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May 1994

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


CAS number: 79-34-5

NIOSH REL: 1 ppm (7 mg/m3) TWA [skin]; NIOSH considers 1,1,2,2-tetrachloroethane to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 5 ppm (35 mg/m3) TWA [skin]

1989 OSHA PEL: 1 ppm (7 mg/m3) TWA [skin]

1993-1994 ACGIH TLV: 1 ppm (6.9 mg/m3) TWA [skin]

Description of substance: Colorless to pale-yellow liquid with a pungent, chloroform-like odor.

LEL: . . Noncombustible Liquid

Original (SCP) IDLH: 150 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Negherbon [1959] that a 30-minute exposure to 146 ppm caused vertigo (along with irritation of the mucous membranes, sense of pressure in the head, and fatigue) in humans; the same effects were noted after a 10-minute exposure to 335 ppm [Lehmann et al. 1936].

Short-term exposure guidelines: None developed


Lethal concentration data:






TimeAdjusted 0.5-hr


Derived value




Carpenter et al. 1949

Izmerov et al. 1982

Lehmann et al. 1936

Smyth 1956









4 hr

2 hr

45 min

4 hr

2,000 ppm (2.0)

1,029 ppm (1.6)

3,094 ppm (1.14)

2,000 ppm (2.0)

200 ppm

103 ppm

309 ppm

200 ppm

Human data: A 30-minute exposure to 146 ppm has caused vertigo, irritation of the mucous membranes, sense of pressure in the head, and fatigue; the same effects were noted after a 10-minute exposure to 335 ppm [Lehmann et al. 1936; Negherbon 1959].


Revised IDLH: 100 ppm

Basis for revised IDLH: The revised IDLH for 1,1,2,2-tetrachloroethane is 100 ppm based on acute inhalation toxicity data in humans [Lehmann et al. 1936; Negherbon 1959] and animals [Izmerov et al. 1982]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for 1,1,2,2-tetrachloroethane at concentrations above 1 ppm.]


1. 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.

2. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 75.

3. Lehmann KB, Schmidt-Kehl L, Ruf H, Crescitelli, Dahl, Eppinghausen, Eshe, Falker, Grotefendt, Junkenita, Maier, Mergner, Pantehtsch, Schlitzer, Shoenes, Spettmann, Wirges, Bamsreiter, Benninger, Lazarus, Manasse, Kummeth, Reuss, Schwarzweller [1936]. The 13 most important chlorinated hydrocarbons of the aliphatic series from the standpoint of occupational hygiene. Arch Hyg Bakteriol 116:132-200 (translated).

4. Negherbon WO [1959]. Handbook of toxicology. Vol. III. Insecticides, a compendium. Wright-Patterson Air Force Base, OH: U.S. Air Force, Air Research and Development Command, Wright Air Development Center, Aero Medical Laboratory, WADC Technical Report 55-16, p. 735.

5. Smyth HF Jr [1956]. Improved communication: hygienic standards for daily inhalation. Am Ind Hyg Assoc Q 17(2):129-185.

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