Sodium hydroxide

CAS number: 1310–73–2

NIOSH REL: 2 mg/m³ CEILING

Current OSHA PEL: 2 mg/m³ TWA

1989 OSHA PEL: 2 mg/m³ CEILING

1993-1994 ACGIH: 2 mg/m³ CEILING

Description of substance: Colorless to white, odorless solid (flakes, beads, granular form).

LEL :. . Noncombustible Solid

Original (SCP) IDLH: 250 mg/m³

Basis for original (SCP) IDLH: No data on acute inhalation toxicity are available on which to base the IDLH for sodium hydroxide. The chosen IDLH, therefore, has been estimated from the mouse intraperitoneal LD₅₀ of 40 mg/kg [Nofre et al. 1963 cited by NIOSH 1974].

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

10-minute EEGL: 2 mg/m³

30-minute EEGL: 2 mg/m³

60-minute EEGL: 2 mg/m³

ACUTE TOXICITY DATA:

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rabbit	Fazekas 1937	oral	-----	500	3,500 mg/m3	350 mg/m3
Mouse	Nofre et al. 1963	i.p.	40	-----	280 mg/m3	28 mg/m3

Human data: Workplace concentrations ranging from 2 to 8 mg/m³ have been associated with irritation of the respiratory system [Ott et al. 1977].

Revised IDLH: 10 mg/m3 Basis for revised IDLH: The revised IDLH for sodium hydroxide is 10 mg/m3 based on acute inhalation toxicity data in workers [Ott et al. 1977]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 8 mg/m3.

REFERENCES:

1. Fazekas JG [1937]. Die veränderungen des blutchemismus bei experimenteller laugenvergiftung. Arch Exp Pathol Pharmakol 184:587-604 (in German).

2. NIOSH [1974]. WB49000. Sodium hydroxide. In: The toxic substances list, 1974 ed. Rockville, MD: 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. 74-134, p. 721.

3. Nofre C, Dufour H, Cier A [1963]. Toxicite generale comparee des anions mineraux chez la souris. In: Comp Rend Hebdom (Juillet 17, 1963), pp. 791-794 (in French). [From NIOSH [1974]. WB49000. Sodium hydroxide. In: The toxic substances list, 1974 ed. Rockville, MD: 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. 74-134, p. 721.]

4. 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. 87-94.

5. Ott MG, Gordon HL, Schneider EJ [1977]. Mortality among employees chronically exposed to caustic dust. J Occup Med 17:813-816.