Virucides are regulated by the United States Environmental Protection Agency. Recent EPA guidelines provide companies with several different options for testing virucides, including ASTM E1053, and AOAC Germicidal Spray Products Test modified for viruses.
Any type of virucide can be tested using ASTM E1053. If a company prefers to utilize AOAC test methods instead, then the proper test method depends on product form and application. For water soluble powder and liquid formulations that require preparation or dilution prior to use, EPA recommends the AOAC Use-Dilution Test modified for viruses or the ASTM E1053. For spray products, EPA recommends the AOAC Germicidal Spray Products Test modified for viruses.
Summary of Virucidal Efficacy Test Methods for EPA
- If requested by the Study Sponsor, the test virus suspension is loaded with organic soil to the appropriate level.
- An inoculum of the test virus is spread over the carrier surface and allowed to dry.
- The dried virus film is treated with the test substance, and held for the specified contact/exposure time.
- At the close of the contact time, the test carrier films are neutralized using a method most suitable for the active ingredient(s) present in the test substance.
- The test suspensions are assayed for the presence of infectious viruses using established methods.
- Virus control, cytotoxicity, neutralization, and sterility controls are also performed, and assayed in parallel with neutralized test suspensions.
- The US EPA requires that the following criteria (among others) be met in order for the test substance to be considered for a basic disinfectant label claim:
- Complete inactivation of the test virus at all dilutions of the assay.
- A 3-log10 reduction of the test virus past the observed level of cytotoxicity, if cytotoxicity is observed.
Strengths of Virucidal Efficacy Test Methods for EPA
- Historically, modified AOAC methods have been most popular with contract testing laboratories for substantiation of virucidal efficacy claims, so EPA is accustomed to the methods.
- This way of testing virucides provides flexibility with regard to product preparation and application to the contaminated surface.
- Modified AOAC methods include only controls critical to determine the reliability of the data, so they are often more cost-effective than the alternative ASTM E1053 test.
- EPA allows one 10-square inch carrier to be used in place of ten one-square inch carriers, which makes the test easier to conduct in the laboratory.
Weaknesses of Virucidal Efficacy Test Methods for EPA
- Data generated for submission to the US EPA using AOAC methods modified for virus testing may not satisfy regulatory agencies in other countries.
- Neutralization of the virucidal agent often requires the use of a physical separation medium such as Sephacryl, which adds experimental complexity.
Microchem Laboratory regularly performs comprehensive GLP studies for submission to EPA or FDA.Antimicrobial