Osmium tetroxide (as Os)

CAS number: 20816–12–0

NIOSH REL: 0.002 mg/m³ (0.0002 ppm) TWA,

0.006 mg/m³ (0.0006 ppm) STEL

Current OSHA PEL: 0.002 mg/m³ TWA

1989 OSHA PEL: 0.002 mg/m³ (0.0002 ppm) TWA,

0.006 mg/m³ (0.0006 ppm) STEL

1993-1994 ACGIH TLV: 0.0016 mg/m³ (0.0002 ppm) TWA,

0.0047 mg/m³ (0.0006 ppm) STEL

Description of substance: Colorless, crystalline solid or pale-yellow mass with an unpleasant, acrid, chlorine-like odor.

LEL: . . Noncombustible Solid

Original (SCP) IDLH: 1 mg Os/m³

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by AIHA [197] that 1 mg/m³ has been suggested as tolerable for 30 minutes [Flury and Zernik 1931]. No other data on acute inhalation toxicity are available which would be useful in determining the IDLH. AIHA [1968] reported that McLaughlin et al. [1946] found that workers exposed to 0.1 to 0.6 mg/m³ suffered from lacrimation and disturbances of vision and in some cases, headache, conjunctivitis, and cough.

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
Rabbit	Brunot 1933	-----	1,316 mg/m3	30 min	987 mg Os/m3 (1.0)	99 mg Os/m3
Rat	Shell 1961	-----	423 mg/m3	4 hr	317 mg Os/m3 (2.0)	32 mg Os/m3
Mouse	Shell 1961	-----	423 mg/m3	4 hr	317 mg Os/m3 (2.0)	32 mg Os/m3

Human data: It has been suggested that 1 mg/m³ is tolerable for 30 minutes [Flury and Zernik 1931]. Workers exposed to 0.1 to 0.6 mg/m³ suffered from lacrimation and disturbances of vision and in some cases, headache, conjunctivitis, and cough [McLaughlin et al. 1946].

Revised IDLH: 1 mg Os/m3 [Unchanged] Basis for revised IDLH: Based on acute inhalation toxicity data in humans [Flury and Zernik 1931; McLaughlin et al. 1946], the original IDLH for osmium tetroxide (1 mg Os/m3) is not being revised at this time.

REFERENCES:

1. AIHA [1968]. Osmium and its compounds. In: Hygienic guide series. Am Ind Hyg Assoc J 29:621-623.

2. Brunot FR [1933]. The toxicity of osmium tetroxide (osmic acid). J Ind Hyg 15:136-143.

3. Flury F, Zernik F [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, p. 254 (in German).

4. McLaughlin AIG, Milton R, Perry KMA [1946]. Toxic manifestations of osmium tetroxide. Br J Ind Med 3:183-186.

5. Shell [1961]. Unpublished report. San Ramon, CA: Shell Chemical Co., p. 8.