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Phosphorus pentachloride

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

CAS number: 10026–13–8

NIOSH REL: 1 mg/m3 TWA

Current OSHA PEL: 1 mg/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.85 mg/m3 (0.1 ppm) TWA

Description of substance: White to pale-yellow, crystalline solid with a pungent, unpleasant odor.

LEL: . . Noncombustible Solid

Original (SCP) IDLH: 200 mg/m3

Basis for original (SCP) IDLH: The chosen IDLH is based on an analogy with phosphorus trichloride (PCl3) and statements by Henderson and Haggard [1943] that 2 to 4 ppm Pcl3 is the maximum concentration allowable for short exposures (0.5 to 1 hour) and 50 to 90 ppm is dangerous for short exposures. Therefore, 200 mg/m3 (24 ppm) is chosen as the IDLH for phosphorus pentachloride.

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50 LCLo Time Adjusted 0.5-hrLC (CF) Derived value
Mouse Henderson & Haggard 1943 —– 1,020 mg/m3 10 min 704 mg/m3 (1.45) 70 mg/m3
Rat Molodkena 1973 205 mg/m3 —– ? ? ?

Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
Rat Molodkena 1973 oral 660 —– 4,620 mg/m3 462 mg/m3

Other data: The vapors of phosphorus pentachloride decompose in the presence of moisture with the subsequent liberation of hydrochloric and phosphoric acids [Henderson and Haggard 1943].

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 70 mg/m3Basis for revised IDLH: The revised IDLH for phosphorus pentachloride is 70 mg/m3 based on acute inhalation toxicity data in animals [Henderson and Haggard 1943]. This may be a conservative value due to the lack of relevant acute toxicity data for workers. However, an IDLH of 70 mg/m3 for phosphorus pentachloride (Pcl5) is roughly equivalent on a “chlorine basis” to the revised IDLH of 50 ppm (i.e., 75 mg/m3) for hydrogen chloride (HCl) which may be appropriate since PCl5 decomposes in the presence of moisture to HCl [Henderson and Haggard 1943].


1. Henderson Y, Haggard HW [1943]. Noxious gases. 2nd ed. New York, NY: Reinhold Publishing Corporation, p. 134.

2. Molodkena NN [1973]. Toxicological comparisons of chlorine phosphate compounds (POCl3, PCl3, PCl5) by single and repeated exposures. Toksikol Nov Prom Khim Vesh 13:104 (in Russian).