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May 1994

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


CAS number: 90-04-0

NIOSH REL: 0.5 mg/m3 TWA [skin]; NIOSH considers o-anisidine to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 0.5 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.1 ppm (0.5 mg/m3) TWA [skin]

Description of substance: Red or yellow, oily liquid with an amine-like odor.

LEL: Unknown

Original (SCP) IDLH: 50 mg/m3

Basis for original (SCP) IDLH: Because no data on acute inhalation toxicity are available for anisidine (o-, p-isomers), the chosen IDLH is based on chronic data. ACGIH [1971] reported that mice survived exposures to 10 to 30 mg/m3 for 2 hours/day, 6 days/week for 1 month; a decrease in the excitability of nerves was noted [Zaeva and Fedorova 1962]. Because mice survived 30 mg/m3, 2 hours/day, 6 days/week for 1 month, a worker should be able to escape from 50 mg/m3 without injury or irreversible health effects.

Short-term exposure guidelines: None developed


Lethal dose data:

SpeciesReferenceRouteLD50(mg/kg)LDLo(mg/kg)Adjusted LDDerived Value
RatIARC 1982oral2,000-----14,000 mg/m31,400 mg/m3
MouseIARC 1982oral1,400-----9,800 mg/m3980 mg/m3
RabbitIARC 1982oral870-----6,090 mg/m3609 mg/m3

Other animal data: Mice have survived exposures to concentrations of 10 to 30 mg/m3 for 2 hours/day, 6 days/week for 1 month with only a decrease in the excitability of nerves noted [Zaeva and Fedorova 1962].

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

Revised IDLH: 50 mg/m3 [Unchanged]

Basis for revised IDLH: Based on subchronic inhalation toxicity data in animals [Zaeva and Fedorova 1962], the original IDLH for o-anisidine (50 mg/m3) is not being revised at this time. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for o-anisidine at concentrations above 0.5 mg/m3.]


  1. ACGIH [1971]. Anisidine (o-, p-isomers). In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 14.
  2. IARC [1982]. IARC monographs on the evaluation of carcinogenic risk of chemicals to humans. Vol. 27. Lyon, France: World Health Organization, International Agency for Research on Cancer, p. 63.
  3. Zaeva GN, Fedorova VI [1962]. Toxsikol Nov Prom Khim Vesh 4:91 (in Russian).
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