Blood-Lead Levels have declined by 75% in the US

Since the virtual disappearance of leaded gas in the United States (it's still sold for use in propeller airplanes), the mean blood-lead level of the American population has declined more than 75 percent. A 1985 EPA study estimated that as many as 5,000 Americans died annually from lead-related heart disease prior to the country's lead phaseout. According to a 1988 report to Congress on childhood lead poisoning in America by the government's Agency for Toxic Substances and Disease Registry, one can estimate that the blood-lead levels of up to 2 million children were reduced every year to below toxic levels between 1970 and 1987 as leaded gasoline use was reduced. From that report and elsewhere, one can conservatively estimate that a total of about 68 million young children had toxic exposures to lead from gasoline from 1927 to 1987.

http://www.globalleadnet.org/advocacy/initiatives/nation.cfm