Biosafety Manual

43 Biosafety Manual ¤ Liquids for disposal • Does organic matter inactivate the disinfectant? (Proteins in organic matter can inactivate or slow down the activity of certain disinfectants, such as bleach.) • What is the shelf life of the disinfectant? • How hazardous is the disinfectant? Refer to the safety data sheet (SDS) and the product label for this information. ¤ Is the disinfectant an eye, skin or respiratory irritant? (If yes, proper PPE is required during use.) ¤ Is the disinfectant toxic (by skin absorption, ingestion or inhalation)? (If yes, proper PPE is required during use.) ¤ Is the disinfectant corrosive to equipment or work surfaces? ¤ Does the disinfectant leave a residue? Types of Chemical Disinfectants The following are outlines of the basic properties and examples of the most common categories of chemical disinfectants, including alcohols, chlorine compounds, liquid formaldehyde, glutaraldehyde, iodophors, peracetic acid, phenolic compounds and quaternary ammonium compounds. Adequate contact time is very important to ensure complete disinfection. Contact time varies with the type of material being disinfected. • Alcohols (for example, ethanol, isopropanol) ¤ These are most effective against lipophilic viruses, less effective against non-lipid viruses and ineffective against bacterial spores. ¤ Optimal disinfection is attained by using 70% ethanol for 15 minutes. ¤ These types of disinfectants evaporate quickly, so sufficient contact time may be difficult to achieve. Concentrations above 70% are less effective because of increased evaporation rate. • Chlorine compounds (for example, household bleach – 5.25% sodium hypochlorite) ¤ Chlorine compounds are effective against vegetative bacteria and most viruses in solutions of 50-500 ppm available chlorine. Bacterial spores require concentrations of 2,500 ppm with extended exposure time. Prions require 20,000 ppm with extended exposure time. ¤ A 5,000-ppm available chlorine solution is preferred for general use because excess organic materials inactivate