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Triorthocresyl phosphate

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

CAS number: 78–30–8

NIOSH REL: 0.1 mg/m3 TWA [skin]

Current OSHA PEL: 0.1 mg/m3 TWA

1989 OSHA PEL: 0.1 mg/m3 TWA [skin]

1993-1994 ACGIH TLV: 0.1 mg/m3 TWA [skin]

Description of substance: Colorless to pale-yellow, odorless liquid or solid (below 52°F).

LEL: . . Unknown

Original (SCP) IDLH: 40 mg/m3

Basis for original (SCP) IDLH: No data on acute inhalation toxicity are available on which to base an IDLH for triorthocresyl phosphate. The chosen IDLH has been estimated from oral toxicity data cited by ACGIH [1971]. ACGIH [1971] reported that serious paralysis has been produced in man by an oral dose of the order of 6 to 7 mg/kg [Patty 1963].

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50




Adjusted LD Derived value
Mouse Bleiberg &Johnson 1965 oral 900 ----- 6,300 mg/m3 630 mg/m3
Rabbit Gross & Grosse 1932 oral ----- 100 700 mg/m3 70 mg/m3
Rat Veronesi et al. 1984 oral 1,160 ----- 8,120 mg/m3 812 mg/m3

Human data: It has been reported that serious paralysis has been produced by an oral dose of about 6.6 mg/kg [Deichmann and Gerarde 1969] and that the probable lethal dose is greater than 28 mg/kg [Patty 1963]. [Note: Oral doses of 6.5 or 28 mg/kg are equivalent to a 70-kg worker being exposed to about 300 or 1,300 mg/m3, respectively, for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 40 mg/m3 [Unchanged]

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for triorthocresyl phosphate. However, based on acute oral toxicity data in humans [Deichmann and Gerarde 1969; Patty 1963], the original IDLH for triorthocresyl phosphate (40 mg/m3) is not being revised at this time.


1. ACGIH [1971]. Triorthocresyl phosphate. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 271-272.

2. Bleiberg MJ, Johnson H [1965]. Effects of certain metabolically active drugs and oximes on tri-o-cresyl phosphate toxicity. Toxicol Appl Pharmacol 7:227-235.

3. Deichmann WB, Gerarde HW [1969]. Tricresyl phosphates. In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., Inc., p. 604.

4. Gross E, Grosse A [1932]. A contribution on the toxicology of ortho-tri-cresyl-phosphates. Arch Exp Pathol Pharmakol 168:473-514 (in German).

5. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1920.

6. Veronesi B, Newland D, Inman A [1984]. The effect of metabolic interference on rodent-sensitivity to tri-ortho-cresyl phosphate (TOCP). Toxicologist 4:55 [Abstract].