Lots of lead in the bones may make a heart unhealthy.
Blood lead concentration has been associated with mortality from different causes. Many effects of lead exposure that might increase risk of death are likely to result from cumulative exposure, for which bone lead is a better marker than blood lead. US occupational standards for lead exposure are currently based on measuring blood levels, which can return to normal a few months after exposure ends. Bone lead, on the other hand, can show exposure that happened years or even decades ago.
Researchers studied 868 men participating in a long-term study of aging in America to find out the association between both blood lead and bone lead with mortality. The average age of the participants was about 67 years. The researchers tested the levels of lead in the men's kneecaps and in their shin-bones. Data regarding age, smoking and race was collected from all the participants.
During the 9 years of follow-up, it was found that 241 men died. Those who ranked in the top third based on their bone lead levels were 3 times more likely to die, and 6 times more likely to die from heart-related causes, than men with the lowest levels.
Also, older men with the highest bone lead levels were more than eight times as likely as those with the least lead in their bones to die of ischaemic heart disease caused by blocked arteries.
The researchers concluded that high levels of blood lead have been tied to a high risk of death from many causes. There are many plausible mechanisms; it could damage the autonomic nervous system, which controls the heart; boost blood pressure; or harm the heart tissues.