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OCR for page 54
Barium
Barium (Ba) is one of the alkaline earth metals, and, because of its high
chemical activity, it never occurs free in nature. It is found chiefly as
bante or heavy spar, BaSO4, and w~thente, BaCO3 (Pidgeon and Preis-
man, 19641. The element is of little importance in animal nutrition.
Barium sulfate is used in taking X-ray photographs of the intestinal
tract. Even though the barium ion, Ba+2, is extremely toxic when ab-
sorbed, barium sulfate (BaSO4) is so slightly soluble that it is nontoxic.
ESSENTIALITY
Evidence is not available to show that barium performs any essential
function in vertebrate animals, although there is a report of depressed
growth in rats and guinea pigs when barium was omitted from the
mineral mixture of the specially purified diets fed to these animals
(Rygh, 19491. It is interesting that barium sulfate (BaSO4) forms the
exoskeleton of the rhizopod Xenophyophora (Vinogradov, 1953~.
METABOLISM
No study appears to have been made of the absorption of natural
barium, but a study of the metabolism of t40Ba in young (2 months) rats
showed 24-hour urinary and fecal excretions to be 7 and 20 percent,
54
OCR for page 55
Barium
55
respectively (Bauer et al., 1956~. The tuba was administered by intra-
pentoneal injection. The study also demonstrated that barium was
deposited in the skeleton.
SOURCES
Barium is present in all soils and in all plants. Only small quantities are
found in plants in most cases. The barium content of different plant
species growing on different soils ranged from 0.5 to 40 ppm with a
mean value of 10 ppm (Underwood, 19771. Certain plant species can
accumulate high concentrations of barium from barium-nch soils. For
example, Juglans regia and Fraxinus pennsylvanica were reported to
contain 2,600 and 1,700 ppm banum, respectively. This ability to accu-
mulate barium is unusual considering the fact that barium is toxic to
most plants even at low concentrations. With the exception of plants
that accumulate barium, the quantities of barium taken up by plants,
even from a soil high in banum, are so low that there is little likelihood
of animals suffering toxic effects by eating the plants.
TOXICOSIS
Barium is extremely toxic when absorbed (SolImann, 19571. The char-
acteristic systemic action of barium is a marked stimulation of muscles
of all types, regardless of innervation. In poisoning by soluble barium
salts, the major signs and symptoms are related to this powerful muscu-
lar stimulation. The action of barium on the gastrointestinal muscula-
ture causes vomiting, severe colic and diarrhea, and hemorrhage. The
cardiovascular effects consist of a marked hypertension due to a spasm
of the arteriolar musculature, intense myocardial stimulation, and ulti-
mately death from systolic cardiac arrest. In addition, barium causes
tremors of skeletal muscles. Paralysis of the central nervous system
may develop late in the course of barium intoxication. Death usually
occurs within an hour, but may be delayed for some time. The fatal
dose for the human is about 0.8 to 0.9 g of barium chloride. Banum
carbonate and sulfide are also toxic but act more slowly and require
larger doses.
The treatment of barium poisoning consists in the precipitation of the
unabsorbed salt remaining in the intestinal tract by the ingestion of a
solution of sodium or magnesium sulfate, which forms the insoluble
barium sulfate and also acts as a cathartic to hasten the elimination of
OCR for page 56
56 MINERAL TOLERANCE OF DOMESTIC ANIMALS
barium from the bowel. Therapy is otherwise purely symptomatic and
supportive.
There is little information published on feeding varying levels of
soluble barium compounds to livestock. Most reports (Spector, 1956),
where these compounds have been administered, indicate that the dose
level was lethal (Table 7~. It should be pointed out that these are not
necessarily minimum lethal dose levels. Maximum tolerance levels
have not been stated.
Martinez and Church (lg70) reported on the effect of barium in
in vitro studies with washed suspensions of rumen microorganisms.
Thirty ppm of barium as barium chloride (BaCI2 2H2O) significantly
depressed cellulose digestion by 15 percent. Subsequent additions of
barium above 30 ppm progressively depressed digestion of cellulose.
An inhibition of slightly over 50 percent resulted with additions of 200
ppm barium.
TISSUE LEVELS
There are very limited data on the level of barium in animal tissue. It
has been reported that humans contain 22 mg of barium, of which 93
percent is present in the bone (Underwood, 1977~. The remainder is
widely distributed throughout the soft tissues in very low concentra-
tions (0.02 and 0.1 ppm wet weight). Garner (1959) indicated that
barium is concentrated by the choroid of the eye and reported a value
of 3.5 ppm wet weight for the rabbit.
MAXIMUM TOLERABLE LEVEL
Based upon extrapolations from toxicity data and in vitro rumen work,
the level of soluble barium in a diet probably should not exceed 20 ppm.
It should be pointed out that the measurement of total barium in a feed
or feed ingredient is not a measure of biologically available barium. A
much better guide for safety purposes would be a procedure whereby
the acid or water soluble barium is determined. Much of the barium
present in most foodstuffs is not available to the animal and is of little
concern. Barium is a potential problem in the feed industry only if
ingredients or mixed feeds inadvertently become contaminated with
soluble forms of the element.
OCR for page 57
sums
~7
Barium is one ~ me One ~ me~s, sud, because ~ its ~~
Beam ac~v~y, it never occurs Me in nature. Conclusive evidence
is not Amble 10 slow ~~ barium pears say essence Duncan in
Treble Amen Barium is enemy toxic Ten bosomed ~~ me
cb~ledshc systemic schon Id by Sheldon ~ muscles ~ ~1
lyres, r ess ~inne~abon. Based upon axon ~ -
~ He level ~ soluble barium in a Net probably should not exceed
20 ~m.
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Barium
REFERENCES
59
Bauer, G. C. H., A. Carlsson, and B. Lindquist. l9S6. A comparative study on the
metabolism of Elba and 45Ca in rats. Biochem. J. 63:535.
Crawford, A. C. 190B. Banum, a Cause of the Loc - Weed Disease. U.S. Dept. Agnc.
Burl Plant Ind. Bull. 129.
Esser, A. 1935. Clinical, anatomical and spectrographic investigation of the central ner-
vous system in acute metal poisoning with particular consideration of their importance
for forensic medicine and tissue pathology. I. Strontium, barium, magnesium, alumi-
num, thorium (radioactive matenal), thallium, zinc, cadmium, mercury. Dtsch. Z. Ger.
Med. 25:239.
Garner, R. J. 1959. Distribution of radioactive barium in eye tissues. Nature (Land.)
184:733.
Martinez, A., and D. C. Church. 1970. Effect of venous mineral elements on in vitro
rumen cellulose digestion. J. Anim. Sci. 31:9B2.
Pidgeon, L. M., and L. Preisman. 1964. Kirk-Othmer Encyclopedia of Chemical Tech-
nology, vol. 3, 2nd ed. John Wiley Bc Sons, New York.
Rygh, O. 1949. Research on trace elements. 1. Importance of strontium, barium and zinc.
Bull. Soc. Chim. Biol. 31:1052.
Schwartze, E. W. 1920. Toxicity of Barium Carbonate to Rats. U.S. Dept. Agnc. Bull.
915.
Sollmann, T. 1957. A Manual of Pharmacology, 8th ed. W. B. Saunders Co., Philadel-
phia.
Spector, W. S., ed. 1956. Handbook of Toxicology, vol. 1. W. B. Saunders Co., Philadel-
phia.
Taucins, E., A. Svilane, A. Valdmanis, A. Buike, R. Zarina, and E. Ya. Fedorova. 1969.
Barium, strontium, and copper salts in chick nutrition. Fiziol. Akt. Komponenty Pitan.
Zhivotn. 199.
Underwood, E. J. 1977. Trace Elements in Human and Animal Nutntion, 4th ed.
Academic Press, New York.
Vinogradov, A. P. 1953. The Elementary Chemical Composition of Manne Organisms.
Sears Foundation, New Haven, Conn.
Representative terms from entire chapter:
barium sulfate
