Toxicity barium

Soluble Compounds. The mechanism of barium toxicity is related to its ability to substitute for calcium in muscle contraction. Toxicity results from stimulation of smooth muscles of the gastrointestinal tract, the cardiac muscle, and the voluntary muscles, resulting in paralysis (47). Skeletal, arterial, intestinal, and bronchial muscle all seem to be affected by barium. 

Thus, by an application of the common ion effect, the solubility of barium sulfate has been reduced to produce 104-fold less free barium ion in solution, thus further reducing the risk of barium toxicity. 

Several studies of animals exposed to barium by parenteral routes indicate that barium decreases in serum potassium (Foster et al. 1977 Jaklinski et al. 1967 Roza and Berman 1971 Schott and McArdle 1974). In one study, dogs intravenously administered barium chloride demonstrated a decrease in serum potassium accompanied by an increase in red blood cell potassium concentration (Roza and Berman 1971). The authors concluded that the observed hypokalemia was due to a shift of potassium from extracellular to intracellular compartments and not to excretion. Additional intravenous studies have linked the observed hypokalemia to muscle paralysis in rats (Schott and McArdle 1974) and cardiac arrhythmias in dogs (Foster et al. 1977). These experiments in animals strongly support the suggestive human case study evidence indicating hypokalemia is an important effect of acute barium toxicity. 

Other Systemic Effects. Other systemic effects have been observed. Barium sulfate was observed to act as an appendocolith in two cases following barium enema procedures (Palder and Dalessandri 1988). This is a rare occurrence and probably not significant in cases of human barium toxicity. Intravenous injection of barium sulfate into pigs increased calcitonin secretion from the thyroid (Pento 1979). This is probably not a significant effect for humans since intravenous exposure is not a common route and the dose required was so high (1.7 mg/kg/minute for 20 minutes) it caused cardiotoxicity. 

Since barium toxicity has been repeatedly demonstrated to significantly decrease serum potassium in both humans and animals (Foster et al. 1977 Gould et al. 1973 Phelan et al. 1984 Roza and Berman 1971), individuals taking diuretics may have a more severe hypokalemic reaction to barium toxicity. 

Hypokalemia is commonly seen in cases of acute barium toxicity and may be responsible for some of the symptoms of barium poisoning (Proctor et al. 1988). Plasma potassium should be monitored and hypokalemia may be relieved by intravenous infusion of potassium (Dreisbach and Robertson 1987 Haddad and Winchester 1990 Proctor et al. 1988). 

Sittig M. 1976. Barium. Toxic metals Pollution control and worker protection. Park Ridge, NJ Noyes Data Corporation, 35-42. 

Chaudry EMA, Wallace A and Mueller RT (1977) Barium toxicity in plants. Commun Soil Sci Plant Anal 8 795-797. 

Wang W (1988) Site-specific barium toxicity to common duckweed, Lemna minor. Aquatic Toxicol 12 203-212. 

Toxic Constituents. The seed coat of European beechnut contains an unidentified toxic substance that makes the feeding of beechnut cake to certain farm animals ha2ardous (47). A toxic concentration (up to 4000 ppm) of barium found in some Bra2il nut kernels (30,48) has been reported to... 

Barium peroxide is a strong oxidizer and can cause fire when in contact with combustible materials. It is a powerful irritant to skin, eyes, and mucous membranes (2). Consequendy, it is also toxic via the subcutaneous route protective clothing should be worn during handling. The LD q value (mouse, oral) is 50 mg/kg (2). 

Barium metal and most barium compounds are highly poisonous. A notable exception is barium sulfate which is nontoxic because of its extreme iasolubihty ia water. Barium ion acts as a muscle stimulant and can cause death through ventricular fibrillation of the heart. Therefore, care must be taken to avoid contact with open areas of the skin. Workers must wear respirators (of type approved for toxic airborne particles), goggles, gloves, and protective clothing at all times. The toxic barium aluminate residue obtained from barium production is detoxified by reaction with a solution of ferrous sulfate and converted iato nontoxic barium sulfate. According to OSHA standards, the TWA value for Ba and Ba compounds ia air is 0.5 mg/m. ... 

Because of its extreme insolubiUty, barium sulfate is not toxic the usual antidote for poisonous barium compounds is to convert them to barium sulfate by administering sodium or magnesium sulfate. In medicine, barium sulfate is widely used as an x-ray contrast medium (see Imaging TECHNOLOGY X-RAY technology). It is also used in photographic papers, filler for plastics, and in concrete as a radiation shield. Commercially, barium sulfate is sold both as natural barite ore and as a precipitated product. Blanc fixe is also used in making white sidewall mbber tires or in other mbber appHcations. 

Toxicity. The toxicity of barium compounds depends on solubility (47—49). The free ion is readily absorbed from the lung and gastrointestinal tract. The mammalian intestinal mucosa is highly permeable to Ba " ions and is involved in the rapid flow of soluble barium salts into the blood. Barium is also deposited in the muscles where it remains for the first 30 h and then is slowly removed from the site (50). Very Httle is retained by the fiver, kidneys, or spleen and practically none by the brain, heart, and hair. 

The more soluble forms of barium such as the carbonate, chloride, acetate, sulfide, oxide, and nitrate, tend to be more acutely toxic (50). Mean lethal doses for ingested barium chloride were 300—500 mg/kg in rats and 7—29 mg/kg in mice (47). 

Administration of 5 ppm barium, the acetate, to mice in the drinking water in a life-time study had no observable effects on longevity, mortality, and body weights, or on the incidence of tumors (53). Long-term studies in rats exposed to Ba " in drinking water containing 5 mg/L, as acetate, or 10—250 mg/L, as chloride, resulted in no measurable toxic effects (47). 

Water-insoluble barium salts are poorly absorbed. In fact, barium sulfate is used as a contrast material for x-ray examination of the gastrointestinal tract based on its limited solubility andlow toxicity (52). Barium sulfate fed to mice at various levels up to 8 ppm dietary Ba ( 1.14 mg/kg-d as Ba " ) for three generations had no significant effects on growth, mortality, morbidity, or reproductive performance (53). 

The threshold of a toxic dose in adult humans is about 0.2—0.5 g Ba the lethal dose in untreated cases is 3—4 g Ba, LD q about 66 mg/kg (47). The fatal dose of barium chloride for humans is reported to be between 0.8 and 0.9 g (0.55—0.60 g of Ba) (50). However, for most of the acid-soluble salts of barium, doses greater than 1 g have been tolerated (51). Lethal doses are summarized in Table 5. Dusts of barium oxide are considered potential dermal and nasal irritants (52). 

Ammonium cyanide may be prepared in solution by passing hydrogen cyanide into aqueous ammonia at low temperatures. It may also be prepared from barium cyanide and ammonium sulfate, or calcium cyanide with ammonium carbonate. It may be prepared in the dry state by gentiy heating a mixture of potassium cyanide or ferrocyanide and ammonium chloride, and condensing the vapor in a cooled receiver. Ammonium cyanide is soluble in water or alcohol. The vapor above soHd NH CN contains free NH and HCN, a very toxic mixture. 

Barium. This drier has been used to some extent in Europe as a substitute for lead. Barium 2-ethyIhexanoate [2457-01-4] has been under governmental scmtiny because of its fairly acute toxicity. 

The common acid acceptors, red lead oxide and barium carbonate, are both toxic when inhaled or ingested. They are, and should be, used in industry as dispersions in EPDM and ECO. SuppHers of red lead oxide include Polymeries, Inc., Rhein Chemie Corp., and Akrochem Co., Akron, Ohio. Barium carbonate in an ECO binder is available from Rhein Chemie Corp. and Synthetic Products Co. 

The most common toxic metals in industrial use are cadmium, chromium, lead, silver, and mercury less commonly used are arsenic, selenium (both metalloids), and barium. Cadmium, a metal commonly used in alloys and myriads of other industrial uses, is fairly mobile in the environment and is responsible for many maladies including renal failure and a degenerative bone disease called "ITA ITA" disease. Chromium, most often found in plating wastes, is also environmentally mobile and is most toxic in the Cr valence state. Lead has been historically used as a component of an antiknock compound in gasoline and, along with chromium (as lead chromate), in paint and pigments. 

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