Deployed military personnel have increased silica in lung tissue
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Key takeaways:
- Researchers found several different categories of PM in both the lungs of deployed military personnel and controls.
- High-intensity exposure to diesel exhaust and burn pit smoke was common in this population.
Lung tissue analysis revealed that deployed military personnel had more silica and other silicates in their lungs than controls, according to results published in International Journal of Environmental Research and Public Health.
“We know that silica dust can damage the small airways and trigger persistent inflammation that may lead to future lung fibrosis,” Cecile Rose, MD, MPH, professor of medicine and occupational pulmonologist at National Jewish Health, told Healio.
“The finding of high proportions of retained silica and silicate dusts in those with deployment-related respiratory disease indicates that these service members will need to be monitored regularly throughout their lifetimes to make sure they do not develop long latency diseases, such as silicosis and lung cancer,” she continued.
“It’s also important that clinicians are aware of the 2022 PACT Act that includes these and other respiratory diseases presumed related to hazardous deployment exposures for which service members may receive benefits,” Rose added.
In this study, Rose and colleagues assessed lung tissue from 24 previously deployed military personnel with lung disease (mean age, 41 years; 21 men; 22 white) and 11 deceased controls without lung disease (mean age, 54.8 years; five men; eight white) to determine how self-reported deployment exposures are linked to particulate matter (PM) in the tissue.
Between the two cohorts, never smoking status was more frequent in deployed military personnel vs. controls (62.5% vs. 27.3%).
Of the military personnel cohort, total median employment duration was about 2.4 years with a median of three unique deployments. Most of these individuals had been deployed to both Iraq and Afghanistan (n = 9; 37.5%) or Iraq only (n = 9; 37.5%). Deployment to Afghanistan only was less common (n = 6; 25%). Other deployment settings found in this cohort included other Southwest Asia locations (n = 9; 37.5%).
When asked about deployment exposures, 22 military personnel experienced high-intensity exposure (at least once a week) to diesel exhaust, and the same number experienced high-intensity exposure to burn pit smoke. High-intensity exposure to sandstorms was less common (n = 6; 26.1%).
Researchers found several different categories of PM in both the lungs of deployed military personnel and controls: aluminum and zirconium oxides, carbonaceous particles, iron oxides, titanium oxides, silica, other silicates and other metals.
Between the two cohorts, those in the deployed group had greater proportions of silica (median, 7.3% vs. 1.8%; P = .004) and other silicates, including aluminosilicates (median, 7.7% vs. 2.2%; P = .003), in their lungs after adjusting for age. Rose told Healio this was unexpected but not a complete surprise.
“Veterans with lung disease are often exposed to high levels of desert dust and sandstorms during their service in Iraq and Afghanistan,” Rose said. “This is particularly true for those with combat job duties. These deployment exposures probably account for the higher proportion of silica and silicates in their lungs.”
In contrast, the proportions of aluminum oxide and zirconium oxide; carbonaceous particles; iron oxide and iron phosphate; iron titanium oxide; titanium oxides and metals (steel, tin, nickel, copper, zinc, etc) did not significantly differ between the deployed group and the control group.
In terms of particle size, researchers frequently found aspect ratios less than three. Overall median particle length was comparable between the two groups, as was overall median particle area.
Despite not reaching statistical significance, researchers observed heightened total PM burden among deployed personnel who had vs. did not have combat jobs.
Further, there was no significant link between self-reported exposures and PM proportions in the deployed group, according to researchers.
Reference:
- Study finds high amounts of silica exposure in previously deployed military veterans. https://www.nationaljewish.org/about-us/news/press-releases/2024-news/study-finds-high-amounts-of-silica-exposure-in-previously-deployed-military-veterans. Published April 3, 2024. Accessed April 8, 2024.