MCL: 0.1 ppm
Source: Used in chrome plating, steel alloys, and pigments. Chromium occurs naturally in rocks and minerals and the most dangerous contaminant is hexavalent chromium, chromium(VI).
Water Treatment: https://tdb.epa.gov/tdb/contaminant?id=10040
Summary: Chromium is element 24 on the periodic table. It is found naturally in rocks and minerals in the form of chromium(0). Chromium(III) and chromium(VI) are produced through industrial methods and are involved in making steel alloys and chrome plating. Chrome plating is widely used in stainless steel. Chromium(VI) is known as hexavalent chromium and is used for its anti-corrosive properties despite being a known carcinogen. It is used in protective coatings. Both trivalent and hexavalent chromium are used in wood preservation and pigments. Trivalent chromium is beneficial for dietary purposes in humans but the total concentration of chromium is federally regulated because the speciation of chromium may change under different conditions in water. Hexavalent chromium may occur naturally and become an environmental contaminant in water from dissolution or erosion. Chromium has a density of 7.14 g/mL at 20 C.
GHS Hazard Statement: H317, H319, H320, H334, H335, H341, H371, H400, H410, GHS07, GHS08, GHS09