The average water sample in Phoenix had the highest level of the toxin among water utilities nationwide serving more than 1 million customers, with almost 400 times the amount of chromium-6 that California scientists set as a health goal. But because that number is an average, it doesn’t quite represent the levels of chromium-6 in the water that customers drink, a city water official said.
Samples from city wells had the highest levels of the contaminant but contribute a small fraction to the tap, said Susan Kinkade, a Phoenix civil engineer. Taking that into consideration, chromium-6 levels in Phoenix drinking water are on average about 20 times the California goal.
The report also found that Glendale’s water had an average chromium-6 level 320 times the health goal. But like Phoenix, the higher levels dwell in groundwater that contributes far less to the water supply than surface water, said Doug Kupel, deputy director of water services in suburban Glendale.
Glendale is already setting aside money in anticipation that the U.S. Environmental Protection Agency will mandate a new limit for chromium-6, he said.
Reaching California’s legal limit of 10 parts per billion would be expensive — but reaching the health goal of .02?
“I don’t think that’s feasible really across the nation,” Kupel said.
“Goal” is a key word there: The EPA’s total chromium limit is 5,000 times the health goal, and based on preventing skin reactions. California is the only state that established a limit specifically for chromium-6, according to the non-profit Environmental Working Group, which authored the report released Monday.
But that is 500 times the amount that the California Office of Health Hazard Assessment recommended and reflects a risk that 500 people out of a million will get cancer.
The Environmental Working Group, an environmental health research and advocacy organization, determined that 12,000 Americans are at risk of cancer from chromium-6 ingestion in its report. The authors used California’s health goal as a benchmark, which would put no more than one-in-a-million at a risk of cancer over a 70-year lifetime.
Chromium-6 gained national attention in the 1990s when then-legal clerk Erin Brockovich helped residents in Hinkley, Calif., settle a massive case against Pacific Gas and Electric Co. The electric utility had polluted the groundwater with cancer-causing chemicals, which Brockovich linked to illnesses in the town.