“Economic Gains Resulting from the Reduction in Children’s Exposure to Lead in the United States”, 2002 (; backlinks; similar):
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) 1976–23199925ya 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 1–5-year-old U.S. children from 1976–4198044ya–1991–3199430ya was 12.3 microg/dL, and the estimated decline 1976–23199925ya 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 $1,313,286.93$723,3002000 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 $199.73$1102000 billion to $579.2$3192000 billion.