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Parathion																				Related Pages
										May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
**CAS number:** 56–38–2
**NIOSH REL:** 0.05 mg/m3 TWA [skin]
**Current OSHA PEL:** 0.1 mg/m3 TWA [skin]
**1989 OSHA PEL:** Same as current PEL
**1993-1994 ACGIH TLV:** 0.1 mg/m3 TWA [skin]
**Description of substance:** Pale-yellow to dark-brown liquid with a garlic-like odor.
**LEL:** . . Unknown
**Original (SCP) IDLH:** 20 mg/m3
**Basis for original (SCP) IDLH:** No useful data on acute inhalation toxicity are available on which to base the IDLH for parathion. If the IDLH were estimated from the statement by AIHA [1971] that “the minimum lethal oral dose for humans has been estimated as ranging from less than 10 mg to 120 mg [Bidstrup 1950; Grob 1950; Hayes 1963],” then an IDLH of 5 mg/m3 would be chosen. This appears to be far too conservative, however, because ACGIH [1971] noted that workers regularly exposed to 2 to 15 mg/m3, with an average concentration of 8 mg/m3, exhibited only a 25% decrease in cholinesterase levels [Kay et al. 1952]. The chosen IDLH, therefore, has been estimated from the female rat oral LD50 of 3 mg/kg cited by ACGIH [1971].
**Short-term exposure guidelines:** None developed
**ACUTE TOXICITY DATA:**
**Lethal concentration data:**

**Species**
    **Reference**
    **LC50**
    **LCLo**
    **Time**
    **Adjusted 0.5-hr** **LC (CF)**
    **Derived value**Rabbit G. pigMouseRat
    Deichmann et al. 1952 Deichmann et al. 1952Izmerov et al. 1982USAF 1977
    ----- ----------84 mg/m3
    50 mg/m314 mg/m315 mg/m3-----
    2 hr 2 hr?4 hr
    80 mg/m322 mg/m3?168 mg/m3
    8.0 mg/m32.2 mg/m3?17 mg/m3**Lethal dose data:**
 
 **Species**
    **Reference**
    **Route**
    **LD50** **(mg/kg)**
    **LDLo** **(mg/kg)**
    **Adjusted LD**
    **Derived value**Mouse RabbitDogCatHorseG. pigRat
    Eto et al. 1966 Kenaga & Morgan 1978Kenaga & Morgan 1978Nishizawa et al. 1961Perkow 1971/1976von Dozent et al. 1955Weiss and Orzel 1967
    oral oraloraloraloraloraloral
    5 1030.93582
    ----- ------------------------------
    35 mg/m370 mg/m321 mg/m36.5 mg/m335 mg/m356 mg/m314 mg/m3
    3.5 mg/m37.0 mg/m32.1 mg/m30.7 mg/m33.5 mg/m35.6 mg/m31.4 mg/m3**Human data:** Workers regularly exposed to 2 to 15 mg/m3 (average of 8 mg/m3) exhibited only a 25% decrease in cholinesterase levels [CDC 1956]. The minimum lethal oral dose has been reported to range from 0.17 to 1.471 mg/kg [Arena 1970; CDC 1956; Hartley and Kidd 1986]. [Note: An oral dose ranging from 0.17 to 1.471 mg/kg is equivalent to a worker being exposed to about 8 to 69 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]
 
 **Revised IDLH:** 10 mg/m3**Basis for revised IDLH:** The revised IDLH for parathion is 10 mg/m3 based on chronic inhalation toxicity data in humans [CDC 1956]. This may be a conservative value due to the lack of relevant acute toxicity data in humans exposed to concentrations above 10 mg/m3.**REFERENCES:**
1. ACGIH [1971]. Parathion. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 195-196.
2. AIHA [1969]. Parathion. In: Hygienic Guide Series. Am Ind Hyg Assoc J *30*:308-312.
3. Arena JM [1970]. Poisoning, toxicology, symptoms, treatments. 2nd ed. Springfield, IL: C.C. Thomas *2*:73.
4. Bidstrup PL [1950]. Poisoning by organic phosphorus insecticides. Br Med J *2*:548-551.
5. CDC [1956]. Clinical memoranda on economic poisons. Atlanta, GA: Communicable Disease Center, Bureau of State Services, Public Health Service, U.S. Department of Health, Education, and Welfare, Public Health Service Publication No. 476, pp. 19-21.
6. Deichmann WB, Pugliese W, Cassidy J [1952]. Effects of dimethyl and diethyl paranitrophenyl thiophosphate on experimental animals. AMA Arch Ind Health Occup Med *5*:44-51.
7. Eto M, Kishimoto K, Matsumura K, Ohshita N, Oshima Y [1966]. Studies on saligenin cyclic phosphorus esters with insecticidal activity. Agri Biol Chem *30*(2):181-185.
8. Grob D [1950]. Uses and hazards of the organic phosphate anticholinesterase compounds. Ann Intern Med *32*:1229-1234.
9. Hartley D, Kidd H, eds. [1986]. Agrochemicals handbook. Nottingham, England: Royal Society of Chemistry. 1983-1986, p. A311.
10. Hayes WJ Jr [1963]. Clinical handbook on economic poisons. Emergency information for treating poisons. Washington, DC: U.S. Government Printing Office, Public Health Service Publication No. 476 (Revised 1963), pp. 35-37.
11. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 52.
12. Kay K, Monkman L, Windish JP, Doherty T, Pare J, Racicot C [1952]. Parathion exposure and cholinesterase response of Quebec apple growers. AMA Arch Ind Hyg Occup Med *6*:252-262.
13. Kenaga EE, Morgan RW [1978]. Commercial and experimental organic insecticides (1978 revision). Entomological Society of America Special Publication *78*-1:16.
14. Nishizawa Y, Fujii K, Kadota T, Miyamoto J, Sakamoto H [1961]. Studies on the organophosphorus insecticides. VII. Chemical and biological properties of new low toxic organophosphorus insecticide. O,O-dimethyl-O-(3-methyl-4-nitrophenyl) phosphorothioate. Agri Biol Chem *25*(8):605-610.
15. Perkow W [1971/1976]. Wirksubstanzen der pflanzenschutz und schadlingsbekampfungsmittel. Berlin, Germany: Verlag Paul Parey, 1971-1976 (in German).
16. USAF [1977]. Proceedings of the 7th annual conference on environmental toxicology. Wright-Patterson Air Force Base, OH: Air Force Systems Command, Aerospace Medical Division, Aerospace Medical Research Technical Report, AMRL-TR-76-125.
17. von Dozent J, Klimmer OR, Pfaff W [1955]. Vergleichende untersuchungen über die toxicität organischer thiophosphorsäureester. Arzneimittel-Forschung (Drug Research) *5*:626-630 (in German).
18. Weiss LR, Orzel RA [1967]. Some comparative toxicologic and pharmacologic effects of dimethyl sulfoxide as a pesticide solvent. Toxicol Appl Pharmacol *11*:546-557.

			
							
								Page last reviewed:  December 4, 2014						Content
							source: 	National Institute for Occupational Safety and Health NIOSH Publications & Products
Immediately Dangerous To Life or Health (IDLH) Values
Table of IDLH Values
Criteria for Determining IDLH Values
Historical Documentation
Original (SCP) Values
Abbreviations for IDLH Documentation
Abbreviations for Journal Titles Follow NIOSH Facebook
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