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

CAS number: 86-88-4

NIOSH REL: 0.3 mg/m3 TWA

Current OSHA PEL: 0.3 mg/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.3 mg/m3 TWA

Description of substance: White crystalline or gray, odorless powder.

LEL: Noncombustible Solid

Original (SCP) IDLH: 100 mg/m3

Basis for original (SCP) IDLH: No useful acute inhalation toxicity data are available on which to base the IDLH for ANTU. The chosen IDLH, therefore, has been estimated from the fatal human oral dose of 1 gram given by Stolman [1969]. According to ACGIH [1971], McClosky and Smith [1945] reported that the acute oral toxicity varies greatly among different species, with rats and dogs being the most susceptible (LD50 of 30 to 50 mg/kg) and rabbits the least susceptible (LD50 of 1,000 mg/kg).

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived Value
Dog AAPCO 1966 oral 0.38 ----- 2.7 mg/m3 0.3 mg/m3
Rat Lehman 1952 oral 6 ----- 42 mg/m3 4.2 mg/m3
Monkey Perkow 1971/76 oral 4,250 ----- 29,750 mg/m3 2,975 mg/m3
Mouse Yakkyoku 1977 oral 5 ----- 35 mg/m3 3.5 mg/m3

Other animal data: It has been reported that the mean oral lethal dose is 4,000 mg/kg in monkeys and is presumably much the same in man [Gosselin et al. 1984].

Human data: The fatal oral dose has been reported to be 1,000 mg [Stolman 1969]. [Note: An oral dose of 1,000 mg is equivalent to a worker being exposed to 650 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 100 mg/m3 [Unchanged]

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for ANTU. However, based on acute oral toxicity data in humans [Stolman 1969] and animals [Gosselin et al. 1984; Perkow 1971/76], the original IDLH for ANTU (100 mg/m3) is not being revised at this time.


  1. AAPCO [1966]. Pesticide chemicals official compendium. Topeka, KS: Association of American Pesticide Control Officials, Inc., p. 57.
  2. ACGIH [1971]. ANTU (alpha-naphthyl-thiourea). In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 15-16.
  3. Gosselin RE, Smith RP, Hodge HC [1984]. Clinical toxicology of commercial products. 5th ed. Section III. Baltimore, MD: Williams and Wilkins Company, pp. 40-42.
  4. Lehman AJ [1952]. Chemicals in foods: a report to the Association of Food and Drug Officials on current developments. Part II. Pesticides. Section III. Subacute and chronic toxicity. Q Bulletin Assoc Food Drug Off U.S. 16:47-53.
  5. McClosky WT, Smith MI [1945]. Studies on the pharmacologic action and the pathology of alpha-naphthylthiourea (ANTU). I. Pharmacology. Public Health Rep 60(38):1101-1113.
  6. Perkow W [1971/76]. Wirksubstanzen der pflanzenschutz und schadlingsbekampfungsmittel. Berlin, Germany: Verlag Paul Parey (in German).
  7. Stolman A, ed. [1969]. Progress in chemical toxicology. Vol. 4. New York, NY: Academic Press, p. 235.
  8. Yakkyoku (Pharmacy) [1977]; 28:329-335 (in Japanese).