Skip directly to 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
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 107–49–3

NIOSH REL: 0.05 mg/m3 TWA [skin]

Current OSHA PEL: 0.05 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.004 ppm (0.47 mg/m3) TWA [skin]

Description of substance: Colorless to amber liquid with a faint, fruity odor.

LEL : . . Noncombustible Liquid

Original (SCP) IDLH: 10 mg/m3

Basis for original (SCP) IDLH: The chosen IDLH is based on the estimated oral lethal dose in man of 100 mg cited by Patty [1963].

Short-term exposure guidelines: None developed


Lethal dose data:





Adjusted LDDerived value
RatEdson 1960oral-----0.53.5 mg/m30.4 mg/m3
G. pigFrawley et al. 1952oral-----2.316 mg/m31.6 mg/m3
MouseKamimura et al. 1963oral-----321 mg/m3 2.1 mg/m3

Human data: TEPP, a cholinesterase inhibitor, has been judged to be twice as toxic as parathion; the American Conference of Governmental Industrial Hygienists TLV for TEPP was based on an analogy to parathion and was half that selected for parathion [ACGIH 1986]. It has been reported that the lethal oral dose is 1.429 mg/kg [CDC 1956; Patty 1963]. [Note: An oral dose of 1.429 mg/kg is equivalent to a 70-kg worker being exposed to 67 mg/m3 for 30 minutes assuming a 50 liter per minute breathing rate and 100% absorption.]

Revised IDLH: 5 mg/m3

Basis for revised IDLH: No inhalation data are available on which to base an IDLH for TEPP. Therefore, the revised IDLH for TEPP is 5 mg/m3 based on acute oral toxicity data in humans [CDC 1956; Patty 1963] and an analogy to parathion [ACGIH 1986] which has a revised IDLH of 10 mg/m3.


1. ACGIH [1986]. TEPP. In: Documentation of the threshold limit values and biological exposure indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 558.

2. 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. 21-23.

3. Edson EF [1960]. Applied toxicology of pesticides. Pharmaceut J 185:361-367.

4. Frawley JP, Hagan EC, Fitzhugh OG [1952]. A comparative pharmacological and toxicological study of organic phosphateÄanticholinesterase compounds. J Pharmacol Exp Ther 105:156-165.

5. Kamimura H, Matsumoto A, Miyazaki Y, Yamamoto I [1963]. Studies on nicotinoids as an insecticide. Part IV. Relation of structure to toxicity of pyridylmethylamines. Agri Biol Chem 27(10):684-688.

6. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1956.

Contact Us:
  • Page last reviewed: December 4, 2014
  • Page last updated: December 4, 2014 The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC-INFO