Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content


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

CAS number: 95–53–4

NIOSH REL: None established; NIOSH considers o-toluidine to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990] that may be absorbed through the skin.

Current OSHA PEL: 5 ppm (22 mg/m3) TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 2 ppm (8.8 mg/m3) TWA [skin], A2

Description of substance: Colorless to pale-yellow liquid with an aromatic, aniline-like odor.

LEL: . . Unknown

Original (SCP) IDLH: 100 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Sax [1975] that 100 ppm is the maximum concentration endurable for 1 hour without serious consequences. No other data are available on which to base the IDLH.

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value




IARC 1982IARC 1982

IARC 1982

Jacobsen 1972

Jacobsen 1972













1,052 ppm816 ppm

1,318 ppm

1,413 ppm

1,475 ppm

105 ppm82 ppm

132 ppm

141 ppm

148 ppm

Other animal data: Rats have survived an 8-hour exposure to saturated vapors of o-toluidine [Smyth et al. 1962].

Human data: It has been reported that a 60-minute exposure to 40 ppm produces severe toxic effects [Goldblatt 1955]. It has been reported that 100 ppm is the maximum concentration endurable for 1 hour without serious consequences [Sax 1975].

Revised IDLH: 50 ppmBasis for revised IDLH: The revised IDLH for o-toluidine is 50 ppm based on acute inhalation toxicity data in humans [Goldblatt 1955; Sax 1975]. [Note: NIOSH recommends as part of its carcinogen policy that the “most protective” respirators be worn for o-toluidine at any detectable concentration.]


1. Goldblatt MW [1955]. Research in industrial health in the chemical industry. Brit J Ind Med 12:1-20.

2. IARC [1982]. ortho-Toluidine and its hydrochloride. In: IARC monographs on the evaluation of carcinogenic risk of chemicals to humans. Vol. 27. Some aromatic amines, anthraquinones and nitroso compounds, and inorganic fluorides used in drinking-water and dental preparations, pp. 155-175.

3. Jacobsen KH [1972]. Short communication: acute oral toxicity of mono- and di-alkyl ring-substituted derivatives of aniline. Toxicol Appl Pharmacol 22:153-154.

4. Sax NI [1975]. o-Toluidine. In: Dangerous properties of industrial materials. 4th ed. New York, NY: Van Nostrand Reinhold Company, pp. 1173-1176.

5. Smyth HF, Carpenter CP, Weil CS, Pozzani UC, Striegel JA [1962]. Range-finding toxicity data: list VI. Am Ind Hyg Assoc J 23:95-107.