School of Public Health and Community Medicine - University of Washington - Aut 2008

According to the Washington State Departmentof Agriculture, Washington has over 100 dairy operations with more than 700 cows.

Among issues discussed at the November 2008 "Health and Safety in Western Agriculture—New Paths" conference, organized by the Pacific Northwest Agricultural Safety and Health Center (PNASH), was the expansion of large-scale agricultural operations and the subsequent potential health risks that pose an emergent concern. For example, growing numbers of large animal feeding operations in the United States have some worried about occupational health hazards not necessarily seen in smaller scale farm operations.

DEOHS researchers, in collaboration with researchers at other universities, are studying large-scale dairy operations. One pilot project being led by Assistant Professor Scott Meschke, with federal funding through PNASH, aims to determine the levels of bioaerosols present in the air of a dairy facility in Yakima County, Washington.

Bioaerosols include microorganisms such as fungi or bacteria from cattle waste, feed, and bedding. Suspended in the air and often attached to organic dust or other particulate matter, bioaerosols can also be allergens, pollen, and bacterial endotoxins. When certain kinds of bacteria break down, endotoxins found on the outer layer of the cell are released. High levels of exposure to endotoxin-containing bioaerosols may put dairy workers at risk for respiratory illness and allergic reactions, as well as other long-term harmful effects.

In air samples taken in one dairy barn, Meschke and his research team found varied levels of bacteria and endotoxins, some as high as 12,500 colony-forming units of bacteria per cubic meter and 3,590 endotoxin units per cubic meter.

While there is no set regulatory level of exposure in occupational health, experts have proposed exposure limits of 500 endotoxin units per cubic meter. Worker exposure varies by length of time in a location, work environment, and what role the worker plays in the dairy operation, among other factors. So, the bioaerosol levels that Meschke’s team found can’t be compared to those experienced by actual workers.

An aerodynamic lens aerosol concentrator in development at Enertechnix in Seattle may help researchers better understand dairy-worker exposures. The patented technology used in the concentrator was originally designed to collect samples of aerosols in large amounts of air, anything from dust to pollen. Then, with the concentrator’s potential to sample air at discrete time intervals and to measure variable levels of exposure, DEOHS researchers foresaw another application.

With a team of graduate assistants, Meschke and Professors Mike Yost and Terry Kavanagh have been working with Enertechnix’s Director of Research and Development Peter Ariessohn, Senior Research Scientist Igor Novosselov, and Engineer Evan Dengler to design and develop an all-in-one personal air sampler. It will include an endotoxin reader that can analyze and identify bioaerosolized particulates and pathogens in real time. :The plastic one-ounce sampler can be worn with a hip-pack battery half the size of a Walkman radio and be able to collect samples continuously for eight hours. With a tool to more accurately measure individual exposure in place and time, Meschke says it may be able to help researchers pinpoint appropriate interventions.

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