The EPA’s “Test method for Efficacy of Copper Alloy Surfaces as a Sanitizer” is designed to quantitatively test the ability of copper and copper alloy surfaces to act as a sanitizer.
Most importantly, this method serves as the technical basis for substantiation of so-called “health claims” for antimicrobial surfaces. In other words, if companies want to say that a surface kills microorganisms of public health concerns, they have to pass this or a similar version of the method.
Summary of the Copper Surfaces as Sanitizers Test Method
Cultured test microorganisms are standardized in growth supportive media to be used in the test.
Organic soil is added to the inoculum to simulate “dirty” conditions.
Control and test surfaces are inoculated with the standardized test microorganism, in quintuplicate, and then allowed to dry for 20-40 minutes at room temperature.
Initial microbial concentrations are determined at “time zero” by elution then dilution and plating of control surfaces immediately following the dry time.
Additional control and treated samples are allowed to sit undisturbed for the duration of the contact time (typically 2 hours).
At the conclusion of the contact time, the surviving test microorganism concentrations are determined by elution then dilution and plating of the control and test samples.
Reduction of microorganisms relative to initial concentrations and the control surface is calculated.
Per the test method, the test substance needs to demonstrate at least a 3 log (99.9%) reduction.
Strengths of the Copper Surfaces as Sanitizers Test Method
The method is somewhat representative of actual surface contamination events since it takes into consideration the drying of the test microorganisms as typically seen on environmental surfaces.
Weaknesses of the Copper Surfaces as Sanitizers Test Method
Test sample composition as stated in the title of the method is specific to copper and copper alloy technologies and Sponsors should avoid using this method to test alternative technologies (quats, silver, peroxides, etc.) unless strictly for R&D purposes.
The method has strict guidelines regarding test samples and those tested should not be waxed, painted, lacquered, varnished, or otherwise coated; therefore limiting the type of treatment that can be applied to a sample.
Label claims supported by this method are limited to indoor, hard, non-porous surfaces where cleaning practices are consistent.
Microchem Laboratory welcomes the so-called “EPA Copper Protocols” since they represent a clear path forward for makers of antimicrobial surfaces desiring public-health-related microbial reduction claims.