CNN reports on a new study this week about the level of chromium-6 found in U.S. drinking water.
The naturally occurring substance was the issue in the Erin Brockovich story, made famous by a movie. As CNN notes, the U.S. has no specific EPA guideline for the chemical in water, though there are strict standards on the substance in air for its potential to cause lung cancer. Only California enforces a water limit — 10 parts per billion. The Environmental Working Group, which has compiled data from across the country, believes 75 percent of samples of water done by water utilities for the EPA from 2013 to 2015 exceeded a safe level.
A study that indicated the substance could cause cancer in rats that drink it prompted California to set a goal of .02 parts per billion in tap water.
You’ll see from the CNN report a divergence of opinion on the question, including high alarm in some quarters, particularly the EWG. It has mapped the concentrations found in water utilities across the country and it’s searchable by county.
The 16 sample ranged from .04 to .10 parts per billion of chromium-6, all well below the legal standard in California, but above the goal standard that California now believes to be a safer level, with negligible health risk from ingestion of water over an extended period..
I’m seeking a comment from CAW, as the major local water supplier, but a search of the map shows various findings in the state.
UPDATE: I spoke with Randy Easley, director of water quality for CAW, who said the numbers compiled by EWG came from a periodic assessment of non-regulated substances in water supplies. (An EPA standard for chromium mentioned by a reader is for all chromium combined, not chromium-6, Easley said.) He said CAW’s water is cleaner than many because it is supplied by lakes who are vigorously protected, rather than from groundwater that can be contaminated by industrial processes. Inevitably, some material can find its way into the system, such as from degradation of chrome plumbing fixtures. But he noted the level here is many times below the California standard. “Everything in our opinion looks pretty good,” he said.