Characterization of Endotoxin Collected on California Dairies Using Personal and Area-Based Sampling Methods

Abstract

Endotoxin, found in the cell wall of gram negative bacteria, is an important contributor to the biological activity of agriculture particulate matter (PM). We analyzed endotoxin in PM collected on 13 California dairies and from the breathing zone of 226 workers during the summer months of 2008. Two particle size fractions were measured: PM_2.5 and inhalable PM. Recombinant factor C assays were used to analyze biologically active endotoxin, while gas chromatography coupled with mass spectrometry in tandem was used to quantify total lipopolysaccharide. Biologically active endotoxin concentrations in the inhalable PM size fraction from area-based samples ranged from 11–2095 EU/m³ and from 45–2061 EU/m³ for personal samples. Total endotoxin in the inhalable PM size fraction ranged from 75–10,166 pmol/m³ for area-based samples and 34–11,689 pmol/m³ for personal samples. Area-based geometric mean concentrations for biologically active endotoxin and total endotoxin in PM_2.5 and inhalable PM size fractions were 3 EU/m³, 149 EU/m³, 60 pmol/m³, and 515 pmol/m³, respectively. Personal geometric mean concentrations in the inhalable PM size fraction were 334 EU/m³, and 1178 pmol/m³. Biologically active and total endotoxin concentration variation was best explained by meteorological data, wind speed, relative humidity, and dairy waste management practices. Differences in endotoxin concentration and composition were found across locations on the dairy.

Keywords:

• 3-OHFA
• agriculture
• dairy
• endotoxin
• particulate matter

ACKNOWLEDGMENTS

Support for this research was provided by the Western Center for Agricultural Health and Safety through National Institute for Occupational Safety and Health (NIOSH) grant number OH007550-06-11, and by the Atmospheric Aerosols and Health training program, a part of the University of California Toxic Substances Research and Teaching Program. Additional funding was provided to The High Plains Intermountain Center for Agricultural Health and Safety through grant number CDC NIOSH 5U50 OH008085. We would like to thank all the staff, dairy workers, and dairy owners who were a part of this research.