44 Biosafety Manual chlorine compounds. This concentration of solution is made by diluting household bleach 1:10 with water. Shelf life for diluted bleach is approximately 24 hours, if kept in a clear container. ¤ Air and light inactivate diluted solutions, so solutions must be freshly made in order to maintain adequate available chlorine concentrations. These solutions should be stored in an airtight, opaque container out of the light. Shelf life is approximately seven days. Otherwise, make up a new solution every day. ¤ Strong oxidizers are very corrosive to metal surfaces, as well as to the skin, eyes and respiratory tract. • Formalin ¤ These disinfectants are effective against vegetative bacteria, spores, and viruses. ¤ Effective concentration is a 5-8% solution of formalin (formaldehyde in water; made by diluting a 37% solution). ¤ Formaldehyde is a suspected human carcinogen and can cause respiratory irritation at very low concentrations. Inhalation limits are 2 ppm for 15 minutes, 0.75 ppm for 8 hours of exposure. ¤ Formaldehyde has an irritating odor and is a sensitizer, so a potential exists for developing allergic reactions. • Glutaraldehyde mixtures (for example, Cidex, Sporicidin, and 3M Glutarex) ¤ Glutaraldehyde mixtures are effective against vegetative bacteria, spores, and viruses (more so than formaldehyde). ¤ Effective concentration is 2%. ¤ Chemically related to formaldehyde, vapors are irritating to the eyes, nasal passages and upper respiratory tract. • Iodophors – organically bound iodine compounds (for example, Wescodyne diluted 1:10 is a popular hand washing disinfectant) ¤ These are effective against vegetative bacteria and viruses, but not against bacterial spores. ¤ Effective concentration is 75-150 ppm. ¤ Iodophors are relatively nontoxic to humans, so they are often used as general disinfectants in antiseptics and surgical soaps. ¤ These disinfectants have built-in indicators: if the solution
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