Possible link between cadmium and severe flu, pneumonia infections

Dec. 29, 2020

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 new study and reported in a press release from the University of Michigan.

“Our study suggests the public in general, both smokers and nonsmokers, could benefit from reduced exposure to cadmium,” said lead author Sung Kyun Park, ScD, MPH, Associate Professor of Epidemiology and Environmental Health Sciences at the University of Michigan School of Public Health.

Long-term exposure to cadmium, even at low levels, may undermine our defense system in the lungs, and people with high levels of the chemical may not be able to cope with influenza virus attacks, Park said.

The study by researchers at U-M, the University of Southern California and the University of Washington was published in the December issue of Environmental Health Perspectives.

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.

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 instead 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 from 1988-1994 and 1999-2006. NHANES is conducted by the National Center for Health Statistics and provides nationally representative survey data on the health and nutritional status of the noninstitutionalized U.S. population.

Nearly 16,000 participants in the 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.

“We couldn’t directly look at cadmium body burden among COVID-19 patients in the early pandemic,” Park said. “Our motivation was to find a modifiable risk factor that can predispose people with COVID-19 infection to develop a severe complication and die of COVID-19.

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