Hexavalent ChromiumMay also be known as: Chromium 6, Cr6, Cr(VI)

There are two potential sources of hexavalent chromium in drinking water – natural sources such as rocks, minerals, and other geology, and localized industrial runoff. Typical U.S. drinking water supplies contain naturally occurring chromium.

National and international regulatory agencies have set drinking water standards to protect the public from all forms of chromium – hexavalent chromium (Cr6) and trivalent chromium (Cr3) – in drinking water. The U.S. government has regulated chromium in drinking water since 1946.

• The Safe Drinking Water Act (SDWA) requires the U.S. Environmental Protection Agency (EPA) to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. EPA has a drinking water standard of 100 parts per billion (ppb) for total chromium. This standard includes all forms of chromium, and the EPA standard assumes 100 percent hexavalent chromium in the water.
• In 2020, the World Health Organization (WHO) issued a final background document that recommends retaining the current WHO guideline value for total chromium of 50 ppb based on newer, high-quality data.
• In 2018, Health Canada issued a final maximum acceptable concentration of 50 ppb for total chromium.
• In 2016, the Texas Commission on Environmental Quality published its final support document setting a reference dose of 0.003 mg/kg, which is equal to about 100 ppb for oral exposure to hexavalent chromium to be protective of both cancer and non-cancer effects. In fact, this hexavalent chromium reference dose corresponds to the current EPA drinking water standard for total chromium of 100 ppb.