Ethyl mercaptan

CAS number: 75–08–1

NIOSH REL: 0.5 ppm (1.3 mg/m³) 15-minute CEILING

Current OSHA PEL: 10 ppm (25 mg/m³) CEILING

1989 OSHA PEL: 0.5 ppm (1 mg/m³) TWA

1993-1994 ACGIH TLV: 0.5 ppm (1.3 mg/m³) TWA

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

LEL:. . 2.8% (10% LEL, 2,800 ppm)

Original (SCP) IDLH: 2,500 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the mouse 4-hour LC₅₀ of 2,770 ppm [Fairchild and Stokinger 1958 cited by ACGIH 1971].

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
Rat Mouse	Fairchild and Stokinger 1958 Fairchild and Stokinger 1958	4,420 2,770	----- -----	4 hr 4 hr	8,840 ppm (2.0) 5,540 ppm (2.0)	884 ppm 554 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat	Fairchild and Stokinger 1958	oral	682	-----	1,849 ppm	185 ppm

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 500 ppm Basis for revised IDLH: The revised IDLH for ethyl mercaptan is 500 ppm based on acute inhalation toxicity data in animals [Fairchild and Stokinger 1958]. This may be a conservative value due to the lack of relevant acute toxicity data for workers.

REFERENCES:

1. ACGIH [1971]. Ethyl mercaptan (ethanethiol). In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 107.

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.