ChromiumChromium is a metal found in natural deposits in the form of ores containing other elements. Chromium is a hard, steel-gray metal that is very brittle. It is classified as a heavy metal. After being refined from chromite ore, its compounds are used in leather tanning and the manufacture of chromic acid, pigments and corrosion-resistant chrome products. Chromium is mainly used in metal alloys such as magnetic tapes, paint pigments, cement, paper and stainless steel. It is also used as an ingredient in drilling mud, used to drill oil wells. Humans need a certain amount of trivalent chromium to stay healthy. However, in other forms, chromium can be toxic to humans. Workers in chromium product factories are at increased risk of lung and nasal cancer. In 1974, Congress passed the Safe Drinking Water Act. This law required the EPA to determine safe levels of chemicals in drinking water that could cause health problems. These levels are called Maximum Contaminant Level Objectives or MCLs....