TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
Developmental Toxicity. The developmental effects of barium have not
been studied extensively in either humans or animals. One limited statistical
study evaluated the degree of correlation between barium concentrations in
drinking water and human congenital malformation rates of the central nervous
system (Morton et al. 1976). Results of the study indicated there was a
negative statistical correlation between these parameters. However, another
limited report provided suggestive evidence that exposure to barium may
potentially be associated with adverse developmental effects (Tarasenko et al.
1977). Reduced survival, underdevelopment, lowered body weight, decreased
lability of the peripheral nervous system, and various blood disorders were
reportedly noted in the offspring of rats following inhalation to barium for
an intermediate exposure period. In the same report, increased mortality,
increased leukocyte count, disturbances in liver function, and increased
urinary excretion of hippuric acid were reportedly noted in the offspring of
rats treated orally to barium during conception and pregnancy.
Epidemiological or occupational studies with humans and/or additional
experimental studies with animals would be useful to better characterize the
potential developmental and teratogenic effects of barium since the evidence
of one animal study suggests that barium exposure may be associated with
developmental toxicity.
Immunotoxicity. The effect of barium on the immune system has not been
well studied. No studies were available regarding immunological effects in
humans or animals following inhalation or dermal exposure to barium. Data
regarding immunological effects following oral exposure are limited to two
investigations with rats (Borzelleca et al. 1988; McCauley et al. 1985).
Results of these studies suggested that acute, intermediate, and chronic oral
exposure to barium was not associated with any changes in thymus weight or
with any gross or microscopic lesions of the thymus or lymph nodes.
Additional studies evaluating a variety of immunological parameters following
various routes of barium exposure would be useful because of the limited
nature of the immunotoxicity database for barium.
Neurotoxicity. Data regarding the neurological effects of barium are
derived primarily from case studies of exposed humans. One case study of a
human provided information suggesting that acute inhalation exposure to barium
may be associated with absence of deep tendon reflexes (Shankle and Keane
1988). Numerous other case studies of humans has provided information
suggesting that acute oral exposure to barium may be associated with numbness
and tingling of the mouth, partial or complete paralysis, and brain congestion
and edema (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; Wetherill et al. 1981). However, acute and intermediate oral
exposure of rats to barium has not been associated with changes in brain
weight or gross or microscopic lesions of the brain (Borzelleca et al. 1968;
Tardiff et al. 1980). No data were available regarding neurological effects
in humans and/or animals following dermal exposure. Based on the suggestive