Environmental metal exposure may increase atherosclerosis risk, study finds

For this study, researchers analyzed data from the Multi-Ethnic Study of Atherosclerosis (MESA) to track about 6,400 adults ages 45 to 84 from 2000 to 2002. Study participants came from different ethnic backgrounds and all were free from clinical cardiovascular disease.

Participants received testing to establish levels of metals in their urine, including non-essential metals — cadmium, tungsten, and uranium — and essential metals, such ascobalt, copper, and zinc.

“There is mounting evidence of the impact of metals on heart disease, particularly for arsenic, lead, and cadmium,” Katlyn E. McGraw, PhD, a postdoctoral research scientist in Environmental Health Sciences at Columbia University’s Mailman School of Public Health and lead author of this study, told Medical News Today.

“Using high precision methods, our lab was able to quantify multiple metals in urine, in addition to arsenic, lead, and cadmium, in a large U.S. sample. Because of existing research on metals as environmental contributors to heart disease, we tested the hypothesis that metal exposures impact calcification in the arteries because it is a clinically relevant, subclinical measure of atherosclerosis and could explain the link between metals and cardiovascular disease risk,” she said.

At the study’s conclusion, McGraw and her team found that metal exposure may be associated with atherosclerosis over 10 years by accumulating coronary calcification.

When examining coronary artery calcium levels by metal, researchers found with urinary cadmium the levels were 51% higher at baseline and 75% higher over the 10-year period, while urinary tungsten, uranium, and cobalt had corresponding coronary artery calcium levels for the 10-year period of 45%, 39%, and 47%, respectively.

When examining copper and zinc levels, researchers noted a decrease in coronary artery calcium levels — copper dropped from 55% at baseline to 33% during the 10-year period and zinc went from 85% down to 57%.

“Based on previous research on cadmium and copper and heart disease, and zinc and diabetes, we were not surprised by these findings. However, we were surprised to find tungsten, uranium, and cobalt were associated with atherosclerosis because there is less existing research on these metals. Therefore, these are somewhat new findings.”
— Katlyn E. McGraw, PhD

When looking at the study results from a demographic perspective, researchers reported higher urinary metal levels in older study participants, those of Chinese descent, and those with less education. Additionally, participants from Los Angeles, CA, had noticeably higher urinary tungsten and uranium levels and to some extent, larger cadmium, cobalt, and copper levels.

“These findings highlight differences in exposure for certain populations based on where they live, previous exposures, and previous behaviors, like smoking),” McGraw said. “Populations experiencing higher metal exposures would be more at risk for atherosclerosis.”

“Doctors could recommend quitting smoking or vaping, testing the water if served by private wells and using drinking water filters if needed, using air purifiers if living near metal emission sources, or recommending having a nutritious diet rich in iron and calcium and B vitamins to protect from accumulation of some metals.”
— Katlyn E. McGraw, PhD

“Ultimately, however, the most important measures to protect communities from metal exposure are related to environmental protection and regulations,” she added.

After reviewing this study, Cheng-Han Chen, MD, a board certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, told MNT that the medical community has known for a long time that environmental exposures, especially pollution, are contributing to the risk of developing cardiovascular disease.

“A lot of the research previously has been on particular matter like airborne particulate matter pollution, and more recently, studies have found this association between not just particles in the air, but also just metal buildup in the body,” Chen continued. “This study does a good job of putting it all together and looking at many different types of metal contaminations and the development of atherosclerotic disease as measured through coronary calcium. And so it just highlights the diverse types of exposures through pollution that can elevate someone’s cardiovascular risk.”

Chen said one thing that is not yet clear is how exactly people are exposed to these metals.

“[This study] doesn’t break it down whether they’re breathing in metal pollutants in the air, or whether it’s coming in as part of food, or it’s coming in through the skin,” he explained. “It’s less clear how we can actually reduce an individual’s exposure. This is more of a sign that we should focus public policy on just reducing the amount of this kind of contamination in our environment such that the population does not get exposed to these pollutants.”

MNT also spoke with Rebecca Fuoco, director of Science Communications at the Green Science Policy Institute, who commented that widespread metal pollution in our air, water, and food system is a policy problem, but there are some steps people can take to limit their personal exposure.

“Surprisingly, our inadvertent ingestion of household dust can be a major source of exposure. You can keep dust levels down in your home by regular vacuuming and wet-mopping, and you can keep your shoes at the door to avoid tracking in contaminated dirt. It’s also important to wash your hands before eating.”
— Rebecca Fuoco