Blood lead levels currently thought to be safe by the
U.S. government, the World Health Organization and many
other authorities are associated with an increased risk of
heart attack and stroke, according to researchers from the
Johns Hopkins Bloomberg
School of Public Health and Tulane University. Study
results demonstrate that environmental lead exposure
remains a major public health problem in the United States.
The study was published Sept. 20 in the online version of
Circulation: Journal of the American Heart
The researchers evaluated the association between
blood lead levels and mortality in 13,946 adult study
participants, who were part of the Third National Health
and Nutrition Examination Survey. Initially recruited
between 1988 and 1994, they were followed for up to 12
years. The mean blood lead level of the study participants
was 2.58 µ/dL (micrograms per deciliter), which is
well below levels currently considered safe by the U.S.
government. Blood lead levels above 2 µ/dL were
associated with an increased risk of heart attack and
"We saw an increased risk of death from all causes and
cardiovascular death in all subgroups — non-Hispanic
whites, non-Hispanic blacks and Mexican-Americans," said
Eliseo Guallar, co-author of the study and an associate
professor in the Bloomberg School's
Department of Epidemiology.
Exposure of the U.S. population continues to come from
old lead-based paint and the residues of automobile
emissions from the decades of lead use in gasoline; the
residues remain in dusts and soil. Some adults also may be
exposed in their place of work. Drinking water can also be
a source of lead exposure due to the presence of lead pipes
and solders. Unsafe consumer products, such as folk
medicines, cosmetics and toys, may also contain lead.
The U.S. Occupational Safety and Health Administration
defines high blood lead in adults as higher than 40
µ/dL. The Centers for Disease Control and
Prevention recommends that women of childbearing age keep
blood lead levels below 10 µ/dL.
Paul Muntner, corresponding author of the study and an
associate professor at Tulane's School of Public Health and
Tropical Medicine, said, "In our data, the association of
blood lead with cardiovascular mortality was evident at
levels as low as 2 µ/dL. As 38 percent of U.S.
adults had lead levels above 2 µ/dL, the public
health implications of these findings are substantial."
The study was co-authored by Andy Menke, Muntner,
Vecihi Batuman, Ellen K. Silbergeld and Guallar. It was
supported by a National Institutes of Health grant from the
COBRE Program of the National Center for Research