Identifying important life stages for monitoring and assessing risks from
exposures to environmental contaminants: Results of a World Health
Organization review
In this paper, we summarize exposure-related issues to consider in determining the most appropriate age
ranges and life stages for risk assessment. We then propose a harmonized set of age bins for monitoring
and assessing risks from exposures to chemicals for global use. The focus is on preconception through
adolescence, though the approach should be applicable to additional life stages. A two-tiered set of early
life age groups is recommended. The first tier involves the adoption of guidance similar to the childhood
age groups recommended by the U.S. Environmental Protection Agency, whereas the second tier consolidates
some of those age groups to reduce the burden of developing age-specific exposure factors for different
regions. While there is no single ‘‘correct’’ means of choosing a common set of age groups to use
internationally in assessing early life exposure and risk, use of a set of defined age groups is recommended
to facilitate comparisons of potential exposures and risks around the globe, the collection of data
and analyses of aggregate exposure and cumulative risk. Application of these age groups for robust
assessment of exposure and risk for specific populations will require region-specific exposure factors
as well as local environmental monitoring data.