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

In an Ecological Risk Assessment "Bioaerosol Transport Modeling and Risk Assessment in Relation to Biosolid Placement" by Scot E. Dowd, Charles P. Gerba, Ian Pepper and Suresh Pillai, published in the Journal of Environmental Quality 29:343-348 (2000) the authors stated:

"There is growing concern regarding exposure to microbial pathogens from biosolids via aerosols, especially in population centers surrounding biosolid application sites. (Dowd et al., 1997) This is a valid concern because aerosols can transmit many enteric microorganisms (Pahren and Jakubowski, 1980)."

'Based upon the estimated bioaerosol release rates, we can apply bioaerosol concentrations and microbial inactivation rates to model transport data and obtain the risk factors associated with breathing air contaminated by microbial pathogens originating from biosolid material."

"The typical route of exposure for organisms that are primarily associated with intestinal infection is based upon the inhalation of bioaerosols, which are deposited in the throat and upper airway and swallowed (Wathes et al., 1988)."

"Additionally, inhaled enteric pathogens may establish throat and respiratory infections that can increase the risk of swallowing an infectious dose (Clemmer et al., 1960)."

"...the potential for an increased risk of work-related illness in such biosolid workers is collaborated (editor: corroborated) by numerous epidemiological studies which have shown higher rates of illness in wastewater workers."

"Clinically, these illnesses were usually manifested as undue tiredness and headaches that were evident after work. Additionally, other symptoms such as respiratory problems, nonspecific bowel dysfunction, irregular heartbeat, nausea, vomiting, and diarrhea were also common complaints."

The ABSTRACT of the Bioaerosol Risk Assessment focuses on the (obvious) conclusion that healthy people who live 6.2 miles from the sludge site are at no risk from sludge bioaerosols. However, a closer reading of the Tables indicates significant risk to people living within 3/4 of a mile of a sludge site .

For example, the exposure risk from airborne bacteria originating in a sludge stockpile to people who five within 1640 feet and have their windows open day and night (such as in the summer) with a wind speed of 11 mph is 400 out I 0,000 - - far in excess of EPA's "acceptable risk" of one out of 10,000.

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