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General Description

  • Synonyms: Difluorochloromethane; Fluorocarbon-22; Freon® 22; Genetron® 22; Monochlorodifluoromethane; Refrigerant 22
  • OSHA IMIS Code Number: 0628
  • Chemical Abstracts Service (CAS) Registry Number: 75-45-6
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: PA6390000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1018 126
  • NIOSH Pocket Guide to Chemical Hazards, Chlorodifluoromethane: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 1000 ppm, 3540 mg/m3 TWA; Appendix A4 - Not Classifiable as a Human Carcinogen
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 1000 ppm, 3500 mg/m3 TWA, 1250 ppm, 4375 mg/m3 STEL

Health Factors

  • Carcinogenic Classification:
  • Potential Symptoms: Irritation of respiratory system; dysesthesia of the tongue, sore throat; nausea, headache, confusion, drowsiness, dizziness; muscular weakness, numbness of legs; tinnitus (ringing in ears), blurred vision; heart palpitations, cardiac arrhythmias; asphyxia; unconsciousness; liver, kidney, spleen injury; frostbite (from liquid)
  • Health Effects: Asphyxiant (HE17); Narcosis (HE8); Acute toxicity requiring hospitalization (HE4)
  • Affected Organs: Respiratory system, cardiovascular system, CNS, liver, kidneys, spleen
  • Notes:
    1. OSHA does not have a PEL for chlorodifluoromethane.
    2. EPA's inhalation reference concentration (daily inhalational exposure likely to be without an appreciable risk of deleterious effects during a lifetime) for chlorodifluoromethane is 50 mg/m3.
    3. Chlorodifluoromethane in the body is not metabolized to a detectable extent, but is largely and rapidly excreted by exhalation.
    4. Human volunteers breathing 327 or 1833 mg/m3 achieved mean peak blood levels of 0.25 and 1.36 µg/ml, respectively, at equilibrium. Two fatal cases reportedly had blood levels of 31.5 and 44.9 µg/ml.
    5. High heat (e.g., from welding) can cause chlorodifluoromethane to decompose into toxic gases, such as phosgene, hydrogen chloride, chlorine, and hydrogen fluoride.
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: Chlorodifluoromethane.
    • International Chemical Safety Cards (WHO/IPCS/ILO): Chlorodifluoromethane.
    • U.S. EPA Integrated Risk Information System: Chlorodifluoromethane (CASRN 75-45-6).
    • Kintz, P., Baccino, E., Tracqui, A. and Mangin, P.: Headspace GC/MS testing for chlorodifluoromethane in two fatal cases. Forensic Sci. Int. 82(2): 171-175, 1996.
    • Kubota, T. and Miyata, A.: Acute inhalational exposure to chlorodifluoromethane (Freon-22): a report of 43 cases. Clin. Toxicol. (Phila.) 43(4): 305-308, 2005.
    • Nieuwenhuizen, M.S. and Groeneveld, F.R.: Formation of phosgene during welding activities in an atmosphere containing chlorinated hydrocarbons. AIHAJ 61(4): 539-543, 2000.
    • Pohanish, R.P. (editor): Chlorodifluoromethane. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 565-567.
    • Woollen, B. H., et al.: Human inhalation pharmacokinetics of chlorodifluoromethane (HCFC22). Int. Arch. Occup. Environ. Health 64(5): 383-387, 1992.
  • Date Last Revised: 05/11/2006

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Carbosieve S-III (130/65 mg sections)
  • maximum volume: 1 Liter
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • analytical solvent: Carbon Disulfide
  • method reference: OSHA Salt Lake Technical Center In-House File
  • method classification: Partially Validated

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