Thinking About Chromium In Drinking Water

By the Water Research Foundation (WRF)

Project 4457 from WRF provides the water community with tools for understanding and communicating the risks associated with contaminants of emerging concern (CECs). As part of the initiative, WRF has created question-and-answer articles for each of four substances: VOCs, chromium, medicines and personal care products, and NDMA. The core message sheets were developed following best practices for risk communication as employed by the Centers for Disease Control and Prevention (CDC). What follows is WRF's core message sheet covering chromium, and specifically chromium-6 (hexavalent chromium).

The United States has some of the safest public water supplies in the world. Our drinking water is treated and monitored to assure that the water being delivered is safe for consumption. While our water is safe, drinking water quality and management is understandably complicated. Small traces of naturally occurring or human-made substances can sometimes find their way into tap water. One such substance is chromium.

What is chromium?
Chromium is a naturally occurring metal common in the earth’s crust. There are multiple forms of chromium,ⁱ and one form, called chromium‐3, is actually a required nutrient for human health, in the right amount.ⁱⁱ Chromium in some forms can be toxic at certain doses, such as chromium‐6 which is also known as hexavalent chromium.

Where does chromium in drinking water come from?
Naturally occurring levels of chromium in water could come from rocks, plants, or soil,ⁱⁱⁱ and are usually at levels well below the federal standard for drinking water. However, human activities such as industrial processes can lead to higher levels of chromium in drinking water.^iv Chromium‐6 compounds are used widely in industrial applications like steel production, textile dye production, wood preserving, and leather tanning.

Why is chromium in drinking water a concern?
Concern has been raised about the potential hazards related to ingestion of chromium‐6 in drinking water because of a 2008 animal study that suggested chromium‐6 may be a human carcinogen if ingested. It is a known human carcinogen when inhaled; the Environmental Protection Agency (EPA), the federal regulatory agency for safe drinking water, is currently investigating whether it is also a human carcinogen when ingested. This investigation will aid in determining whether a new drinking water standard is needed for chromium‐6 versus the existing regulation for total chromium.^v Federal drinking water standards currently limit hexavalent chromium in drinking water by limiting the total amount of chromium that can be in water.

What solutions exist for chromium?
Chromium is easily detected in water, even in extremely low concentrations (0.000 000 001). Treatment technologies exist to reduce or remove chromium from drinking water; water providers manage hexavalent chromium levels by controlling total chromium levels.^vivii Many, but not all, home water filters can remove chromium when operated and maintained correctly.^viii Bottled water also must meet the Food and Drug Administration (FDA) standard for chromium. The EPA has provided guidance to public water systems for monitoring chromium so that they can assess existing water treatment’s effectiveness.

Source of information
This information is based on detailed technical information prepared by Dr. Shane Snyder. Dr. Snyder is a Professor of Chemical & Environmental Engineering, and holds joint appointments in the College of Agriculture and School of Public Health, at the University of Arizona. He also co‐directs the Arizona Laboratory for Emerging Contaminants (ALEC) and the Water & Energy Sustainable Technology (WEST) Center. For nearly 20 years, Dr. Snyder’s research has focused on the identification, fate, and health relevance of emerging water pollutants. Dr. Snyder has been invited to brief the Congress of the United States on three occasions on emerging issues in water quality. He has served on several US EPA expert panels and is currently a member of the EPA’s Science Advisory Board drinking water committee. He was recently appointed to the World Health Organization’s Drinking Water Advisory Panel.

ⁱ US EPA. (2013a). Basic Information about Chromium in Drinking Water. [Website]. Last updated 12/13/2013. Washington DC: United States Environmental Protection Agency (US EPA), Office of Water. http://water.epa.gov/drink/contaminants/basicinformation/chromium.cfm
ⁱⁱ US EPA. (2013a). Basic Information about Chromium in Drinking Water. [Website]. Last updated 12/13/2013. Washington DC: United States Environmental Protection Agency (US EPA), Office of Water. http://water.epa.gov/drink/contaminants/basicinformation/chromium.cfm
ⁱⁱⁱ Cal/EPA. (2011). Public Health Goal for Hexavalent Chromium (Cr VI) in Drinking Water.July 2011. Prepared by the California Environmental Protection Agency (Cal/EPA), Office of Environmental Health Hazard Assessment, Pesticide and Environmental Toxicology Branch. http://oehha.ca.gov/water/phg/pdf/Cr6PHG072911.pdf
^iv IARC. (2012). IARC Monographs (Volume 100C‐9): A review of human carcinogens: Arsenic, metals, fibres, and dusts: Chromium (VI) compounds. International Agency for Research on Cancer (IARC). http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C‐9.pdf
^v file:///C:/Users/admsnyders2/Downloads/CHROMIUMVI_ERD_TOXREVIEW_9‐30‐10.PDF
^vi AWWA (2014). http://www.drinktap.org/home/water‐information/water‐quality/ucmr3/chromium.aspx. Accessed April 23, 2014.
vii AWWA. (2013). Chromium in Drinking Water: A Technical Information Primer. Denver, Colorado: American Water Works Association (AWWA). http://www.awwa.org/Portals/0/files/legreg/documents/UpdatedChromiumInDrinkingWaterSummaryFinal.pdf
^viii US EPA. (2013a). Basic Information about Chromium in Drinking Water. [Website]. Last updated 12/13/2013. Washington DC: United States Environmental Protection Agency (US EPA), Office of Water.