What Is Hexavalent Chromium?
Hexavalent chromium (Cr(VI)) is a form of the element chromium, which is one of the most abundant chemical elements found in the earth’s crust. 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 (Cr(VI) and Cr(III)) in drinking water. Cr(III), also known as trivalent chromium, can also be naturally present in drinking water and is a micronutrient that is essential for metabolism. The human body naturally detoxifies low levels of Cr(VI) into non-toxic Cr(III), no matter the source. The EPA, for example, has a drinking water standard of 100 parts per billion (ppb) for total chromium. See what various regulatory agencies have to say about hexavalent chromium here.
The EPA’s IRIS Assessment for Hexavalent Chromium
In October 2022, the EPA released a draft Cr(VI) Integrated Risk Information System (IRIS) assessment of oral and inhalation exposure for public comment. The EPA’s IRIS program identifies human health hazards associated with a substance. The IRIS program, however, has a troubling history of being out of step with the best available science and methods, lacking transparency, and being unresponsive to peer review and stakeholder recommendations. This draft IRIS assessment for hexavalent chromium is at odds with the findings of over 30 peer-reviewed studies, which support a threshold for effects and a non-linear, dose-dependent response.