New Pass Criteria for the UDM

AOAC International, a standards-setting organization, recently published changes to test methods used by disinfectant manufacturers to register their products with the United States Environmental Protection Agency (EPA), notably the Use-Dilution Method (UDM) for Pseudomonas aeruginosa and Staphylococcus aureus. The methods now permit a greater number of failures per test, reducing the impact of ordinary variability on failure rates.  Specifically, the method now permits up to 3 or 6 failing carriers out of each set of 60 tested for Staph and Pseudomonas, respectively.  Additionally, manufacturers must now test each batch of product for a given microorganism on different days to ensure acceptance of the data by EPA.