISEA 2006 Conference Abstracts Supplement: Symposium Abstracts: Abstracts
*U.S. EPA, NERL; †U.S. EPA, NHEERL; and ‡NICHD NCS PO
The National Children's Study (NCS) is a longitudinal cohort study that is designed to follow a nationally representative sample of American children from before conception or early pregnancy until age 21 years. The Children's Health Act of 2000 directs a consortium of United States Federal agencies to: 1) evaluate the effects of both chronic and intermittent exposures on child health and human development; and 2) investigate mechanisms of developmental disorders and environmental factors that influence health and developmental processes to identify factors that are helpful, harmless, and harmful. Exposures very early in pregnancy are difficult to measure directly because women may be unaware of their pregnancies, and the logistics of timing and collecting samples during these early windows are challenging.
The NCS is focused on enrolling women who are likely to become pregnant as well as those early in pregnancy to assess the impact on child health and development due to in utero exposures that occur early in pregnancy. Couples planning pregnancy will be visited up to 4 times in the 6 months after enrollment (or moving into this group) to assess pregnancy status, exposures, and to collect biologic specimens. Once pregnant, study visits are scheduled for each trimester: a home and clinic visit in the first trimester and a clinic visit in the second and third trimesters. Environmental factors to be studied are prioritized based on the core hypotheses for the NCS, which have been developed over the past 5 years with input from a variety of scientists and stakeholders (www.nationalchildrensstudy.gov). The NCS defines environment broadly, including chemical, physical, biologic, behavioral, and social factors, as well as genetic factors and their interactions with environmental exposures.
To evaluate the effects of both chronic and intermittent exposures, the study needs to develop approaches to capture the frequency, magnitude, and duration of peak or intermittent exposures and carefully consider the impact of these measures on both participant burden and study costs. Approaches for exposure assessment in the NCS will likely involve a combination of environmental and biologic samples together with questionnaire and diary reporting. A strategy for their use is based on 2 related concepts: 1) core measures obtained for the entire cohort and the use of validation subsamples for more detailed exposure measurements (ie, for measurement error adjustment); and 2) a hierarchical approach that relates measures obtained at different levels of aggregation (eg, individual, residential, community, and region). A comprehensive pilot study will assess the feasibility of enrolling women using a household-based screening approach and will demonstrate the acceptability of biologic and environmental sample collection during pregnancy.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.