1. Introduction
CREM Co Labs is a leading provider of testing services, including rigorous efficacy evaluations for hard surface disinfectants. These disinfectants play a vital role in safeguarding public health by reducing the spread of harmful microorganisms in various environments. Validating the effectiveness of these products requires strict adherence to guidelines established by regulatory agencies such as the Environmental Protection Agency (EPA) in the United States and Health Canada. These guidelines ensure that disinfectants marketed for specific uses meet stringent performance standards, thereby protecting consumers and public health. This overview aims to provide a comprehensive understanding of the efficacy testing requirements for hard surface disinfectants as outlined by both the EPA and Health Canada, offering valuable information for potential clients of CREM Co Labs seeking to navigate these complex regulatory landscapes.
2. Health Canada Hard Surface Disinfectant Efficacy Testing Guidelines
Health Canada is the federal department responsible for helping Canadians maintain and improve their health, and this includes regulating the sale of disinfectants in Canada. The agency recognizes different categories of disinfectant claims based on the spectrum of antimicrobial activity a product demonstrates . These categories include limited disinfectants, general (broad-spectrum) disinfectants, and hospital/healthcare disinfectants. The required efficacy testing varies depending on the specific claim a manufacturer wishes to make.
2.1. Limited Disinfectants:
Limited disinfectants are defined as products effective against either Gram-positive or Gram-negative bacteria, but not both . To substantiate such a claim, specific tests are mandated. The AOAC Use-Dilution Method 955.14 is a key procedure used to assess efficacy against Gram-negative bacteria, specifically Salmonella enterica (ATCC 10708) . This method involves inoculating stainless steel carriers with the test bacterium, exposing them to the disinfectant at a specific dilution and contact time, and then transferring the carriers to a growth medium to determine if any viable bacteria remain . For this test, three samples of the biocide from three separate batches are required, and sixty inoculated carriers are needed per batch . The initial inoculum count for S. enterica should be between 1.0 x 10^5^ and 1.0 x 10^6^ colony-forming units (CFU) per carrier . To pass this test, at least 59 out of the 60 carriers must show no growth of the test organism for each batch tested .
Similarly, the AOAC Use-Dilution Method 955.15 is used to evaluate the efficacy of limited disinfectants against Gram-positive bacteria, using Staphylococcus aureus (ATCC 6538) as the test organism . The procedure mirrors that of Method 955.14, with three batches and 60 carriers per batch required . The inoculum count for S. aureus is higher, ranging from 1.0 x 10^6^ to 1.0 x 10^7^ CFU per carrier . The passing criterion for this test is that at least 57 out of 60 carriers must be negative for growth per batch .
For limited disinfectant sprays, Health Canada requires the AOAC 961.02 (Germicidal Spray Products as Disinfectants Test) . This method involves spraying the disinfectant onto inoculated and dried test carriers, typically microscope slides, and then assessing the survival of the microorganisms . The inoculum count for S. enterica in this test is between 1.0 x 10^4^ and 3.2 x 10^5^ CFU per carrier, while for S. aureus, it is between 1.0 x 10^5^ and 3.2 x 10^6^ CFU per carrier . A passing result requires 59 out of 60 carriers to show no growth .
For single-use towelettes claiming limited disinfectant efficacy, either a Modified AOAC 961.02 method or ASTM E2362 can be used . These methods adapt the principles of the spray test to the wipe application of towelettes . The inoculum counts are the same as those for the AOAC 961.02 spray test, and the passing criterion remains 59/60 carriers negative for growth . It is important to note that for all limited disinfectant testing, each of the three required batches must be tested on a different day .
2.2. General (Broad-Spectrum) Disinfectants:
General, or broad-spectrum, disinfectants are those that demonstrate effectiveness against both Gram-positive and Gram-negative bacteria . To achieve this claim under Health Canada guidelines, a product must meet the requirements for limited disinfectants against both Staphylococcus aureus and either Salmonella enterica or Pseudomonas aeruginosa (ATCC 15442) . This necessitates successful completion of the relevant AOAC Use-Dilution Methods (955.14, 955.15, and 964.02 for P. aeruginosa), as well as the AOAC 961.02 test and its modifications for sprays and towelettes, against the specified organisms . The number of batches and carriers per batch remain the same as those for limited disinfectants for each test organism.
2.3. Hospital and Healthcare Disinfectants:
Hospital and healthcare disinfectants have the most stringent requirements, as they must be effective against both Gram-positive and Gram-negative bacteria, specifically including Pseudomonas aeruginosa (ATCC 15442), a bacterium known for its resistance to some disinfectants and its prevalence in healthcare settings . The required tests for this category are the AOAC Use-Dilution Method 964.02 for Pseudomonas aeruginosa and 955.15 for Staphylococcus aureus . Similar to the other categories, three batches and 60 carriers per batch are required for each organism . The passing criterion for P. aeruginosa using the Use-Dilution method is 54/60 carriers negative for growth per batch . For sprays and towelettes claiming hospital disinfectant efficacy, the AOAC 961.02 and modified methods are used against both P. aeruginosa and S. aureus, with the same inoculum counts and passing criteria as mentioned for limited disinfectants .
2.4. Claims Against Additional Bacteria (Non-Spore Forming):
Manufacturers may wish to claim efficacy against specific non-spore forming bacteria beyond the core test organisms. In such cases, Health Canada requires the AOAC Use-Dilution Method to be performed using the specific bacterium claimed on the label . This testing is in addition to meeting the requirements for either general or hospital/healthcare disinfectants. For these additional claims, two New Chemical Lot (NCL) batches of the product are required, separately compounded, with ten carriers needed per batch . The inoculum count should be between 1.0 x 10^4^ and 1.0 x 10^5^ CFU per carrier, and the passing criterion is stricter, requiring 10/10 carriers to be negative for growth per batch at the proposed contact time . Again, the AOAC 961.02 and modified methods are also applicable for sprays and towelettes making claims against additional bacteria.
2.5. Confirmatory Efficacy Data:
For both general and hospital/healthcare disinfectants, Health Canada also mandates confirmatory efficacy data . This involves testing against the core bacteria ( Staphylococcus aureus and either Salmonella enterica or Pseudomonas aeruginosa, depending on the claim) using two Lower Certified Limit (LCL) batches of the product and ten carriers per batch. This additional testing serves to further validate the consistency and reliability of the disinfectant’s performance.
3. EPA Guidelines for Hard Surface Disinfectant Efficacy Testing
The EPA plays a parallel role in the United States, regulating antimicrobial pesticides, including disinfectants, to ensure their safety and effectiveness . The agency’s requirements for efficacy testing are primarily outlined in the Office of Chemical Safety and Pollution Prevention (OCSPP) Series 810 Product Performance Test Guidelines, with OCSPP 810.2200 specifically addressing disinfectants for use on hard surfaces . Similar to Health Canada, the EPA also recognizes categories of disinfectants based on their spectrum of activity: limited spectrum, general or broad-spectrum, and hospital or healthcare disinfectants .
3.1. Disinfectant Efficacy Testing (Based on OCSPP 810.2200):
The EPA’s guidelines in OCSPP 810.2200 provide detailed procedures and performance standards for various disinfectant claims .
3.1.1. Limited Spectrum Disinfectants:
For limited spectrum disinfectants, effective against either Staphylococcus aureus (ATCC 6538) or Salmonella enterica (ATCC 10708), the EPA recommends the AOAC Use-Dilution Method or the Germicidal Spray Test (AOAC 961.02), which can be modified for towelettes or utilize ASTM E2362 . The performance standards for the Use-Dilution method require three independent tests against the chosen organism at the Lower Certified Limit (LCL). For S. aureus, the standard is 0-3 positive carriers out of sixty, and for S. enterica, it is 0-1 positive carriers out of sixty . For spray products and towelettes, the product should kill the test microorganisms on 59 out of each set of 60 carriers/slides . Three batches of the product at the LCL are required, with 60 carriers tested against either organism for the Use-Dilution method and the same for the spray test .
3.1.2. General or Broad-Spectrum Disinfectants:
To claim general or broad-spectrum efficacy, the product must demonstrate effectiveness against both Staphylococcus aureus (ATCC 6538) and Salmonella enterica (ATCC 10708) . The same test methods are used as for limited spectrum disinfectants: AOAC Use-Dilution Method or Germicidal Spray Test (including modifications for towelettes) . The performance standards are also the same for each organism as in the limited spectrum category . Testing involves three batches at the LCL, with 60 carriers tested against each organism .
3.1.3. Hospital or Healthcare Disinfectants:
Hospital or healthcare disinfectants under EPA guidelines must be effective against Staphylococcus aureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 15442) . The recommended test methods remain the AOAC Use-Dilution Method or Germicidal Spray Test (and towelette modifications) . The performance standards for the Use-Dilution method are 0-3 positive carriers out of 60 for S. aureus and 0-6 positive carriers out of 60 for P. aeruginosa . For spray products and towelettes, the requirement is 59/60 negative carriers for each organism . Again, three batches at the LCL are tested, with 60 carriers per organism .
3.1.4. Disinfectants for Internal Toilet and Urinal Bowl Surfaces:
For disinfectants specifically intended for internal toilet and urinal bowl surfaces, the EPA recommends a modified AOAC Use-Dilution Method that includes a 5% organic soil challenge added to the bacterial inoculum . The test organisms depend on the primary disinfectant claim (limited, broad, or hospital), and the performance measures are the same as those specified for the corresponding primary claim . Sixty carriers must be tested against each of three batches of the product at the LCL .
3.1.5. Additional Microorganisms:
The EPA also has specific requirements for claiming efficacy against additional microorganisms . For bacteria other than the primary test organisms, the AOAC Use-Dilution Method is used with 10 carriers per batch and two batches tested at the nominal concentration. The performance standard is 10/10 negative carriers . For fungicidal claims, the AOAC Fungicidal Activity of Disinfectants test requires all fungal spores (Trichophyton mentagrophytes) to be killed at 10 and 15 minutes (no positive carriers). Modifications of the Use-Dilution Method, Germicidal Spray Test, and towelette tests also require 10/10 negative carriers . For virucidal claims, the product must demonstrate complete inactivation of the virus at all dilutions tested, or a ≥ 3-log10 reduction if cytotoxicity is present . For tuberculocidal claims, the AOAC Tuberculocidal Activity of Disinfectants test requires no positive carriers, while the Quantitative Tuberculocidal Activity Test (primarily for glutaraldehyde-based products) requires a ≥ 4 log10 reduction of Mycobacterium bovis .
3.1.6. Specific Considerations for Different Product Types:
The EPA provides specific guidance for different disinfectant product types . Spray products, including aerosols, trigger sprays, and pump dispensers, are typically evaluated using the AOAC Germicidal Spray Products as Disinfectants Test (AOAC 961.02) . For towelette products, a modified AOAC 961.02 or ASTM E2362 is recommended . The guidelines emphasize specific procedures for handling and using towelettes during testing, such as using sterile gloves and ensuring an unused area of the towelette is used for each wipe . Under certain conditions, bridging data from an existing EPA-registered bulk liquid formulation to a disinfectant towelette product is permitted, but this is not allowed for tuberculocidal claims .
3.2. Sanitizer Efficacy Testing (Based on OCSPP 810.2300):
While the primary focus here is on disinfectants, it is important to briefly note the EPA’s guidelines for sanitizers, which are covered in OCSPP 810.2300 . Sanitizers are defined as substances that reduce the bacteria population in the inanimate environment by significant numbers but do not necessarily eliminate all bacteria . The EPA distinguishes between sanitizers for food contact and non-food contact surfaces . For non-food contact surfaces, the recommended test method is ASTM E1153, which requires a 99.9% reduction within 5 minutes against Staphylococcus aureus and Klebsiella pneumoniae . For food contact surfaces, a higher reduction of 99.999% is required within 30 seconds . For toilet and urinal bowl surface sanitizers, ASTM E1153 is also used, requiring a >99.9% reduction within 5 minutes . Testing for sanitizers on porous surfaces may involve the use of unglazed ceramic tile .
3.3. Interim Guidance for Porous Surface Disinfectant Claims:
Recognizing that standard EPA registration primarily covers hard, non-porous surfaces, the agency has issued interim guidance to support the addition of disinfectant efficacy claims for porous materials in non-residential settings . This guidance outlines specific testing and application procedures for registering such products. For bactericidal claims on porous materials, products must first meet all efficacy requirements for hard, non-porous surface disinfectant claims . Testing should be conducted against Staphylococcus aureus and Pseudomonas aeruginosa using the EPA’s proposed “Interim Quantitative Method” on three representative porous materials: vinyl seating fabric, privacy curtain fabric, and non-PVC fabric . The performance standard requires a minimum mean 4.0-log reduction in ≤ 10 minutes on all three materials . For virucidal claims on porous surfaces, products must have already met the porous surface bactericidal claims . Testing uses the same “Interim Quantitative Method” against all claimed viruses, with a performance standard of a minimum mean 3.0-log reduction in ≤ 10 minutes on the same porous surfaces . A wetness test is also required to ensure the product remains wet for the entire contact time . Consultation with the EPA is recommended for testing on additional porous materials or for application methods beyond liquids, sprays, and foams .
3.4. Draft Guidance for Pre-Saturated/Impregnated Antimicrobial Towelettes for Disinfection Claims:
The EPA has also released draft guidance specifically for evaluating the efficacy of pre-saturated/impregnated antimicrobial towelettes for disinfection claims against bacteria on hard, non-porous surfaces . This draft guidance introduces a new standardized test method, ASTM E3363, which is designed specifically for antimicrobial towelettes and assesses both the chemical inactivation of microbes and their mechanical removal from a surface . The agency believes this guidance will streamline the registration process for towelette products . It is important to note that this document is a draft and is not yet binding .
4. Comparative Analysis of EPA and Health Canada Guidelines
Both the EPA and Health Canada employ a similar categorization system for hard surface disinfectants, recognizing limited spectrum, general/broad-spectrum, and hospital/healthcare claims. This suggests a common understanding of the spectrum of antimicrobial activity required for different applications. Both agencies also heavily rely on the standardized methods developed by AOAC International, particularly the Use-Dilution Method (various versions) and the Germicidal Spray Products Test (AOAC 961.02), indicating an international consensus on the validity and reliability of these test methods for evaluating disinfectant efficacy.
The primary test organisms required for each claim type are also largely consistent between the two agencies. Salmonella enterica and Staphylococcus aureus are key indicators for limited and broad-spectrum efficacy, while Pseudomonas aeruginosa is essential for hospital/healthcare disinfectant claims, reflecting the importance of these bacteria in public health and infection control.
However, there are notable differences in the specific passing criteria for some tests. For instance, in the AOAC Use-Dilution Method, Health Canada generally requires a higher number of negative carriers to pass compared to the EPA’s allowance of a certain number of positive carriers. This difference in performance standards could have implications for product formulation and testing strategies for manufacturers seeking registration in both regions.
Furthermore, each agency has unique requirements or specific considerations. The EPA has developed interim guidance for disinfectants intended for porous surfaces, addressing a growing need in healthcare and institutional settings. The EPA has also issued draft guidance on a new standardized test method (ASTM E3363) specifically for antimicrobial towelettes, acknowledging the increasing prevalence of this product format. Health Canada, on the other hand, has specific requirements for New Chemical Lot (NCL) batches when making claims against additional non-spore forming bacteria, demonstrating a focus on ensuring efficacy for expanded label claims.
The following table provides a concise comparison of the key efficacy tests and criteria for different disinfectant claim types under both EPA and Health Canada guidelines:
| Disinfectant Claim Type | Agency | Test Method(s) | Key Test Organisms | Primary Passing Criteria |
|---|---|---|---|---|
| Limited Spectrum | Health Canada | AOAC 955.14 or 955.15 (Use-Dilution), AOAC 961.02 (Spray), Modified AOAC/ASTM (Towelette) | Salmonella enterica or Staphylococcus aureus | Use-Dilution: ≥ 59/60 (Salmonella) or ≥ 57/60 (Staph) negative carriers; Spray/Towelette: ≥ 59/60 negative carriers |
| EPA | AOAC Use-Dilution, AOAC 961.02 (modified for towelettes or ASTM E2362) | Salmonella enterica or Staphylococcus aureus | Use-Dilution: ≤ 1 (Salmonella) or ≤ 3 (Staph) positive carriers; Spray/Towelette: ≥ 59/60 negative carriers | |
| General (Broad-Spectrum) | Health Canada | AOAC 955.14, 955.15, 964.02 (Use-Dilution), AOAC 961.02 (Spray), Modified AOAC/ASTM (Towelette) | Staphylococcus aureus and (Salmonella enterica or Pseudomonas aeruginosa) | Use-Dilution: Meet criteria for each organism; Spray/Towelette: ≥ 59/60 negative carriers for each organism |
| EPA | AOAC Use-Dilution, AOAC 961.02 (modified for towelettes or ASTM E2362) | Staphylococcus aureus and Salmonella enterica | Use-Dilution: Meet criteria for each organism; Spray/Towelette: ≥ 59/60 negative carriers for each organism | |
| Hospital/Healthcare | Health Canada | AOAC 964.02 and 955.15 (Use-Dilution), AOAC 961.02 (Spray), Modified AOAC/ASTM (Towelette) | Pseudomonas aeruginosa and Staphylococcus aureus | Use-Dilution: ≥ 54/60 (Pseudomonas) and ≥ 57/60 (Staph) negative carriers; Spray/Towelette: ≥ 59/60 negative carriers for each organism |
| EPA | AOAC Use-Dilution, AOAC 961.02 (modified for towelettes or ASTM E2362) | Pseudomonas aeruginosa and Staphylococcus aureus | Use-Dilution: ≤ 6 (Pseudomonas) and ≤ 3 (Staph) positive carriers; Spray/Towelette: ≥ 59/60 negative carriers for each organism | |
| Porous Surfaces (Bactericidal) | EPA | Interim Quantitative Method | Staphylococcus aureus and Pseudomonas aeruginosa | ≥ 4.0-log reduction in ≤ 10 minutes on three representative porous materials |
| Porous Surfaces (Virucidal) | EPA | Interim Quantitative Method | All claimed viruses | ≥ 3.0-log reduction in ≤ 10 minutes on the same porous materials |
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5. Conclusion
Understanding and adhering to the efficacy testing guidelines set forth by both the EPA and Health Canada is paramount for manufacturers of hard surface disinfectants. While both agencies share a common framework in terms of disinfectant categorization and reliance on AOAC methods, there are important distinctions in specific test parameters, passing criteria, and additional requirements for certain product types or claims. These differences underscore the need for manufacturers to carefully consider their target markets and ensure their products undergo the appropriate testing to meet the regulatory standards of each region. CREM Co Labs possesses the expertise and capabilities to conduct the full spectrum of efficacy tests required by both the EPA and Health Canada. We invite potential clients to contact us to discuss their specific disinfectant testing needs and how our services can support their regulatory compliance objectives.