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

CAS number: 463–51–4

NIOSH REL: 0.5 ppm (0.9 mg/m3) TWA, 1.5 ppm (3 mg/m3) STEL

Current OSHA PEL: 0.5 ppm (0.9 mg/m3) TWA

1989 OSHA PEL: 0.5 ppm (0.9 mg/m3) TWA, 1.5 ppm (3 mg/m3) STEL

1993-1994 ACGIH TLV: 0.5 ppm (0.86 mg/m3) TWA, 1.5 ppm (2.6 mg/m3) STEL

Description of substance: Colorless gas with a penetrating odor.

LEL: . . Unknown

Original (SCP) IDLH*: Unknown [*Note: "Effective" IDLH = 25 ppm -- see discussion below.]

Basis for original (SCP) IDLH: No data on acute inhalation toxicity are available on which to base an IDLH for ketene. For this draft technical standard, therefore, the respirators have been selected on the basis of the assigned protection factor afforded by each device up to 50 ´ the OSHA PEL of 0.5 ppm (i.e., 25 ppm); only the "most protective" respirators are permitted for use in concentrations exceeding 25 ppm.

Short-term exposure guidelines: None developed


Lethal concentration data:





TimeAdjusted 0.5-hr


Derived value
MouseMendenhall & Stokinger 195917-----10 min12 ppm (0.69)1.2 ppm
MouseTreon et al. 1949-----2330 min23 ppm (1.0)2.3 ppm
RabbitTreon et al. 1949-----532 hr85 ppm (1.6)8.5 ppm
G. pigTreon et al. 1949-----532 hr85 ppm (1.6)8.5 ppm
CatTreon et al. 1949-----75010 min518 ppm (0.69)52 ppm
MonkeyTreon et al. 1949-----20010 min138 ppm (0.69)14 ppm
MouseTreon et al. 1949-----5010 min35 ppm (0.69)3.5 ppm
RabbitTreon et al. 1949-----1,00010 min690 ppm (0.69)69 ppm

Human data: It has been stated that 5 ppm is the lowest concentration productive of a clinically relevant physiologic response [Stokinger 1960].

Revised IDLH: 5 ppm

Basis for revised IDLH: The revised IDLH for ketene is 5 ppm based on acute inhalation toxicity data in humans [Stokinger 1960] and animals [Treon et al. 1949]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 5 ppm.


1. Mendenhall RM, Stokinger HE [1959]. Tolerance and cross-tolerance development to atmospheric pollutants ketene and ozone. J Appl Physiol 14:923-926.

2. Stokinger HE [1960]. Toxicologic interactions of mixtures of air pollutants. Review of recent developments. Int J Air Pollut 2:313-326.

3. Treon JF, Sigmon H, Kitzmiller KV, Heyroth FF, Younker WJ, Cholak J [1949]. Physiologic response of animals exposed to airborne ketene. J Ind Hyg Toxicol 31:209-219.

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