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California Dairy Environmental Health Research Initiative (Cal-DEHRI)

The data collection phase of the study has already occurred. We are no longer recruiting Dairies into the study, but when results have been analyzed, we will be happy to share information. Please e-mail the Study Coordinator: Diane Mitchell at dcmitchell@ucdavis.edu with any requests.

The primary aims of this study are: (1) To determine whether working in a modern, large Californian dairy has any effects on the breathing health of worker; and (2) To perform exposure assessments at a sample of these dairies to better understand the exposure to air pollutants of the workers, and the possible environmental impacts.

California dairies produce approximately 21% of the total U.S. milk production (more than any other state). The dairy industry in California is concentrated in the San Joaquin Valley. In recent years the total milk production has increased, while the number of dairies in California has declined, due to an increase in the number of cows per dairy. Currently, dairies throughout the state have an average of over 900 milking cows. New dairies are larger, starting production with several thousand milking cows.

Modern management keeps the milking cows in concrete-floored and open-sided freestall barns. Each cow produces approximately 120 lbs of manure daily, which is flushed with water from the freestalls into large manure ponds ("lagoons") located on the dairy. Non-lactating cows and heifers (cows before being bred) are generally housed in dirt-floored drylot corrals, from where the manure is scraped, rather than flushed, several times per year to be applied on cropland as fertilizer. Between the scraping intervals the accumulating manure dries out. Dust (aerosols) can be created in the air from this dried manure due animal locolmotion (i.e. kicking hooves, running, etc). Dust on dairies are generally highest in the summer and during the rainy season, dust levels decrease but gases like ammonia increase. The current study examines the exposure and health effects of the conditions for dairy workers. Additional research is required in order to better understand both the health hazard and the relationship between air quality and exposure on Californian dairies.




The Cal-Dehri Study is a collaboration between University of California, Davis departments of Animal Science and Public Health Science, and Colorado State University and is funded by a grant from the National Institute of Occupational Safety and Health (2006-2011) Reproduction of material on this web site is hereby granted solely for personal use. No other use of this material is authorized without prior written approval ofthe UC Regents.

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