Sensitive population subsets in relation to effects of low doses.

This paper presents an overview of current knowledge relative to identification and quantification of sensitive population subgroups, utilization of sensitive subgroups for studying low dose-effects and issues in formulating environmental policies from information on sensitive subsets of the population. General factors that contribute to sensitivity are developmental periods, genetic conditions, nutritional deficiencies, predisposing diseases and personal habits. An illustration of age-related sensitivity to radiation is given, which shows that one would need to examine ten times the number of metaphase cells from individuals age 25 as from those age 55 to obtain equivalent statistical precision in identifying increased numbers of radiation induced aberrations. Hence, knowledge of susceptible subsets is useful for study design and analysis. Important concerns noted in proposing standards include: whether to protect the entire population when only a small fraction is at increased risk; what emphasis should be placed on alteration of the predisposing factors, e.g., nutrition; and how to acquire the additional protection for sensitive groups in standards based on the general population.