Chromium occurs naturally in the environment as chrome iron ore, or chromite, and it is rarely found naturally in drinking water. Chromium, as an organo-metallic complex, is one of the most recent additions to the list of elements essential to human and animal nutrition. It is widely distributed in soils and plants. The U.S. EPA has determined that there is no evidence that a lifetime of exposure to chromium in drinking water below 0.1 mg/L has potential to cause cancer. However, large doses of chromium are toxic to both plants and animals.
The most toxic from of chromium dissolved in water is the ion Cr+6, used in leather tanning and the control of bacteria in cooling systems. Cr+6 was the contaminant that was the basis of the story-line for the "Erin Brokovich" movie. Although trace amounts of Cr+6 have been found in some aquifers, the most common source is industrial pollution.
Persons with "traces of chromium" in their drinking water are encouraged to have their water tested again to see what form of Cr is present. Some forms of Cr are more harmful than others.
The EPA has approved the following for chromium: Coagulation/Filtration, Ion Exchange, Reverse Osmosis, and Lime Softening. The eXtension Drinking Water page, Home Water Treatment Devices, posts information about treatment systems.
