Interpreting the Laboratorial and Field Efficacy Evaluation of Disinfectants in China: GBT 38502 and GBT 38504

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Interpreting the Laboratorial and Field Efficacy Evaluation of Disinfectants in China: GB/T 38502 and GB/T 38504The latest overhaul of China’s disinfection product regulation goes back as far as 2002, when all related technical matters were simultaneously compiled into the "Technical Standard for Disinfection (version 2002)". The 200-page document offered great value to authorities and testing institutes in assessing product quality, safety, and efficacy, the precondition for entering China's market. After years of regulatory reform, the premarketing surveillance of non-new disinfection products has been delegated to the health department at the provincial level, and regulatory studies can be conducted either by enterprises or third-party testing institutes (CMA-accredited). To improve compliance, help enterprises and testing facility comply and align with international practices, some of the product specifications, testing methods, and technical practice were revised, supplemented, and released in the form of national/industrial standards. Early this year, the Chinese Standardization Administration (SAC) announced seven disinfectant-related standards to be implemented on October 1. Two of these standards related to efficacy evaluation in the most common scenarios. This article explains the enforceability, product scope, and other elements affecting product qualification, etc. to keep overseas enterprises up-to-date with best practices.

  • GB/T 38502-2020 Test Method of Bactericidal Effect of Disinfectant in laboratory
  • GB/T 38504-2020 Evaluation Method of Disinfection Effect of Spray Disinfection

PREMARKETING ASSESSMENT AND RECORDING FILING OF DISINFECTION PRODUCTS

Currently, enterprises of Class I and Class II disinfection products need to complete a comprehensive evaluation on the product label, manual, test data, product standard/enterprise standard, hygienic license (homemade product)/documentary evidence & customs declaration (imported product), product formula(disinfectants, anti-microbial agents and sterilization indicators) or component diagram (disinfecting instruments), etc. After performing a series of physic-chemical, harmful/microbial contaminant, stability, bactericidal effect, field trial, toxicity, performance tests, the enterprise should compile the test reports, product information, supporting documents and conclusion in a designated format referred to as the "Report on the Hygiene and Safety Evaluation of Disinfection Product" and summited it to the provincial health authorities (upload online). The health authorities may take a formal examination on the dossier, but producers (homemade product) or Chinese responsible agents (imported product) shall be liable for the authenticity of the test reports and information, as well as the consequences arising from follow-up surveillance or quality disputes.

In 2018, NHC sorted out the tests required for the initial filing, renewal, and amendment, as well as the type, sequential order, and layout of other documents required for the evaluation and promulgate the technical requirements in a hygienic industry standard, the "WS 628-2018 Technical Requirements for the Hygiene and Safety Evaluation of Disinfectant Products".

The test report can be issued from an in-house or third-party lab accredited by CMA (or 2 non-CMA labs) as long as the tests are conducted per the “Technical Standard for Disinfection (version 2002)” or subsequently promulgated standards. As these testing method/evaluation guidelines can also serve as the reference basis for enforcement activities and quality arbitration, they have considerable enforceability if they are published in the form of recommended ones (containing a capital letter T in the code name).

The test reported can be issued from an in-house or third-party lab accredited by CMA (or 2 non-CMA labs) as long as the tests are conducted per the “Technical Standard for Disinfection (version 2002)” or subsequently promulgated standards. As these testing method/evaluation guidelines can also serve as the reference basis for enforcement activities and quality arbitration, they have considerable enforceability if they are published in the form of recommended ones (containing a capital letter T in the code name).

The performance of a disinfectant can be strongly affected by multiple factors such as target object, target organism, application method, duration(of disinfection treatment), the concentration of an active ingredient, pH value, temperature, presence of an interfering substance, etc. It would be beneficial for enterprises to understand the scope, condition, process, criteria, and other technical details and to make correct labels, manuals, and sales promotion.

LABORATORIAL BACTERICIDAL EFFECT AND SPRAY DISINFECTION EVALUATION

The bactericidal efficacy is usually measured by eight typical microbes, representing common bacteria, pathogenic bacteria, fungi, viruses, and spore, and their occurrence increasingly differs from treated sites and objects. WS 628 classifies these sites and objects into 19 types and the Class I and Class II disinfectants targeting specific site or object need to be tested with corresponding microbe(s) designated in bellow table:

Target Objects and Microbes Designated for the Laboratorial Efficacy Tests of Class I and Class II Disinfectants (WS 628-2018)

 

 

Target Object (use purpose)

Staphylococcus aureus

Escherichia coli

Pseudomonas

aeruginosa

Candida albicans

Aspergillus niger

Mycodacterium chelonei

Poliovirus

Spore of Bacillus subtilis var. Niger

Class I

1.Medical instruments and supplies (sterilization)

 

 

 

 

 

 

 

2.Medical instruments and supplies (high-level disinfection)

 

 

 

 

 

 

 

3.Medical instruments and supplies (endoscope disinfection)

CR

CR

CR

CR

 

CR

CR

CR

4.Skin

 

 

 

 

 

5.Mucosa

 

 

 

 

 

Class II

6.Medical instruments and supplies (medium-level disinfection)

 

 

7.Medical instruments and supplies (low-level disinfection)

 

 

 

 

8.Surgical hand

 

 

 

 

 

9.Hygienic hand

 

 

 

 

 

10.Portable water

 

 

 

 

 

 

 

11.Swimming pool water

 

 

 

 

 

 

 

12.Hospital sewage

 

 

 

 

 

 

 

13.Surface of hard objects

CR

CR

CR

 

 

 

14.Fabric and surface of porous objects

 

CR

CR

 

 

 

15.Tableware

 

 

 

 

 

 

16.Food processing tools and equipment

 

 

 

 

 

 

 

17.Fruits and vegetables

 

 

 

 

 

 

 

18.Indoor air

 

 

 

 

 

 

 

 

19.Contaminants (excrement, secretion, blood and other contaminants)

 

 

 

 

 

 

 

√: required;

CR: conditionally required

Aside from the “compulsory microbes” listed above, the “optional microbes” would be additionally tested depending in specific scenarios, product label and function claims:

  • If an endoscope disinfectant was labeled for high-level disinfection, spore germicidal test would be additionally required, or else the disinfectant needs to be tested with other six microbes excluding Aspergillus niger;
  • A hard surface disinfectant was labeled targeting common bacteria in a hospital, Pseudomonas aeruginosa test will be required;
  • A surface-use disinfectant labeled for sanitary ware treatment will be additionally required for Candida albicans test;
  • A surface-use disinfectant claimed to be effective against fungus will be required for Aspergillus niger test;
  • If a disinfectant was labeled to be effective against a specific "optional" or other microbes, the efficacy should be additionally validated with the specific or representative microbe. For example, if a disinfectant claims that it can remove novel coronavirus 2019(a lipophilic virus with the highest sensitivity to biocides), it should be tested with poliovirus, a hydrophilic virus more resistant than novel coronavirus 2019, but the only representative microbe of all viruses.

Products formulated with the most frequently used active ingredients may have waived test scope, which includes glutaraldehyde, ethanol, sodium hypochlorite, chlorinated lime and calcium hypochlorite.

Target Objects and Microbes Designated for the Laboratorial Efficacy Tests of Glutaraldhyde, Ethanol and Hypochlorite Disinfectants

 

 

Target Object (use purpose)

Escherichia coli

Staphylococcus aureus

Candida albicans

Poliovirus

Mycodacterium chelonei

Spore of Bacillus subtilis var. Niger

Other microbe labeled

Class I

Glutaraldhyde

Medical instruments and supplies (sterilization)

 

 

 

 

 

 

Medical instruments and supplies (high-level disinfection)

 

 

 

 

 

 

Endoscope

 

 

 

 

 

 

Ethanol

Skin

 

 

 

 

 

Class II

Medical instruments and supplies (medium-level disinfection)

 

 

 

 

 

 

Object surface and medical instruments (low-level disinfection)

 

 

 

 

 

 

Surgical hand

 

 

 

 

 

 

Hygienic hand

 

 

 

 

 

 

Hypochlorite

Hygienic hand

 

 

 

 

 

 

 

Swimming pool water

 

 

 

 

 

 

 

Hospital sewage

 

 

 

 

 

 

 

Surface of hard objects

 

choose either of the two

 

 

 

CR

Fabric and surface of porous objects

 

 

 

 

 

CR

Tableware

 

 

 

 

 

 

Food processing tools and equipment

 

 

 

 

 

 

 

Fruits and vegetables

 

 

 

 

 

 

 

Contaminants

 

 

 

 

 

 

 

After the assessment at a laboratory scale, a disinfection product will be further assessed at a realistic condition with field trial (or simulated one), required for almost all types of disinfectants.

GB/T 38502-2020 details the procedures and criteria for the most idealistic scenarios: moderate-size or concrete object treated with a direct-contact pattern such as mixing, painting, and immersion, etc., the procedures and criteria for the laboratory and field trial on spray-applied disinfectants (disinfectors using spray method) targeting surface or air are separately specified in GB/T 38504-2020. To help readers better distinguish the applicability of these two standards, we summarized the product types (treated object and application method), stage and their necessity in the table below:

Methodology, Necessity and Stages of Efficacy Evaluation of Disinfectant/Disinfector in China

Target objectLaboratorySimulatedField   
Medical instruments and supplies (sterilization)     
Medical instruments and supplies (high-level disinfection)     
Medical instruments and supplies (endoscope disinfection)     
Skin choose either of the two   
Mucosa choose either of the two   
Medical instruments and supplies (medium-level disinfection)     
Medical instruments and supplies (low-level disinfection)     
Surgical hand choose either of the two   
Hygienic hand choose either of the two   
Portable water choose either of the two   
Swimming pool water choose either of the two   
Hospital sewage     
Fabric and surface of porous object     
Tableware     
Fruits and vegetables choose either of the two   
Contaminants      
Surface of hard object choose either of the two   
Food processing tools and equipment choose either of the two   
Air     
Tested following GB/T 38502-2020 with the designated microbes specified in WS 628   
Tested under other methodology   
If the disinfectant/disinfector was spray-applied, the laboratorial test, simulated field trial and field trial should be tested under GB/T 38504-2020, if not, the test and trials should be tested with other methodology.   

CRITICAL DETERMINANTS FOR PRODUCT PERFORMANCE EVALUATION

During laboratory test, a disinfectant will be repeatedly tested with the lowest effective concentration (indicated on product label) at three different times and each repetition consists of 3 groups with different durations: 0.5 times, 1.0 times and 1.5 times of the onset time (indicated on product label). If it is for routine surveillance purposes, 1 duration time with the lowest effective concentration will suffice. GB/T 38502-2020 offers 3 procedures for different forms of products and a correct test system shall be selected correctly:

  • Suspension quantitative method - the default procedure for most products;
  • Carrier quantitative method (immersion treatment) - paste, gel and viscous product, rinse-off product or ready-to-use formulation;
  • Carrier qualitative method (sterilization treatment) - mainly for Class I disinfectants (5 repetitions, at least 30 samples, 0.5 times of the onset time with the lowest concentration level).

The test system would be added with a designated level of organic interfering substance, depending on the cleanliness of the target object to simulate real-life conditions.

At the test endpoint (terminal of the duration planned), a neutralization identification test will be involved to validate the removal of the residual bacterial effect of the disinfectant, either by introduction with neutralizing substance or filtration-rinse process.

The identification should be performed respectively in line with the microbe tested:

  • For the efficacy test using general commensal bacteria, the system can be validated with the alternative of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa
  • For disinfectant tested with spore, Candida albicans, Mycobacterium chelonei, and Aspergillus niger, the system should be validated with the corresponding microbe respectively;
  • If another microbe was used, the system should be validated with the microbe.

A disinfectant shall qualify the neutralization identification test and satisfy the following criteria:

Test System

Targeting/Tested Microbe and Logarithmic Value of the Microbe Population Reduced

Suspension quantitative method

General vegetative bacteria or spore: no less than 5.00;

Candida albicans, Mycodacterium chelonei and Aspergillus niger: no less than 4.00

Carrier quantitative method

All kinds of microbes tested: no less than 3.00

Carrier qualitative method (sterilization)

No reproduction detected

In addition to the effective concentration and duration assessed above, product performance would be affected by temperature, pH value and the presence of organic interfering substances. GB/T 38502-2020 also specific the design, procedure and criteria for the rating of the impacts.

The spray-applied surface disinfectants are tested following similar considerations: the lowest effective concentration, three duration times, and three repetitions, as well as neutralization validation, and the carrier spray quantitative method is the only procedure used. The agent materials, equipment, and procedures for the simulated trial and field trial for these categories of disinfectants.

The laboratory(simulated) evaluation of air spray disinfection is performed at air cabinet, and Staphylococcus Albus is designated as the only test microbe (indicative microbe), while during the field trial, Beta-haemolytic streptococcus shall not be detected. The criteria for the different stage are summarized as follows:

Criteria for the Efficacy Evaluation of Spray Disinfection

Stage

Target Object

Indicative Microbe and Logarithmic Value of the Population Reduced

Laboratorial test

Surface

  • Staphylococcus aureus: no less than 3.00;
  • Escherichia coli: no less than 3.00;
  • Pseudomonas aemginosa: no less than 3.00;
  • If additional target microbe was indicated on product label, the microbe should be tested and the logarithmic value shall not be less than 3.00

Air

  • Staphylococcus albus: no less than 3.00;
  • If additional target microbe was indicated on product label, the microbe should be tested and the logarithmic value shall not be less than 3.00

Simulated field trial

Surface

  • Staphylococcus aureus or Pseudomonas aemginosa: no less than 3.00;
  • (use the most resistant microbe detected during the laboratorial test)

Field trial

Surface

  • Natural bacteria: no less than 1.00;
  • Target microbe shall not be detected;

Air

  • Natural bacteria: no less than 1.00;
  • Beta-haemolytic streptococcus shall not be detected

CLOSING

As a special category of health-related products, disinfectant function claims need to be supported with test data to substantiate:

  • The target object and microbe indicated on product labels vs. the time and cost of testing;
  • The onset time guaranteed vs. the information on user’s instruction;
  • The differences in the procedures, agents, and apparatuses used and operative skills between overseas lab and CMA-accredit lab;

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