By the  way I forgot to ...

By the  way I forgot to mention that Chrome VI is not a cancer risk anywhere near drinking water exposure levels. Canada has recently updated the technical rationale for its drinking water guideline with all of the new and very substantial toxicology data base, and kept its original value of 50 ppb; the US standard is 100 ppb. It concluded, as has been  recognized for at least 70 years, that ingested Cr VI is a threshold carcinogen, meaning that there is a safe level without risk. Humans have a much greater innate CrVI to CrIII reduction capacity than the test mouse that had the cancers in the very high dose test studies that triggered the activity. California's 10 ppb standard has been rescinded in the last few weeks by the court because they did not provide the appropriate impact analysis that is required in their statute.