High levels of cadmium, a chemical found in cigarettes and in contaminated vegetables, are associated with higher death rates in patients with influenza or pneumonia, and may increase the severity of COVID-19 and other respiratory viruses, according to a study posted on the website of the University of Michigan (UM) on Wednesday.
Interested in looking into the association between cadmium and COVID-19, but understanding that little data would be available to look at this link, the researchers focused on studying the potential association of cadmium to other viral infections: influenza and pneumonia.
The researchers utilized data from the U.S. National Health and Nutrition Examination Survey (NHANES) from 1988-1994 and 1999-2006.
Nearly 16,000 participants in two separate cohorts were used for the analysis. Cadmium was measured in urine in the first survey and blood in the second. And because tobacco has more than 3,000 chemical components, researchers also looked at cadmium levels in nonsmokers.
After adjusting for age, sex, race/ethnicity, education, body mass index, serum cholesterol and hypertension, researchers found that patients with cadmium levels in the 80th percentile were 15 percent more likely to die of influenza or pneumonia compared to those in the 20th percentile.
Among those who never smoked, the difference was even greater with a 27 percent higher risk of mortality among those in the 80th percentile compared to the 20th percentile.
"The associations we found need to be verified in other populations and also studied with respect to cadmium's potential impact on COVID-19 related morbidity and mortality," said senior author Howard Hu, professor and chair of Department of Preventive Medicine at the University of Southern California (USC) and an occupational/environmental physician.
"Unfortunately, the human body finds it much more difficult to excrete cadmium than other toxic metals, and its presence in many nutritious foods means it is critical to continue reducing sources of environmental pollution that contribute to its presence in air, soil and water."
Early in the pandemic, as data was starting to come out of Wuhan, China, a large percentage of people dying from the coronavirus shared a few characteristics - they were male, smokers and older.
The study, jointly conducted by researchers at UM, USC and the University of Washington, has been published in the December issue of Environmental Health Perspectives.