Lead exposure might be responsible for 10 times more premature deaths than previously thought

A new study suggests that lead exposure may be responsible for nearly 10 times more deaths in the United States than previously thought.

Scientists have discovered that nearly 412,000 deaths each year in the US can be attributed to lead contamination. That number is ten times higher than the Institute for Health Metrics and Evaluation at the University of Washington in Seattle had previously reported.

“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. Still, lead represents a leading cause of disease and death, and it is important to continue our efforts to reduce environmental lead exposure,” explained Professor Bruce Lanphear, from Simon Fraser University in Canada.

Lanphear and colleagues estimated that 28.7% of heart disease-related premature deaths in the US could be caused by lead exposure, which comes to a total of 256,000 deaths annually.

Researchers used data from the Third National Health and Nutrition Examination Survey, which monitored 14,289 US adults for 20 years. Of the 4,422 participants who died by 2011, approximately 18% of them could have been saved by reducing blood lead concentrations to 1.0 micrograms per deciliter.

Compared to those with low lead blood concentrations, people with high lead levels (over 6.7 micrograms) had the risk of premature death from any cause increased by 37%, the risk of cardiovascular death increased by 70%, and double the risk of death from ischemic heart disease.

“Our study calls into question the assumption that specific toxicants, like lead, have ‘safe levels’, and suggests that low-level environmental lead exposure is a leading risk factor for premature death in the USA, particularly from cardiovascular disease,” Professor Lanphear said in a statement.

Lead exposure can contribute to cardiovascular disease by various pathways. Lead affects the epithelial cells of the blood vessels, which increases the chances of developing plaques that can then cause a heart attack. Lead contamination also leads to kidney damage, which causes high blood pressure and probably acts synergistically with plaque formation.

Also, if you live near an airport, your blood lead levels will be a little higher than if you live farther away due to the lead found in the aviation gas used in single piston jets.

“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. Currently, low levels of lead exposure are an important, but largely ignored risk factor for deaths from cardiovascular disease,” said Professor Lanphear.

The team admits that the study’s principal limitation is that the research relied heavily on one blood concentration measurement taken at the beginning of the study period, almost 20 years ago.

“Our reliance on a single blood test as opposed to serial blood tests means that we have underestimated the impact of lead exposure on cardiovascular disease,” Lanphear said. “There are some things in the study design itself that we really couldn’t change.”

The team urges the retirement of lead-contaminated housing, lead-laden jet fuels, lead water pipes, and the reduction of emissions from smelters and lead battery facilities.

“We’ve made tremendous progress in reducing these exposures in the past four to five decades,” Lanphear added. “But our blood levels are still 10 to 100 times higher than our pre-industrial ancestors,” Lanphear concludes.

Scientific reference: Bruce Lanphear , Stephen Rauch, Peggy Auinger, Ryan W Allen , Richard W Hornung. Low-level lead exposure and mortality in US adults: a population-based cohort study. The Lancet Public Health, 2018 DOI: 10.1016/S2468-2667(18)30025-2