Safety cabinets in the genetic engineering facility – Class 2 safety cabinets

In the AGCT-Gentechnik.report 03/2023 of March 31, 2023 The functionality of the Class 1 Microbial Safety Cabinet (MSC) was presented. While experimenters are protected from exposure to potentially hazardous biological agents when using such cabinets, sterile work with biological material is not guaranteed due to the airflow introduced from the outside and directed directly into the work area.

The Class 2 MSW However, in addition to personal protection, it also ensures the possibility of sterile work. In genetic engineering or molecular biology S1 laboratories, this property is the main reason for the use of Class 2 MSW, as sterility is essential, especially when cultivating cell lines. While personal protection is secondary when working with biological substances that are not considered harmful to health (risk group 1 or safety level 1), the combination of personal protection and a sterile work area is essential even from safety level 2 onwards.

In Class 2 MSW, the experimental material is protected from contamination in two ways. Firstly – and in contrast to Class 1 MSW – the air flow directed into the work surface is first passed through a HEPA (high-efficiency particulate absorbing) filter, thus ensuring sterile performance.

Furthermore, the airflow within the workbench is directed from top to bottom and is low in turbulence. The airflow should be as laminar as possible; ideally, the airflow planes do not mix. This creates a situation in the work and experiment area where biological aerosols generated there are not easily transferred vertically—i.e., to neighboring experimental material—but are instead directed downwards and through a second HEPA filter to the outside.

Personal protection in Class 2 MSW is therefore achieved by this laminar "air curtain" directed from top to bottom. Therefore, in the interests of personal protection, it is particularly important with Class 2 MSW that the airflow in the workbench is disturbed, i.e., swirled, by as few objects as possible. Storing only the most necessary materials in the work area is therefore particularly important when working under Class 2 MSW. And, since generating the laminar airflow is also technically demanding, close technical testing should be implemented. The minimum requirements for testing MSW are set out in Section 8 Paragraph 6 of the BioStoffV. This states that the employer must regularly check the function of technical protective measures - such as the MSW - and their effectiveness at least every two years. There is no equivalent requirement in genetic engineering legislation.