Assessing a Medley of Metals: Combined Exposures and Incident Coronary Heart Disease

Metals occur naturally in the environment, but they can also be introduced as pollutants. Some exposures to environmental metals occur through air, water, food, and consumer products, whereas other exposures occur on the job. Several previous studies have evaluated associations between heart disease outcomes and exposure to individual metals, including arsenic. Yet humans are exposed to many metals simultaneously in daily life. A new study in Environmental Health Perspectives investigates the associations between exposures to multiple metals and coronary heart disease (CHD) in a large Chinese cohort. Air and water pollution are major public health concerns in China, where cardiovascular disease is a leading cause of death. “Metals are one of the potential components to many of these pollution sources,” says coauthor An Pan, an epidemiologist at HuazhongUniversity of Science and Technology inWuhan. Study participants were members of the Dongfeng-Tongji cohort, an ongoing prospective study of retired employees of the Chinese auto manufacturer Dongfeng Motor Corporation. Senior author Tangchun Wu, dean of the School of Public Health at Huazhong University, is the principal investigator of the DongfengTongji cohort. Wu and colleagues measured levels of 23 different metals in blood plasma collected from more than 27,000 retired workers in Shiyan. Over the course of 3–5 years of follow-up, a total of 1,621 study participants who were free of cardiovascular disease at baseline experienced incident CHD, including events such as heart attacks, stable or unstable angina, and coronary revascularization procedures (e.g., bypass surgery). The researchers matched these individuals with 1,621 controls who were free of CHD at baseline as well as at the end of the follow-up period. Researchers found significant associations between blood concentrations of five metals (titanium, arsenic, selenium, aluminum, and barium) and CHD risk, after adjusting for other cardiovascular risk factors. When the researchers combined these five metals in the same model, they estimated that participants in the highest quartile of arsenic and titanium exposure were 78% and 32% more likely, respectively, to have experienced a CHD event than participants in the lowest quartile. Conversely, participants in the highest quartile of selenium exposure were estimated to be 33% less