Submitted to: Applied Biosafety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 6, 2007
Publication Date: March 20, 2008
Citation: Sites, J.E., Annous, B.A., Walker, P.N., Burke, A.M. 2008. Development and Validation of a Pilot Scale Enhanced Biosafety Level Two Containment for Performance Evaluation of Produce Disinfection Technologies. Applied Biosafety. 13(1):30-44. Interpretive Summary: Current technologies available for use by the produce industry result in no more than 99% reductions in pathogen levels and fall short of meeting the U.S. Food and Drug Administration's target of 99.999% reductions. More effective decontamination technologies and more effective decontamination equipment are needed. Interventions found to be effective in the laboratory should be scaled up in a pilot plant facility to facilitate commercialization of the technology. However, human pathogens could not be introduced into the pilot plant in its original configuration because of concerns for the safety of equipment operators or other personnel in the pilot plant area, and researchers found it necessary to use non-pathogenic surrogate organism in place of the target pathogenic organism. Such studies were inherently limited because surrogate organisms do not behave in a manner identical to that of their pathogenic counterparts. A Biosafety Level Two (BSL-2) pilot plant, designed to accommodate experiments using human pathogens, was required to facilitate validation and commercialization of new technologies for decontaminating produce containing human pathogens. The goal of this research was to design, fabricate, install, and validate the unique BSL-2 containment, commercial-scale produce washing equipment, and associated remote control and decontamination systems. The validation of BSL-2 containment and processing treatment demonstrated that the containment chamber was fully successful in containing and deactivating air borne and surface attached bacteria and bacteria suspended in solution. Thus, the research community now has a safe, workable, and proven engineering tool providing an ability to conduct pilot-plant scale decontamination studies of produce and equipment using human pathogens instead of surrogates. Also, we developed a commercial-scale surface pasteurization process capable of inactivating more than 99.999% of pathogens on artificially inoculated cantaloupes. These findings will assist food industry and regulatory agencies in establishing processing guidelines to guard against pathogens, thereby decreasing the incidence of food poisoning outbreaks.
Technical Abstract: The development and validation of the enhanced Biosafety Level Two containment system located at the produce pilot plant facility of the U.S. Department of Agriculture - Eastern Regional Research Center is presented. This multi-purpose containment is used to enclose commercial-scale processing equipment for fruits and vegetables washing and sanitizing processes or other decontamination equipment where aerosol generation is likely and complete protection is required for the researchers. The containment is operated under a negative pressure with all exhausted air being passed through two hydrophobic HEPA filters. During operation, personnel are excluded from the containment, materials are introduced into and removed from the containment via pass-throughs, and equipment is operated via computer control and glove ports. At the completion of any series of processing trials, vegetative bacterial cells within the chamber and in the processing water are inactivated by raising the internal temperature of the chamber, and all contents, including equipment, processing water and waste water sufficiently to inactivate all bacterial cells, except spore formers, using industrial steam at atmospheric pressure. Also, we have demonstrated the feasibility and safety of conducting multiple trials using pathogenic bacteria with pilot scale processing equipment within the containment and then, inactivating surviving vegetative bacterial cells with the steam-in-place process. Furthermore, we validated commercial-scale surface pasteurization processing equipment capable of significantly reducing (in excess of 5 logs/cm2) cell densities of Salmonella on inoculated cantaloupes using BSL-2 containment.