'Safe' blood lead levels linked to risk of death

September 18, 2006

Blood lead levels generally considered safe may be associated with an increased risk of death from many causes, including cardiovascular disease and stroke, according to a report in Circulation: Journal of the American Heart Association.

Researchers studied lead levels below 10 micrograms per deciliter (μg/dL) which previously has been considered safe.

The levels studied are common and considerably lower than lead levels perceived by the government as a concern to public health, said Paul Muntner, Ph.D., author of the study and an associate professor of epidemiology and medicine at Tulane University School of Public Health and Tropical Medicine in New Orleans.

"Our study found the association of blood lead with cardiovascular death to be evident at levels as low as 2 ìg/dL," he said. "Since 38 percent of U.S. adults had lead levels above 2 ìg/dL in 1999-2002, the public health implications of these findings are substantial."

The Occupational Safety and Health Administration (OSHA) defines high blood lead in adults as higher than 40 μg/dL. The Centers for Disease Control and Prevention recommend that women of child-bearing age have blood lead levels below 10 μg/dL.

Researchers said the study questions the current belief about what lead levels are safe in the population.

"We wanted to know whether there was an association between the current blood lead levels among U.S. adults and coronary heart disease, stroke or cancer," Muntner said.

Since the mid-1970s, when lead was no longer added to gasoline or household paint and lead was banned for use in soldering food cans, average blood lead levels in American adults have decreased from 13.1 μg/dL to 1.6 μg/dL.

"Even though lead levels are much lower than before, the current levels are still orders of magnitude higher than pre-industrial levels," Muntner said.

Today lead is mostly used to make batteries. It is also used to make ammunition (bullets), pipes and roofing materials. According to OSHA, exposure to lead can occur in at least 120 occupations including lead smelting, battery manufacturing, ship building/repair, auto manufacturing and printing. Breathing contaminated air, eating contaminated food or soil, or drinking contaminated water are ways people can be exposed to lead. Inhalation of airborne lead is generally the most significant source of occupational lead absorption.

The researchers used data from the Third National Health and Nutrition Examination Survey Mortality Follow-Up Study, involving 13,946 adults whose blood lead levels were collected and measured between 1988 and 1994.

When researchers studied those who died by Dec. 31, 2000, they found that death from any cause, cardiovascular disease, heart attack and stroke increased progressively at higher lead levels.

Compared to participants with blood lead below 1.9 μg/dL, participants with blood lead between 3.6 μg/dL and 10 μg/dL had: "The increased risk of all-cause and cardiovascular deaths with increased lead levels affected all groups we studied: non-Hispanic whites, non-Hispanic blacks and Mexican Americans, as well as males and females," Muntner said. "The risk of death from cancer did not increase at the blood lead levels that our study investigated.

"Our study had limited ability to evaluate the risks of lead exposure associated with blood lead levels below 2 μg/dL. Future research is needed to identify the level of lead exposure that is not associated with major health outcomes. Although markedly reduced, the current blood lead levels may not be low enough, and we believe that practical and cost-effective methods for reducing lead exposure in the general U.S. population are needed."
Co-authors are: Andy Menke, M.P.H.; Vecihi Batuman, M.D.; Ellen K. Silbergeld, Ph.D.; and Eliseo Guallar, M.D., Dr.P.H.
The National Institutes of Health partially funded the study.

Statements and conclusions of study authors published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.

American Heart Association

Related Heart Attack Articles from Brightsurf:

Top Science Tip Sheet on heart failure, heart muscle cells, heart attack and atrial fibrillation results
Newly discovered pathway may have potential for treating heart failure - New research model helps predict heart muscle cells' impact on heart function after injury - New mass spectrometry approach generates libraries of glycans in human heart tissue - Understanding heart damage after heart attack and treatment may provide clues for prevention - Understanding atrial fibrillation's effects on heart cells may help find treatments - New research may lead to therapy for heart failure caused by ICI cancer medication

Molecular imaging identifies link between heart and kidney inflammation after heart attack
Whole body positron emission tomography (PET) has, for the first time, illustrated the existence of inter-organ communication between the heart and kidneys via the immune system following acute myocardial infarction.

Muscle protein abundant in the heart plays key role in blood clotting during heart attack
A prevalent heart protein known as cardiac myosin, which is released into the body when a person suffers a heart attack, can cause blood to thicken or clot--worsening damage to heart tissue, a new study shows.

New target identified for repairing the heart after heart attack
An immune cell is shown for the first time to be involved in creating the scar that repairs the heart after damage.

Heart cells respond to heart attack and increase the chance of survival
The heart of humans and mice does not completely recover after a heart attack.

A simple method to improve heart-attack repair using stem cell-derived heart muscle cells
The heart cannot regenerate muscle after a heart attack, and this can lead to lethal heart failure.

Mount Sinai discovers placental stem cells that can regenerate heart after heart attack
Study identifies new stem cell type that can significantly improve cardiac function.

Fixing a broken heart: Exploring new ways to heal damage after a heart attack
The days immediately following a heart attack are critical for survivors' longevity and long-term healing of tissue.

Heart patch could limit muscle damage in heart attack aftermath
Guided by computer simulations, an international team of researchers has developed an adhesive patch that can provide support for damaged heart tissue, potentially reducing the stretching of heart muscle that's common after a heart attack.

How the heart sends an SOS signal to bone marrow cells after a heart attack
Exosomes are key to the SOS signal that the heart muscle sends out after a heart attack.

Read More: Heart Attack News and Heart Attack Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.