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:

                                                                              
                                                                     Derived
Species   Reference    Route   LD50       LDLo        Adjusted LD     Value
______________________________________________________________________________
BaCl2
 Rabbit  Barnes and     oral   -----  112 mg Ba/kg   785 mg Ba/m3  79 mg Ba/m3
         Eltherington
         1973
Dog      Barnes and     oral   -----   59 mg Ba/kg   416 mg Ba/m3  42 mg Ba/m3
         Eltherington
         1973 
 Rat     Calvery 1942   oral   78 mg      -----      545 mg Ba/m3  55 mg Ba/m3
                               Ba/kg
 G. pig  Calvery 1942   oral   50 mg      -----      350 mg Ba/m3  35 mg Ba/m3
                               Ba/kg 
 Mouse   Coulston and   oral   -----   46 mg Ba/kg   323 mg Ba/m3  32 mg Ba/m3
         Korte 1975
Ba(NO3)2
 Rat     Marhold 1972   oral  187 mg      -----    1,306 mg Ba/m3 131 mg Ba/m3
                              Ba/kg
 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
 
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. Yakkyoku (Pharmacy) [1980]; 31(10):1247-1252 (in Japanese).