• In BAL samples, 66% of patients with lung malignancy had microplastics detected vs. 46% of patients without malignancy.
• This pattern was also found in the subset with both BAL and tissue samples.

A larger proportion of adults with vs. without lung malignancy had microplastics detected in bronchoalveolar lavage samples, according to a poster presented at the European Respiratory Society International Congress.

“The immediate clinical message is one of restraint as much as action: This observational study does not justify testing patients for microplastics or changing cancer care,” Ilias E. Dimeas, MD, respiratory medicine physician and fellow at the University College Dublin School of Medicine and the University of Thessaly, told Healio.

“However, the environment our patients breathe is changing, and clinicians should recognize environmental exposure as an important but still underexplored part of respiratory health and keep asking basic research questions about what reaches the lungs and what happens next,” Dimeas said.

In a prospective observational study, Dimeas and colleagues evaluated bronchoalveolar lavage (BAL) samples from 50 adults with newly diagnosed lung malignancy following diagnostic bronchoscopy and 50 adults without lung malignancy following bronchoscopy (controls) to determine if the groups differ in microplastic detection and burden.

Microplastic burden in paired airway tissue samples from 26 adults with lung malignancy and 24 controls were also assessed.

“Microplastics have become an unavoidable part of our environment, yet we still know remarkably little about what happens after they enter the human body,” Dimeas told Healio. “If we are breathing these particles every day, we need to understand where they end up, how much their levels vary between people and whether they are simply passengers or active participants in disease.”

In the collected samples, researchers found 232 microplastic particles. Microplastics were detected in more than half of the patients (70%) and samples (60%).

In the BAL samples, a significantly greater proportion of patients with vs. without lung malignancy had microplastics detected (66% vs. 46%; P = .044).

BAL microplastic burden was also significantly larger among those with vs. without lung malignancy (P = .045), according to the poster.

Switching to the subset with paired BAL and tissue samples, researchers again observed a significantly greater proportion of patients with vs. without lung malignancy with microplastics detected (P = .02). The lung malignancy group also had a significantly larger microplastic total burden (P = .025).

In a model adjusted for age, sex and smoking exposure, researchers continued to find an independent association between higher BAL microplastic burden and lung malignancy (OR = 2; 95% CI, 1.01-3.95).

Lastly, the relationship between BAL microplastic burden and tissue microplastic burden in those with malignancy was inverse.

“The greatest surprise was that, among patients with lung cancer who provided paired samples, those with more microplastics in their lung-wash sample tended to have fewer in the corresponding tissue sample, and vice versa,” Dimeas told Healio. “Lung washing samples particles from the airspaces, whereas tissue captures particles embedded within the lung, so this may point to compartment-specific distribution, but it will require confirmation and further validation.

“The next step is to move from asking ‘Are microplastics there?’ to asking ‘What are they doing?’” Dimeas added. “We have begun laboratory experiments examining how different plastics interact with lung cells and are analyzing samples from patients with chronic lung diseases, while larger, multicenter and longitudinal studies will be needed to distinguish cause, consequence and coincidence.”

Ilias E. Dimeas, MD, can be reached at idimeas@gmail.com.