Alternative disinfection

Cleanroom disinfection is a routine process in many pharmaceutical, biotech and cosmetic industries. Procedures for regularly wiping surfaces are often complemented by periodic aerosol-based disinfections. The chemicals used are always the result of a compromise between the broad spectrum biocidal action on micro-organisms, efficiency, potential corrosivity, residuals and toxicity issues. Formaldehyde-based chemicals are often used because of their broad-spectrum action and their sporicidal activity. The well-known reverse side of the coin is their toxicity, their corrosive nature and the time and special precautions needed to vent the rooms after disinfection. A normal procedure for cleanroom disinfection using formaldehyde can take two days or more. Minntech Corporation has manufactured biocides for many years for medical applications, particularly for devices with blood contact, as well as for the disinfection of ultrapure water systems in pharmaceutical plants and similar industries. Because of the stringent requirements of these applications, Minntech uses pharmaceutical-quality raw materials to produce its proprietary Hydrogen Peroxide/Peracetic Acid-based biocides. The high quality level of these raw materials results in minimised levels of residuals and trace heavy metals. Minncare, which is a highly effective bactericide, fungicide, mycobactericide, sporicide and virucide, is one such biocide. It can be used for surface disinfection (wiping process) and/or for aerosol-based clean room disinfection using the new Minncare Dry Fog system recently introduced to the European markets by Minntech International in the Netherlands. The system is not available in the USA.

Minncare Dry Fog system The autoclavable Minncare Dry Fog system produces a fog of ultrafine droplets of precisely 7.5 microns diameter. The droplets bounce off surfaces without wetting them (dry fog), and the vapour-phase Minncare disperses rapidly and effectively throughout the room. It is fully biodegradable and is less corrosive than aldehyde-based liquids, as has been shown in independent materials testing. The total process time using this combination is extremely short: between two and five hours for cleanrooms up to 1000m3 including venting time. Numerous pharmaceutical companies that have been looking for an alternative solution to the use of formaldehyde or other toxic chemicals have tested the performance of Minncare Dry Fog in their plants in various countries, including France, Switzerland, Germany, India and China. Below is just one simple example of a pharmaceutical company that had previously tested its existing disinfection procedure (using formaldehyde) and achieved only a 3 log reduction in bacterial spores. Using the same evaluation protocol and the same microbiological indicators they then tested the Minncare Dry Fog system. Although this test was performed in a relatively small cleanroom, other examples exist for effective disinfection of volumes up to 1000m3 (even divided in multiple rooms) using a single Minncare Dry Fog system.

Example: Test conditions: Cleanroom: Class C in a pharmaceutical production facility Volume: 69m3 Configuration: see Fig.1. Various metallic trolleys, electrical spare elements and other equipment were placed inside the room Configuration of the Minncare Dry Fog system: only one nozzle used. See Fig.1 for positioning within the room Diffused solution: 103ml of Minncare diluted in 1036ml of purified water Diffusion time: 29 minutes Contact time: 60 minutes Venting time: 20 minutes Total procedure time: 109 minutes (1 hour 49 min) including venting Control of the diffusion: Three humidity sensors were placed within the room in order to control the good dispersion of the diluted Minncare (see the humidity curves and the RH sensor positioning in the drawing) Control of the disinfection efficacy: 6-log spore strips (B. subtilis ATCC 9372 - Icare 6-log spores on stainless steel supports and B. stearothermophilus ATCC 7953 - Icare 6-log spores on stainless steel supports) were placed in critical locations (see room diagram). These were recovered after the disinfection procedure for testing and quantification in an independent test laboratory Residual chemical controls: After the disinfection process, the levels of residual HP and Acetic Acid were easily measured in the air using the Renatest Vapour Detection system of calibrated detection tubes.

Results After a 1 hour 49 minute disinfection procedure time, including venting: Microbiology: less than 1 residual spore on each biological indicator thus achieving a 6LRV at each locatio. Condensation: No traces of condensation were observed on any surfaces Corrosion: No traces of corrosion were observed anywhere, including on all the accessories placed within the room Residuals: No traces of deposits were found on the surfaces. The measured HP residual in air: <0.1 ppm and Acetic Acid residual in air: <5 ppm The Minncare Dry Fog system proved to be a very effective and safe system for aerosol-based disinfection of cleanrooms. Adapted to volumes up to 1000m3, it can effectively replace existing formaldehyde-based systems, providing substantial savings in time and cost, as well as a reduction in risk from toxic chemicals.