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

CAS number: 62–73–7

NIOSH REL: 1 mg/m3 TWA [skin]

Current OSHA PEL: 1 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.90 mg/m3 (0.1 ppm) TWA [skin]

Description of Substance: Colorless to amber liquid with a mild, chemical odor.

LEL:. . Unknown

Original (SCP) IDLH: 200 mg/m3

Basis for original (SCP) IDLH: No useful data on acute inhalation toxicity are available on which to base the IDLH for dichlorvos. If the IDLH were estimated from the female rat oral LD50 of 55 mg/kg [Mattson et al. 1955 cited by Patty 1963], an IDLH of 400 mg/m3 would be chosen. On the basis of an analogy with parathion, however, which has an OSHA PEL of 0.1 mg/m3 and an IDLH of 20 mg/m3, an IDLH of 200 mg/m3 has been chosen for dichlorvos which has an OSHA PEL of 1 mg/m3.

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50 LCLo Time Adjusted 0.5-hrLC (CF) Derivedvalue
RatMouse Gig Sanit 1968Gig Sanit 1968 15 mg/m313 mg/m3 ———- 4 hr4 hr 30 mg/m3 (2.0)16 mg/m3 (2.0) 3.0 mg/m32.6 mg/m3


Lethal dose data:

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



Hartley and Kidd 1984Ikuzawa et al. 1966

Kokshareva et al. 1977

Technical News 1972










700 mg/m3427 mg/m3

70 mg/m3

119 mg/m3

70 mg/m343 mg/m3

7.0 mg/m3

12 mg/m3


Human data: Exposure to a concentration of 1 mg/m3 for 7.5 to 8.5 hours resulted in a plasma cholinesterase depression of 20 to 25% [Hunter 1964].



1. Gig Sanit [1968]; 33(10):35 (in Russian).

2. Hartley D, Kidd H, eds. [1984]. Agrochemical handbook. Nottingham, England: Royal Society of Chemistry, 1983-86, p. A141.

3. Hunter C [1964]. Communication to TLV Committee from Tunstall Laboratory, Sittingbourne, Kent, England. [From ACGIH [1991]. Dichlorvos. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 446-448.]

4. Ikuzawa M, Yonemoto S, Aoki H, Sumimoto S, Matsumoto K, Ohara K [1966]. Studies on the toxicity of various insecticides for mice (I) on the oral acute toxicity of single and mixed insecticides. J Osaka Cty Med Cntr 15:553-563.

5. Kokshareva NV, Kovtun SD, Kagan YS, Mizyukova IG, Medvedev BM [1977]. Action of diethixime, a new cholinesterase reactivator, on the central nervous system. Bulletin Exp Biol Med 83:32-35.

6. Mattson AM, Spillane JT, Pearce GW [1955]. Organophosphorus insecticides: dimethyl 2,2-dichlorovinyl phosphate (DDVP), an organic phosphorus compound highly toxic to insects. J Agri Food Chem 3(4):319-321.

7. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1942.

8. Technical news: ortran. [1972]. Japan Pesticide Information No. 13, pp. 36-38.