Effects of combined exposure to heavy metals on lower respiratory flora and its role of lung injury in rats.

Introduction: Exposure to heavy metals is a growing environmental concern. Although exposure to individual metals is associated with pulmonary damage, real-world exposure typically involves multiple metals simultaneously. This study hypothesizes that combined exposure to nickel, copper, and arsenic induces lung injury through disruption of the bronchoalveolar lavage fluid (BALF) microbial ecosystem in rats. The primary objective of this study was to verify the hypothesis. Methods: Thirty-two male Sprague-Dawley (SD) rats were randomly assigned to four groups: one control group and three exposure groups (low, medium, and high doses). The exposed groups received mixed heavy metal aerosols containing nickel (Ni), copper (Cu), and arsenic (As) at low (Ni: 210.9 ng/m Results: Compared exposure to Ni, Cu, and As induced dose-dependent lung damage, including inflammation, alveolar deformation, and bronchial thickening, accompanied by significant declines in lung function, including a 21.2% reduction in tidal volume and a 34.5% increase in airway resistance in the high-dose group ( Conclusions: Combined exposure to Ni, Cu, and As disrupts respiratory microbiota and impairs lung function in rats. These findings highlight a critical link between environmental heavy metal exposure and respiratory health, underscoring the need for stricter regulation of metal pollutants and further research into microbiota-related lung injury mechanisms.