TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
histopathological lesions of the lung have not been observed in rats exposed
to 0.7 mg barium/kg/day as barium acetate in drinking water for lifetime
(Schroeder and Mitchener 1975a).
Cardiovascular Effects. The most commonly observed cardiovascular
effects in cases of acute ingestion of barium compounds are hypertension and
abnormalities in heart rhythm (Das and Singh 1970; Diengott et al. 1964; Gould
et al. 1973; Wetherill et al. 1981). Myocardial damage was observed in a few
cases (Lewi and Bar-Khayim 1964; McNally 1925; Talwar and Sharma 1979). Ln
one atypical case, hypotension was observed (Talwar and Sharma 1979).
No adverse effects on blood pressure or cardiac rhythms were observed in
a study in which volunteers consumed 0.21 mg barium/kg/day for 4 weeks (Wones
et al. 1990). In this study, the subjects' preexposure blood pressure and
cardiac rhythm served as the control for comparison with postexposure values.
This study is somewhat limited in that the number of subjects evaluated was
small (n=11) and the absorption and/or serum levels of barium were not
assessed. An epidemiological study of communities consuming drinking water
containing elevated barium levels also did not provide evidence that chronic
exposure to barium in drinking water was associated with increased blood
pressure, hypertension, stroke, heart disease, or altered electrocardiograms
(Brenniman and Levy 1985; Brenniman et al. 1979a, 1979b, 1981). However, this
study is limited in that blood pressure was determined in a single 20-minute
session and not followed over a longer period (e.g., months, years), exposure
conditions were not well-characterized (duration, frequency), individual
exposure doses were not determined, and the incidence of hypertension, stroke,
and heart disease was determined by responses to a survey questionnaire and
not by testing and/or diagnosis.
Cardiovascular effects have been evaluated in acute, intermediate, and
chronic oral studies with experimental animals. Acute studies have been
limited to histological examination of the heart following 1-day or 10-day
gavage exposure of rats to doses as high as 198 mg barium/kg/day as barium
chloride (Borzelleca et al. 1988). No microscopic lesions of the heart were
observed. Other cardiovascular parameters were not evaluated.
Results from several studies with experimental animals indicate that
intermediate and chronic oral exposure to barium is associated with adverse
cardiovascular effects (Kopp et al. 1985; Perry et al. 1983, 1985, 1989). In
a series of experiments, rats were administered barium chloride in drinking
water either for 1, 4, or 16 months (Perry et al. 1983, 1985, 1989).
Elemental barium doses in the l-month study were either 0, 0.071, 0.71, or
7.1 mg/kg/day. Elemental barium doses in the 4-month study were either 0,
0.0643, 0.643, or 6.43 mg/kg/day. Elemental barium doses in the 16-month
study were either 0, 0.054, 0.54, or 5.4 mg/kg/day. In the l-month study,
significant increases in blood pressure were noted in rats treated with
7.1 mg/kg/day; no change in blood pressure was noted in rats treated with