text: The most prominent example of toxic chromium is hexavalent chromium ( Cr ( VI ) ) .
simplified: Another type of chromium ( Cr6 + ( chromate , hexavalent chromium ) , in the +6 oxidation state ) can cause cancer or make people sick , even though most people do not get exposed to it much . Hexavalent chromium was important in the movie Erin Brockovich .