Lead poisoning may hasten death for millions

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Lanphear, MD, with Simon Fraser University in Canada, and colleagues also linked environmental lead exposure to 412,000 total deaths each year in the U.S. They noted their estimate is 10 times higher than the previous one, likely because earlier calculations assumed levels below 5 μg/dL weren't associated with any increased mortality risk.

"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". In 2013, heart disease caused one in every three deaths in the country, or about 800,000 people that year alone.

"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", explains Prof. "The HR (hazard ratio) for all-cause mortality from tobacco exposure was larger than that for concentration of lead in blood, but only 20% of the USA population smoked tobacco".

The new research challenges "the assumption that specific toxicants - like lead - have "safe levels", he said in a statement. The US Occupational Safety and Health Administration (OSHA) requires employers to remove workers from exposure when their blood lead levels rise to 50 µg/dL in the construction industry or 60 µg/dL in other industries, and they can return to work when their blood lead levels go down to 40 µg/dL.

According to the U.S. Environmental Protection Agency (EPA), children are most susceptible to the harms of lead exposure; their developing bodies absorb the chemical in higher amounts and their brains and nervous systems and more sensitive to it.

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. Of those, 1,801 died from cardiovascular disease and 988 passed away from heart disease. In a majority of cases, the condition is heart disease.

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People with high levels of at least 6.7mg were twice as likely to die from ischaemic heart disease compared with people having low levels of lead in their blood.

Researchers also wrote the level of lead concentration was indicative of the 10th to 90th percentiles of such concentrations.

"Currently, low levels of lead exposure are an important, but largely ignored risk factor for deaths from cardiovascular disease", adds Prof.

"Our study findings suggest that low-level environmental lead exposure is an important risk factor for death in the US, particularly from cardiovascular disease", the paper states. And adult exposure to lead even at levels so low that they've been considered relatively benign is actually deadly enough to be considered a leading cause of death in the US.

The researchers called for more aggressive measures to retire contaminated housing, phase out lead-laden jet fuels, replace lead pipes in plumbing, and reduce emissions from smelters and lead battery factories.

"A key conclusion to be drawn from this analysis is that lead has a much greater effect on cardiovascular mortality than previously recognized", wrote Philip J. Landrigan, MD, MSc, in a related editorial. In addition, they were unable to control for all potential confounders such as air pollution or arsenic exposure, both of which are established CVD risk factors.

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