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Dichlorodifluoromethane. OSHA Guideline.
Occupational Safety & Health Administration, U.S. Department of Labor
http://www.osha-slc.gov/SLTC/healthguidelines/dichlorodifluoromethane/recognition.html
(Downloaded Nov 6, 2001)
OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR
DICHLORODIFLUOROMETHANE
INTRODUCTION
This guideline summarizes pertinent information about dichlorodifluoromethane for workers and employers as well as for physicians, industrial hygienists, and other occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new information is available.
SUBSTANCE IDENTIFICATION
* Formula
CCl(2)F(2)
* Structure
(For Structure, see paper copy)
* Synonyms
Refrigerant 12, freon 12, propellant 12, halon 122, difluorodichloromethane, FC 12, freon F-12.
* Identifiers
1. CAS No.: 75-71-8
2. RTECS No.: PA8200000
3. DOT UN: 1028 12
4. DOT label: Nonflammable gas
* Appearance and odor
CHEMICAL AND PHYSICAL PROPERTIES
* Physical data
1. Molecular weight: 120.9
2. Boiling point (at 760 mm Hg): -29.8 degrees C (-21.6 degrees F)
3. Specific gravity (water = 1): 1.49 (at boiling point)
4. Vapor density: 4.2
5. Melting/Freezing point: -157.7 degrees C (-252 degrees F)
6. Vapor pressure at 20 degrees C (68 degrees F): 4332 mm Hg
7. Solubility: Nearly insoluble in water; soluble in most organic solvents.
8. Evaporation rate: Data not available.
* Reactivity
1. Conditions contributing to instability: Heat.
2. Incompatibilities: Contact between dichlorodifluoromethane and chemically active metals such as sodium, potassium, calcium, powdered aluminum, zinc, and magnesium should be avoided.
3. Hazardous decomposition products: Toxic gases and vapors such as hydrogen chloride, phosgene, and hydrogen fluoride may be released in a fire involving dichlorodifluoromethane.
4. Special precautions: None reported.
* Flammability
1. Flash point: Not applicable.
2. Autoignition temperature: Not applicable.
3. Flammable limits in air: Not applicable.
4. Extinguishant: Use an extinguishant that is suitable for the materials involved in the surrounding fire.
EXPOSURE LIMITS
* OSHA PEL
* NIOSH REL
* ACGIH TLV
* Rationale for Limits
* Routes of Exposure Exposure to dichlorodifluoromethane can occur through inhalation and eye or skin contact [Sittig 1991].
* Summary of toxicology
1. Effects on Animals: Dichlorodifluoromethane is a narcotic at high concentrations and an asphyxiant at very high concentrations in experimental animals. The LC(50) in rats, rabbits, and guinea pigs for a 30-minute exposure is 800,000 ppm. Exposure to 600,000 ppm dichlorodifluoromethane for 2 hours caused death in rats but not in guinea pigs [ACGIH 1991; Sax and Lewis 1989]. Mice exposed to 10,000 ppm for 24 hours survived but sustained lung tissue alterations. In dogs, monkeys, and guinea pigs exposed to 200,000 ppm for 40 hours per week for 10 to 12 weeks, generalized tremor and other signs of narcosis were noted. Microscopic liver injury was noted in guinea pigs exposed to 810 ppm continuously for 90 days, although no such injury was observed among rats, rabbits, dogs, and monkeys similarly exposed. Cardiac arrhythmias were observed in 5 to 12 dogs exposed both the 50,000 ppm dichlorodifluoromethane and exogenous epinephrine. Constriction of the airways has been noted in animals exposed to 50,000 to 100,000 ppm [ACGIH 1991]. The effects of direct eye contact with liquefied dichlorodifluoromethane under pressure are usually minimal, unless the eyelids are prevented from shutting, in which case temporary freezing of the eye surface may occur. Damage from this type of severe exposure resolved within 3 days [Grant 1986].
2. Effects on Humans: In high concentrations, dichlorodifluoromethane can cause narcosis, unconsciousness, cardiac arrhythmias, cardiac arrest, and asphyxiation, either as a result of dichlorodifluoromethane's narcotic effects or as a consequence of its displacement of oxygen in the atmosphere. Many nonoccupational deaths have been reported from the sniffing of fluorochlorinated hydrocarbon aerosols, including dichlorodifluoromethane; the mechanism of action in these cases is believed to be cardiac arrhythmias caused by sensitization of the myocardium to epinephrine [Hathaway et al. 1991]. Studies in volunteers showed that inhalation of 10,000 ppm of dichlorodifluoromethane for 2.5 hours caused a 7 percent reduction in standardized psychomotor scores; however, at 1,000 ppm for 8 hours/day, 5 days/week, for a total of 17 repetitive exposures, no abnormal responses occurred [Clayton and Clayton 1982]. Exposure to 40,000 ppm for 8 minutes caused generalized sensory losses, ringing in the ears, apprehension, and slurred speech; at 110,000 ppm for 11 minutes, there were cardiac arrhythmias, amnesia, and a marked decrease in consciousness [Hathaway et al. 1991]. An individual exposed to 150,000 ppm experienced loss of consciousness [Parmeggiani 1983]. Individuals with cardiac or respiratory disorders may prove especially susceptible to dichlorodifluoromethane [NLM 1995]. Contact with the liquid can cause frostbite because of the rapid evaporation of this chemical [Sittig 1991].
* Signs and symptoms of exposure
1. Acute exposure: The most common symptoms of exposure to dichlorodifluoromethane are those associated with narcosis, which include dizziness, drowsiness, trembling, irregular heartbeat, unconsciousness, and, if the concentration is extremely high, death through asphyxiation. If liquefied dichlorodifluoromethane contacts the eyes or skin, pain, redness, and then whiteness of the affected tissue may occur if the contact was sufficiently severe to cause frostbite. Blistering may occur after tissue is thawed [Hathaway 1991].
2. Chronic exposure: No signs or symptoms of chronic exposure to dichlorodifluoromethane have been reported in humans.
* Emergency medical procedures: [NIOSH to supply]
5. Rescue: Remove an incapacitated worker from further exposure and implement appropriate emergency procedures (e.g., those listed on the Material Safety Data Sheet required by OSHA's Hazard Communication Standard [29 CFR 1910.1200]). All workers should be familiar with emergency procedures, the location and proper use of emergency equipment, and methods of protecting themselves during rescue operations.
EXPOSURE SOURCES AND CONTROL METHODS
The following operations may involve dichlorodifluoromethane and lead to worker exposures to this substance:
* Formerly used as aerosol propellants for cosmetics, pharmaceuticals, insecticides, paints, adhesives, and cleaners (almost all fluorochloro-carbon-propelled aerosol uses were banned by EPA in 1978); used as a refrigerant in home and commercial air conditioners; used as a rocket propellant; used to prepare frozen tissue sections
* Used as a blowing agent for cellular polymers; used as a low-temperature solvent or diluent in fumigants for food sterilization, and as a solvent or degreaser in paints and varnish removers and in polymerization processes
* Used as a foaming agent in fire extinguishing aerosols; used in immersion quick freezing of food products; used to chill cocktail glasses
* Used in water purification; copper and aluminum purification, petroleum recovery, and in manufacture of glass bottles
* Used in regulating devices for leak detection; used in thermal expansion valves; used as insulators and generator windings in manufacture of materials for electrical applications
* Used in organic synthesis of freons and resins; used as a working fluid for heat pumps and in hydraulic fluids
Methods that are effective in controlling worker exposures to dichlorodifluoromethane, depending on the feasibility of implementation, are as follows:
Workers responding to a release or potential release of a hazardous substance must be protected as required by paragraph (q) of OSHA's Hazardous Waste Operations and Emergency Response Standard [29 CFR 1910.120].
Good sources of information about control methods are as follows:
1. ACGIH [1992]. Industrial ventilation--a manual of recommended practice. 21st ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
2. Burton DJ [1986]. Industrial ventilation--a self study companion. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
3. Alden JL, Kane JM [1982]. Design of industrial ventilation systems. New York, NY: Industrial Press, Inc.
4. Wadden RA, Scheff PA [1987]. Engineering design for control of workplace hazards. New York, NY: McGraw-Hill.
5. Plog BA [1988]. Fundamentals of industrial hygiene. Chicago, IL: National Safety Council.
OSHA is currently developing requirements for medical surveillance. When these requirements are promulgated, readers should refer to them for additional information and to determine whether employers whose employees are exposed to dichlorodifluoromethane are required to implement medical surveillance procedures.
* Medical Screening
* Preplacement medical evaluation
* Periodic medical evaluations
* Termination medical evaluations
* Biological monitoring
WORKPLACE MONITORING AND MEASUREMENT
Determination of a worker's exposure to airborne dichlorodifluoromethane is made using two charcoal tubes in series (first tube 400/200 mg second tube 100/50 mg sections, both 20/40 mesh). Samples are collected at a maximum flow rate of 0.05 liter/minute until a maximum collection volume of 4 liters is reached. The sample is then treated with methylene chloride. Analysis is conducted by gas chromatography using a flame ionization detector (GC/FID). This method is described in the OSHA Computerized Information System [OSHA 1994] and in NIOSH Method No. 1018 and is fully validated [NIOSH 1994b].
If liquified dichlorodifluoromethane contacts the skin, workers should flush the affected areas immediately with plenty of tepid water.
Clothing contaminated with dichlorodifluoromethane should be removed immediately and should not be reworn until the dichlorodifluoromethane has evaporated from the clothing.
A worker who handles dichlorodifluoromethane should thoroughly wash hands, forearms, and face with soap and water before eating, using tobacco products, using toilet facilities, applying cosmetics, or taking medication.
Workers should not eat, drink, use tobacco products, apply cosmetics, or take medication in areas where dichlorodifluoromethane is handled, processed, or stored.
Dichlorodifluoromethane should be stored in a cool, dry, well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard [29 CFR 1910.1200]. Containers of dichlorodifluoromethane should be protected from physical damage and ignition sources, and should be stored separately from chemically active metals such as sodium, potassium, calcium, powdered aluminum, zinc, and magnesium should be avoided.
In the event of a spill or leak involving dichlorodifluoromethane, persons not wearing protective equipment and clothing should be restricted from contaminated areas until cleanup has been completed. The following steps should be undertaken following a spill or leak:
1. Notify safety personnel.
2. Remove all sources of heat and ignition.
3. Ventilate area of leak to disperse the gas.
4. If possible without risk, stop leak. Do not release leaking cylinder gas to the atmosphere because of CF-12's role in ozone depletion.
5. If leak cannot be repaired, empty into a combustion chamber with a combustible fuel and burn. Insure complete combustion to prevent phosgene formation.
6. Refer to local/state air pollution control authority before incineration.
SPECIAL REQUIREMENTS
U.S. Environmental Protection Agency (EPA) requirements for emergency planning, reportable quantities of hazardous releases, community right-to-know, and hazardous waste management may change over time. Users are therefore advised to determine periodically whether new information is available.
* Emergency planning requirements
* Reportable quantity requirements for hazardous releases
* Community right-to-know requirements
* Hazardous waste management requirements
* Conditions for respirator use
* Respiratory protection program
Workers should use appropriate personal protective clothing and equipment that must be carefully selected, used, and maintained to be effective in preventing skin contact with dichlorodifluoromethane. The selection of the appropriate personal protective equipment (PPE) (e.g., gloves, sleeves, encapsulating suits) should be based on the extent of the worker's potential exposure to dichlorodifluoromethane. The resistance of various materials to permeation by dichlorodifluoromethane is shown below:
Material | Resistance |
neoprene | good to excellent |
natural rubber | poor |
polyvinyl chloride | poor |
styrene-butadiene rubber | poor |
To evaluate the use of these PPE materials with dichlorodifluoromethane, users should consult the best available performance data and manufacturers' recommendations. Significant differences have been demonstrated in the chemical resistance of generically similar PPE materials (e.g., butyl) produced by different manufacturers. In addition, the chemical resistance of a mixture may be significantly different from that of any of its neat components.
Any chemical-resistant clothing that is used should be periodically evaluated to determine its effectiveness in preventing dermal contact. Safety showers and eye wash stations should be located close to operations that involve dichlorodifluoromethane.
Splash-proof chemical safety goggles or face shields (20 to 30 cm long, minimum) should be worn during any operation in which a solvent, caustic, or other toxic substance may be splashed into the eyes.
In addition to the possible need for wearing protective outer apparel (e.g., aprons, encapsulating suits), workers should wear work uniforms, coveralls, or similar full-body coverings that are laundered each day. Employers should provide lockers or other closed areas to store work and street clothing separately. Employers should collect work clothing at the end of each work shift and provide for its laundering. Laundry personnel should be informed about the potential hazards of handling contaminated clothing and instructed about measures to minimize their health risk.
Protective clothing should be kept free of oil and grease and should be inspected and maintained regularly to preserve its effectiveness.
Protective clothing may interfere with the body's heat dissipation, especially during hot weather or during work in hot or poorly ventilated work environments.
REFERENCES
ACGIH [1991]. Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
ACGIH [1994]. 1994-1995 Threshold limit values for chemical substances and physical agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
CFR. Code of Federal regulations. Washington, DC: U.S. Government Printing Office, Office of the Federal Register.
Clayton G, Clayton F [1981-1982]. Patty's industrial hygiene and toxicology. 3rd rev. ed. New York, NY: John Wiley & Sons.
DOT [1993]. 1993 Emergency response guidebook, guide 12. Washington, DC: U.S. Department of Transportation, Office of Hazardous Materials Transportation, Research and Special Programs Administration.
Genium [1992]. Material safety data sheet No. 308. Schenectady, NY: Genium Publishing Corporation.
Grant WM [1986]. Toxicology of the eye. 3rd ed. Springfield, IL: Charles C Thomas.
Hathaway GJ, Proctor NH, Hughes JP, and Fischman ML [1991]. Proctor and Hughes' chemical hazards of the workplace. 3rd ed. New York, NY: Van Nostrand Reinhold.
Lewis RJ, ed. [1993]. Hawley's condensed chemical dictionary. 12th ed. New York, NY: Van Nostrand Reinhold Company.
Mickelsen RL, Hall RC [1987]. A breakthrough time comparison of nitrile and neoprene glove materials produced by different glove manufacturers. Am Ind Hyg Assoc J 48(11): 941-947.
Mickelsen RL, Hall RC, Chern RT, Myers JR [1991]. Evaluation of a simple weight-loss method for determining the permeation of organic liquids through rubber films. Am Ind Hyg Assoc J 52(10): 445-447.
NIOSH [1987a]. NIOSH guide to industrial respiratory protection. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 87-116.
NIOSH [1987b]. NIOSH respirator decision logic. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 87-108.
NIOSH [1992]. Recommendations for occupational safety and health: Compendium of policy documents and statements. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 92-100.
NIOSH [1994a]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-116.
NIOSH [1994b]. NIOSH manual of analytical methods. 4th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.
NIOSH [1995]. Registry of toxic effects of chemical substances: Dichlorodifluoromethane. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, Division of Standards Development and Technology Transfer, Technical Information Branch.
NJDH [1992]. Hazardous substance fact sheet: Dichlorodifluoromethane. Trenton, NJ: New Jersey Department of Health.
NLM [1995]. Hazardous substances data bank: Dichlorodifluoromethane. Bethesda, MD: National Library of Medicine.
OSHA [1994]. Computerized information system. Washington, DC: U.S. Department of Labor, Occupational Safety and Health Administration.
Parmeggiani L [1983]. Encyclopedia of occupational health and safety. 3rd rev. ed. Geneva, Switzerland: International Labour Organisation.
Patnaik P [1992]. A comprehensive guide to the hazardous properties of chemical substances. New York, NY: Van Nostrand Reinhold.
Sax NI, Lewis RJ [1989]. Dangerous properties of industrial materials. 7th ed. New York, NY: Van Nostrand Reinhold Company.
Schwope AD, Costas PP, Jackson JO, Stull JO, Weitzman DJ [1987]. Guidelines for the selection of chemical protective clothing. 3rd ed. Cambridge, MA: Arthur D. Little Company. [Available from the American Conference of Governmental Industrial Hygienists, 6500 Glenway Avenue, Building 7, Cincinnati, OH 45211.]
Sittig M [1991]. Handbook of toxic and hazardous chemicals. 3rd ed. Park Ridge, NJ: Noyes Publications.
USC. United States code. Washington. DC: U.S. Government Printing Office.
Windholz M, ed. [1983]. Merck Index 10th ed. Rahway, NJ: Merck & Company.