Scientific knowledge in recent years has demonstrated that children are a vulnerable population subgroup with special susceptibilities and unique exposures to environmental factors that have important implications for public health practices and risk assessment approaches. The heightened susceptibility of children derives primarily from the unique biological and physiological features that characterize the various stages of development from conception through adolescence as well as from certain behavioral characteristics and external factors that may result in increased exposure levels. This new volume in the Environmental Health Criteria (EHC) Series provides a systematic analysis of the scientific principles to be considered in assessing health risks in children; taking into account their unique susceptibilities. The terms children and child as used in this report include the stages of development from conception through adolescence. This new EHC builds on previous volumes addressing methodologies for assessing risks in children: EHC 30 Principles for Evaluating Health Risks to Progeny Associated with Exposure to Chemicals During Pregnancy (WHO 1984) and EHC 59 Principles for Evaluating Health Risks from Chemicals During Infancy and Early Childhood: The Need for a Special Approach (WHO 1986). The central focus of this volume is on the child (developing embryo fetus infant etc.) rather than on a specific environmental agent target organ or disease. Thus it addresses the difficult task of integrating all what is known about both exposure information toxicity data and health outcome at different life stages, which is especially challenging when data are limited for particular life stages (e.g. during pregnancy). The book will be useful to public health officials' research and regulatory scientists and risk assessors.