title: Risk assessment methodologies for carcinogenic compounds in indoor air.
abstract: OBJECTIVE
  The purpose of this study was to compare different methods for calculating maximal allowable concentrations of potentially carcinogenic substances in indoor air. Benzene, tetrachloroethylene, trichloroethylene, and vinyl chloride were selected as the model substances.
  
  
  METHODS
  Estimates were used of carcinogenic potency from quantitative risk assessment, lowest observable effect levels (LOEL) from animal experiments and epidemiologic studies combined with safety factors, and estimation from occupational exposure limits with safety factors. The estimates were compared with actual concentrations in buildings in Denmark.
  
  
  RESULTS
  Concentrations of benzene, tetrachloroethylene, trichloroethylene, and vinyl chloride of the order of 10, 20, 200, and 40 ppb, respectively, in indoor air were found to correspond to a 10(-4) lifetime risk of cancer.
  
  
  CONCLUSIONS
  The estimated maximal allowable concentrations of carcinogenic compounds obtained from indoor air by quantitative risk assessment using a lifetime risk of 10(-4) or using LOEL values and suitable safety factors appear to be comparable and reasonable. Calculations based on occupational exposure limits and safety factors generally give comparable or somewhat higher values. Using a lifetime risk of 10(-6) for quantitative risk assessment does not seem reasonable considering the risks associated with the activities of everyday life.
authors.affiliation: National Institute of Occupational Health, Copenhagen, Denmark.
authors.forename: B A
authors.initials: BA
authors.lastname: Nexø
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D000818:Animals; D002273:Carcinogens / Q000032:analysis*; D003718:Denmark; D006801:Humans; D008452:Maximum Allowable Concentration; D016273:Occupational Exposure / Q000032:analysis; D012307:Risk Factors
chemical_list: D002273:Carcinogens