TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
37.5 mg barium/kg/day in drinking water was not associated with lesions of the
brain upon gross and microscopic examination (McCauley et al. 1985; Tardiff et
al. 1980), or with any changes in brain weight (Tardiff et al. 1980). No
lesions of the brain were observed in rats following chronic oral exposure to
nominal doses of 15 mg barium/kg/day in drinking water (McCauley et al. 1985).
The intermediate and chronic drinking water studies are of limited value for
assessing the effects of barium on the brain because the barium compound
tested was not specified and because the chow used to feed the rats was
contaminated with 12 ppm barium; thus, no true "untreated" control group was
available for comparison.
The highest NOAEL values for neurological effects in each species and
duration category are recorded in Table 2-1 and plotted in Figure 2-1.
2.2.2.5 Developmental Effects
Studies regarding developmental effects of barium following oral
exposure are limited to one human study (Morton et al. 1976) and one animal
study (Tarasenko et al. 1977). A statistically significant negative
correlation was found between barium concentrations in drinking water and
human congenital malformation rates of the central nervous system in South
Wales (Morton et al. 1976). A negative correlation implies that as the barium
concentration in drinking water increased, the rate of central nervous system
malformations decreased. This statistical study is of limited value in
identifying a NOAEL for developmental effects because exposure conditions
(duration and frequency of exposure, dose, number of subjects exposed) were
not characterized.
Developmental effects were reported in one study in which female rats
were treated orally during conception and pregnancy with approximately 18.3 mg
barium/kg/day as barium carbonate (Tarasenko et al. 1977). Reported effects
in offspring included increased mortality, increased leukocyte count,
disturbances in liver function, and increased urinary excretion of hippuric
acid. The latter study is inadequate for evaluating developmental effects of
oral barium exposure because of major study limitations. These limitations
include a general lack of information provided by the authors regarding
experimental methods, exposure conditions, and test results, and no
information as to the number of animals tested, the purity of the test
material, the statistical methods used, and whether or not controls were used.
No other animal studies evaluating developmental effects were available.
2.2.2.6 Reproductive Effects
No studies were located regarding reproductive effects in humans after
oral exposure to barium. However, limited data are available from acute,
intermediate, and chronic animal studies in which certain reproductive organs
were weighed and examined grossly and microscopically following oral barium
exposure. Acute gavage exposure of rats to doses as low as 198 mg