Published: Wed, March 14, 2018
Medicine | By Douglas Stevenson

Low levels of lead linked to death from heart disease

Low levels of lead linked to death from heart disease

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. 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. They estimated that 28.7 percent of premature cardiovascular disease deaths (256,000/ 892,000) could be attributable to lead exposure, including a high proportion of ischemic heart disease deaths (lead was linked to 37.4% of all IHD deaths [185,000/495,000]).

Lead was once routinely used products like gasoline, paint and plumbing and persists in the environment.

"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", he explained. 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.

From the 1990s until 2015, the US Centers for Disease Control considered anything less than 10 µg/dL to be a "low" level of exposure for adults, though the CDC does not consider any level of lead to be "safe".

The new research challenges "the assumption that specific toxicants - like lead - have "safe levels", he said in a statement.

An global 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.

The risk of succumbing to coronary heart disease doubled in such cases, the study found.

Nearly one in 10 participants had lead levels that were undetectable to the blood test, so were given a reference level of 0.7 µg/dL (8%, 1,150/14,289 participants).

By tracking more than 14,000 adults over 20 years, researchers discovered that even people with low levels of lead in their blood had an increased risk of mortality and were more likely to suffer from a heart-disease related death.

The authors adjusted their findings based on a number of comorbidities, including age, sex, household income, body mass index, diabetes, smoking status, dietary habits and amount of cadmium in urine.

Stemming the risk requires a range of public health measures, Lanphear said in a journal news release, such as "abating older housing, phasing out lead-containing jet fuels, replacing lead-plumbing lines and reducing emissions from smelters and lead battery facilities".

Professor Kevin McConway, Emeritus Professor of Applied Statistics at the Open University, said: "The researchers make a very important point in their report - that it is more accurate to view this study as estimating how many deaths might have been prevented if historical exposures to lead had not occurred".

"Lead represents a leading cause of disease and death, and it is important to continue our efforts to reduce environmental lead exposure", Lanphear said.

They were not, however, able to factor out the possible impact of exposure to arsenic or air pollution.

"A key conclusion to be drawn from this analysis is that lead has a much greater impact on cardiovascular mortality than previously recognised".

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