MCL: 2 ppm
Source: Naturally occurring, most common source is discharge from industrial processes such as the petroleum industry.
Summary: Barium is element 56 on the periodic table and is found naturally in rocks in compounds such as barium sulfate or barium carbonate. These compounds may be used by oil refineries to create drilling mud, and as such it may appear as a contaminant in water sources as a discharge from these refineries. Elemental barium has 2 valence electrons in its outermost shell, and is highly reactive with elements such as oxygen (oxidizes rapidly). Elemental barium is uncommon in nature. Barium sulfate is also used to improve visualization of x-rays of the gastrointestinal tract.
GHS Hazard Statement: H260, H261, H302, H314, H315, H318, H319, H332, H335, H370, H372, GHS02, GHS05, GHS07, GHS08