From Our 2006 Archives
Lead in Blood: 'Safe' Levels Too High?
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Average Americans Tested Had Level High Enough for Increased Heart Disease Death Risk
In fact, people with only a fifth the level of lead in their blood now considered 'high' are more likely to die of heart attack or stroke, the study shows.
These findings suggest the threshold for 'high' blood levels of lead may not fully take into account lead's heart risks, according to the study.
The study appears in Circulation's rapid access online edition.
A 'high' blood level is now defined as more than 10 micrograms of lead per deciliter of blood (10 mcg/dL).
Most Americans -- 99% -- fall below that threshold, write the researchers, who include Andy Menke, MPH, of Tulane University School of Public Health.
But an increased likelihood of death from heart attack or stroke has started to be seen in people with blood levels greater than 2 mcg/dL, according to Menke and colleagues.
14,000 Adults Tested
Data for the study came from nearly 14,000 adults who had their blood lead levels checked between 1988 and 1994 for government health studies.
Their average blood lead level was 2.58 mcg/dL.
Those with higher blood lead levels were more likely to be older, black or Mexican American, male, and smokers.
Participants were followed for up to 12 years, until the end of 2000.
During that time, a total of 1,661 participants died.
That number includes 267 from heart attacks, 141 from stroke, and 411 from cancer.
After adjusting for risk factors such as ethnicity, income, education level, and urban living, the researchers found that those with blood levels greater than 2 mcg/dL were more likely to die of heart disease, heart attack, or stroke -- but not cancer.
For their study, the researchers divided the adults into three groups based on blood lead levels. The highest had a blood level from 3.63 mcg/dL to 10 mcg/dL. The lowest had less than 1.93 mcg/dL.
Compared with the lowest blood level group, the highest had an 89% increased risk for death from heart attack.
The risk of death from stroke was 2.5 times greater in the highest blood level group than in the lowest.
Such increased risks started at blood levels greater than 2 mcg/dL.
It's not clear if the lead levels reflected current or past lead exposure, the researchers note.
SOURCES: Menke, A. Circulation, rapid access edition; Sept. 18, 2006. WebMD Health News: "CDC: Dangerous Blood Levels Down." News release, American Heart Association.
© 2006 WebMD Inc. All rights reserved.
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