Nitric oxide

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 [1975] 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 [1976] 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 LC (CF)	Derived value
Rabbit Mouse Rat Mouse	Carson et al. 1962 Flury and Zernik 1931 Ivanov and Szubaev 1979 Pflesser 1935	315 ----- 854 320	----- 2,500 ----- -----	15 min 12 min 4 hr ?	249 ppm (0.79) 1,850 ppm (0.74) 1,709 ppm (2.0) ?	25 ppm 185 ppm 171 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.

REFERENCES:

1. Bodansky O [1951]. Methemoglobinemia and methemoglobin-producing compounds. Pharmacol Rev 3:144-195.

2. Carson TR, Rosenholtz MS, Wilinski FT, Weeks MH [1962]. 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 [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, pp. 157-165 (in German).

4. Ivanov NG, Szubaev EN [1979]. 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 [1976]. 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 [1935]. The significance of nitric oxide in poisoning by nitrous gases. Arch Exp Pathol Pharmakol 179:545-557 (in German).

7. Sax NI [1975]. Nitric oxide. In: Dangerous properties of industrial materials. 4th ed. New York, NY: Van Nostrand Reinhold Company, pp. 961-962.