TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
purulent discharge, conjunctivitis, and slight opacity of the cornea
developed. Although these findings suggest that barium carbonate may be a
dermal and ocular irritant, these particular investigations are inadequate for
establishing the dermal and ocular effects of barium because of a number of
significant study limitations. The authors provided few details regarding
experimental methods and results, and no information as to the concentration
of barium carbonate used, the number of animals used, and whether or not
controls were used. Furthermore, rats are not typically used to evaluate the
skin and eye irritating effects of compounds.
No studies were located regarding the following health effects in humans
or animals after dermal exposure to barium:
2.2.3.3 Immunological Effects
2.2.3.4 Neurological Effects
2.2.3.5 Developmental Effects
2.2.3.6 Reproductive Effects
2.2.3.7 Genotoxic Effects
Genotoxicity studies are discussed in Section 2.4.
2.2.3.8 Cancer
No studies were located regarding cancer in humans after dermal exposure
to barium. Dysplasia of the cervical epithelium was reportedly induced in a
woman who had a barium chloride solution applied to her cervix (Ayre 1966).
The use of dimethyl sulfoxide in combination with the barium chloride solution
reportedly enhanced the ability of barium chloride to induce dysplasia.
Dysplasia can be regarded as a potential precancerous lesion. The
significance of the observations reported in this study are difficult to
assess, since only one subject was exposed and because there have been no
reports of similar findings in other human or animal studies. Also, the
vehicle used was not specified in this study.
No studies were located regarding cancer in animals after dermal
exposure to barium. However, results of one skin-painting study with mice
suggest that barium hydroxide extract derived from tobacco leaf may act as a
tumor-promoting agent (Van Duuren et al. 1968). In this study, mice were
treated dermally for an unspecified period of time with either barium
hydroxide extract alone, 7,12-dimethylbenz(a)anthracene (DMBA) alone (an
initiating agent), or a combination of DMBA and barium hydroxide extract.
After 1 year, none of the mice treated with barium hydroxide extract developed
skin tumors. However, 3 out of 20 mice treated with DMBA alone and 7 out of
20 mice treated with a combination of both barium hydroxide extract and DMBA
developed skin papillomas and carcinomas. These results provide limited, but
suggestive evidence that barium hydroxide extract of tobacco leaf acted as a
tumor-promoting agent. However, it can not be determined whether or not this