Metal exposure from environmental pollution is linked to increased calcium buildup in the coronary arteries at levels comparable to established risk factors such as smoking and diabetes, according to a study published today in JACC, the American College of Cardiology’s flagship magazine. The findings support the idea that metals in the body are linked to the evolution of plaque accumulation in the arteries and could give a new method for managing and preventing atherosclerosis.
“Our findings highlight the importance of considering metal exposure as a significant risk factor for atherosclerosis and CVD,” said 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 new prevention and treatment strategies that target metal exposure.”
Atherosclerosis is a disorder in which plaque builds up in the arteries, narrowing and hardening them. This can limit blood flow and lead to clot formation. It is the underlying cause of heart attacks, strokes, and peripheral artery disease (PAD), which are the most frequent types of cardiovascular illness. Atherosclerosis creates calcium in the coronary arteries (CAC), which can be detected noninvasively to predict future cardiac events.
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.
Katlyn E. McGraw
“This groundbreaking study underscores the critical associations of metal exposure from environmental pollution to cardiovascular health,” said Harlan M. Krumholz, the Harold H. Hines, Jr. Professor at Yale and Editor-in-Chief of JACC. “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.”
Exposure to environmental pollutants like metals is a newly recognized risk factor for CVD, but there isn’t a lot of research on its association with CAC. Researchers in this study sought to determine how urinary metal levels, biomarkers of metal exposure and internal doses of metals impact CAC.
Researchers measured urine metal levels in the Multi-Ethnic research of Atherosclerosis (MESA) prospective cohort, which followed 6,418 men and women aged 45-84 from varied racial origins who were free of clinical CVD at the start of the research in 2000-2002. They looked at non-essential (cadmium, tungsten, uranium) and necessary (cobalt, copper, zinc) metals that are both common in US populations and linked to CVD. Cadmium, tungsten, uranium, cobalt, copper, and zinc contamination is caused by agricultural and industrial processes such as fertilizers, batteries, oil production, welding, mining, and nuclear energy production. Tobacco smoke is the leading cause of cadmium exposure.
Results provided evidence that metal exposure may be associated with atherosclerosis over 10 years by increasing coronary calcification.
When comparing the highest and lowest quartiles of urinary cadmium, CAC levels were 51% higher at baseline and 75% higher over the 10-year period. Over the 10-year period, urinary tungsten, uranium, and cobalt CAC levels increased by 45%, 39%, and 47%, respectively. After adjusting for clinical variables, the estimations for copper and zinc decreased from 55% to 33% and 85% to 57%, respectively.
Non-essential and essential urine metal levels vary according to demographic variables. Higher urine metal levels were observed in elderly participants, Chinese participants, and those with less education. Participants in Los Angeles exhibited significantly higher urinary tungsten and uranium levels, as well as somewhat higher cadmium, cobalt, and copper levels.
The study’s analysis also considered traditional CVD risk factors such as smoking, diabetes, and LDL-cholesterol levels. The associations between metals and CAC progression were comparable in magnitude to those for traditional risk factors.
“Pollution is the greatest environmental risk to cardiovascular health,” McGraw said. “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.”
Limitations of the study include the unavailability of plaque transition measures in MESA, changes in exposure sources and other factors causing variability of certain measured metals, and the potential for residual and unknown confounding of time-varying exposure measurements.
In an accompanying editorial, Sadeer Al-Kindi, MD, Associate Director of Cardiovascular Prevention and Wellness at the Houston Methodist DeBakey Heart and Vascular Center, stated that the study’s findings had significant implications for public health, health equality, and clinical practice.
“The field of environmental cardiovascular medicine, exemplified by this research, offers an emerging frontier in cardiovascular disease prevention and treatment,” Al-Kindi told reporters. “Addressing environmental risk factors like metal exposure will significantly reduce the global burden of cardiovascular disease and address long-standing health disparities.”
