Environmental-level exposure to metals and metal-mixtures associated with spirometry-defined lung disease in American Indian adults: Evidence from the Strong Heart Study

Environ Res. 2022 May 1;207:112194. doi: 10.1016/j.envres.2021.112194. Epub 2021 Oct 13.


Background: American Indians have a higher burden of chronic lung disease compared to the US average. Several metals are known to induce chronic lung disease at high exposure levels; however, less is known about the role of environmental-level metal exposure. We investigated respiratory effects of exposure to single metals and metal-mixtures in American Indians who participated in the Strong Heart Study.

Methods: We included 2077 participants with data on 6 metals (As, Cd, Mo, Se, W, Zn) measured from baseline urine samples (1989-1991) and who underwent spirometry testing at follow-up (1993-1995). We used generalized linear regression to assess associations of single metals with spirometry-defined measures of airflow limitation and restrictive ventilatory pattern, and continuous spirometry. We used Bayesian Kernel Machine Regression to investigate the joint effects of the metal-mixture. Sensitivity analyses included stratifying by smoking status and diabetes.

Results: Participants were 40% male, with median age 55 years. 21% had spirometry-defined airflow limitation, and 14% had a restrictive ventilatory pattern. In individual metal analyses, Cd was associated with higher odds of airflow limitation and lower FEV1 and FEV1/FVC. Mo was associated with higher odds of restrictive ventilatory pattern and lower FVC. Metal-mixtures analyses confirmed these models. In smoking stratified analyses, the overall metal-mixture was linearly and positively associated with airflow limitation among non-smokers; Cd was the strongest contributor. For restrictive ventilatory pattern, the association with the overall metal-mixture was strong and linear among participants with diabetes and markedly attenuated among participants without diabetes. Among those with diabetes, Mo and Zn were the major contributors.

Conclusions: Environmental-level exposure to several metals was associated with higher odds of spirometry-defined lung disease in an American Indian population. Exposure to multiple metals, including Cd and Mo, may have an under-recognized adverse role on the respiratory system.

Keywords: Airflow obstruction; American Indian; Arsenic; Cadmium; Lung function; Metal mixtures; Molybdenum; Restrictive lung disease; Selenium; Tungsten; Zinc.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • American Indians or Alaska Natives
  • Bayes Theorem
  • Environmental Exposure* / analysis
  • Female
  • Forced Expiratory Volume
  • Humans
  • Lung Diseases* / chemically induced
  • Lung Diseases* / epidemiology
  • Male
  • Middle Aged
  • Spirometry