A new study has found that high levels of the chemical cadmium, is associated with an increased risk of death in patients with influenza or pneumonia. Scientists suggest that the chemical, found in cigarettes and contaminated vegetables, could increase the severity of other respiratory illnesses, such as COVID-19. The study’s results, published this month in the journal Environmental Health Perspectives, highlight the potential health benefits of reducing public exposure to cadmium.
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Smokers at higher risk of COVID-19 deaths
Previous research has highlighted the detrimental impact long-term cadmium exposure has on human health, with evidence showing even at low levels it can negatively impact the lungs. Because of this, people exposed to relatively high levels of cadmium may not be able to cope with the influenza virus’s effect on the lungs.
At the beginning of the pandemic, researchers immediately highlighted that those most at risk of dying from COVID-19 were men who smoked and were older. This evidence encouraged researchers from U-M, the University of Southern California and the University of Washington to conduct a study looking into how cadmium exposure may impact COVID-19.
Understanding that there would be little data available to explore this relationship, the researchers also investigated the association between cadmium and other viral infections that impact the respiratory tract: influenza and pneumonia.
The relationship between cadmium and COVID-19 mortality
To explore this relationship, data was acquired from the U.S. National Health and Nutrition Examination Survey (NHANES) from the years 1988 to 1994, and 1999 to 2006. Data available from NHANES is collected by the National Center for Health Statistics and provides a representative view of the health and nutritional status of those living in the US.
Data from a total of almost 16,000 participants were included in the analysis. Levels of cadmium were measured in the first survey via urine samples, and in the second survey via blood samples. The researchers looked at the cadmium levels in nonsmokers as well as smokers, given the huge amount of chemicals present in cigarettes (which may have impacted the results).
The researchers adjusted for the factors of age, body mass index, education, hypertension, race/ethnicity, serum cholesterol, and sex, and found that cadmium evens were related to an increased risk of dying from influenza or pneumonia. Those with cadmium levels in the 80th percentile had a 15% increased chance of death from these illnesses in comparison to those with cadmium levels in the 20th percentile.
This risk increased for those who had never smoked with the data revealing that non-smokers with cadmium levels in the 80th percentile were 27% more likely to die from influenza or pneumonia in comparison to those with cadmium levels in the 20th percentile.
While the researchers were not able to direct look at the impact of cadmium levels on COVID-19 mortality, their results highlight that higher levels of cadmium exposure are related to higher mortality from respiratory viruses.
COVID-19 may not be a one-time event. Our findings suggest that the public can benefit from reduced cadmium exposure when the next pandemic occurs. This cannot be done suddenly and takes time through policy changes.”
Sung Kyun Park, lead author
The evidence shows that cadmium may predispose people to more severe symptoms of COVID-19. The study’s authors suggest that to protect themselves from the more severe effects of COVID-19, smokers should stop smoking. In addition, the public should moderate their intake of foods that contain relatively high levels of cadmium, such as cereal, rice, animal organs, soybeans, and some leafy vegetables.
The authors stress that maintaining a healthy diet is important and that vitamins can be sourced from other fruits and vegetables that have relatively low cadmium levels, such as broccoli and cabbage.
Park, S.K. et al. (2020). Environmental Cadmium and Mortality from Influenza and Pneumonia in U.S. Adults. Environmental Health Perspectives. DOI: https://doi.org/10.1289/EHP7598