FILE - This Sept. 13, 1979, file photo shows motorists as downtown parking lots fill up in Los Angeles. Over 170 million of people born in the United States who were adults in 2015 were exposed to harmful levels of lead as children, according to a study published in the Proceedings of the National Academy of Sciences on Monday, March 7, 2022. The researchers looked only at lead exposure caused by leaded gasoline, the dominant form of lead exposure from the 1940s to the late 1980s, according to data from the U.S. Geological Survey. (AP Photo/Wally Fong, File)