Chromium III vs. Chromium VI

In environmental chemistry we watched the movie Erin Brockovitch.  The movie is about the court case of  Hinkley vs. Pacific Gas and Electric (PG&E). The people of Hinkley, California were being poisoned with chromium VI in their drinking water. PG&E used chromium VI which causes fatal diseases and health effects such as cancer and infertility, and told the residents that it was chromium III which is vital to the body to avoid heart conditions.  Erin was a single mother and get a job at a small lawyers firm.  While working there she uncovers that PG&E is poisoning the residents of Hinkley by allowing chromium VI to pollute their ground water. Chromium III (good chromium) is vital to your body in small amounts, however, too much of a good thing is often bad, and if you are exposed to too much chromium III it can cause negative health effects.  Chromium VI is all around bad stuff, it can cause a wide variety of cancers, and just about any other disease you can think of.  The movie Erin Brockovitch is based on a true story. I would like to know how people can sleep at night knowing that they could stop the deaths of many innocent people, I surely couldn't.