Chromium 6 and Erin Brockvich are getting more press again. The California Department of Health has placed a health goal of 0.02 ppb on Chromium 6 is drinking water but the reality is that 10 ppb is about the best that can be expected since Chrome, both as 3 and 6 are fairly common in US ground water, especially in the more desert regions of the southwestern US. It was recently "discovered" that Chromium 6 at about 2 ppb is common in North Carolina ground water and based on a larger EPA study about 218,000,000 people in the US have greater than 0.02 ppb in their water supplies.
So Ms. Brockovich has picked up the battle again and quoted something interesting, "12,000 excess cases of cancer by the end of the century." So in 84 years the US can expect 12,000 "excess" cases of cancer based on testing of mice and rats. Mice and rats are not "human" so there is some debate on how valid animal test actually is, so Chromium 6 is listed as a "probable" carcinogen not a known carcinogen like say Vodka. A UK study estimated that 4% of all UK cancers were "caused" by drinking alcohol and the Chromium 6 "crisis" should produce an excess cancer rate on the order of 0.0003% which is close to negligible in my opinion.
California is known for attempting extremely conservative health standards while 1 in a million is generally considered negligible, the 0.02 ppb looks to be about 1 in 2.25 million. 1 or 2 ppb is generally considered "safe" with the EPA picking 10 ppb as an action level. For some perspective, you have a 1 in 6000 chance of dying in a car crash driving 10,000 miles per year and about a 1 in 16,000 chance of not making back from a hike in the mountains. I am pretty sure mountain biking increases your risk. The current US risk for all cancers is in the about 50% over a lifetime and 84 years is one ample lifetime.
So while by her own sources there is as close to negligible risk as is possible, that doesn't stop Ms. Brockovich from trying to make some health related point to save the good people of the US from some evil corporate demon. I am all for clean water, but this is getting bizarre.