TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

51
2. HEALTH EFFECTS
Singh 1970; Diengott et al. 1964; McNally 1925; Ogen et al. 1967; Talwar and
Sharma 1979), a single intermediate-duration experimental study (Wones et al.
1990), and several human epidemiological studies or statistical studies
examining mortality and morbidity rates in communities having exposure to
barium through drinking water supplies (Brenniman and Levy 1985; Brenniman et
al. 1979a, 1979b, 1981; Elwood et al. 1974; Schroeder and Kraemer 1974).
Dermal studies are limited to one case report of an exposed individual
(Stewart and Hummel 1984).
The majority of studies conducted on animals have been oral exposure
studies (Figure 2-2). These oral studies have focused on examining mortality
or various systemic effects following acute (Borzelleca et al. 1988; Boyd and
Abel 1966; Tardiff et al. 1980), intermediate (McCauley et al. 1985; Perry et
al. 1983, 1985, 1989; Tarasenko et al. 1977; Tardiff et al. 1980), and chronic
exposure (Kopp et al. 1985; McCauley et al. 1985; Perry et al. 1983, 1985,
1989; Schroeder and Mitchener 1975a, 1975b). Available inhalation studies
with experimental animals (Hicks et al. 1986; Tarasenko et al. 1977) can only
suggest information on the health effects of barium because these studies have
a number of limitations and deficiencies. Dermal studies with experimental
animals are limited to one skin irritation study (Tarasenko et al. 1977) and
one study evaluating the tumor-promoting activity of barium (Van Duuren et al.
1968).
2.9.2 Data Needs
Acute-Duration Exposure. The majority of experimental studies involving
acute.exposure to barium chloride have focused on oral exposure of rats
(Borzelleca et al. 1988; Tardiff et al. 1980). These studies have determined
acute oral LD 50
values, as well as evaluated systemic effects. Systemic
effects were evaluated primarily by monitoring body weights, selected organ
weights, and various hematological and blood chemistry parameters, and by
performing gross and microscopic examinations of selected organs and tissues.
These studies have provided evidence that barium chloride is lethal by oral
ingestion (LD 50
s range from 132 to 277 mg/kg). The study by Borzelleca et al.
(1988) has also provided evidence that acute oral barium exposure is
associated with reduced blood urea nitrogen, inflammation of the intestines,
accumulation of fluid in the trachea, decreased liver/brain weight ratio,
darkened liver, increased kidney/body weight ratio, decreased body weight,
decreased ovary weight, and decreased ovaries/brain weight ratio. This study
has also provided information as to the barium levels inducing these effects
in experimental animals. In the only available acute inhalation study,
limited evidence was provided suggesting that barium exposure is potentially
associated in rats with increased blood pressure and bronchoconstriction
(Hicks et al. 1986). However, this inhalation study was limited in that no
controls were used, Limited acute testing of experimental animals also has
provided suggestive evidence that barium carbonate is both a dermal and ocular
irritant (Tarasenko et al. 1977). Given the available data from acute