Dichloromonofluoromethane

CAS number: 75–43–4

NIOSH REL: 10 ppm (40 mg/m³) TWA

Current OSHA PEL: 1,000 ppm (4,200 mg/m³) TWA

1989 OSHA PEL: 10 ppm (40 mg/m³) TWA

1993-1994 ACGIH TLV: 10 ppm (42 mg/m³) TWA

Description of Substance: Colorless gas with a slight, ether-like odor.

LEL:. . Nonflammable Gas

Original (SCP) IDLH: 50,000 ppm

Basis for original (SCP) IDLH: ACGIH [1971] reported that 52,000 ppm produced incoordination, irregular breathing, and tremors in guinea pigs [Underwriters' Laboratory 1935]. Scheel (member of the Standards Completion Program Respirator Committee), in evaluating the work of Aviado and Belej [1974], indicated cardiac toxicity at 100,000 ppm. Based on the above data, an IDLH of 50,000 ppm has been chosen.

Existing short-term exposure guidelines: National Research Council [NRC 1984] Emergency Exposure Guidance Levels (EEGLs):

1-hour EEGL: 100 ppm

24-hour EEGL: 3 ppm

ACUTE TOXICITY DATA

Lethal concentration data:

Species	Reference	LC50	LCLo	Time	Adjusted 0.5-hr LC (CF)	Derived value
Mouse Rat G. pig Mouse	Kozbakova 1976 Tappan and Waritz 1964 von Weigand 1971 von Weigand 1971	>800,000 mg/m3 49,900 ppm ----- -----	----- ----- 100,000 ppm 100,000 ppm	2 hr 4 hr <1 hr <1 hr	>373,832 ppm (2.0) 99,800 ppm (2.0) <125,000 ppm (1.25) <125,000 ppm (1.25)	>37,383 ppm 9,980 ppm <12,500 ppm <12,500 ppm

Other animal data: In 5-minute cardiac sensitization screening tests, 2 of 12 unanesthetized dogs exposed to 10,000 ppm of dichloromonofluoromethane plus intravenous epinephrine showed evidence of serious arrhythmia; no response was noted at 5,000 ppm [Mullin 1975].

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 5,000 ppm Basis for revised IDLH: The revised IDLH for dichloromonofluoromethane is 5,000 ppm based on acute inhalation toxicity data in animals [Mullin 1975; Tappan and Waritz 1964; von Weigand 1971]. This may be a conservative value due to the lack of relevant acute toxicity data for workers.

REFERENCES:

1. ACGIH [1971]. Dichloromonofluoromethane. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 81-82.

2. Aviado DM, Belej MA [1974]. Toxicity of aerosol propellants on the respiratory and circulatory systems. I. Cardiac arrythmia in the mouse. Toxicology 2:31-42.

3. Kozbakova AE [1976]. Comparative toxicity of chlorinated and fluorinated methane and ethane derivatives. Gig Tr Prof Zabol 20(11):38-41 (in Russian).

4. Mullin LS [1975]. Unpublished data. Newark, DE: Haskell Laboratory, E.I. DuPont de Nemours and Company, November 1975. [From ACGIH [1991]. Dichlorofluoromethane. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 434-435.]

5. NRC [1984]. Emergency and continuous exposure limits for selected airborne contaminants. Vol. 2. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 41-45.

6. Tappan CH, Waritz RS [1964]. Unpublished data: acute inhalation toxicity of Freon-21^® (fluorodichloromethane). Report No. 128-64. Newark, DE: E.I. DuPont de Nemours and Company, Haskell Laboratory for Toxicology and Industrial Medicine, November 1964.

7. Underwriters' Laboratory [1935]. The comparative life, fire, and explosion hazards of dichloromonofluoromethane (F21). Miscellaneous Hazard Report No. 2630. [From ACGIH [1971]. Dichloromonofluoromethane. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 81-82.]

8. von Weigand W [1971]. Investigations on the inhalation toxicity of fluorine derivatives of methane, ethane, and cyclobutane. Zentralbl Arbeitsmed Arbeitsschutz 21:149-156 (in German).