From an analysis of more than 14,000 people in the USA, researchers found that exposure to low lead levels from the late 1980s to the mid-1990s was linked to a higher risk of cardiovascular and all-cause death over the next 20 years. "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".
"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.
Metin Avkiran, associate medical director at the British Heart Foundation, added: "This study adds to the substantial evidence that exposure to lead can have long-term consequences".
Lanphear analyzed earlier U.S. government research from the National Health and Nutrition Examination Survey (NHANES).
"Lead represents a leading cause of disease and death, and it is important to continue our efforts to reduce environmental lead exposure", Lanphear said. All participants completed home interviews, had been tested for lead in their urine and were followed through 2011.
"In our study, 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 researchers wrote.
However, they acknowledged the use of a single baseline lead value to predict outcomes over the following 20 years was not ideal; serial measurements may have been more informative.
Of that figure, exposure to the toxic metal may be an "important, but largely overlooked" risk factor behind the 256,000 annual cardiovascular disease deaths in the country, the authors found.
An increase in lead concentration from the 10 to the 90 percentile was linked to a 37 percent greater chance of all-cause mortality, a 70 percent greater chance of cardiovascular mortality and a 2.08-fold risk of death from ischemic heart disease.
"Our study estimates the impact of historical lead exposure on adults now aged 44 years old or over in the United States of America, whose exposure to lead occurred in the years before the study began", he explained.
Exposure to traces of lead in petrol and paint may be linked to hundreds of thousands of premature deaths each year. Lanphear and his team sought to determine how exposure to lead contributes to all-cause mortality and cardiovascular disease (CVD) mortality in the U.S.
In children, lead exposure may cause developmental, behavioral, and learning problems, as well as anemia and problems with hearing.
They were not, however, able to factor out the possible impact of exposure to arsenic or air pollution. Lead exposure has been associated with hardened arteries, high blood pressure and coronary heart disease, according to the researchers.
"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".