Asa Bradman¹ and Robin M. Whyatt²

¹Center for Children’s Environmental Health Research, School of Public Health, University of California, Berkeley, California, USA; ²Columbia Center for Children’s Environmental Health, Mailman School of Public Health, Columbia University, New York, New York, USA

Abstract
The National Children’s Study is a proposed longitudinal cohort study to evaluate the relationships between children’s health and the environment. Enrollment is estimated to begin in September 2005, and 100,000 children will be followed 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 exams during infancy 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 (e.g., food and residential or agriculture pesticide use) and by multiple routes (inhalation, ingestion, dermal). Effects may depend on the developmental stage when exposure occurs. Sequential sampling is likely to be required and may involve a combination of environmental and biologic monitoring as well as collection of questionnaire data. In this article we review measurements that can be used to characterize exposures. These 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 will necessitate evaluation of the time frame 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. Key words: biomonitoring, early childhood, environment, exposure assessment, in utero, National Children’s Study, pesticides. Environ Health Perspect 113:1092-1099 (2005). doi:10.1289/ehp.7769 available via http://dx.doi.org/ [Online 12 May 2005]

This article is part of the mini-monograph “Assessing Exposures to Environmental Agents during the National Children’s Study.”

Address correspondence to R.M. Whyatt, Joseph L. Mailman School of Public Health, Columbia University, 60 Haven Ave., B-109, New York, NY 10032 USA. Telephone: (646) 459-9609. Fax: (646) 459-9610. E-mail: rmw5@columbia.edu

The authors have contributed equally to the work and are listed alphabetically.

We gratefully acknowledge R. Weldon for her review of pesticides in breast milk. We also thank other members of the Exposure to Chemical Agents Workgroup of the National Children’s Study for their input and comments during the preparation of the manuscript.

The National Children’s Study provided support for the preparation of the manuscript. A.B. was supported partly by the U.S. Environmental Protection Agency (U.S. EPA) grant R82679, National Institute of Environmental Health Sciences (NIEHS) grant PO1ES09605, and National Institute for Occupational Safety and Health grant RO1 OH07400. R.M.W was supported partly by NIEHS grants P50 ES09600, 5 RO1 ES08977, RO1ES111158, and RO1 ES012468 and U.S. EPA grants R827027 and 8260901.

The authors declare they have no competing financial interests.

Received 19 November 2004; accepted 12 May 2005.

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