Wildland firefighter work task-related smoke exposures at prescribed burns and their effect on proinflammatory biomarkers and urinary mutagenicity
Adetona, Anna Marie
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Objectives: 1) To characterize smoke particles on personal air filters, 2) determine differences in smoke particles according to work tasks, 3) estimate inhaled dose of smoke particles using estimated ventilation rate data, 4) assess cross-work shift (before work shift to after work shift) changes in proinflammatory responses according to work tasks, and 5) characterize occupational smoke exposures using urinary mutagenicity among wildland firefighters. Methods: Repeated measures on twelve subjects with the United States Forest Service were collected on prescribed burn and non-burn days during January-July 2015. Personal particulate matter (PM2.5), carbon monoxide (CO), accelerometer data, and before-, after-, and morning-after- work shift dried blood spots (DBS), blood smears, and urines were collected. Accelerometer measurements were used to estimate ventilation rate and inhaled dose of PM2.5. Light absorbing carbon (LAC) was measured as a surrogate for black carbon (BC) and divided by PM2.5 concentrations to calculate mass absorption efficiencies. DBS were analyzed for inflammatory mediators using the Meso Scale Discovery assay and leukocyte populations were assessed on blood smears. Urine was analyzed for mutagenic potency using the Ames assay and for malondialdehyde (MDA) using High-Performance Liquid Chromatography. Results: Firefighters conducting lighting (lighters) had an estimated 1.3 times higher, though not significant, inhaled amount of PM2.5 compared to those managing fire boundaries (holders). Lighters had a three-fold higher exposure to LAC and significant cross-work shift increases in interleukin-8, C-reactive protein, and serum amyloid A, compared to holders. Positive associations were observed between interleukin-8 and segmented-neutrophil (p=0.0179), and mass absorption efficiency (p=0.0080), respectively. Though not significant, lighters had a two-fold higher cross-work shift increase in crude urinary mutagenicity compared to holders and non-burn day exposures. Positive associations were found between creatinine-adjusted urinary mutagenicity and MDA (p=0.0905), CO (p=0.0459), and mass absorption efficiency (p=0.1333), respectively. Conclusion: Healthy seasonal wildland firefighters conducting lighting at prescribed burns had higher acute proinflammatory responses compared to other tasks. Data suggest that intermittent diesel exposures contribute to acute health responses, while urinary mutagenicity may serve as a suitable measure of integrated occupational smoke exposures of wildland firefighters.