Chromium-6, a carcinogen, contaminates the tap water of two-thirds of Americans at levels above what scientists say is safe, according an analysis of federal water testing data by the Environmental Working Group.
Under an Environmental Protection Agency program, from 2013 to 2015, local water utilities took more than 60,000 water samples and found chromium-6 in more than 75 percent of them. The EWG's analysis of the EPA data estimates that water supplies serving 218 million Americans have potentially unsafe levels of the chemical.
The EWG's interactive map shows the chromium-6 test results by county for the 50 states. Of major metro areas, Phoenix has the highest level of the contaminant, followed by St. Louis County, Houston, Los Angeles, and Suffolk County, New York. But every U.S. water system serving more than 1 million people has chromium-6 concentrations that could be harmful, the EWG analysis found.
Government scientists in California and other states say very low levels of chromium-6 can cause cancer in people. But federal regulations are stalled by a chemical industry challenge of how the EPA calculates cancer risk, said David Andrews, a senior scientist at the EWG and co-author of the report. Of the states, only California has set a legal limit for chromium-6 in drinking water, although the limit is too high to protect public health, Andrews said.
“Houston, we have a problem," said Erin Brockovich, a consumer advocate whose investigation of deaths and disease in a small desert town brought chromium-6 to national attention. "More than 20 years ago, we learned that this dangerous chemical poisoned the tap water of California communities, and now these tests and EWG’s report show that roughly 218 million Americans are being served drinking water polluted with potentially dangerous levels of this known carcinogen.”
“But, in that time, the EPA hasn't set drinking water standards for any previously unregulated contaminant, and there are disturbing signs the agency may again do nothing about chromium-6,” she said. “This is an abject failure by the EPA, including members of Congress charged with overseeing the agency, and every American should be outraged by this inaction.”
Chromium-6 is used in steel production and chrome plating and to lower the temperature in electrical power plants’ cooling towers. It's also in the ash from coal-burning power plants, which is usually dumped into unlined pits where it can get into drinking water.
Inhaling airborne chromium-6 particles can cause lung cancer, and ingesting it through tap water is linked to stomach cancer, liver damage, reproductive problems, and harm to children's brain development.
Comparing the EPA test results to the California scientists' calculations, the EWG estimates that if left untreated, chromium-6 contamination of drinking water could cause more than 12,000 cases of cancer by the end of the century.
But California water quality officials, under intense lobbying from industry, adopted a chromium-6 drinking water standard 500 times the level the state's scientists deemed safe, Andrews said, adding in New Jersey and North Carolina, political appointees quashed state scientists’ efforts to protect public health.
“Americans deserve to know if there are potentially harmful levels of a cancer-causing chemical in their tap water,” he said.