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The Japanese Industrial Standards (JIS) L 1902 method, titled "Testing Antibacterial Activity and Efficacy on Textile Products", is designed to test the ability of fabrics that have been treated with antimicrobial agents to prevent microbial growth and to kill microorganisms, over an 18 hour period. Within the official standard method, there are 3 types of tests - 1 qualitative and 2 quantitative. The qualitiative method, the "Halo Method", is similar to a Zone of Inhibition with a few modifications, including adding inoculum into the molten agar and allowing it to solidify prior to adding the test piece to the surface. Of the two quantitative methods, the "Absorption Method", is similar to another popular antimicrobial textile test method, AATCC 100 and is the focus of this webpage.
The JIS L 1902 method has since been adopted more or less intact as an International Standards Organization (ISO) method, ISO 20743.
Summary of the JIS L 1902 Test
- The test microorganism is prepared by growth in a liquid culture medium.
- The suspension of test microorganism is standardized by dilution in a nutritive broth (this affords microorganisms the potential to grow during the test). The level of nutrition present in the nutritive broth is important, and is specified by the method. Growth of the microorganism is required on the control fabric for the test to be valid.
- Control and test fabrics are inoculated with microorganisms in triplicate, ensuring that the inoculum is only in contact with the fabrics.
- Initial microbial concentrations are determined at "time zero" by elution, then dilution, and plating of control fabrics immediately after inoculation.
- Additional inoculated control and test fabrics are allowed to incubate undisturbed in sealed containers at body-temperature for 18 hours.
- After incubation, final microbial concentrations are determined. Reduction of microorganisms relative to initial concentrations and the control fabric is calculated.
- Controls are run to ensure that the neutralization/elution method effectively neutralizes the antimicrobial agent in the test fabrics.
Strengths of the JIS L 1902 Test
- The method parameters are more carefully spelled out than an alternative antimicrobial fabric method called AATCC 100.
- The method is quantitative and results are generally reproducible.
- The method tests for both bacteriostatic (growth-inhibiting) and bactericidal (bacteria-killing) properties on a given antimicrobial fabric.
- Microbial concentrations are standardized, and bacteria are provided with nutrients during the incubation period, which provide them with ample opportunity to grow if the test fabrics aren't sufficiently antimicrobial.
- The method stipulates triplicate experimentation, which helps researchers estimate the precision of the individual tests and increases overall experimental accuracy.
- The method includes a "pass/fail" criterion for the calculated levels of antimicrobial activity observed in test samples, making determinations of antimicrobial activity less discretionary.
Weaknesses of the JIS L 1902 Test
- The relationship between product performance in the JIS L 1902 method and actual outcomes, such as odor inhibition or infection control, is not well understood.
- The method is generally not accepted by U.S. EPA for so-called "health claims."
- Test fabrics that are hydrophobic can be difficult to test with this method.
Microchem Laboratory has a great deal of experience running JIS L 1902 studies for both R&D and claims validation purposes.