ASTM E2946-21. Standard Test Method for Determining the Bacteria-Reducing Effectiveness of Food-Handler Handwash Formulations Using Hands of Adults.  

Test accredited by ENAC (Spanish National Accreditation Entity).

This test is specifically designed to evaluate the effectiveness of the products to eliminate bacteria from food-handlers hands contaminated experimentally in conditions of moderate or high organic load, using the hands of adults. For this, the hands of a group of adult subjects (at least eight for each combination of test substance to be analyzed), who have refrained from using any product containing antimicrobial agents for at least one week before the test to which the laboratory will provide a personal hygiene kit, without antimicrobial products, of exclusive use during the test. The hands are contaminated with Escherichia coli incorporated in a medium with moderate organic load, consisting of meat broth added to the bacterial suspension to simulate the conditions of organic load, or high organic load constituted by hamburger meat, which is then distributed by all surfaces of the hands and fingers to give rise to a minimum population of initial recovery of ≥107 colony-forming units (CFU)/hand.

The test product is evaluated, after a single cycle of contamination/application, previously performing a complete hand washing to remove grease and dirtiness, drying with completely clean paper. Subsequently, the hands are contaminated with a broth containing moderate or high organic load, according to indications of the promoter of the test, and Escherichia coli. The subject's hands are contaminated with the test bacteria before the reference recovery and before the application of the test material. The hands are sampled for the initial recovery, immediately after the contamination of the first hand, afterwards a cleaning wash is carried out, and after the initial recovery and before the contamination of the second hand, the hands are contaminated and the product under testing is applied. The bacterial recovery is carried out after the washings with the reference control and with the test substance, placing bags in the right and left hand of the subject and adding sampling solution with neutralizer to each one, being able to aspirate aseptically a known volume of sample to proceed with the sowing.

The effectiveness of the test material is determined by comparing the number of bacteria recovered from contaminated hands after a single application of the test material with the number of bacteria recovered from contaminated hands not exposed to the test material. The results obtained in the plate counts (CFU/hand) are averaged and the log10 of the reductions are determined in each recovery/wash interval, such a significant reduction will be evaluated with the Wilcoxon statistical method.

The customer must indicate instructions for use on the test material to be tested, such as the concentration and instructions on how to add the product. As well as, indicate if wanted to incorporate interfering substance with moderate or high organic load. The applicant for the test must record these requirements on the test form.