The purpose of decontamination is to protect the laboratory worker, the environment, and anyone who enters the laboratory, or handles laboratory products taken away from the lab. It also reduces the likelihood of cross-contamination in other laboratories. But with such strong chemicals and rigorous processes, some containment coatings can often be stripped away creating another source of contamination within the laboratory.
Decontamination generally renders an area, device, item, or material safe to handle. The primary objective being to reduce the level of microbial contamination so that infection transmission is eliminated. Depending on the level and type of contaminant, the decontamination process could be anything from ordinary soap and water to a full sterilisation procedure through steam cleaning (perhaps the most cost-effective way of decontaminating a device or item).
Decontamination in laboratory settings often requires longer exposure times because pathogenic microorganisms may be protected from contact with decontaminating agents due to their structure.
Chemical germicides used for decontamination range in activity from high–level disinfectants (i.e., high concentrations of sodium hypochlorite [chlorine bleach]), which might be used to decontaminate spills of cultured or concentrated infectious agents in research or clinical laboratories, to low-level disinfectants or sanitizers for general housekeeping purposes or spot decontamination of environmental surfaces in healthcare settings.
If dangerous and highly infectious agents are present in a laboratory, the methods for decontamination of spills, laboratory equipment, or infectious waste are very stringent and may include prolonged autoclave cycles, incineration of waste or gaseous treatment of surfaces using chlorine or Formaldehyde.
Decontamination of Large Spaces
Space decontamination is a specialised activity and should only be performed by specialists with proper training and protective equipment. The decontamination requirements for CAT-3 and CAT-4 laboratory spaces have major implications on the overall design of these facilities.
The interior surfaces of CAT-3 laboratories must be water resistant in order for them to be easily cleaned and decontaminated using gaseous fumigation. Penetrations in these surfaces should be sealed or capable of being sealed for decontamination purposes. Thus, in the CAT-3 laboratory, surface decontamination, not fumigation, is the primary means of decontaminating space. Care should be taken that penetrations in the walls, floors and ceilings are kept to a minimum and are “sight sealed.” Verification of the seals is usually not required for most CAT-3 laboratories.
The CAT-4 laboratory design requires interior surfaces that are water resistant AND sealed to facilitate fumigation. These seals must be tested and verified to ensure containment in order to permit both liquid disinfection and fumigation. Planned fumigation is required in a CAT-4 suite laboratory due to the risk of outbreaks, and to allow routine maintenance and certification of the space and equipment.
Procedures for decontamination of large spaces such as incubators or rooms are varied and influenced significantly by the type of pathogenic agent involved, the characteristics of the structure containing the space, and the materials present in the space. The primary methods for space decontamination follow.
Formaldehyde gas at a concentration of 0.3 grams/cubic foot for four hours is often used for space decontamination. Gaseous formaldehyde can be generated by heating formalin solution in specialised apparatus, thereby converting it to formaldehyde gas. The humidity must be controlled and the system works optimally at 80% relative humidity. This method is effective in killing microorganisms but toxicity issues are present.
Hydrogen Peroxide Vapor
Hydrogen peroxide can be vaporized and used for the decontamination of glove boxes as well as small room areas. Vapor phase hydrogen peroxide has been shown to be an effective sporicide at concentrations ranging from 0.5 mg/L to <10 mg/L. The optimal concentration of this agent is about 2.4 mg/L with a contact time of at least one hour. This system can be used to decontaminate glove boxes, walk in incubators and small rooms. An advantage of this system is that the end products (i.e., water) are not toxic. Low relative humidity can be used.
Chlorine Dioxide Gas
Chlorine dioxide gas sterilization can be used for decontamination of laboratory rooms, equipment, glove boxes, and incubators. The concentration of gas at the site of decontamination should be approximately 10 mg/L with contact time of one to two hours.
Chlorine dioxide possesses the bactericidal, virucidal and sporicidal properties of chlorine, but unlike chlorine, does not lead to the formation of trihalomethanes or combine with ammonia to form chlorinated organic products (chloramines).
Introducing the Wallglaze range
The use of such virulent cleaning chemicals requires the specification of resilient and easy to clean wall, floor and ceiling finishes that can withstand the intensive cleaning and decontamination processes.
CS Wallglaze Containment Coatings have been specifically designed for the internal walls and ceilings of hygiene and contaminant sensitive environments. The Wallglaze range offers various levels of chemical resistance, ranging from Wallsheen’s resistance to mild alkalines, right up to Armourglaze’s resistance to strong acids, formaldehyde, solvents and peroxides used in fumigation and radioactive decontamination.
Being an elastomeric system, the Wallglaze range can absorb impact without cracking or flaking. For increased abrasion and impact resistance, and to deal with differential laboratory air pressures and temperatures, fibreglass reinforcement options are also available across the Wallglaze product range.
The Wallglaze range also features non-leaching anti-microbial agents, which include bactericides and fungicides in every coat of the system. Third party tests have verified that Wallglaze offers a complete defence against most species of mould, bacteria and yeasts including MRSA, Salmonella, E-coli, and many others. Due to the non-leaching properties of these anti-microbial agents, Wallglaze’s ability to prevent microbial growth does not diminish with intensive cleaning.
Wallglaze remains fully active against micro-organisms in excess of 15 years and has been shown to last 10 years, with a straightforward re-coating being all that is required to fully restore protection after this long lifespan.
Information for this blog post has sourced from the CDC – Biosafety in Microbiological and Biomedical Laboratories (BMBL) 5th Edition:
U.S. Centers for Disease Control and Prevention, Biosafety in Microbiological and Biomedical Laboratories (BMBL) available athttp://www.cdc.gov/biosafety/publications/bmbl5/index.htm . Accessed: 15/04/2014