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Particulate Matter, Endotoxin, and Worker Respiratory Health on Large Californian Dairies

Mitchell, Diane C. PhD; Armitage, Tracey L. MS; Schenker, Marc B. MD, MPH; Bennett, Deborah H. PhD; Tancredi, Daniel J. PhD; Langer, Chelsea Eastman PhD, MPH; Reynolds, Stephen J. PhD; Dooley, Greg PhD; Mehaffy, John PhD; Mitloehner, Frank M. PhD

Journal of Occupational and Environmental Medicine: January 2015 - Volume 57 - Issue 1 - p 79–87
doi: 10.1097/JOM.0000000000000304
Original Articles

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.

From the Department of Public Health Sciences (Drs Mitchell, Schenker, and Bennett, Langer,* and Ms Armitage); Department of Pediatrics (Dr Tancredi), University of California Davis; Department of Environmental and Radiological Health Sciences (Dr Reynolds); Center for Environmental Medicine (Dr Dooley), Colorado State University, Ft Collins; and (Dr Mitloehner) Department of Animal Science, University of California, Davis. *Dr Langer's current address is Centre for Research in Environmental Epidemiology, Barcelona, Spain.

Address correspondence to: Diane C. Mitchell, PhD, Department of Public Health Sciences, University of California, Davis, CA 95616 (

Support for this research was provided by the National Institute for Occupational Safety and Health grants #U50-OH00770 and 5U54-OH008085 and the University of California Toxic Substances Research and Teaching Program through the Atmospheric Aerosols and Health (AAH) Lead Campus Program.

The authors declare no conflicts of interest.

Copyright © 2015 by the American College of Occupational and Environmental Medicine