TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
hazardous waste sites because of the route of exposure and because there has
been no documentation of this effect occurring in humans following normal
exposure routes.
Limited studies have been done in vitro on mammalian gastrointestinal
systems. Generally, they indicated that barium induced intestinal secretion
by releasing intracellular calcium, which combined with calmodulin to
stimulate the secretory process (Hardcastle et al. 1983a, 1983b, 1985).
Barium also increased gastrointestinal tissue sugar accumulation and decreased
mucosal to serosal galactose fluxes. The two proposed mechanisms for this are
(1) activation of the calcium-calmodulin complex or (2) direct action of
barium on smooth muscle tone (Alcalde and Ilundain 1988). The relevance of
these effects on the gastrointestinal tract is unknown.
Hematological Effects. No reliable studies were available regarding
hematological effects in humans or animals following inhalation or dermal
exposure to barium. There is suggestive evidence from case reports that acute
inhalation, oral, and dermal exposure of humans is associated with lowered
blood potassium levels (Diengott et al. 1964; Gould et al. 1973; Lewi and Bar-
Khayim 1964; Phelan et al. 1984; Shankle and Keane 1988; Stewart and Hummel
1984; Talwar and Sharma 1979; Wetherill et al. 1981). These findings suggest
that humans exposed to barium by various routes may be at increased risk for
minor hematological effects.
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.
Musculoskeletal Effects. No studies were available in humans or animals
regarding musculoskeletal effects of barium following dermal exposure. Case
reports of humans indicate that acute inhalation and acute oral exposure to
barium has been associated with muscle weakness and paralysis (Das and Singh
1970; Diengott et al. 1964; Gould et al. 1973; Lewi and Bar-Khayim 1964;
McNally 1925; Morton 1945; Ogen et al. 1967; Phelan et al. 1984; Shankle and
Keane 1988; Wetherill et al. 1981). Occupational exposure has not, however,
been found to result in radiologically apparent barium deposits in skeletal
muscle or bone (Essing et al. 1976). Very limited animal data are available
regarding musculoskeletal effects. No adverse effects on the musculoskeletal