BURN pit exposure in veterans, correlated with increased anthracotic pigment burden measured by microscopy in lung tissue biopsies.
Military deployment has been linked to complex airborne hazards, yet pinpointing which exposures contribute most to deployment-related distal lung disease remains difficult. In a tissue-based analysis of post-9/11 veterans with deployment-related distal lung disease (DDLD), investigators used a quantitative lung particulate analysis approach to measure retained lung particulates directly within biopsy samples.
Burn Pit Exposure and Lung Pigment Burden
The study compared 24 veterans with DDLD to two comparator groups: 10 smokers with respiratory bronchiolitis (RB) and 10 healthy controls. Veterans were predominantly male (88%) and younger than both comparator groups (mean age 41 years versus 47 years in RB and 53 years in healthy controls).
After adjusting for age, the anthracotic pigment fraction, a measure of dark carbonaceous particulate burden, was similar between DDLD and RB (1.69% versus 1.37%, respectively). However, pigment burden was significantly higher in DDLD compared with healthy controls (0.52%), suggesting increased particulate deposition in affected veterans versus baseline levels seen in controls.
Crucially, higher anthracotic pigment fraction in veterans was significantly associated with greater reported burn pit exposure, while no significant association was found with sandstorm exposure or diesel exhaust.
What the Particulate Signature Suggests
To evaluate mineral dust retention, the investigators also quantified birefringent dust density as a marker of retained silica and silicates. Birefringent dust density was significantly increased in smokers with RB (28.89/mm²) compared with both DDLD veterans (8.93/mm²) and healthy controls (9.44/mm²). This divergence in particulate profiles suggests that carbonaceous particulates, rather than silica or silicate-rich dust, may be more strongly linked to burn pit exposure in this veteran cohort.
Why This Matters for Clinicians
These findings support a measurable relationship between burn pit exposure and anthracotic particulate burden in lung tissue among veterans with DDLD. The study also highlights how quantitative microscopy may help differentiate exposure signatures, particularly in patients where reported exposures overlap and clinical presentations are heterogeneous. In parallel, broader respiratory research continues to examine the impact of air pollution exposure and particulate matter (PM2.5) on lung health, reinforcing the clinical relevance of inhaled particulate burdens across settings.
Reference: Hua JT et al. Quantitative lung particulate analysis links increased anthracotic pigment burden to burn pit exposure in post-9/11 veterans with distal lung disease. Sci Rep. 2025;15:43992.
