WHAT IS CHROMIUM-6?
Hexavalent chromium (chromium (VI), Cr (VI), chromium-6) refers to chemical compounds that contain the element chromium in the +6 oxidation state. Additional hexavalent chromium compounds are chromium trioxide and various salts of chromate and dichromate. Chromium 6 is used in textile dyes, wood preservation, anti-corrosion products, chromate conversion coatings, and a variety of niche uses. Industrial uses of hexavalent chromium compounds include chromate pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and chromic acid electroplated onto metal parts to provide a decorative or protective coating.
CHROMIUM-6 can be formed when performing "hot work" such as welding on stainless steel or melting chromium metal. In these situations the chromium is not originally hexavalent, but the high temperatures involved in the process result in oxidation that converts the chromium to a hexavalent state. Hexavalent chromium can also be found in drinking water and public water systems.
Inhaled hexavalent chromium is recognized as a human carcinogen (causing cancers in humans). Workers in many occupations are exposed to hexavalent chromium. Problematic exposure is known to occur among workers who handle chromate-containing products and those who grind and/ or weld stainless steel. Workers who are exposed to hexavalent chromium are at increased risk of developing lung cancer, asthma, or damage to the nasal epithelia and skin. Within the European Union, the use of hexavalent chromium in electronic equipment is largely prohibited by the Restriction of Hazardous Substances Directive.
WHAT IS IT USED FOR?
Chromium-6 is rare in nature, and is produced by industrial processes. Chromium-6 is used in electroplating, stainless steel production, leather tanning, textile manufacturing and wood preservation, according to the National Toxicology Program (PDF). Chromium-6 is also found in the ash from coal-burning power plants and used to lower the temperature of water in the cooling towers of power plants.
HOW MUCH CHROMIUM-6 ARE YOU AND YOUR NEIGHBORS DRINKING?
Check out Environmental Working Group's Interactive Chromium-6 Map below to see the current levels of Chromium-6 in your community's water supply.
LONG-TERM HEALTH EFFECTS
In 2008, a two-year study by the National Toxicology Program found that drinking water with chromium 6, or hexavalent chromium, caused cancer in laboratory rats and mice. Based on this and other animal studies, in 2010, scientists at the respected and influential California Office of Environmental Health Hazard Assessment concluded that ingestion of tiny amounts of Chromium-6 can cause cancer in people, a conclusion affirmed by state scientists in New Jersey and North Carolina. There also is human evidence that drinking Chromium 6 contaminated water can cause cancer. A study in China found high rates of stomach cancers in people whose water was contaminated with so much Chromium-6 from a smelter that it had turned yellow.
The California scientists set a so-called public health goal of 0.02 parts per billion in tap water, the level that would pose negligible risk over a lifetime of consumption. (A part per billion is about a drop of water in an Olympic-size swimming pool.) But in 2014, after aggressive lobbying by industry and water utilities, state regulators adopted a legal limit 500 times the public health goal. It is the only enforceable drinking water standard at either the state or federal level.
Chromium 6 Contamination Bedevils Calif. City
- New drinking water test results show chromium-6 problem goes beyond city of Houston (KPRP Houston)
- Paramount metal finisher suspends operations after violating Chromium 6 pollution limit (Los Angeles Times)
- Water Worries: Carcinogen found in SWLA water systems (KPLC 7 SW Louisiana)
- Toxin delays bids for water plant in Shrewsbury (Telegram, Worcester, MA)
- New report finds 'Erin Brockovich' chemical in US drinking water (CNN)
- Chromium-6 in Tap Water: Why the 'Erin Brockovich' Chemical Is Dangerous (Live Science)
- More North Carolina Residents Warned Of Contaminated Drinking Water (Think Progress)
- 15 Years After 'Erin Brockovich', Town Still Fearful of Polluted Water (Los Angeles Times)
- Chromium in Drinking Water Causes Cancer: National Toxicology Program results "clearly" indicate that the heavy metal is carcinogenic (Scientific American)