A recent study has revealed that exposure to metals from environmental pollution is linked to an increase in calcium deposits in coronary arteries, on par with traditional risk factors like smoking and diabetes. This research, published today in JACC, the leading journal of the American College of Cardiology, suggests that metal accumulation in the body contributes to the development of arterial plaque and may open up new avenues for the prevention and management of atherosclerosis.
“Our findings emphasize the significance of recognizing metal exposure as a major risk factor for atherosclerosis and cardiovascular disease (CVD),” stated Katlyn E. McGraw, PhD, a postdoctoral research scientist at Columbia University Mailman School of Public Health and the study’s lead author. “This could lead to innovative prevention and treatment methods focused on reducing metal exposure.”
Atherosclerosis is characterized by the thickening and hardening of the arteries due to plaque accumulation, leading to restricted blood flow and an increased risk of clots. It is a primary cause of heart attacks, strokes, and peripheral artery disease (PAD), which are the most prevalent types of cardiovascular diseases. The condition results in coronary artery calcium (CAC), a marker that can be measured non-invasively to predict future cardiac events.
“This pioneering study highlights the crucial connections between metal exposure from environmental pollution and cardiovascular health,” remarked Harlan M. Krumholz, the Harold H. Hines, Jr. Professor at Yale and Editor-in-Chief of JACC. “It challenges our understanding of cardiovascular disease prevention by urging us to consider factors beyond the usual risk elements, advocating for stricter environmental regulations and emphasizing the need for ongoing research in this vital field.”
Although exposure to environmental metals is a newly identified risk factor for CVD, research on its link to CAC has been limited. The researchers aimed to explore how levels of metals in urine, which serve as indicators of exposure and internal metal presence, correlate with CAC.
Utilizing data from the Multi-Ethnic Study of Atherosclerosis (MESA), which tracked 6,418 men and women aged 45-84 from varied racial backgrounds and free from clinical CVD, the researchers measured urinary metal levels at the study’s outset between 2000 and 2002. They focused on both non-essential metals (cadmium, tungsten, uranium) and essential metals (cobalt, copper, zinc), which are commonly found in the U.S. population and are linked to CVD. Pollution from cadmium, tungsten, uranium, cobalt, copper, and zinc arises from agricultural and industrial activities such as fertilizers, batteries, oil production, and coal mining, with tobacco smoke being a primary source of cadmium exposure.
The results indicated a potential association between metal exposure and increased levels of vascular calcification over a decade.
When comparing the highest to the lowest quartile of urinary cadmium, CAC levels were found to be 51% higher at the start and 75% higher across the ten-year study period. For urinary tungsten, uranium, and cobalt, respective CAC levels were 45%, 39%, and 47% higher over the same period. The estimates for copper and zinc levels decreased after adjusting for clinical factors, dropping from 55% to 33% and from 85% to 57%, respectively.
Urinary metal levels also exhibited variation based on demographic factors. Older participants, those who identified as Chinese, and individuals with lower education levels tended to have higher urinary metal levels. Participants from Los Angeles had significantly elevated urinary levels of tungsten and uranium, along with increased levels of cadmium, cobalt, and copper.
Analysis within the study also took into account traditional risk factors associated with CVD such as smoking, diabetes, and LDL-cholesterol. The relationships between metal exposure and CAC progression were found to be similar to those linked to conventional risk factors.
“Pollution poses the greatest environmental threat to cardiovascular health,” stated McGraw. “With the widespread presence of these metals due to industrial and agricultural practices, this study highlights the urgent need for increased awareness and regulatory actions to diminish exposure and safeguard cardiovascular health.”
Some limitations of the study include the lack of data on plaque transition measures in MESA, variations in exposure sources affecting the measurement of certain metals, and the potential for unknown confounding factors influencing the results.
In a related editorial, Sadeer Al-Kindi, MD, Associate Director of Cardiovascular Prevention and Wellness at the Houston Methodist DeBakey Heart and Vascular Center, noted that the evidence from this study carries significant implications for public health, health equity, and clinical practices.
“This research exemplifies the emerging field of environmental cardiovascular medicine. Addressing environmental risk factors like metal exposure has the potential to greatly diminish the global burden of cardiovascular disease and to tackle persistent health disparities,” Al-Kindi stated.
