Phosphorus pentachloride

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

ACUTE TOXICITY DATA:

Lethal concentration data:

Species	Reference	LC50	LCLo	Time	Adjusted 0.5-hr LC (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/m3 Basis 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].

REFERENCES:

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).