Malathion

IDLH Documentation
CAS number: 121­75­5

NIOSH REL: 10 mg/m3 TWA [skin]

Current OSHA PEL: 15 mg/m3 TWA [skin]

1989 OSHA PEL: 10 mg/m3 TWA [skin]

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

Description of substance: Deep­brown to yellow liquid with a garlic­like 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.

Short­term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal concentration data:

Species
Reference
LC50
LCLo
Time
Adjusted 0.5-hr

LC (CF)
Derived value
CatIzmerov et al. 1982
-----
10 mg/m3
4 hr
20 mg/m3 (2.0)
20 mg/m3 (2.0)
RatSapegin & Mikhailov 1986
84.6 mg/m3
-----
4 hr
169 mg/m3 (2.0)
17 mg/m3

Lethal dose data:

Species
Reference
Route
LD50

(mg/kg)
LDLo

(mg/kg)
Adjusted LD
Derived value
RatIzmerov et al. 1982
oral
290
-----
2,030 mg/m3
203 mg/m3
MouseIzmerov et al. 1982
oral
190
-----
1,330 mg/m3
133 mg/m3
G. pigvon Dozent et al. 1955
oral
570
-----
3,990 mg/m3
399 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 70­kg 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].

REFERENCES:

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

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

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

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 33:240­243.

6. Sapegin DE, Mikhailov VV [1986]. Combined effect of carbophos, high temperature and an excess of ultraviolet radiation. Gig Sanit 51(3):73­75 (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. Arzneimittel­Forschung (Drug Research) 5:626­630 (in German). Go back to the Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)