Chromium - 6  has been found in dangerous levels in the tap water of over 200 million American households.  

Chromium - 6 gained national attention after the release in 2000 of the movie "Erin Brockovich", the true story about an activist who discovered that chromium - 6 had polluted the water in a small town in California.

An interactive map by the Environmental Working Group based on findings from the ​EPA illustrates a breakdown of the findings. It clearly illustrates the presence of chromium - 6 in water systems in all 50 states.   The report compiled thousands of samples from across the country from 2013 to 2015. The metal was found in almost 90 percent of the water systems sampled. Surprisingly, the EPA has never set a limit for the amount of chromium - 6 allowed in drinking water.

California is the only state which has enforced a maximum contaminant level of 10 parts per billion​ (the equivalent of 10 drops of water in an Olympic - sized swimming pool).  It's worth noting that the Environmental Working Group has stated that even California's stringent standard still allows for an unsafe level of chromium - 6.

Activist Erin Brockovich has issued a written statement stating that "whether it is chromium -6, PFOA, or lead, the public is looking down the barrel of a serious water crisis across the country that has been building for decades".  Brockovich went on to state that the reason for the crisis comes down to "corruption, complacency and utter incompetence". 

So what exactly is chromium - 6 and why is it harmful?

Chromium - 6, also known as hexavalent chromium, is a naturally occurring element found in rocks, soil, plants, volcanic dust and gases, and even animals, according to the National Toxicology Program. ​ There are several different types of chromium, not all of which are harmful. For example, chromium - 3 is actually an essential nutrient for the body. On the other hand,  chromium - 6  is a chemical compound and is very rare in nature.  Hexavalent chromium can cause lung cancer if inhaled and lung tumors if ingested, according to federal health officials. In 2008 the National Toxicology Program conducted a 2 year study and found that drinking water with chromium - 6 caused cancer in laboratory rats and mice. Chromium - 6 has also been found to cause liver damage as well as reproductive and developmental problems. 

So what does the Environmental Protection Agency have to say about the dangers of hexavalent chromium?  The EPA did not directly address the Environmental Working Group's report. Instead, an EPA representative  ​stated that the agency is working on a health assessment of chromium - 6 that will be released in 2017. 

Bill Walker and David Andrews of the Environmental Working Group have stated that this means more delays and a whole lot of wasted time. "When you find widespread evidence of contamination, do something about it. Don't just study it to death," Walker said, noting that the new report is not about "trying to raise the alarm about a single chemical. We're kind of using chromium - 6 as a poster child for systemic failures of drinking water regulation."

Read the full report here. ​