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May 1994
 

Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)


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

RatFairchild and Stokinger 1958oral682-----1,849 ppm185 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.

 
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