27
Barium [Ba, 56]
and Ba is able to enter the bloodstream. Pulmonary baritosis (or simply known as
baritosis) is a type of benign nonfibrotic pneumoconiosis, which can be precipitated
by the inhalation of Ba particles (usually BaSO 4 ). Inhaled Ba particles can lie in the
lungs for years, without producing symptoms or causing impairment in lung function
(ATSDR 2007a).
Chronic exposure to Ba is often associated with effects on the cardiovascular system. There may be a connection between its high levels in drinking water and high
blood pressure, as well as cardiac mortality (Reilly 2002).
The most important route of exposure to Ba appears to be the ingestion of Ba
through drinking water and food. Particles containing Ba may be inhaled into the
lungs, but little is known regarding the absorption of Ba by this route. However, there
are data that suggest that Ba may interact with other cations and certain drugs.
The cations K, Ca, and Mg also interact with Ba. Barium exposure, for example,
may cause a buildup of K inside the cell, resulting in extracellular hypokalemia,
which is believed to mediate Ba-induced paralysis. In fact, K is a powerful antagonist of the cardiotoxic and paralyzing effects of Ba in animals, and is used as an
antidote in cases of acute Ba poisoning. Ca and Mg suppress the uptake of Ba by pancreatic islets, in vitro. Conversely, Ba, in low concentrations, stimulates Ca uptake in
these cells (ATSDR 2007a).
Barium is present in all food groups, at varying concentration, with the highest in nuts (Table 4.2). Tolerable daily intake of 0.2 mg Ba/kg bw/day is set by the
WHO. Mean daily intake of Ba was estimated from 0.75 to 1.33 mg/person, including both food and fluids (WHO 2001b). In the United Kingdom, in 2006, the population dietary exposure to Ba was 0.847 mg/day, and this increased from 0.58 mg/day
reported in 1994 (Rose et al. 2010).