Lead Exposure and Heart Disease

There have been several reports suggesting that the amounts of lead in the body are associated with an increase in cardiac mortality.  These have been based on blood lead concentrations.  Now a group of Harvard physicians have examined the risk of death in relation to bone lead levels, which are more likely to represent long-term cumulative exposure to the heavy metal.  Their results are published in the journal Circulation.

The researchers analyzed data from 868 men from the Department of Veterans Affairs Normative Aging Study that started in 1963, when the men’s age averaged 67.  Lead in the blood and bones were measured, using X-ray fluorescence.  During the next 9 years there were 241 deaths in the collective.

The subjects were classified into 3 groups (tertiles), based on the lead concentrations in their patellae (kneecaps).  The risk of death from cardiovascular disease was 6 times greater in men from the tertile with the highest levels of bone lead compared to the men in the tertile with the lowest levels.  And the risk of death from any cause was 2.5 times greater in the highest vs. the lowest tertile.  These results were independent of age, smoking, education, race, use of alcohol, physical activity, body mass index (BMI), cholesterol or other lipid levels, high blood pressure, or diabetes.  In other words, the relationship was pretty watertight.

The chief investigator of the study has stated “The findings with bone lead are dramatic. . . [and] suggest that, even in an era when current exposures are low, past exposures to lead represent an important predictor of cardiovascular death, with important public health implications worldwide.” 

While air pollution has been the main source of lead in recent years, it has fallen since lead-free gasoline has been introduced.  However, most of the lead in the body has been there for a number of years.  It’s been proposed that the half life of lead in the patella is about 8 years, and in the tibia (shinbone) a matter of decades.  We should be alert for current sources of lead, to avoid adding to the quantities in the body that are probably already there.