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ISO 846 Test

Evaluation of the action of microorganisms on plastics
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Quick understanding about test

ISO 846: 1997 โ€“ Evaluation of the action of microorganisms on plastics

Purpose

This test evaluates the action of microorganisms on plastics under defined environmental conditions.

Application

Applicable to a wide range of plastic products that are used in construction, medical, and agricultural industries.

Mandatory test strains

  • Aspergillus niger (ATCC 6275)
  • Penicillium funiculosum
  • Paecilomyces variotii (ATCC 18502)
  • Trichoderma virens (ATCC 9645) and more.

View Additional Available Test Strains

Methodology

  • Method A: Fungal-growth test
  • Method B: Determination of fungistatic effects
  • Method C: Resistance to bacteria
  • Method D: Resistance to microbially active soil (soil-burial test)

Benefits

  • Help manufacturers in optimizing plastic formulations.
  • Ensures compliance with industry standards .
Turnaround Time
It typically takes 28 days .

Results

Results are evaluated by observing and measuring the effects of microbial activity on plastic samples.

Passing criteria

The passing criteria typically require no significant changes in physical properties, weight, or appearance of the plastic material after microbial exposure.

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Know more about the test

Abstract

ISO 846 specifies test conditions and requirements for the measurement of the resistance of plastics to microbial attack, specifically fungi, bacteria, and other soil microorganisms. Plastics are generally highly durable. However, they are not completely immune to avoid microbial degradation.  Therefore, evaluating their resistance to microbial attack is crucial to ensure their durability.

It’s important to note that this standard does not test the biodegradability of plastics. The standard specifically tests the resistivity of plastics to microbial attack.

Importance of ISO 846 Test

The ISO 846 test is essential for assessing the long-term performance of plastics in environments susceptible to microbial growth. By closely reconstructing practical usage scenarios, the test provides critical insights into the microbial resistance of plastic materials. This is important in industries where the degradation of plastics may lead to impaired safety, functionality and product service life. Through visual assessments and measurements of physical properties, the test ensures that plastic products meet the required standards for durability and performance in microbial-rich environments.

Industries where ISO 846 test is relevant

ISO 846 tests can be applied to different industrial products that are used in high humidity and soil-rich environments. ISO 846 testing is applicable across a wide range of industries where plastics are exposed to moisture, soil, or humid environments. This includes sectors like construction, healthcare, agriculture, consumer goods, and electronics. The test helps manufacturers ensure their plastic materials can withstand microbial attack, maintain performance, and meet hygiene or durability standards in real-world conditions.

Test organisms

At MIS, the ISO 846 test is generally performed using the following strains:

  • Bacteria: Pseudomonas aeruginosa (ATCC 15442)

  • Fungi: Aspergillus niger (ATCC 6275), Penicillium funiculosum, Paecilomyces variotii (ATCC 18502), Trichoderma virens (ATCC 9645) and Chaetomium globosum (ATCC 6205)

ISO 846 test methods

Method A: Fungal-growth test

In this method, plastic test specimens treated with antimicrobial treatments are exposed to a mixed suspension of fungal spores with insufficient nutritive medium (no carbon source) under conditions of โ‰ฅ95% relative humidity. The fungi grow only if the plastic acts as a nutrient source. Suppose the material does not contain nutritive components; the fungal mycelium does not develop, preventing plastic degradation. The test is applicable for comparing the inherent resistance of plastics to attack by fungi in the absence of other organic materials.

Method B: Determination of fungistatic effects

Method B involves exposing treated plastic specimens to fungal spores on a complete nutrient medium, providing a carbon source for the fungi. Even when the plastic does not contain nutritive elements, fungi can grow on the surface because of the nutrient medium, possibly attacking the material through their metabolic products. The test determines whether the plastic possesses any fungistatic or fungicidal properties by comparing growth between biocide-treated and nontreated specimens.

Method C: Resistance to bacteria

This test assesses the plastic materials’ resistance to bacteria in an incomplete medium without a carbon source. If no bacterial growth occurs in the agar around the specimen, the plastic lacks nutritive components.

Method D: Resistance to microbially active soil (soil-burial test)

This test method evaluates plastics which are in contact with soil for long-term periods, such as those used in outdoor applications. Test specimens are buried in microbially active soil of known water-holding capacity and moisture content. The aim is to determine the resistance of the plastic material to microbial attack during an extended period of exposure to high humidity and soil microbiota.

At Microbe Investigations Switzerland (MIS), we offer comprehensive antimicrobial testing services for products claiming microbial protection, including textiles, disinfectants and coatings. Our advanced microbiology testing facility enables precise evaluation of antimicrobial efficacy, ensuring compliance with international standards.

In addition to ISO 846 microbial testing for plastics, MIS performs other testing methods such as ISO 22196, JIS Z 2801, ASTM G21 and ISO 21702 to check the antimicrobial efficacy of treated plastic materials.

For more information on ISO 846 testing or to explore our antimicrobial plastic testing services, contact us today.

Frequently Asked Questions

DR. Martinoz Scholtz

MIS Labs
What is the ISO 846 test?
ISO 846 is an international standard that provides test methods for determining the resistance activity of plastics to microbial attacks.
What are the products that can be tested with the test?
Non-porous plastic materials such as roofing membranes, storage containers, vinyl siding, medical devices and ceramics can be tested using this standard.
What is the turnaround time for the test?
It takes approximately 28 days to complete the test, depending on the test organisms.
On how many (bacteria/fungi) can your ISO 846 testing lab perform tests?

At Microbe Investigations, we perform the test using Pseudomonas aeruginosa (ATCC 15442) and Aspergillus niger (ATCC 16888). Other strains can also be added as per the customerโ€™s request.

Why is the test important?
The test helps in determining the resistance of plastics to microbial degradation when they are exposed to fungi, bacteria and microorganisms present in soil. It also helps maintain product durability and achieve compliance with regulatory standards.
What are the different parts of the ISO 846 standard?
The standard consists of four methods: Method A for testing fungal resistance; Method B for assessing fungistatic effect; Method C for testing bacterial resistance; and Method D, a soil-burial test.
What is the significance of a high resistance rating in this test?
A high resistance rating would suggest that the material possesses great durability to microbial growth, promoting longer product life and ensuring that regulatory requirements are adequately met.
How does temperature affect the test results?
Temperature affects the growth rate of microorganisms and also the rate of degradation of plastics. Therefore, it is necessary to conduct the tests at specified temperatures for consistent and reliable results.

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