Personal Exposures to Inorganic and Organic Dust in Manual Harvest of California Citrus and Table Grapes

Abstract

The aim of this study was to determine characteristics of personal exposure to inorganic and organic dust during manual harvest operations of California citrus and table grapes. Personal exposures to inhalable dust and respirable dust were measured five times over a 4-month period of harvesting season. We analyzed components of the dust samples for mineralogy, respirable quartz, endotoxin, and total and culturable microorganisms. Workers manually harvesting were exposed to a complex mixture of inorganic and organic dust. Exposures for citrus harvest had geometric means of 39.7 mg/m³ for inhalable dust and 1.14 mg/m³ for respirable dust. These exposures were significantly higher than those for table grape operations and exceeded the threshold limit value for inhalable dust and respirable quartz. Exposures for table grape operations were lower than the threshold limit value, except inhalable dust exposure during leaf pulling. Considered independently, exposures to inhalable dust and respirable quartz in citrus harvest may be high enough to cause respiratory health effects. The degree of vigorous contact with foliage appeared to be a significant determining factor of exposures in manual harvesting.

Keywords:

• agricultural dust
• bioaerosols
• endotoxin
• harvest
• inorganic dust

ACKNOWLEDGMENTS

We appreciate Mark Nieuwenhuijsen's assistance in manuscript preparation and review, Laurel Beckett's statistical assistance, and Jeannine A. DeKoster's evaluation of total bacteria and fungi.

Funding for this study was provided by the Western Center for Agricultural Health and Safety at UC Davis, funded by a grant from the National Institute for Occupational Safety and Health, Cooperative Agreement # U07/CCU9061202; the Center for Environmental Health Sciences, funded by a grant from the National Institute of Environmental Health Sciences, grant #P30ES05707; and Hatch Project CA-D*-LAW-4525-H, California Agricultural Experiment Station. Analyses performed at the University of Iowa were supported by the NIEHS-sponsored Environmental Health Science Research Center, grant # NIH/NIEHS P30ES05605.

Notes

^A SD = standard deviation.

^B GM = geometric mean.

^C GSD = geometric standard deviation.

^A SD = standard deviation.

^B GM = geometric mean.

^C GSD = geometric standard deviation.

^A SD = standard deviation.

^B GM = geometric mean.

^C GSD = geometric standard deviation.

^D Four samples were < LOD.

^E Two samples were < LOD.

^F One sample was < LOD.

^A Results are reported as percentage of particles identified, with a particle count of 1000 per sample.