Exposure to Lead in Children – How Low Is Low Enough?

Summarizes recent epidemiological studies regarding the incidence of elevated blood lead concentrations in children in the United States. The key findings include: (1) strong and significant associations persist between blood lead concentrations and IQ, with data indicating an accelerated decline in IQ as a function of blood lead concentrations above the Centers for Disease Control (CDC) definition of elevated blood lead concentration; and (2) girls with slightly elevated blood lead concentrations between 8 to 18 years of age had evidence of delayed puberty. Cautious interpretation of the findings regarding IQ is advised because lead exposure is more common among disadvantaged children, which means that maternal IQ, socioeconomic factors, and other characteristics of the home environment also enter into an understanding of factors affecting IQ. However, the second set of findings raises the possibility of the effects of lead exposure on hormonally mediated processes, not limited to puberty. Previous research and current data suggest that the effects of lead exposure are long lasting and irreversible. Therefore, prevention offers the only strategy. Moreover, the fact that even low lead concentrations have adverse effects means no safety margin for existing exposures.