While the history of immunotoxicology research involving experimental animals of immature ages dates back over several decades, there exist remarkably little data, to date, directly comparing the impact of developmental status on immunotoxicological risk. Given the size of the nonadult human population and the potential for differential vulnerability among the various ages, this represents a serious gap of knowledge in efforts to minimize environ-mentally linked health risks. This article frames the issues surrounding developmental immunotoxicological evaluations. In particular, the issues introduced include those of potential animal models, strain/genotype selection, gender, age of exposure, and age of assessment. Recent research results involving early exposure to lead (Pb) and other chemicals are discussed to highlight the nature of the decisions that are available and the potential cost–benefit associated with various approaches to evaluation.
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