EPA recently released its draft Integrated Risk Information System (IRIS) toxicological review of hexavalent chromium (also known as chromium-6). Hexavalent chromium is used in pigment manufacturing, metal finishing and chrome plating, stainless steel production, leather tanning, and wood preservatives. It has various other industrial applications as well. The metal is also emitted into the air when fossil fuels are burned.
The metal gained significant attention in 2000 with the release of the movie Erin Brokovich. The film detailed the story of a class action lawsuit by Californians against Pacific Gas & Electric Company for dumping wastewater containing chromium into ponds, subsequently polluting groundwater supplies.
Hexavalent chromium is a known carcinogen in humans when inhaled, including increased lung cancer rates found in workers exposed at higher than normal levels in industries that process or use chromium or chromium compounds. The metal is also known to cause nasal and sinus cancers, kidney and liver damage, nasal and skin irritation, and other adverse health effects.
Less information has been known about the effects of ingesting hexavalent chromium. EPA’s current standard for the metal in drinking water is a maximum contaminant level of 100 parts per billion. The draft IRIS reports that ingestion through drinking water is likely carcinogenic, and once finalized, EPA will use the IRIS review to make assessments of risk related to ingestion exposure.
The draft is currently open for public comment until December 19, 2022. EPA Scientific Advisory Board will hold a hearing to discuss hexavalent chromium following the closing of the comment period.