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May 1994

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


CAS number: 79–00–5

NIOSH REL: 10 ppm (45 mg/m3) TWA [skin]; NIOSH considers 1,1,2-trichloroethane to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 10 ppm (45 mg/m3) TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 10 ppm (55 mg/m3) TWA [skin]

Description of substance: Colorless liquid with a sweet, chloroform-like odor.

LEL: . . 6% (10% LEL, 6,000 ppm)

Original (SCP) IDLH: 500 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the UCC [1972] report that 500 ppm killed 1 of 6 rats in 4 hours, and 4 of 6 rats in 8 hours.

Short-term exposure guidelines: None developed


Lethal concentration data:


SpeciesReferenceLC50 LCLoTimeAdjusted 0.5-hr


Derived value
CatArch Hyg Bakteriol 1936 -----13,100 mg/m34.5 hr4,957 ppm (2.1)496 ppm
RatCarpenter et al. 1949 -----2,000 ppm4 hr4,000 ppm (2.0)400 ppm
RatUCC 1972LC17: 500 ppm-----4 hr1,000 ppm (2.0)100 ppm
RatUCC 1972LC67: 500 ppm ----- 8 hr1,250 ppm (2.5)125 ppm

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


Revised IDLH: 100 ppm

Basis for revised IDLH: The revised IDLH for 1,1,2-trichloroethane is 100 ppm based on acute inhalation toxicity data in animals [UCC 1972]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for 1,1,2-trichloroethane at concentrations above 10 ppm.]


1. Arch Hyg Bakteriol [1936]; 116:131 (in German).

2. Carpenter CP, Smyth HF Jr, Pozzani UC [1949]. The assay of acute vapor toxicity and the grading and interpretation of results on 96 chemical compounds. J Ind Hyg Toxicol 31(6):343-346.

3. UCC [1972]. Toxicology studies: 1,1,2-trichloroethane. New York, NY: Union Carbide Corporation.

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