Question from Claire
Hi Debra! I love your site and find the information to be extremely helpful!
I had a question about chromium in crock pots.
I recently tested five crock pots with an XRF device to check for lead.
Though the lead levels were okay (they all ranged from 14 ppm to 257 ppm) they all had varying amounts of chromium (2637 ppm, 6813 ppm, 3567 ppm, 2554 ppm, and 4223 ppm).
The XRF device does not tell you what type of chromium it is, so I don’t know if it is trivalent or hexavalent. The levels were pretty high. Do you think this would be okay?
I know you have posted about chromium electroplated into another metal before, but was curious what your thoughts were since this would be chromium on stoneware. Thanks so much!
Debra’s Answer
First, there is no safe level for lead, so I don’t consider these levels to be “OK.” Since cookware is available that doesn’t leach lead, I prefer to use the lead-free cookware.
Now about the chromium. Chrome is used by potters in the forms of green chromium oxide, iron chromite, and potassium dichromate. These are used in slips and glazes as colorants.
EWGs Skin Deep Cosmetics Database has this to say about Chromium Oxide
“Chromium oxide is a mineral pigment, Cr2O3, used as a colorant in a variety of products. This ingredient contains trivalent chromium, a form of chromium that functions as an essential trace element in human metabolism.”
Iron chromite and potassium dicromate are also naturally occuring.
So I would say that any chromium found in pottery would likely be trivalent.
There is some data that would tell us how much trivalent chromium would be safe or harmful. There is no “safe upper limit” established for chromium as a dietary supplement. Apparently chromium ingested is very poorly absorbed. So while those numbers may sound huge, it’s not very toxic and little may be absorbed European Food Safety Authority.
How many milligrams of chromium are in those crockpots? Well, 6813 ppm is 6.813 mg/g. 1 gram is 1000 milligrams. Even at 6813 ppm, for each gram of material only 6/1000ths would be chromium. And 250 mg of chromium is considered OK.
I think the chromium is fine, but somebody correct me if this math doesn’t look right.
My conclusion is: I’m not concerned about the chromium, but am concerned about the lead.
