title: Optimizing acidified bleach solutions to improve sporicidal efficacy on building materials.
abstract: OBJECTIVE
  We evaluated whether lowering pH (with acetic acid) and raising free available chlorine (FAC) levels in bleach solutions would improve efficacy in inactivating Bacillus spores on different materials. We also determined how varying pH and FAC levels affected bleach stability.
  
  
  RESULTS
  Acidified bleach solutions with pH levels of 4.5, 6 and 7.5 and FAC levels between 5000 and 10,000 ppm were evaluated for decontamination efficacy against Bacillus subtilis spores inoculated onto test coupons made from wood, ceramic and galvanized steel. Lowering the pH or increasing the FAC level improved efficacy in some of the tests, but depended on the material, which significantly affected decontamination efficacy. The acidified bleach at pH of 7.5 was significantly less effective than bleach at a pH of 4.5 or 6. The FAC levels in the bleach were the most stable at pH 4.5, and stability at pH 4.5 was not significantly affected by the initial FAC level.
  
  
  CONCLUSIONS
  It may be advisable to use bleach solutions with lower pH (rather than high FAC levels) in light of both the decontamination efficacy and bleach stability results. For wood materials, use of sporicides other than acidified bleach may be warranted.
  
  
  CONCLUSIONS
  These results may be useful in preparing acidified bleach solutions for decontamination of materials contaminated with spores such as Bacillus anthracis.
authors: United States Environmental Protection Agency, National Homeland Security Research Center, Research Triangle Park, NC 27711, USA. wood.joe@epa.gov
authors: J P
authors: JP
authors: Wood
authors: M W
authors: MW
authors: Calfee
authors: M
authors: M
authors: Clayton
authors: N
authors: N
authors: Griffin-Gatchalian
authors: A
authors: A
authors: Touati
mesh_terms: D001408:Bacillus anthracis / Q000187:drug effects; D001412:Bacillus subtilis / Q000187:drug effects* / Q000502:physiology; D003252:Construction Materials / Q000382:microbiology*; D004202:Disinfectants / Q000494:pharmacology*; D006997:Hypochlorous Acid / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects*
chemical_list: D004202:Disinfectants; D006997:Hypochlorous Acid