TOXICOLOGICAL PROFILE FOR BARIUM AND COMPOUNDS ...

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2. HEALTH EFFECTS
through public drinking water supplies, food, or ambient air generally should
not pose a significant health risk to humans because of the very low levels of
barium that would typically be associated with these types of exposures.
Since barium is a frequent contaminant at hazardous waste sites, humans
living or working near these sites may potentially become exposed to barium.
Concentrations of barium in soil or groundwater may be significantly elevated
over background levels at hazardous waste sites, thereby posing a potential
health risk to humans. Soil contaminated with barium is of concern because
airborne dusts generated from contaminated surface soil through the action of
wind may potentially expose individuals by inhalation. Airborne barium dusts
generated from contaminated surface soil could potentially form residues on
foods that are ingested. There is also the potential that children may ingest
barium through hand to mouth contact following playing in contaminated soil.
Groundwater contaminated with barium is of concern because of the potential
for humans to ingest such water. Contaminated soil and groundwater also are
of concern because individuals may directly become exposed dermally through
airborne dusts, through direct contact with contaminated soil from
construction, excavation, or recreational activities, and/or through direct
contact by showering with contaminated water.
There is little quantitative information regarding the extent of barium
absorption following inhalation, oral, or dermal exposure. Available evidence
indicates that barium is absorbed to some extent following inhalation, oral,
and dermal exposure; however, absorption in some cases is expected to be
limited. For example, there is some evidence that gastrointestinal absorption
of barium in humans is less than 5-30% of the administered dose. These latter
data suggest that although individuals may become exposed orally to high
levels of barium, adverse health effects may not necessarily develop because
of the limited gastrointestinal absorption. Another important factor
affecting the development of adverse health effects in humans is the
solubility of the barium compound to which the individual is exposed. Soluble
barium compounds would generally be expected to be of greater health concern
than insoluble barium compounds because of the greater potential of soluble
barium compounds to be absorbed by the body.
The different barium compounds have different solubilities in water and
body fluids and therefore they serve as variable sources of the Ba 2+
ion. The
Ba 2+
ion and the soluble compounds of barium (notably chloride, nitrate,
hydroxide) are toxic to humans. The insoluble compounds of barium (notably
sulfate and carbonate) are inefficient sources of Ba 2+
ion because of limited
solubility and are therefore generally nontoxic to humans (IL0 1983). The
insoluble, nontoxic nature of barium sulfate has made it practical to use this
particular barium compound in medical applications such as enema procedures
and in x-ray photography of the gastrointestinal tract. Barium provides an
opaque contrasting medium when ingested or given by enema prior to x-ray
examination. Under these routine medical situations, barium sulfate is
generally safe. However, barium sulfate or other insoluble barium compounds