CHILDREN's SUSCEPTIBILITY TO CHEMICALS: A REVIEW BY DEVELOPMENTAL STAGE

Abstract

Concerns about adequate protection of children's health from chemicals in the environment have created a need for research to identify how children's risks differ from adults’. A systematic review of factors that affect child sensitivity throughout development may be useful for research and practice in this area. We summarized available literature and other peer-reviewed information on factors that affect pharmacokinetics and exposure in an age-based developmental framework. Biological processes related to chemical absorption (gastrointestinal, dermal, and pulmonary), distribution, metabolism, and excretion were considered, along with reference to behaviors and other factors associated with child-specific exposures. The available information was summarized in a timeline of maturation for biological processes. It indicates variability in the duration and timing of maturation for each biological function. Possible implications for understanding pediatric sensitivity to environmental chemicals are discussed in light of factors affecting exposure through development. Themes that emerge from the evidence are presented as hypothesis-generating conclusions. This approach may be useful for evaluating developmental trends of susceptibility, and for identifying time periods and/or chemical classes of particular concern and thus important to consider in risk assessment.

The authors acknowledge Ruth Etzel for valuable review comments on the final draft of a report on which this article is based. Martha Embrey, Lisa Ragain, and Prem Sarin provided useful feedback to earlier drafts. We also thank the JTEH reviewers for their input in revising the article. This work was supported by Cooperative Agreement CX 826396-01-0 with the U.S. Environmental Protection Agency, Office of Water, Health and Ecological Criteria Division. Opinions are those of the authors and do not represent official opinions of the agency or its employees.