Biological Indicator – Formaldehyde

How to use

Important factors for sterilisation using formaldehyde are gas concentration, relative air humidity and temperature. The sterilisation conditions may, for example, be 70 mg/l formalin, >90% relative humidity, and a temperature of 70°C. High relative humidity is crucial for killing microbes effectively. Due to the low sterilisation temperature, the process is intended for sterilisation of heat-sensitive instruments such as endoscopes with sensitive optics, single-use medical devices or implants. Formaldehyde has also been used to decontaminate cleanrooms and is used to a certain extent to decontaminate isolators and LAF benches, but, in this case, it can be difficult to maintain sufficiently high temperature and humidity.

The disadvantages of formaldehyde sterilisation are that it is difficult to measure and therefore to control the physical parameters and to achieve adequate humidification. Moreover, formaldehyde is a carcinogen that irritates the mucous membranes and can trigger allergies, and it is important to degas the products once sterilisation is complete. Because of the resulting uncertainty, SSI Diagnostica recommends that sterilisation testing using biological indicators be carried out for every single individual sterilisation cycle. Biological indicators are also used for validation/revalidation.