Toxic Metals: The Poisons that are “Killing Us Softly”

Chronic exposure to low levels of lead, cadmium and arsenic through commonly used household items, air, water, soil and food is associated with an increased risk of cardiovascular disease, according to a new American Heart Association scientific statement.

Howard Hu, MD, MPH, ScD, Flora L. Thornton Chair, provides expert commentary as a sitting member of the board of directors of Pure Earth, a New York City-based international not-for-profit organization “dedicated to solving toxic pollution problems in low- and middle-income countries, where human health is at risk.”

– By Howard Hu, MD, MPH, ScD

Lamas and colleagues and the American Heart Association deserve praise for publishing the Scientific Statement on Contaminant Metals as Cardiovascular Risk Factors. Along with other recent high-profile discussions of similar topics¹, the Statement hopefully signals a turning point in the recognition of environmental exposures to toxic metals as risk factors for cardiovascular disease that are widespread, preventable, and potentially treatable, with major implications for policy and clinical practice, world-wide.

Three of the eight authors of the Statement had previously published a 2021 Viewpoint in these pages² that set forth the proposition that the burden of proof has been met for lead and cadmium as cardiovascular risk factors. In the current Statement, the evidence for these two toxic metals–as well as arsenic– are reviewed in depth, showcasing a body of evidence that has reached a crescendo. The combination of in vivo and in vitro studies demonstrating oxidative stress, impaired vascular endothelial function, chronic inflammation, disturbances of lipid metabolism and myocardial function, and other abnormalities, together with well-conducted prospective epidemiological studies demonstrating hypertension, epigenetic dysregulation, dyslipidemia, subclinical atherosclerosis, coronary artery/ischemic heart disease, and death from cardiovascular disease is difficult to ignore.

Aspects of some of these relationships had been previously confirmed by panels of experts; for example, the relationship of low-level lead exposure to increased blood pressure and hypertension was deemed to be causal based on systematic reviews of the evidence published in 2007 by experts convened by the Association of Occupational and Environmental clinics³ and in 2012 by the Office of Health Assessment and Translation of the National Toxicology Program⁴. However, neither lead nor any other toxic metal is mentioned, let alone discussed, as a risk factor in chapters on hypertension in the most current editions of widely read clinical textbooks (such as Harrison’s Principles of Internal Medicine⁵).

Read the full commentary