I wish NBC News had linked to the study-and that I had time to read it even if had. It sounds interesting, and at the same time, incredible that they are able to make such an estimate.

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The peer-reviewed study, published Monday in the journal Proceedings of the National Academy of Sciences, focuses on people born before 1996 — the year the U.S. banned gas containing lead.

Exposure to leaded gasoline lowered the IQ of about half the population of the United States, a new study estimates.

Overall, the researchers from Florida State University and Duke University found, childhood lead exposure cost America an estimated 824 million points, or 2.6 points per person on average.