Several industrial processes use hexavalent chromium.

Chromium-6 on Tap

Surely you've seen the reports about the Environmental Working Group's study, titled Chromium-6 in U.S. Tap Water, by now. I was first struck with the level of hexavalent chromium found in Norman, Oklahoma's sample (12.9 ppb) and how little was said about that, except by Norman, of course. (The next highest level of chromium-6 was 2 ppb in Honolulu.)

Andy Rieger of The Norman Transcript wrote an article on Sunday in which Norman utilities Director Ken Komiske noted that chromium is a naturally occurring element whose levels fluctuate. Residents get their drinking water from a blend of Lake Thunderbird's surface water, which is treated, and raw well water. According to Rieger's article, the city taps into groundwater from the Garber-Wellington aquifer and it is known for containing some heavy metals.

Komiske and other utility directors test for total chromium (100 ppb maximum contaminant level goal). Total chromium is an EPA standard that addresses both trivalent chromium, an essential mineral, and the toxic version, which research has linked to intestinal cancer. The agency standard was developed in 1992 and mentions only allergic dermatitis as one of the metal's health effects. EWG is urging U.S.EPA to "get with the program" and set a meaningful standard already.

Environmental Working Group graph showing levels of hexavalent chromium found during one sampling event.

Click here for larger image.

The 35 cities that were tested had previously reported high total chromium. So I also was surprised to find that Plano, Texas (the only Texas city tested) had a nondetectable level. But, as you know, that's not necessarily good news. It was just one sample.

The federal agency is not the only one dragging its feet. Although California has been working for some time on a chromium-6 standard (think: Erin Brokovich and Hinkley, Calif., 1996), its agencies should have had rules in place by Jan. 1, 2004. More recently, Cal EPA proposed a 0.06 ppb level to lower the health risk while U.S. EPA is conducting more review.

Do you think everyone in Norman should attach reverse osmosis filters to their taps now or is 12 ppb on one particular day just a proverbial drop in the chemical bucket?

Posted by L.K. Williams, EPonline on Dec 20, 2010

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