Metals in the body from pollutants linked to the progression of harmful plaque buildup in the arteries

Exposure to metals from environmental pollution is associated with increased calcium buildup in the coronary arteries at levels comparable to traditional risk factors such as smoking and diabetes, according to a study from the Columbia University Mailman School of Public Health.

The findings support the fact that metals in the body are associated with the progression of plaque buildup in the arteries and may provide a new strategy for controlling and preventing atherosclerosis. The results are published in the Journal of the American College of Cardiology.

“Our findings highlight the importance of considering metal exposure as a significant risk factor for atherosclerosis and cardiovascular disease,” said Katlyn E. McGraw, Ph.D., a postdoctoral fellow in Environmental Health Sciences at the Columbia Mailman School and lead author of the study. “This could lead to new prevention and treatment strategies that target metal exposure.”

Atherosclerosis is a condition in which the arteries become narrowed and hardened due to a buildup of plaque, which can restrict blood flow and cause clots. It is an underlying cause of heart attacks, strokes and peripheral vascular disease (PAD), the most common forms of cardiovascular disease (CVD). Atherosclerosis causes coronary artery calcium (CAC), which can be measured non-invasively over time to predict future cardiac events.

Exposure to environmental pollutants such as metals is a newly recognized risk factor for cardiovascular disease, but not much research has examined its association with CAC.

Researchers in this study sought to determine how urinary metal levels, biomarkers of metal exposure, and internal doses of metals affect CAC.

The researchers used data from the Multi-Ethnic Study of Atherosclerosis (MESA), which followed 6,418 men and women aged 45-84 years from different racial backgrounds, free of clinical cardiovascular disease, to measure metal levels in urine to be measured at the start of the survey in 2000-2002. They examined non-essential (cadmium, tungsten, uranium) and essential (cobalt, copper, zinc) metals, both common in the US population and associated with cardiovascular disease.

Widespread cadmium, tungsten, uranium, cobalt, copper and zinc pollution occurs from agricultural and industrial applications such as fertilizer, batteries, oil production, welding, mining and nuclear energy production. Tobacco smoke is the main source of cadmium exposure.

The results provided evidence that metal exposure may be associated with atherosclerosis over a 10-year period through increasing coronary calcification.

When comparing the highest with the lowest quartile of urinary cadmium, CAC values ​​were 51% higher at baseline and 75% higher over the 10-year period. For tungsten, uranium and cobalt in urine, the corresponding CAC levels over ten years were 45%, 39% and 47% higher respectively.

For copper and zinc, the corresponding estimates fell from 55% to 33% and from 85% to 57%, respectively, after adjusting for factors such as cardiovascular risk factors such as blood pressure and blood pressure medications, high cholesterol and diabetes mellitus.

Urinary metal levels also varied depending on demographic characteristics. Higher metal levels in urine were observed in older participants, Chinese participants and those with lower education. Participants from Los Angeles had significantly higher levels of tungsten and uranium in their urine, and slightly higher levels of cadmium, cobalt and copper.

An earlier article on Atherosclerosis (MESA), the research team studied the methodology for validating ultra-trace element concentrations in urine for small sample volumes in large epidemiological studies.

“There are actually small amounts of these metals found everywhere, but this study really highlights that even low exposure affects cardiovascular health,” says Kathrin Schilling, Ph.D., assistant professor of Environmental Health Sciences at Columbia Mailman School.

“Even with efforts to control exposure to metals in water, air and food, we need to pay more attention to analyzing toxic metals in populations for the purpose of exposure prevention and intervention.”

“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 increased awareness and regulatory action 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 measures.