American Industrial Hygiene Conference and Exposition, May 10-15, 2003, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 2003 May; :56
During the week of February 4-7,2002, NIOSH conducted a health hazard evaluation at the Trenton Processing and Distribution Center in response to a request from the United States Postal Service for collaborative research to evaluate air sampling methods for Bacillus anthracis spores prior to and subsequent to operation of a delivery bar code sorter (DBCS). Two hundred and fifty-six air samples were collected using mixed cellulose-ester filters, polytetrafluoroethylene filters, gelatin-coated filters, dry filter units which used polyester felt filter disks, and Andersen single-stage cascade impactors using trypticase soy agar plates with 5% sheep blood. One hundred and six wipe samples were collected using sterile polyester/rayon pads moistened with sterile water. Initial sample analysis for B. anthracis indicated that prior to operating the DBCS, all MCE, PTFE, GEL, and DFU filters were negative; however, 19% of Andersen samples were positive. Subsequent to operating the DBCS, all sample media indicated some positive samples, which included 91 % of Andersen samples. The re-analysis of the remaining sample pellet of previously negative filter samples collected prior to and subsequent to DBCS operation resulted in additional positive samples. This clearly demonstrates that not only are all evaluated methods capable of collecting B. anthracis spores to some degree, and re-aerosolization is possible through mechanical means. Additionally, since positive samples were found at various locations prior to operation of the DBCS, it suggests that walking and light work in the enclosure may have been sufficient to re-aerosolize B. anthracis spores at low concentrations. The positive samples from the re-analysis indicate that if the complete specimen pellet is not consumed in the initial analysis, then there exists a potential for false negative results. This determination can play a significant factor in the selection of air sampling methodologies when considering the intent of sampling, e.g., screening, characterization, or clearance.
American Industrial Hygiene Conference and Exposition, May 10-15, 2003, Dallas, Texas