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May 1994

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


CAS number: 75–31–0

NIOSH REL: The 1989 OSHA PEL may not be protective to workers.

Current OSHA PEL: 5 ppm (12 mg/m3) TWA

1989 OSHA PEL: 5 ppm (12 mg/m3) TWA, 10 ppm (24 mg/m3) STEL

1993-1994 ACGIH TLV: 5 ppm (12 mg/m3) TWA, 10 ppm (24 mg/m3) STEL

Description of substance: Colorless liquid with an ammonia-like odor.

LEL: . . Unknown

Original (SCP) IDLH: 4,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by ACGIH [1971] that 0 of 6 rats died from a 4-hour exposure to 4,000 ppm and 6 of 6 rats died after a 4-hour exposure to 8,000 ppm [Smyth et al. 1951]. No other quantitative data are available on which to base the IDLH.

Short-term exposure guidelines: None developed


Lethal concentration data:


SpeciesReferenceLC50(ppm)LCLo(ppm)TimeAdjusted 0.5-hr


Derived value
RatNCI 19744,000-----4 hr8,000 ppm (2.0)800 ppm
MouseShell 1961-----7,00040 min7,630 ppm (1.09)763 ppm
RatSmyth et al. 1951 LC100: 8,000-----4 hr16,000 ppm (2.0) 1,600 ppm

Other animal data: It has been reported that rats have survived an exposure to 4,000 ppm for 4 hours [Smyth et al. 1951].

Human data: Volunteers have complained of nose and throat irritation after brief exposures to concentrations ranging from 10 to 20 ppm [Amoore and Hautala 1983].


Revised IDLH: 750 ppm

Basis for revised IDLH: The revised IDLH for isopropylamine is 750 ppm based on acute inhalation toxicity data in animals [NCI 1974; Shell 1961]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 20 ppm.


1. ACGIH [1971]. Isopropylamine. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 141-142.

2. Amoore JE, Hautala E [1983]. Odor as an aid to chemical safety: odor threshold compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. J Appl Toxicol 3(6):272-290.

3. NCI [1974]. Memorandum (June 17, 1974). Interagency Collaborative Group on Environmental Carcinogenesis, National Cancer Institute.

4. Shell [1961]. Unpublished report. New York, NY: Shell Chemical Corporation, p. 7.

5. Smyth HF Jr, Carpenter CP, Weil CS [1951]. Range-finding toxicity data: list IV. AMA Arch Ind Hyg Occup Med 4:119-122.

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