Higher Cadmium Levels are linked to Higher Mortality from Influenza or Pneumonia in Older Adults

by | Jan 18, 2021 | 2020, COVID-19, Environmental Health, Heavy Metals, Immune Health

Written by Joyce Smith, BS. This study suggests that higher cadmium exposure is associated with higher mortality from influenza and pneumonia.

lung healthStudies have shown that 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. (Worldwide exposure of environmental cadmium has been shown to be immunotoxic to lungs 1.) Inhaled environmental smoke from tobacco smokers and ingestion of cadmium-contaminated foods are two major sources of cadmium exposure 2. Cadmium exposure incites cytokines 3 and lung inflammation impairs immune function 4 and disrupts tight junction integrity in the airway 5.

Park and colleagues hypothesize that eliminating identifiable risk factors for influenza and pneumonia may help minimize the negative effects of COVID-19. Using data from the Nutrition Examination Survey NHANES database, they investigate 6 the perspective association of biomarkers of cadmium exposure with mortality as it relates to influenza and pneumonia. The analysis included participants 45 years and younger who were enrolled in two separate cohorts: NHANES-III (n=7,173) and NHANES1999–2006 (n=8,678), with a median follow-up of 17.3 and 11.4 years respectively. Creatinine-corrected urine cadmium levels were measured in the NHANES III cohort and blood cadmium levels in the NHANES 1999–2006 cohort to determine potential associations between cadmium and mortality from influenza or pneumonia.

After adjusting for age, sex, race/ethnicity, education, body mass index, serum cholesterol and hypertension, researchers found that patients in the NHANES-III with cadmium levels in the 80th percentile were 15% more likely to die of influenza or pneumonia compared to those in the 20th percentile (p=0.002). Among those who never smoked, the difference was even greater with a 27% higher risk of mortality among those in the 80th percentile compared to the 20th percentile (p=0.002). The risk of influenza or pneumonia mortality increased exponentially with age, starting from around age 70 years and a steeper increase in the high-exposure group compared with the low-exposure group was seen starting from around age 80 years.

Overall, the results collectively suggest the implementation of environmental health policies that monitor cadmium exposure in air, soil, water, mining and various industries, including the manufacturing of batteries, pigments, plastics as well as the presence of cadmium in foods. Among the NHANES participants, the following food groups were the greatest contributors to total cadmium intake: cereals and bread (34%), leafy vegetables (20%), potatoes (11%), legumes and nuts (7%), and stem/root vegetables (6%), with an average total dietary Cadmium consumption of 4:63 ug/day 7.

The study authors suggest the implementation of environmental policies that monitor cadmium exposure via air, water, mining and various industries including batteries, pigments, and plastics and their presence in foods. They speculate that higher cadmium exposure might worsen COVID-19 outcomes and suggest n-acetyl cysteine as a possible treatment. N-acetyl cysteine, a precursor of reduced glutathione and a well-known antioxidant, has been shown to reduce cadmium toxicity in cultured liver and renal cells 8 and improve the viability of lung cells exposed to cadmium chloride by 45-84% 9.  Further research that focuses on cadmium as a risk factor for worse COVID-19 outcomes and n-acetyl cysteine as a potential mitigator are recommended.

Source: Park, Sung Kyun, Coralynn Sack, Matti J. Sirén, and Howard Hu. “Environmental Cadmium and Mortality from Influenza and Pneumonia in US Adults.” Environmental health perspectives 128, no. 12 (2020): 127004.

Posted January 18, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. Cohen MD. Pulmonary immunotoxicology of select metals: aluminum, arsenic, cadmium, chromium, copper, manganese, nickel, vanadium, and zinc. Journal of immunotoxicology. 2004;1(1):39-69.
  2. Satarug S. Dietary Cadmium Intake and Its Effects on Kidneys. Toxics. 2018;6(1).
  3. Låg M, Rodionov D, Ovrevik J, Bakke O, Schwarze PE, Refsnes M. Cadmium-induced inflammatory responses in cells relevant for lung toxicity: Expression and release of cytokines in fibroblasts, epithelial cells and macrophages. Toxicol Lett. 2010;193(3):252-260.
  4. Koller LD. Immunotoxicology of Environmental and Occupational Metals London UK: TaylorandFrancis; 1998.
  5. Cao X, Lin H, Muskhelishvili L, Latendresse J, Richter P, Heflich RH. Tight junction disruption by cadmium in an in vitro human airway tissue model. Respir Res. 2015;16(1):30.
  6. Park SK, Sack C, Sirén MJ, Hu H. Environmental Cadmium and Mortality from Influenza and Pneumonia in U.S. Adults. Environ Health Perspect. 2020;128(12):127004.
  7. Kim K, Melough MM, Vance TM, Noh H, Koo SI, Chun OK. Dietary Cadmium Intake and Sources in the US. Nutrients. 2018;11(1).
  8. Luo YH, Wu SB, Wei YH, et al. Cadmium-based quantum dot induced autophagy formation for cell survival via oxidative stress. Chem Res Toxicol. 2013;26(5):662-673.
  9. Odewumi CO, Latinwo LM, Ruden ML, Badisa VL, Fils-Aime S, Badisa RB. Modulation of cytokines and chemokines expression by NAC in cadmium chloride treated human lung cells. Environmental toxicology. 2016;31(11):1612-1619.