Influenza News: Study Shows That Cadmium Linked To More Severe Influenza And Pneumonia Infections And Maybe COVID-19 Too!
: A new study by researchers from University of Michigan School of Public Health-U.S., University of Washington School of Public Health-U.S., Jorma Gallen-Kallela Memorial Research Library-Finland and the Keck School of Medicine-University of Southern California-U.S. have found that cadmium is linked to more severe outcomes in influenza and pneumonia infections and also possibly even in the case of COVID-19.
The research findings were published in the peer reviewed journal: Environmental Health Perspectives. https://ehp.niehs.nih.gov/doi/10.1289/EHP7598
Environmental cadmium exposure is widespread. In humans, cadmium is poorly excreted, triggers pulmonary inflammation, reduces pulmonary function, and enhances lung injury by respiratory syncytial virus.
The study team led by Dr Sung Kyun Park from the department of Epidemiology, University of Michigan School of Public Health examined the association of cadmium burden with mortality related to influenza or pneumonia.
The study involved the analysis of the National Health and Nutrition Examination Survey (NHANES) which included 7,173 and 8,678 participants ≥45≥45 years of age enrolled in NHANES-III and NHANES 1999–2006, respectively. Associations were evaluated between cadmium and mortality from influenza or pneumonia during a median follow-up of 17.3 y (NHANES-III, based on creatinine-corrected urine cadmium) and 11.4 y (NHANES 1999–2006, based on blood cadmium). Survey-weighted Cox proportional hazard models were used to compute hazard ratios (HRs) comparing the mortality of individuals at the 80th vs. the 20th percentile of cadmium concentrations.
In NHANES-III, after adjustment for sex, race/ethnicity, education, body mass index, serum cholesterol, hypertension, and NHANES phase (or cycle), the HR comparing influenza or pneumonia mortality among participants with creatinine-corrected urinary cadmium in the 80th vs. 20th percentile was 1.15 (95% CI: 1.05, 1.26; p=0.002p=0.002) in the population as a whole and 1.27 (95% CI: 1.12, 1.43; p=0.002p=0.002) among never smokers. In NHANES 1999–2006, adjusted HRs for the 80th vs. 20th percentile of blood cadmium were 1.14 (95% CI: 0.96, 1.36; p=0.15p=0.15) for the overall population and 1.71 (95% CI: 0.95, 3.09; p=0.07p=0.07) in never smokers.
The study found that among middle-aged and older adults in the United States, higher cadmium burdens are associated with higher mortality from influenza or pneumonia. This raises the possibility that cadmium may worsen outcomes from COVID-19 infections.
The study team had been conducting studies on cadmium toxicity for many years and knew that it is damaging to the lungs through a mechanism that may involve compromising the lung’s immune system.
The study the undertook was therefore designed to use the data available from a very large general population study, the U.S. National Health and Nutrition Examination Survey (NHANES), to see whether cadmium exposure increases the risk of death from viral infections and pneumonia.
Cadmium is a toxic metal pollutant that individuals have been exposed to due to its dispersion into air, soil, water, an
d sewage from mining, smelting, and the manufacturing (and associated emissions) of nickel-cadmium batteries, pigments, plastics, and other products.
Also such dispersion has led to the uptake of cadmium in many plant species that humans consume (as well as tobacco, a major source of cadmium exposure), as well as in animal meats, particularly organs such as the liver and kidneys.
The study team used data from the NHANES study’s adult participants on cadmium levels in urine, which signify accumulated body burdens of cadmium, and examined their relationship to each participant’s subsequent risk of dying from influenza virus or pneumonia.
The team found that in comparison to participants whose cadmium levels were low (in the lowest 20%), participants whose cadmium levels were high (in the top 20%) had a 15% higher risk of dying from influenza or pneumonia.
The risk was even higher among never-smokers (27%).
Importantly unlike the main route of excretion for most other toxic metals, cadmium is not effectively excreted by the kidneys.
The study team also suspects that cadmium could be responsible for the severity of COVID-19 infections in some individuals.
The study team plans on further assessing the link between cadmium and COVID-19 severity as more data is now available on COVID-19. They aim to directly study the potential role of cadmium burdens in worsening COVID-19 severity in terms of severe lung disease and death.
The study team advices that smokers should stop smoking since cigarettes are a major source of cadmium. Meat eaters should consider avoiding organ meats, particularly the liver and kidneys. Unfortunately, other sources of dietary cadmium include foods that are consumed by many as part of a balanced, nutritious diet, such as rice, cereal grains, potatoes, and leafy vegetables.
As with regards to vegetables, a dietary strategy could be shifting to vegetables like cabbage and broccoli, which do not concentrate cadmium. Most of all, policy changes are needed to reduce the sources of pollution that contribute to cadmium in our food supply.
Because of the difficulty for individuals to avoid cadmium exposure given its presence in many common foods, it is imperative to continue policy efforts that reduce and eliminate the discharge of cadmium pollution into the environment; and to continue the monitoring of cadmium in foods and in samples of the general population (such as NHANES, which continues to collect data on a general population sample of Americans throughout the United States).
The study team next aims to leverage the archived urine samples and data of patients hospitalized with COVID-19 to directly test the hypothesis that cadmium burdens may worsen pulmonary and mortality outcomes from COVID-19.
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