People Aren't as Safe From Lead as Thought, Study Suggests

Tuesday, 13 Mar, 2018

As many as 412,000 Americans die prematurely every year - mostly from cardiovascular disease - due to past exposure to small amonts of the toxic metal, a new United States study suggested. However, because lead can contribute to conditions such as high blood pressure and hardening of arteries, it is also believed to contribute to cardiovascular and heart disease.

People can be exposed to lead via fuel, paint and plumbing, as well as around smelting sites or by handling lead batteries.

"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", says lead author Professor Bruce Lanphear, Simon Fraser University, Canada.

"This work has implications in Australia where we often see lead exposures in a number of inner city areas, for example in Sydney and Melbourne, as well as in mining communities and also nationally through drinking water fixtures and fittings", said Dr Paul Harvey, a postdoctoral researcher from the Department of Environmental Sciences at Macquarie University. All were given a medical examination at the start of the study that included a blood test for lead, with readings ranging from less than 1mg per decilitre of blood to 56mg.

At the outset, the average level of lead found in the participants' blood was 2.7 µg/dL, but ranged from less than 1 to 56 µg/dL.

"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".

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

The study said "the estimated number of deaths from all causes and cardiovascular disease that were attributable to concentrations of lead in blood were surprisingly large; indeed, they were comparable with the number of deaths from current tobacco smoke exposure".

The research found that people with high lead levels were at 37 per cent greater risk of premature death from any cause, 70 per cent times greater risk of cardiovascular death, and double the risk of death from ischemic heart disease, compared to those with lower levels.

"What this study suggests is there's no apparent safe level" for adults, said the principal author of the study, Bruce Lanphear of Simon Fraser University, in Canada.

"Estimating the contribution of low-level lead exposure is essential to understanding trends in cardiovascular disease mortality and developing comprehensive strategies to prevent cardiovascular disease".

This led researchers to conclude that 28.7 per cent of premature cardiovascular disease deaths were linked to lead exposure.

Lead was added to petrol until the 1990s to boost engine compression, and was also widely used to improve the performance of household paint before being banned in the USA in 1978 and the European Union in 1992 "after concerns over the effects it was having on the environment and children's brains", adds the paper.

The new research challenges "the assumption that specific toxicants - like lead - have "safe levels", he said in a statement. A key conclusion to be drawn from this analysis is that lead has a much greater impact on cardiovascular mortality than previously recognized...

The figure covers 18 per cent of all deaths in the US. Comparatively, 20% of the U.S. population smoke, but the risk of premature death is higher (HR=1.75 95%CI = 1.50-2.05) than for low-level lead exposure.