Tissue Digestion - The Tissue Digestion Process

> Chemistry of the WR2 Process
> Composition of Animal Tissues
> Effects of Alkaline Hydrolysis
> Results of the WR2 Process
> Applications of the WR2 Process
> Aldehyde-Containing Fixatives and Embalming Fluids
> Infectious Waste
> Biological Warfare Agents
> Chemotherapeutic Agents
> Control and Safety Systems

Infectious Waste

The WR2 Process destroys all pathogens listed as index organisms by the State and Territorial Association on Alternative Treatment Technologies (see STAATT I [April 1994] and STAATT II [December 1998] reports) and to be recommended in the new STAATT III Guidelines [2006].  The STAATT guidelines call for a system to be able to prove efficacy in the destruction of infectious agents by producing a 6 log10 reduction in vegetative infectious agents and a 4 log10 reduction in spore-forming agents.  While each state has its own regulations for approving alternative treatment technologies for regulated medical waste, most of them are derived from or equivalent to the STAATT guidelines. The BioSAFE/WR2 Process has been approved for the treatment of infectious waste in all states in which specific application for such approval has been made, including, among others, New York, Pennsylvania, Florida, California, Ohio, Massachusetts, and North Carolina, and is approved by rule or by definition as a sterilizer in other states because of the time and temperature parameters at which it operates. Table III-2 below presents a representative example of the efficacy test results on which these approvals were based.

For a number of years, results from different laboratories have indicated that the infectivity of brain macerates or homogenates containing prions (proteinaceous infectious particles, the agents that cause transmissible spongiform encephalopathies (TSE), such as Mad Cow Disease and Creutzfeldt-Jakob Diease) are destroyed by combined treatment with heat and alkali. In 2001, the USDA APHIS selected a BioSAFE/WR2 Tissue Digestor for destruction of sheep with an unidentified TSE suspected of being BSE and has subsequently used and/or included in regulatory language the use of the BioSAFE/WR2 Alkaline Hydrolysis process for safe disposal of sheep with scrapie, deer and elk with chronic wasting disease (CWD), and Specified Risk Material (SRM) removed from cattle slaughtered for human consumption. A BioSAFE/WR2 Mobile Tissue Digestor at the APHIS facility at the University of Wisconsin has safely disposed of more than one million pounds of CWD contaminated deer culled in the Wisconsin eradication program since its commissioning in December 2003. 

Validation studies conducted at the Neuropathogenesis Unit, Institute of Animal Health, University of Edinburgh (funded by the UK Ministry of Agriculture, Food, and Fisheries) using a BioSAFE/WR2 Lab 30 Digestor to produce a hydrolysate from BSE prion-doped sheep brain provided additional data that led to the amendment of the original European Union Animal Byproducts Legislation [EC 1774/2002] approving Alkaline Hydrolysis at Elevated Temperature (the BioSAFE/WR2 Process) for treatment and disposal of all categories of Animal Byproduct Wastes, especially including prion-containing or suspect Category 1 Byproducts [EC 92/2005].

Table III-2 Efficacy Testing Results

CFU = Colony forming units; PFU = Plaque-forming units on Escherichia coli ATCC 15597