TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
either appearance of or degree of hypokalemia and hypertension. Observation
of hypokalemia and hypertension together is indicative of barium exposure,
however, other toxicants and disease states can produce these effects.
2.5.2 Biomarkers Used to Characterize Effects Caused by Barium
The organs most sensitive to the toxic effects of barium are the organs
of the cardiovascular and gastrointestinal systems, muscles, and nerves.
Gastrointestinal disturbances are usually the first symptoms of acute barium
exposure. Hypokalemia, hypertension, and abnormalities in heart rhythm
frequently occur. General muscle weakness is a frequent symptom, sometimes
followed by paralysis. Nerve conduction is often affected, resulting in
numbness and tingling of the mouth, neck and extremities. Loss of deep tendon
reflexes may also occur. Not all symptoms appear in every case of acute
barium poisoning. The presence of other toxicants and disease states may also
cause these effects. More information on the specific effects of barium
toxicity can be found in Section 2.2.
2.6 INTERACTIONS WITH OTHER CHEMICALS
There are no data regarding the interaction between barium and various
chemicals potentially found at hazardous waste sites. However, there are data
that suggest that barium may interact with other cations and certain
prescription drugs. Drug interactions are of relevance because individuals
exposed to barium by living or working near hazardous waste sites contaminated
with this substance may also be taking prescription drugs.
The cations potassium, calcium, and magnesium also interact with barium.
Barium exposure, for example, may cause a buildup of potassium inside the cell
resulting in extracellular hypokalemia which is believed to mediate bariuminduced
paralysis. In fact, potassium is a powerful antagonist of the
cardiotoxic and paralyzing effects of barium in animals (Foster et al. 1977;
Jaklinski et al. 1967; Roza and Berman 1971; Schott and McArdle 1974) and is
used as an antidote in cases of acute barium poisoning. Calcium and magnesium
suppress uptake of barium in vitro in pancreatic islets. Conversely, barium,
in low concentrations, stimulate calcium uptake in these cells. Although the
data are insufficient to determine the significance of these findings to human
health effects, displacement of calcium may be the mechanism by which barium
stimulates insulin release (Berggren et al. 1983).
Among the drugs which are known to interact with barium, the
barbiturates sodium pentobarbital and phenobarbital were found to have an
increased depressive effect on the hearts of rats exposed to barium (Kopp et
al. 1985; Perry et al. 1983, 1989). This hypersensitivity of the
cardiovascular system to anesthesia was not observed in similarly treated
animals that were anesthetized with xylazine plus ketamine. Results of the
study indicated that the hypersensitivity was specific .to the barbiturates and
not a generalized effect of anesthesia (Kopp et al. 1985).