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May 1994

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


CAS number: 86-50-0

NIOSH REL: 0.2 mg/m3 TWA [skin]

Current OSHA PEL: 0.2 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.2 mg/m3 TWA [skin]

Description of substance: Colorless crystals or a brown, waxy solid.

LEL: Noncombustible Solid

Original (SCP) IDLH: 20 mg/m3

Basis for original (SCP) IDLH: Because no useful data on acute inhalation toxicity are available concerning the toxic effects produced by azinphos-methyl, the chosen IDLH has been based on an analogy with parathion, which has an IDLH of 20 mg/m3.

Short-term exposure guidelines: None developed



Lethal concentration data:

SpeciesReferenceLC50LCLoTimeAdjusted 0.5-hr LC (CF)Derived Value
RatNewell and Dilley 197869 mg/m3-----1 hr86 mg/m3 (1.25)8.6 mg/m3
RatSanderson 196179 mg/m3-----1 hr99 mg/m3 (1.25)9.9 mg/m3

Lethal dose data:

SpeciesReferenceRouteLD50(mg/kg)LDLo(mg/kg)Adjusted LDDerived Value
RatDubois et al. 1957oral16-----115 mg/m312 mg/m3
G. pigDubois et al. 1957oral80-----560 mg/m356 mg/m3
RatGaines 1960oral11-----77 mg/m37.7 mg/m3
RatGaines 1960oral13-----91 mg/m39.1 mg/m3
MouseMurphy et al. 1976oral8.6-----60 mg/m36.0 mg/m3
RatSanderson 1961oral7-----49 mg/m34.9 mg/m3
MouseSato 1959oral8-----56 mg/m35.6 mg/m3
DogWorthing 1991oral10-----70 mg/m37.0 mg/m3v

Human data: Eight workers exposed to concentrations as high as 9.6 mg/m3 (no time period given) showed no signs or symptoms of illness [Jegler 1964].

Revised IDLH: 10 mg/m3

Basis for revised IDLH: The revised IDLH for azinphos-methyl is 10 mg/m3 based on acute inhalation toxicity data in humans [Jegler 1964] and animals [Newell and Dilley 1978; Sanderson 1961]. This may be a conservative value due to the lack of acute toxicity data for workers exposed to concentrations above 10 mg/m3.


  1. DuBois KP, Thursh DR, Murphy SD [1957]. Studies on the toxicity and pharmacologic actions of the dimethoxyl ester of benzotriazine dithiophosphoric acid. J Pharmacol Exp Ther 119:208-218.
  2. Gaines TB [1960]. Acute toxicity of pesticides in rats. Toxicol Appl Pharmacol 2:88-99.
  3. Jegler Z [1964]. Exposure to guthion during spraying and formulating. Arch Environ Health 8:565-569.
  4. Murphy SD, Cheever KL, Chow AYK, Brewster M [1976]. Organophosphate insecticide potentiation by carboxylesterase inhibitors. Proc Eur Soc Toxicol 17:292-300.
  5. Newell GW, Dilley JV [1978]. Teratology and acute toxicology of selected chemical pesticides administered by inhalation. Menlo Park, CA: Stanford Research Institute, p. 18. Prepared for Health Effects Research Laboratory, U.S. EPA, EPA-60011-78-003.
  6. Sanderson DM [1961]. Treatment of poisoning by anticholinesterase insecticides in the rat. J Pharm Pharmacol 13:435-442.
  7. Sato I [1959]. Studies on organic phosphorus gusathion and phosdrin. I. The toxicity of gusathion and phosdrin. Kuma Med J 12(1):312-317.
  8. Worthing CR, ed. [1991]. Azinphos-methyl. In: The pesticide manual: a world compendium. 9th ed. Old Woking, Surrey, England: Unwin Brothers Limited, p. 46.
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