ISO 846 Plastics - Evaluation of the Impact of Microorganisms

The ISO 846 standard published by the International Standards Organization (ISO) defines test methods for determining the deterioration of plastics by the influence of fungi and bacteria and soil microorganisms. However, the purpose of these test methods is not to determine the biodegradability of plastics or the degradation of natural fiber composites.

In the ISO 846 standard, the type and degree of deterioration are determined as follows:

• Visual inspection
• Changes in mass
• Changes in other physical properties

The test methods described are applicable to all plastic products that have a flat surface and can thus be easily cleaned. Only porous materials such as plastic foams are an exception.

The test methods defined in this standard are:

• Method A: Fungal growth test
• Method B: Determination of the fungistatic effect
• Method C: Procedure with bacteria
• Method D: Soil burying test

This standard uses the same test corks as the IEC 60068-2-10 standard published by the International Electrotechnical Commission (IEC) (Environmental tests - Part 2-10: Tests - Test J and guidance: Mold growth). The IEC method, using so-called pooled samples, involves inoculating the samples with a spore suspension, incubating the inoculated samples, and evaluating fungal growth as well as any physical attack on the samples.

In the test methods described in the ISO 846 standard, the test volume and the test strains used depend on the intended application for the plastic.

Under certain climatic and environmental conditions, microorganisms can settle and colonize the surface of plastic products. This not only damages the plastic itself, but also affects the serviceability of building materials and systems containing plastic parts.

The effects of microorganisms on plastics are affected by two different processes:

• Direct effect: Degradation of plastics that act as a nutritive agent for the growth of microorganisms.
• Indirect effect: The effect of metabolic products of microorganisms, eg discoloration or further deterioration.

This standard addresses both processes and their combined action.

Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer testing services for evaluating the effects of microorganisms on plastics under the ISO 846 standard, utilizing a trained and expert staff and advanced technological equipment.