Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 10102–43–9
NIOSH REL: 25 ppm (30 mg/m3) TWA
Current OSHA PEL: 25 ppm (30 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 25 ppm (31 mg/m3) TWA
Description of substance: Colorless gas.
LEL: . . . Nonflammable Gas
Original (SCP) IDLH: 100 ppm
Basis for original (SCP) IDLH: No useful data on acute inhalation toxicity are available on which to base the IDLH for nitric oxide. The chosen IDLH, therefore, is based on the statement by Sax  that 100 to 150 ppm oxides of nitrogen are dangerous for short exposures of 30 to 60 minutes. The chosen IDLH seems reasonable because NIOSH  cited a rabbit 15-minute LC50 of 315 ppm for nitric oxide [Carson et al. 1962].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Species||Reference||LC50 (ppm)||LCLo (ppm)||Time||Adjusted 0.5-hr|
|Carson et al. 1962|
Flury and Zernik 1931
Ivanov and Szubaev 1979
|249 ppm (0.79)|
1,850 ppm (0.74)
1,709 ppm (2.0)
|25 ppm |
Other animal data: Guinea pigs have survived an exposure at 175 ppm for an unstated period [Bodansky 1951].
Human data: It has been stated that exposures to oxides
of nitrogen between 100 and 150 ppm are dangerous for exposures
of 30 to 60 minutes [Sax 1975].
|Revised IDLH: 100 ppm [Unchanged]
Basis for revised IDLH: Based on acute inhalation toxicity data in humans [Sax 1975], the original IDLH for nitric oxide (100 ppm) is not being revised at this time.
1. Bodansky O . Methemoglobinemia and methemoglobin-producing compounds. Pharmacol Rev 3:144-195.
2. Carson TR, Rosenholtz MS, Wilinski FT, Weeks MH . The responses of animals inhaling nitrogen dioxide for single, short-term exposures. Am Ind Hyg Assoc J 23:457-462.
3. Flury F, Zernik F . Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, pp. 157-165 (in German).
4. Ivanov NG, Szubaev EN . About the limitation of the content of nitrogen dioxide in the air of the working zone. Toksikol Nov Prom Khim Vesh 15:53-58 (in Russian).
5. NIOSH . QX05250. Nitrogen monoxide. In: Registry of toxic effects of chemical substances, 1976 ed. 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. 76-191, p. 780.
6. Pflesser G . The significance of nitric oxide in poisoning by nitrous gases. Arch Exp Pathol Pharmakol 179:545-557 (in German).
7. Sax NI . Nitric oxide. In: Dangerous properties of industrial
materials. 4th ed. New York, NY: Van Nostrand Reinhold Company,
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