"Our study estimates the impact of historical lead exposure on adults now aged 44-years-old or over in the US, whose exposure to lead occurred in the years before the study began", says lead author Bruce Lanphear, of Simon Fraser University, Canada. 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 United States, scientists kept tabs on more than 14,000 adults who took a national health survey between 1988 and 1994, then again in 2011.
Professor Bruce Lanphear, who led the study at Canada's Simon Fraser University, said: "Our study estimates the impact of historical lead exposure on adults now aged 44 years old or over in the U.S., whose exposure to lead occurred in the years before the study began".
Metin Avkiran, associate medical director at the British Heart Foundation, said: "This study adds to the substantial evidence that exposure to lead can have long-term consequences".
So, what is the link between lead exposure and heart disease?
The figure is "10 times more than previously thought and could put deaths from lead exposure on a par with smoking", says The Independent.
An worldwide study has found that low-level lead exposure could be responsible for 30 per cent of premature deaths from cardiovascular disease in the United States. Over the last 10 years, research has found an array of health effects in adults at low levels; the US Department of Health and Human Services published a monograph in 2012 showing that even very low blood lead levels raised a person's risk for hypertension, heart disease, and reduced kidney function.
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After the median follow-up of 19.3 years, 4,422 people died-including 1,801 from CVD and 988 from heart disease.
Lead was undetectable in the blood of almost one in 10 of the volunteers tested.
"Our study calls into question the assumption that specific toxicants, like lead, have 'safe levels, '" Bruce Lanphear, a professor at Simon Fraser University and the lead author on the paper, said in a statement.
"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".
People with high blood levels had a 70 percent greater risk of dying from cardiovascular disease than those with lower levels. The authors were also unable to control for all potential confounding factors, such as exposure to arsenic or air pollution, which are also risk factors for cardiovascular disease. "Public health measures, such as [upgrading] 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".
"A key conclusion to be drawn from this analysis is that lead has a much greater impact on cardiovascular mortality than previously recognised".
Studies into and policies based on dangers of low-level lead exposure normally focus on children, and the IQ points they stand to lose when too much of the heavy metal reaches their developing brains.