A new interactive map details where hexavalent chromium, the notorious “Erin Brockovich” carcinogen, contaminates tap water serving 251 million people, exceeding levels scientists say are safe. Researchers at the Environmental Working Group analyzed federal and state water testing data to create the map.
The updated map includes 918 new detections of toxic hexavalent chromium, or chromium-6, in California since the last version of EWG’s map was released, in 2016. Chromium-6 contaminates water in all 50 states, Puerto Rico, the Northern Mariana Islands and Guam.
“Too many people are exposed to chromium-6 in their drinking water,” said Tasha Stoiber, Ph.D., a senior scientist at EWG. “Communities across the country have water with potentially harmful levels of this carcinogen.”
In January, researchers at the University of California, Berkeley, and the University of California, Los Angeles, found that 371,000 Californians are drinking water that may contain high levels of chromium-6, or chemicals like arsenic and nitrate. The researchers found disproportionate harm to communities of color and emphasized that the results of the study likely understated the number of people affected by unsafe drinking water.
“People have a right to clean and affordable drinking water served by community water systems and wells,” Stoiber said. “Despite knowledge of chromium-6 contaminating tap water, the Environmental Protection Agency has done nothing.”
There are no federal rules limiting chromium-6 in drinking water. The EPA has a drinking water standard of 100 parts per billion, or ppb, for total chromium, which includes all forms of chromium, including chromium-6. That standard is based on potential adverse dermatological effects over many years, such as allergic dermatitis and other skin reactions.
In 2007, the National Toxicology Program, a branch of the National Institutes of Health, published finding that long-term exposure to chromium-6 caused cancer in rodents. The EPA in 2008 then began a review of the harmful health effects linked to exposure to chromium-6 in drinking water. That review is ongoing.
“It is inexcusable the government has done so little to protect us from exposure to chromium-6, which has been shown to cause cancer,” said David Andrews, Ph.D., a senior scientist at the EWG.
“In nearly 15 years, the EPA has been unable to publish a completed human health assessment of chromium-6, which further blocks any progress toward a health-protective drinking water standard for this carcinogen. Every American should be outraged by this inaction,” Andrews added.
Government scientists in California and other states say extraordinarily low levels of chromium-6 can cause cancer in people. An analysis by state scientists in California showed that exposure in water suggests chromium-6 may cause stomach cancer.
If inhaled, chromium-6 particles can cause lung cancer. Ingestion through tap water is linked to stomach cancer, liver damage, reproductive problems and harm to children's brain development.
Under an EPA program, from 2013 to 2015, local water utilities took more than 60,000 water samples and found chromium-6 in more than three out of four. The EPA’s tests were spurred by a 2010 EWG investigation that found elevated levels of chromium-6 in the tap water of 31 of 35 cities sampled.
Chromium-6 is used to lower the temperature in electrical power plants’ cooling towers. Contamination can also originate from the improper disposal of industrial wastes, especially those created during the manufacture of chrome metal plating, wood and textiles products, and stainless steel. Chromium-6 is also a naturally occurring metallic element and can enter water sources through erosion, from natural deposits.