In this study we quantify economic benefits from projected improvements in worker
productivity resulting from the reduction in children's exposure to lead in the United
States since 1976. We calculated the decline in blood lead levels (BLLs) from 1976
to 1999 on the basis of nationally representative National Health and Nutrition Examination
Survey (NHANES) data collected during 1976 through 1980, 1991 through 1994, and 1999.
The decline in mean BLL in 1- to 5-year-old U.S. children from 1976-1980 to 1991-1994
was 12.3 microg/dL, and the estimated decline from 1976 to 1999 was 15.1 microg/dL.
We assumed the change in cognitive ability resulting from declines in BLLs, on the
basis of published meta-analyses, to be between 0.185 and 0.323 IQ points for each
1 g/dL blood lead concentration. These calculations imply that, because of falling
BLLs, U.S. preschool-aged children in the late 1990s had IQs that were, on average,
2.2-4.7 points higher than they would have been if they had the blood lead distribution
observed among U.S. preschool-aged children in the late 1970s. We estimated that each
IQ point raises worker productivity 1.76-2.38%. With discounted lifetime earnings
of $723,300 for each 2-year-old in 2000 dollars, the estimated economic benefit for
each year's cohort of 3.8 million 2-year-old children ranges from $110 billion to