Carbon monoxide

IDLH Documentation

CAS number: 630­08­0

NIOSH REL: 35 ppm (40 mg/m³) TWA, 200 ppm (229 mg/m³) CEILING

Current OSHA PEL: 50 ppm (55 mg/m³) TWA

1989 OSHA PEL: 35 ppm (40 mg/m³) TWA, 200 ppm (229 mg/m³) CEILING

1993­1994 ACGIH TLV: 25 ppm (29 mg/m³) TWA

Description of Substance: Colorless, odorless gas.

LEL: . . 12.5% (10% LEL, 12,500 ppm)

Original (SCP) IDLH: 1,500 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that a 1­hour exposure to 1,000 to 1,200 ppm would cause unpleasant, but no dangerous symptoms [Henderson et al. 1921]. Patty [1963] also reported that 1,500 to 2,000 ppm might be a dangerous concentration for an exposure of 1 hour [Henderson et al. 1921].

Existing short­term exposure guidelines: National Research Council [NRC 1987] Emergency Exposure Guidance Levels (EEGLs):

10­minute EEGL: 1,500 ppm

30­minute EEGL: 800 ppm

60­minute EEGL: 400 ppm

24­hour EEGL: 50 ppm

ACUTE TOXICITY DATA

Lethal concentration data:

Other animal data: The median effective concentrations to produce incapacitation (EC₅₀s) in rats have been determined to be 2,667 ppm and 1,450 ppm in 15 and 30 minutes, respectively [Hartzell et al. 1985].

Other human data: It has been stated that a 1­hour exposure to 1,000 to 1,200 ppm would cause unpleasant but no dangerous symptoms, but that 1,500 to 2,000 ppm might be a dangerous concentration after 1 hour [Henderson et al. 1921a, 1921b]. In general, a carboxyhemoglobin (COHb) level of 10­20% will only cause slight headaches [NIOSH 1972] and a COHb of 11­13% will have no effect on hand and foot reaction time, hand steadiness, or coordination [Stewart and Peterson 1970]. At a COHb of 35%, manual dexterity is impaired [Stewart 1975]. At 40% COHb, mental confusion, added to increasing incoordination, precludes driving an automobile [Stewart 1975]. A 30­minute exposure to 1,200 ppm will produce a COHb of 10­13% [NIOSH 1972].

REFERENCES:

1. Hartzell GE, Priest DN, Switzer WG [1985]. Modeling of toxicological effects of fire gases. II. Mathematical modeling of intoxication of rats by combined carbon monoxide and hydrogen cyanide. J Fire Sci 3:115­128.

2. Henderson Y, Haggard HW, Teague MC, Prince AL, Wunderlich RM [1921]. Physiological effects of automobile exhaust gas and standards of ventilation for brief exposures. J Ind Hyg III(3):79­92.

3. Henderson Y, Haggard HW, Teague MC, Prince AL, Wunderlich RM [1921]. Physiological effects of automobile exhaust gas and standards of ventilation for brief exposures. IV. Concordance of the standard here proposed with the observations of other investigators. J Ind Hyg III(4):137­146.

4. Lefaux R [1968]. Practical toxicology of plastics. Cleveland, OH: Chemical Rubber Co.

5. NIOSH [1972]. NIOSH criteria for a recommended standard: occupational exposure to carbon monoxide. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. HSM 73­11000.

6. NRC [1987]. Emergency and continuous exposure guidance levels for selected airborne contaminants. Vol. 7. Ammonia, hydrogen chloride, lithium bromide, and toluene. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 17­38.

7. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 930.

8. Rose CS, Jones RA, Jenkins LJ Jr, Siegel J [1970]. The acute hyperbaric toxicity of carbon monoxide. Toxicol Appl Pharmacol 17:752­760.

9. Stewart RL [1975]. The effect of carbon monoxide on humans. Am Rev Pharmacol 15:409­423.

10. Stewart RL, Peterson MR [1970]. Experimental human exposure to carbon monoxide. Arch Environ Health 12:154­164.

11. Tab Biol Per [1933]; 3:231 (in German).
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