Originally Posted by veggiemafia
What's the difference between the molecular structures of hexavalent chromium and trivalent chromium (other than the number of bonds, I get that much) that leads to hexavalent chromium releasing harmful chemicals? Is it something left over after the chroming process that's not left over with trivalent chromium?
Information on potential hazards of hexavalent chromium
(Cr+6):
Many chromium compounds with a valence of 6 are
called chromates, dichromates, or chromic acid;
most have a yellow color, and all are toxic
[343,751]. Hexavalent chromium compounds tend to
be oxidizers and are associated with cancer risk
and kidney damage [751].
Hexavalent chromium is more toxic than the +3 form
because its oxidizing potential is high
[24,751,929] and it easily penetrates biological
membranes [24]. Chromium +6 is unstable [24] and
can be reduced to chromium +3 by many oxidizing
agents [751].
Metallic and acidic +6 chromates and
dichromates tend to be strong oxidizing agents
[751].
Strong oxidizing agents can cause damage to
DNA and many other tissue structures.
Certain hexavalent chromium (Cr+6) compounds when
administered via inhalation at high doses have the
potential to induce lung tumors in humans and
experimental animals [929]. However, at low levels
of exposure hexavalent chromium ions are reduced in
human bodily fluids such as gastric juice,
epithelial lining fluid of the respiratory tract,
blood, and other fluids, before the 6+ ions can
interact with DNA, unless the dose is sufficient to
overwhelm the body's reduction capacity [929].
Source