Barium (soluble compounds, as Ba)

CAS number: 7440-39-3 (Metal)

NIOSH REL: 0.5 mg Ba/m3 TWA

Current OSHA PEL: 0.5 mg Ba/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.5 mg Ba/m3 TWA

Description of substance: Varies

Original (SCP) IDLH*: 1,100 mg Ba/m³ [*Note: "Effective" IDLH = 250 mg Ba/m³ -- see discussion below.]

Basis for original (SCP) IDLH: From the standpoint of deriving an appropriate IDLH, the soluble Ba compounds BaCl2 and Ba(NO3)2 prove to be the most acutely toxic. Browning [1969] reported that:

the toxic dose of BaCl2 for man was 200 to 500 mg [Lydtin et al. 1965]; Patty [1963] cited 800 to 900 mg of BaCl2 (550 to 600 mg as Ba) as the fatal dose for man [Sollman 1953]. Acute toxicity data in animals show Ba(NO3)2 equally as toxic as BaCl2. As no data on the acute inhalation toxicity of either of these two barium compounds exist, the IDLH is based on a calculated dose for a 30-minute exposure for man required to attain an intake of 200 mg BaCl2 (as Ba), assuming a minute volume of 7.5 liters/minute and an 80% retention. Therefore, the IDLH is calculated to be about 1,100 mg Ba/m3. However, respirators have been selected on the basis of the assigned protection factor afforded by each device up to 500 x the OSHA PEL of 0.5 mg Ba/m3 (i.e., 250 mg Ba/m³); only the "most protective" respirators are permitted for use in concentrations exceeding 250 mg Ba/m³. Short-term exposure guidelines . None developed

ACUTE TOXICITY DATA

Lethal dose data:

Species	Reference	Route	LD50	LDLo	Adjusted LD	Derived Value
BaCl2
Rabbit	Barnes and Eltherington 1973	oral	-----	112 mg Ba/kg	785 mg Ba/m3	79 mg Ba/m3
Dog	Barnes and Eltherington 1973	oral	-----	59 mg Ba/kg	16 mg Ba/m3	42 mg Ba/m3
Rat	Calvery 1942	oral	78 mg	-----	545 mg Ba/m3	55 mg Ba/m3
G. pig	Calvery 1942	oral	50 mg	-----	350 mg Ba/m3	35 mg Ba/m3
Mouse	Coulston and Korte 1975	oral	-----	46 mg Ba/kg	323 mg Ba/m3	32 mg Ba/m3
Ba(NO3)2
Rat	Marhold 1972	oral	187 mg	-----	1,306 mg Ba/m3	131 mg Ba/m3
Rabbit	Yakkyoku 1980	oral	-----	79 mg Ba/kg	552 mg Ba/m3	55 mg Ba/m3
Dog	Yakkyoku 1980	oral	-----	421 mg Ba/kg	2,944 mg Ba/m3	294 mg Ba/m3

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Human data: It has been reported that the lethal oral dose is 43 to 57 mg Ba/kg Reeve 1979]. [Note: An oral dose of 43 to 57 mg Ba/kg is equivalent to a 70-kg worker being exposed to 2,007 to 2,660 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 50 mg Ba/m3 Basis for revised IDLH: Basis for "Revised" IDLH: No inhalation toxicity data are available on which to base an IDLH for soluble barium compounds. Therefore, the revised IDLH for soluble barium compounds is 50 mg Ba/m3 based on acute oral toxicity data in humans [Reeve 1979] and animals [Barnes and Eltherington 1973; Calvery 1942; Coulston and Korte 1975; Yakkyoku 1980]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 50 mg/m3.

REFERENCES:

1. Barnes CD, Eltherington LG, eds. [1973]. Drug dosages in laboratory animals: a handbook. Berkeley, CA: University of California Press, p. 53.
2. Browning E [1969]. Toxicity of industrial metals. 2nd ed. New York, NY: Appleton-Century-Crofts, p. 64.
3. Calvery HO [1942]. Trace elements in foods. Food Res 7:313-331.
4. Coulston F, Korte F, eds. [1975]. Heavy metal toxicity, safety and hormology. In: Environmental Quality & Safety, Supplement 1. New York, NY: Georg Thieme Publishers, pp. 1-120.
5. Lydtin H et al. [1965]. Uber barium vergiftung. Munchener Medizinische Wochenschrift 107:1045 (in German).
6. Marhold JV [1972]. Sbornik vysledku toxixologiekeho vysetreni latek a pripravku. Prague, Czechoslovakia: Institut Prumyclu, p. 10 (in Czechoslovakian).
7. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1000.
8. Reeve AL [1979]. Barium. In: Friberg L, et al., eds. Handbook of toxicology of metals. New York, NY: Elsevier/North Holland, pp. 321-328. Sollman TA [1953]. Manual of pharmacology and its applications to therapeutics and toxicology. 7th ed. Philadelphia, PA: W.B. Saunders Company, p. 479. >LI>Yakkyoku (Pharmacy) [1980]; 31(10):1247-1252 (in Japanese).