NIOSH logo and tagline

Sulfuric acid

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 7664–93–9

NIOSH REL: 1 mg/m3 TWA

Current OSHA PEL: 1 mg/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 1 mg/m3 TWA, 3 mg/m3 STEL

Description of substance: Colorless to dark-brown, oily, odorless liquid.

LEL: . . Noncombustible Liquid

Original (SCP) IDLH: 80 mg/m3

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by ACGIH [1971] that guinea pigs died after 2.75 hours of exposure at 87 mg/m3 [Treon et al. 1950].

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

10-minute EEGL: 5 mg/m3

30-minute EEGL: 2 mg/m3

60-minute EEGL: 1 mg/m3


Lethal concentration data:

Species Reference LC50 LCLo Time Adjusted 0.5-hrLC (CF) Derived value
G. pig Amdur et al. 1952a 50 mg/m3 —– 8 hr 125 mg/m3 (2.5) 13 mg/m3
Rat Izmerov et al. 1982 510 mg/m3 —– 2 hr 816 mg/m3 (1.6) 82 mg/m3
Mouse Izmerov et al. 1982 320 mg/m3 —– 2 hr 512 mg/m3 (1.6) 51 mg/m3
G. pig Raule 1954 18 mg/m3 —– ? ? ?
G. pig Treon et al. 1950 —– 87 mg/m3 2.75 hr 154 mg/m3 (1.77) 15 mg/m3

Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
Rat Smyth et al. 1969 oral 2,140 —– 14,980 mg/m3 1,498 mg/m3

Human data: In exposures of 5 to 15 minutes, some volunteers found 5 mg/m3 to be very objectionable, while others found it less so [Amdur et al. 1952b]. The lethal oral dose has been reported to be 135 mg/kg [Arena 1970]. [Note: An oral dose of 135 mg/kg is equivalent to a worker being exposed to about 6,300 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]


1. ACGIH [1971]. Sulfuric acid. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 239-240.

2. Amdur MO, Schulz RZ, Drinker P [1952a]. Toxicity of sulfuric acid mist to guinea pigs. AMA Arch Ind Hyg Occup Med 5:318-329.

3. Amdur MO, Silverman L, Drinker P [1952b]. Inhalation of sulfuric acid mist by human subjects. AMA Arch Ind Hyg Occup Med 6(4):305-313.

4. Arena JM [1970]. Poisoning, toxicology, symptoms, treatments. 2nd ed. Springfield, IL: C.C. Thomas, p. 73.

5. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 107.

6. NRC [1984]. Emergency and continuous exposure limits for selected airborne contaminants. Vol. 1. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 107-112.

7. Raule A [1954]. Occupational diseases caused by sulfuric acid. Med Lav 45:590-599 (in Italian).

8. Smyth HF Jr, Carpenter CP, Weil CS, Pozzani UC, Striegel JA, Nycum JS [1969]. Range-finding toxicity data: list VII. Am Ind Hyg Assoc J 30(5):470-476.

9. Treon JF, Dutra FR, Cappel J, Sigmon H, Younker W [1950]. Toxicity of sulfuric acid mist. AMA Arch Ind Hyg Occup Med 2:716-734.