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n-Butyl mercaptan

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

CAS number: 109–79–5

NIOSH REL: 0.5 ppm (1.8 mg/m3) 15-minute CEILING

Current OSHA PEL: 10 ppm (35 mg/m3) TWA

1989 OSHA PEL: 0.5 ppm (1.5 mg/m3) TWA

1993-1994 ACGIH TLV: 0.5 ppm (1.8 mg/m3) TWA

Description of Substance: Colorless liquid with a strong, garlic-, cabbage-, or skunk-like odor.

LEL: . . Unknown

Original (SCP) IDLH: 2,500 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the mouse 4-hour LC50 of 2,500 ppm [Fairchild and Stokinger 1958] cited by ACGIH [1971]. It was also chosen to make the IDLH for butyl mercaptan consistent with the IDLH of 2,500 ppm for ethyl mercaptan, a compound with similar acute toxicity.

Short-term exposure guidelines: None developed


Lethal concentration data:






Adjusted 0.5-hr







Fairchild and Stokinger 1958

Fairchild and Stokinger 1958

Marhold 1986







4 hr

4 hr

30 min

8,040 ppm (2.0)

5,000 ppm (2.0)

770 ppm (1.0)

804 ppm

500 ppm

77 ppm

Human data: Accidental exposure for 1 hour to an estimated concentration of 50 to 500 ppm has been reported to cause muscular weakness, malaise, sweating, nausea, vomiting, headache, and confusion [Gobbato and Terribile 1968].

Revised IDLH: 500 ppm

Basis for revised IDLH: The revised IDLH for n-butyl mercaptan is 500 ppm based on acute inhalation toxicity data in workers [Gobbato and Terribile 1968] and animals [Fairchild and Stokinger 1958], and to be consistent with ethyl mercaptan which has a revised IDLH of 500 ppm.


1. ACGIH [1971]. n-Butyl mercaptan (n-butanethiol). In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 34.

2. Fairchild EJ II, Stokinger HE [1958]. Toxicologic studies on organic sulfur compounds. I. Acute toxicity of some aliphatic and aromatic thiols (mercaptans). Am Ind Hyg Assoc J 19:171-189.

3. Gobbato F, Terribile PM [1968]. Toxicological properties of mercaptans. Folia Medica 51:329-341. [From ACGIH [1991]. n-Butyl mercaptan. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 183-184.]

4. Marhold J [1986]. Prehled prumyslove toxikologie: organicke latky. Prague, Czechoslovakia: Avicenum, p. 982 (in Czechoslovakian).