Yellow Water: No Need to Have Panicked?
Hexavalent chromium (Cr (VI)) turns well water yellow. Disgusting, sure, but is it harmful? Well, when inhaled Cr (VI) can cause lung cancer in humans; and that's all it took to launch a lawsuit on behalf of the citizens of Hinkley, CA whose groundwater had been contaminated with Cr (VI). The case settled for $333 million and spawned the movie Erin Brockovich.
So what was the cancer burden from Cr (VI) in Hinkley? According to a new study reported on in the LATimes (Fewer Cancers Found in Hinkley Than Expected) the answer is none whatsoever. In fact, while 224 cancers would have been expected in an unexposed population of similar size and demographic make up, only 196 cancers were identified in Hinkley - more than a 12% decrease in cancer.
There's not much new in the literature on Cr (VI) and the claim that hexavalent chromium in water causes cancer is at best controversial. The newest paper supporting a link, "A Quantitative Assessment of the Carcinogenicity of Hexavalent Chromium by the Oral Route and its Relevance to Human Exposure" found that long suffering lab mice exposed to many times the levels in Hinkley developed cancer of the small intestine (not among the complaints chronicled by the panicked residents in the LATimes' report). The finding was said to provide further support for the claim that Cr (VI) is "likely to be carcinogenic to humans". Nevertheless, epidemiologists have yet to identify a clear case in which it actually has been carcinogenic to humans.
