Decontamination in clinical laboratories is a crucial process that involves removing or neutralizing contaminants such as bacteria, viruses, and other harmful substances to ensure a safe working environment for laboratory staff and accurate test results. This process typically involves cleaning, disinfecting, and sterilizing laboratory equipment, surfaces, and waste materials. So, decontamination is a process that makes medical devices, instruments, or environmental surfaces safe to handle. There are different levels of decontamination, ranging from high-level sterilization to simple cleaning with soap and water.
All infectious materials and contaminated equipment should be decontaminated before being washed, stored, or discarded. Each person working with biohazardous material should be responsible for its proper handling. The four main categories of physical and chemical means of decontamination are: heat, liquid disinfection, vapors and gases, and radiation.
Heat decontamination includes wet and dry heat. Wet heat, also known as autoclaving, is the most effective method and is suitable for sterilizing laboratory equipment and decontaminating biohazard wastes. Dry heat is less efficient and requires longer times and/or higher temperatures to achieve sterilization.
Liquid disinfectants are classified as halogens, acids, alkalis, heavy metal salts, quaternary ammonium compounds, phenolic compounds, aldehydes, ketones, alcohols, and amines. The effectiveness of liquid disinfectants varies with the organism, concentration, contact time, and other conditions of use. Always use chemical disinfectants in accordance with labeled instructions.
Vapors and gases, when used in closed systems and under controlled conditions of temperature and humidity, provide excellent disinfection. Radiation is also a method of decontamination.
Ionizing radiation is capable of destroying microorganisms but is not a practical tool for laboratory use. On the other hand, the UV-C band of ultraviolet radiation contains wavelengths (250-270 nm, with 265 nm being the optimum) that can effectively eliminate most microorganisms in air, water, and on surfaces. However, it's important to note that organisms must be directly exposed to the UV light as dirt, dust, and shadows can shield them, which can limit the effectiveness of the UV lamp.
UV radiation is typically used to reduce levels of airborne microorganisms and maintain good air hygiene in airlocks, animal holding areas, ventilated cabinets, and laboratory rooms. It's also used in biological safety cabinets (BSC) and some laboratory rooms to reduce surface contamination. However, EH&S Biosafety strongly discourages the use of UV lamps in BSCs.
It's crucial to take precautions when using UV lamps as they can cause burns to the eyes (photokeratitis) and skin of people exposed for even a short period of time. Therefore, it's recommended to activate UV lights only when the area is unoccupied and to use proper shielding when UV lamps are in use. It's also important to interlock UV lamps used for space decontamination with the general room or cabinet illumination, so turning on the lights turns off the UV. New and visiting personnel should be warned about the hazardous effects of UV radiation and the appropriate precautions to take.
Proper maintenance is critical for the effective use of UV lamps for decontamination purposes. It's important to clean UV lamp bulbs every other week by turning off the UV lamp and wiping off the surface of the room temperature lamp bulb with 70% alcohol or as per the manufacturer's instructions. Before replacing bulbs, the BSC should be cleared of equipment and material, and disinfected with 10% bleach and then cleaned with 70% ethanol. The bulb should be installed with gloved hands to prevent oil build-up, and the lamp bulbs should be disinfected before disposal as universal waste. Finally, it's recommended to check lamp efficiency monthly with a UV meter or monitoring strip.
Here are some links that provide more information about decontamination in clinical laboratories:
CDC Guidelines for Environmental Infection Control in Health-Care Facilities: https://www.cdc.gov/infectioncontrol/guidelines/environmental/index.html
WHO Guidelines on Decontamination and Reprocessing of Medical Devices for Health Care Facilities: https://www.who.int/publications/i/item/9789241549851
Clinical Laboratory Improvement Amendments (CLIA) Regulations on Decontamination: https://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA
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