Low-level lead exposure could be linked to 265,000 premature deaths from cardiovascular disease among U.S. adults each year, according to a study published in the March issue of The Lancet Public Health.
Low levels of lead can remain in the environment as a result of past industrial use. People may also be exposed to lead more directly in their everyday lives. Workers such as painters, contractors and recyclers, as well as people in communities with high levels of lead contamination, such as central cities and Superfund sites, are at an increased risk of lead exposure, said lead study author Bruce Lanphear, MD, MPH, faculty of health sciences at Simon Fraser University in Canada.
Researchers looked at the impact of historical environmental lead exposure on mortality from all causes, cardiovascular disease and ischemic heart disease, using data from the Third National Health and Nutrition Examination Survey. Participants in the survey, who were ages 44 and older, were enrolled from 1988 to 1994 and followed up to 2011. They provided blood samples to determine concentrations of lead. The study found that people with high levels of lead in their blood had a greater risk of dying from any cause, cardiovascular disease and ischemic heart disease. The findings corresponded to 412,000 deaths annually from all causes, 256,000 deaths annually from cardiovascular disease and 185,000 deaths annually from ischemic heart disease.
According to the study, the findings point to about 400,000 deaths in the U.S. each year that can be attributed to lead exposure, an estimate 10 times greater than the previous one from the Institute for Health Metrics and Evaluation.
“Previous estimates relied on the assumption that there is a threshold for the cardiovascular toxicity of lead,” Lanphear told The Nation’s Health. “We found that there was no threshold. The hazard ratio or relative risk increased steeply at the lowest levels of exposure.”
The latest research underscores the risks that even low levels of lead exposure carry. Lanphear noted that previous research has shown lead, as well as other pollutants, to be harmful at low levels.
“Our finding, that there is no threshold for toxic chemicals, should no longer be surprising,” Lanphear said. “Indeed, we and others have found that there are proportionately greater risks or steeper increases in risk at the lower levels of exposure for some of the most well-studied toxic chemicals, like lead, air pollution, benzene and asbestos. These studies indicate that we need to achieve near-zero exposures to protect people’s health.”
He pointed to regulations that have been successful in reducing lead exposure from industries such as housing, food and aviation, and called for population-based strategies to further reduce the amount of lead that people encounter in their environments.
“We have known for several decades that lead is a cause of hypertension,” Lanphear said. “It is time to expand our focus on population strategies that target lead, arsenic, air pollution and other environmental influences and make it harder to become sick.”
For more information, visit https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30025-2/fulltext.
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