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May 2001 update - compiled by Helane Shields - prepared for WWW by ESRA

In a 1993 report "HAZARDS FROM PATHOGENIC MICROORGANISMS IN LAND DISPOSED SEWAGE SLUDGE" by Timothy Straub, Ian Pepper and Charles Gerba (Reviews of Environmental Contamination and Toxicology, Vol. 132), the authors made the following statements about sludge bioaerosols (pages 71 and 72):

"Many enteric microorganisms can effectively be transmitted by aerosols.... Organisms in such aerosols can be transmitted by inhalation. . . "

"The number of microorganisms in aerosols depends on the type of sludge disposed, method of application, and number of microorganisms in the sludge. The greatest amount of aerosol generation would occur during the application of sludges with a low solids content applied as slurries during spray application. Dumping of sludges from trucks onto the soil or into trenches and area fills would also generate aerosols on impact."

"Some aerosoling would occur during the application of sludge. Greater numbers of pathogenic microorganisms would be aerosoled during disposal of primary rather than treated sludges."

"If wind velocities at a site are great enough, suspension sludge particles could occur (USEPA, 1986). Most sludges would not be easily resuspended because of their moisture content and tendency to mat as they dry."

"Dried sludges, however, may be very light and fine in texture and, therefore, easily resuspended. If dried sludge is not covered at windy sites, winds will attain speeds capable of suspending the sludge from the working face."

"Aerosols could (also) be transported downwind to exposure areas distant from the disposal site.

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