A rationale for lowering the blood lead action level from 10 to 2 microg/dL

Abstract

Fifteen years ago, in 1991, the U.S. Centers for Disease Control and Prevention (CDC) established 10 microg/dL as the lowest level of concern for children's blood lead levels. This value is extremely important because, historically, policy makers and public health officials generally have acted to remove sources of lead exposure only after the CDC's level of concern had been exceeded. A growing body of evidence, however, reveals that blood lead levels below 10 microg/dL may impair neurobehavioral development. There is now sufficient and compelling scientific evidence for the CDC to lower the blood lead action level in children. This review argues that a level of 2 microg/dL is a useful and feasible replacement. Although it can be argued, in turn, that no threshold for the health effects of lead is demonstrable, analytically a blood level of 2 microg/dL is readily and accurately measured and provides a benchmark for successful prevention. Lowering the level of concern would encourage and accelerate the investments needed to ensure that children are protected from lead exposure in their homes, schools, and play settings. Such a program would also offer economic advantages because of the coupling between lead, educational attainment, earnings and anti-social conduct. By lowering the blood action level, CDC will promote policies and initiatives designed to further reduce children's exposure to this potent developmental neurotoxicant.

Fig. 1

The gradual decline in acceptable blood lead levels in children. The 2006 number is the recommend value based on current scientific knowledge.

Fig. 2

Estimated losses in IQ if lead had remained in gasoline 1970–1990.

Fig. 3

Losses associated with five-point drop in IQ on a population of 100 million. Based on Weiss (1988) and modified by http://www.ourstolenfuture.org/NewScience/behavior/iqshift.htm.

Fig. 4

The consequences of a one point (1%) drop in IQ depending on the mean population IQ (Weiss, 2000).

Fig. 5

Effect of reductions in mean IQ on the proportion of scores in the superior range.

Fig. 6

Combined effects on weekly earnings (based on 1997 dollars) of cognitive ability (based on IQ) and educational attainment. Based on Ceci et al. (1997).