Particulate matter, endotoxin, and worker respiratory health on large Californian dairies

Abstract

Objective: To assess respiratory exposures and lung function in a cross-sectional study of California dairy workers.

Methods: Exposure of 205 dairy and 45 control (vegetable processing) workers to particulate matter and endotoxin was monitored. Pre- and postshift spirometry and interviews were conducted.

Results: Geometric mean inhalable and PM2.5 concentrations were 812 and 35.3 μg/m3 versus 481.9 and 19.6 μg/m3, respectively, for dairy and control workers. Endotoxin concentrations were 329 EU/m3 or 1122 pmol/m3 and 13.5 EU/m3 or 110 pmol/m3, respectively, for dairy and control workers. In a mixed-effects model, forced vital capacity decreased across a work shift by 24.5 mL (95% confidence interval, -44.7 to -4.3; P = 0.018) with log10 (total endotoxin) and by 22.0 mL (95% confidence interval, -43.2 to -0.08; P = 0.042) per hour worked.

Conclusions: Modern California dairy endotoxin exposures and shift length were associated with a mild acute decrease in forced vital capacity.

FIGURE 1.

Mean geometric exposures in dairy and control facilities. Mean particulate concentrations and 95% confidence intervals.

FIGURE 2.

Cross-shift changes in pulmonary function by quartile of exposure concentration. 2a: Inhalable PM/m3, 2b: PM2.5/m3, 2c: Total Endotoxin (pmol/m3), 2d: Active Endotoxin (EU/m3).