Lead exposure causes one in three cardiovascular deaths

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As many as 412,000 Americans die prematurely every year - mostly from cardiovascular disease - due to historic exposure to low levels of the toxic metal, a USA study suggests.

Professor Bruce Lanphear who is from Simon Fraser University in Canada tells,"Today, lead exposure is much lower because of regulations banning the use of lead in petrol, paints and other consumer products, so the number of deaths from lead exposure will be lower in younger generations".

"But if we're underestimating the impact of lead exposure on cardiovascular disease mortality and other important outcomes beyond IQ, then it might have a big impact on the way we make investments in preventing lead poisoning exposure".

The authors note some limitations, including that their results rely on one blood lead test taken at the start of the study and therefore can not determine any effect of further lead exposure after the study outset.

Lead is most widely recognized as a hazard to children, who can suffer intellectual damage from even minimal exposure.

Exposure to traces of lead in petrol and paint may be linked to hundreds of thousands of premature deaths each year.

Overall, 18% of USA participants who died from all causes during the period reviewed were found to have more than 1mg/dl of lead in their blood. But only 20% of Americans now smoke, while lead exposure is more common, affecting 90% of people in the study.

Additionally, the study took only one reading of lead in participants' blood, when levels were likely to have changed over time.

For example, people with the highest lead levels were more likely to be men, smokers, and less educated, with poorer diets, high cholesterol, hypertension and diabetes, all of which are risk factors for cardiovascular disease.

Over an average 19.3 years of follow-up, a total of 4,422 deaths occurred. Of those, 1,801 died from cardiovascular disease and 988 passed away from heart disease. An increase of lead concentration in the participants' blood from 1 µg/dL to 6.7 µg/dL, was linked to ischemic heart disease mortality (HR = 2.08; 95% CI, 1.52-2.85, or 185,000 deaths a year); CVD mortality (HR = 1.7; 95% CI, 1.3-2.22, or 256,000 deaths a year); and all-cause mortality (HR = 1.37; 95% CI, 1.17-1.6).

These subjects were also 70 percent more likely to die from CVD, and their risk of death from heart disease was doubled.

Lead was undetectable in the blood of almost one in 10 of the volunteers tested.

Are there any "safe levels" of toxicants?

The figures quoted apply to the U.S., and it is unclear how levels of lead exposure in Britain compare, but "if results were similar in this country it would mean 100,000 deaths a year could be linked to past lead pollution", says The Times.

"Despite the striking reductions in concentrations of lead in blood over the past 50 years, amounts found nowadays in adults are still ten times to 100 times higher than people living in the pre-industrial era".

In what USA Today says is the first study using a nationally representative sample to look at how low-level lead exposure is tied to deaths in the U.S., scientists kept tabs on more than 14,000 adults who took a national health survey between 1988 and 1994, then again in 2011.

"It is not surprising that lead exposure is overlooked; it is ubiquitous, but insidious and largely beyond the control of patients and clinician. Public health measures, such as abating older housing, phasing out lead-containing jet fuels, replacing lead-plumbing lines, and reducing emissions from smelters and lead battery facilities, will be vital to prevent lead exposure".