Remember the movie Erin Brockovich (1)? Julia Roberts played a single mom fighting Pacific, Gas & Electric for contaminating the groundwater of Hinkley, California with hexavalent chromium, Cr(VI). True Story. Those poor folks in Hinkley had to contend with increased levels of cancer, allergic reactions, itchy rashes, crusty skin lesions, and kidney and liver failure (2). But then why is Cr used everywhere in everyday life? And I mean everywhere (3). It’s in stainless steel flatware, the bumpers of older model cars, the shiny plating on tools like rachets, sockets, and wrenches, and leather tanning (just FYI, I’m never buying leather again) (4, 5). In fact, Cr pigments are so bright, Cr was once used in the iconic yellow school bus paint (6, 7) but was discontinued because, well, it was toxic.
Or is it? Check out your multivitamins. Right there on the label: Chromium 52 mcg, 149% (8) of your daily allowance. So, is Cr toxic or safe?
The 23rd-most common element in the earth’s crust, Cr is silvery and hard in its pure form and is perfect for electroplating and protecting almost anything—from plastic to appliances (9). There are two types of Cr we need to be aware of: hexavalent Cr(VI) also called chromium oxide (CrO3) which is the genotoxic, carcinogenic form (PG&E paid $333 million to the inhabitants of Hinkley), and Cr(III), trivalent Cr3+, an essential micronutrient important in sugar metabolism, type 2 diabetes (10), and mood improvement(11, 12).
So why the gummy bears as a background to the Cr square above? (POSSIBLE SPOILER ALERT!) In The Third Warrior, my latest Nicky Matthews Mystery, gummy bears and Cr play an important role in solving the mystery as do sugar cravings and mood, uh, unimprovement. So (shameless plug) BUY MY BOOK (13) and all will be revealed J. And don’t forget the first book in the series, Hearts of the Missing (14).
- https://link.springer.com/article/10.1007/BF01707671 [link.springer.com]