A Strategy for Comparing the Contributions of Environmental Chemicals and Other Risk Factors to Children's Neurodevelopment

A Strategy for Comparing the Contributions of Environmental Chemicals and Other Risk Factors to Children's Neurodevelopment
http://ehp03.niehs.nih.gov/article/info:doi/10.1289/ehp.1104170

Abstract

Background. The impact of environmental chemicals on children's neurodevelopment is sometimes dismissed as unimportant because the magnitude of the impairments are considered to be "clinically insignificant." Such a judgment reflects a failure to distinguish between individual and population risk. The population impact of a risk factor depends both on its effect size and its distribution (or incidence/prevalence).

Objective. To develop a strategy for taking into account the distribution (or incidence/prevalence) of a risk factor as well as its effect size in order to estimate its population impact on children's neurodevelopment.

Methods. The total numbers of Full-Scale IQ points lost among U.S. children, ages 0 to 5 years were estimated for chemicals (methylmercury, organophosphate pesticides, lead) and a variety of medical conditions and events (e.g., preterm birth, traumatic brain injury, brain tumors, congenital heart disease).

Discussion. Although the data required for the analysis were available for only three environmental chemicals (methylmercury, organophosphate pesticides, lead), the results suggest that their contributions to neurodevelopmental morbidity are substantial, exceeding those of many non-chemical risk factors.

Conclusion. A method for comparing the relative contributions of different risk factors provides a rational basis for establishing priorities for reducing neurodevelopmental morbidity in children.