Skip directly to local search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home
May 1994

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


CAS number: 121–75–5

NIOSH REL: 10 mg/m3 TWA [skin]

Current OSHA PEL: 15 mg/m3 TWA [skin]

1989 OSHA PEL: 10 mg/m3 TWA [skin]

1993-1994 ACGIH TLV: 10 mg/m3 TWA [skin]

Description of substance: Deep-brown to yellow liquid with a garlic-like odor.

LEL: . . Unknown

Original (SCP) IDLH: 5,000 mg/m3

Basis for original (SCP) IDLH: No useful data on acute inhalation toxicity are available on which to base the IDLH for malathion. The chosen IDLH, therefore, has been estimated from the statement by Stolman [1969] that the acute oral LD50 values for mice and rats range from 480 to 5,800 mg/kg.

Short-term exposure guidelines: None developed


Lethal concentration data:


SpeciesReferenceLC50 LCLoTimeAdjusted 0.5-hr


Derived value
CatIzmerov et al. 1982 -----10 mg/m34 hr20 mg/m3 (2.0)20 mg/m3 (2.0)
RatSapegin & Mikhailov 1986 84.6 mg/m3-----4 hr169 mg/m3 (2.0) 17 mg/m3

Lethal dose data:






Adjusted LDDerived value
RatIzmerov et al. 1982 oral290-----2,030 mg/m3203 mg/m3
MouseIzmerov et al. 1982 oral190-----1,330 mg/m3133 mg/m3
G. pigvon Dozent et al. 1955 oral570-----3,990 mg/m3399 mg/m3

Human data: Workers exposed to initial concentrations up to 85 mg/m3 for 1 hour (that may have declined rapidly) over 42 consecutive days suffered no adverse effects [Golz 1959]. Workers exposed to concentrations that peaked at 56 mg/m3 and averaged 3.3 mg/m3 for 5 hours had normal cholinesterase levels [Culver et al. 1956]. A lethal oral dose of 246 to 471 mg/kg has been reported [Farago 1967; Jusic and Milic 1978]. [Note: An oral dose of 246 to 471 mg/kg is equivalent to a 70-kg worker being exposed to about 11,500 to 22,100 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]


Revised IDLH: 250 mg/m3

Basis for revised IDLH: The revised IDLH for malathion is 250 mg/m3 based on acute toxicity data in humans [Farago 1967; Golz 1959; Jusic and Milic 1978].


1. Culver D, Caplan P, Batchelor GS [1956]. Study of human exposure during aerosol application of malathion and chlorthion. AMA Arch Ind Health 13:37-50.

2. Farago A [1967]. Fatal, suicidal malathion poisonings. Arch Toxikol 23:11-16 (in German).

3. Golz HH [1959]. Controlled human exposures to malathion aerosols. AMA Arch Ind Health 19:516-523.

4. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 56.

5. Jusic A, Milic S [1978]. Neuromuscular synapse testing in two cases of suicidal organophosphorous pesticide poisoning. Arch Environ Health 33:240-243.

6. Sapegin DE, Mikhailov VV [1986]. Combined effect of carbophos, high temperature and an excess of ultraviolet radiation. Gig Sanit 51(3):73-75 (in Russian)

7. Stolman A, ed. [1969]. Progress in chemical toxicology. Vol. 4. New York, NY: Academic Press, Inc., p. 213.

8. von Dozent J, Klimmer OR, Pfaff W [1955]. Vergleichende untersuchungen über die toxicität organischer thiophosphorsäureester. Arzneimittel-Forschung (Drug Research) 5:626-630 (in German).

Contact Us: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO