Metal exposure a ‘significant risk factor’ for cardiovascular disease

New research has established a link between exposure to metal pollutants in the air and increased calcium buildup in the coronary arteries, at a level comparable to established risk factors like smoking and diabetes

The study was published in the journal of the American College of Cardiology.

Metals such as arsenic, cadmium, chromium, copper, lead, mercury, nickel and zinc are released by a range of industrial and agricultural sources, but may also occur naturally in the environment. They can cause harmful effects in plants, animals and humans as a result of long-term or frequent exposure to high concentrations in air, water or soil. Tobacco smoke is the main source of cadmium exposure.

Katlyn E. McGraw, PhD, a postdoctoral research scientist at Columbia University Mailman School of Public Health and lead author of the study said: ‘Our findings highlight the importance of considering metal exposure as a significant risk factor for atherosclerosis and cardiovascular disease (CVD). This could lead to new prevention and treatment strategies that target metal exposure.’

Atherosclerosis is the buildup of fats, cholesterol and other substances on the artery walls, known as plaque. This restricts blood flow and is an underlying cause of heart attacks, strokes, and peripheral artery disease. Aherosclerosis causes coronary artery calcium, which can be measured with a CT scan, giving a good indication of someone’s risk of heart disease, often before other warning signs appear.

Harlan M. Krumholz, the Harold H. Hines, Jr. Professor at Yale and Editor-in-Chief of JACC said: ‘This groundbreaking study underscores the critical associations of metal exposure from environmental pollution to cardiovascular health. It challenges us to broaden our approach to CVD prevention beyond traditional risk factors and to advocate for stronger environmental regulations, and it underscores the need for continued research in this critical area.’

Researchers used data from the Multi-Ethnic Study of Atherosclerosis cohort, tracking 6,418 men and women aged 45-84 to measure urinary metal levels at the beginning of the study in 2000-2002.

Results provided evidence that metal exposure may be associated with atherosclerosis over 10 years by increasing coronary calcification.

• For urinary cadmium, coronary artery calcium levels were 51% higher at baseline and 75% higher over the 10-year period.
• For urinary tungsten, uranium and cobalt, the corresponding coronary artery calcium levels over the 10-year period were 45%, 39%, and 47% higher, respectively.

Higher urinary metal levels were seen in older participants, Chinese participants and those with less education. Participants from Los Angeles had markedly higher urinary tungsten and uranium levels, and slightly higher cadmium, cobalt, and copper levels.

The associations between metals and coronary artery calcium development were found to be comparable to those for smoking and diabetes.

McGraw said. ‘Pollution is the greatest environmental risk to cardiovascular health. Given the widespread occurrence of these metals due to industrial and agricultural activities, this study calls for heightened awareness and regulatory measures to limit exposure and protect cardiovascular health.”

In an accompanying editorial comment, Sadeer Al-Kindi, MD, Associate Director of Cardiovascular Prevention and Wellness at the Houston Methodist DeBakey Heart and Vascular Center, said: ‘The field of environmental cardiovascular medicine, exemplified by this research, offers an emerging frontier in cardiovascular disease prevention and treatment. Addressing environmental risk factors like metal exposure will significantly reduce the global burden of cardiovascular disease and address long-standing health disparities.’