Airborne metals and malignant pleural effusions: the role of oxidative stress

An excess of pleural fluid production can result in a condition known as pleural effusion, characterized by the accumulation of fluid in the space between the lungs and the chest wall. Malignant pleural effusions are defined as the presence of neoplastic cells in pleural fluid. The presence of malignant pleural effusions has been attributed to lung cancer, which is present in 15% of patients at the time of diagnosis. The development of pleural effusion has been strongly linked to environmental factors, including exposure to air pollution, chemical compounds, and occupational hazards. The present study examines the association between the induction of oxidative stress in malignant pleural effusion and the presence of air pollution metals or metalloids. A search was conducted using the following databases: PubMed, Science Direct, and the Cochrane Library, to identify all original scientific articles published through 30 January 2026. The following search combination terms were utilized: trace elements, heavy metals, metalloids, particulate matter, air pollution, pleural effusion, oxidative stress, antioxidant enzymes, and lung cancer. The findings revealed a higher concentration of zinc in malignant pleural effusions compared to benign pleural effusions, a statistically significant difference. Furthermore, an elevated concentration of trace elements, including copper, chromium, lead, selenium, and iron, has been documented in malignant pleural effusions. However, these observations did not demonstrate statistical significance. With respect to antioxidant activity, an increase in superoxide dismutase activity was observed in malignant pleural effusion, as well as in the oxidative stress markers Lactate Dehydrogenase, Malondialdehyde, and Reactive Oxygen Species Modulator 1. The presence of metals or metalloids of anthropogenic origin identified in pleural effusions has the potential to increase the production of reactive oxygen species, increasing oxidative stress damage and supporting the progression of respiratory diseases, such as lung cancer.