"Things have substantially improved with the virtual elimination of leaded gasoline, restrictions on lead paint and other efforts to limit releases of industrial lead into the environment," A. Russell Flegal, professor of environmental toxicology at the University of California, Santa Cruz, said in a statement. "But the historic legacy of lead pollution persists -- a 2005 study showed 90 percent of the current atmospheric lead pollution in Los Angeles basin originally came from leaded gasoline -- and new inputs of industrial lead are adding to it."
U.S. atmospheric lead concentrations dropped by 89 percent in the past three decades, and average blood lead levels in U.S. children have shown a corresponding decline. However, blood lead levels are still about 100 times higher than the natural background level, and there is no known threshold for lead toxicity, Flegal said.
Major sources of lead emissions include the burning of coal, especially in countries such as China and India, and these emissions spread around the globe, Flegal said.
Lead is restricted in the United States, but lead taints food, health products and children's toys imported from other countries. U.S. customs officials last year seized 1,400 Halloween pirate costumes imported from China that contained 11 times the allowable level of lead.
Flegal presented the findings at the annual meeting of the American Association for the Advancement of Science in Boston.