"Safe" Blood Levels Need Redefining

Blood lead levels currently considered safe by the U.S. government have been found to be associated with increased risk of death from many causes, including heart disease and stroke, according to a report in Circulation: Journal of the American Heart Association.

The new study by Paul Muntner, associate professor of epidemiology and medicine at Tulane University School of Public Health and Tropical Medicine, questions current thinking about what lead levels are safe in the general adult population.

Earlier studies on U.S. adults indicated that blood lead levels above 40 µg/dL (micrograms per deciliter) are associated with increased risks of cardiovascular, cancer and mortality for several adult groups having occupational exposure to lead. For the general population, studies have shown that blood lead levels above 10 µg/dL are associated with these same mortality risks.

The Occupational Safety and Health Administration currently defines high blood lead in adults as higher than 40 µg/dL. The Centers for Disease Control and Prevention recommends that women of childbearing age keep blood lead levels below 10 µg/dL.

The Tulane study recommends reassessment of what levels ought to be considered safe, based on data correlating relatively low blood lead levels and death due to cardiovascular causes. The researchers used data from the Third National Health and Nutrition Examination Survey Mortality Study, which involved a nationally representative sample of U.S. adults whose blood lead levels were collected and measured between 1988 and 1994.

"In our data, the association of blood lead with cardiovascular mortality was evident at levels as low as 2 µg/dL," says Muntner. "As 38 percent of U.S. adults had lead levels above 2 µg/dL, the public health implications of these findings are substantial."

Co-authors of the study are: Andy Menke, Tulane University School of Public Health and Tropical Medicine; Vecihi Batuman, Tulane University School of Public Health and Tropical Medicine; Ellen K. Silbergeld, Johns Hopkins Bloomberg School of Public Health and and Eliseo Guallar, Johns Hopkins Bloomberg School of Public Health.