Cobalt is a metal which is commonly used as a binding metal in jewellery and household objects like cutlery.
Cobalt allergy has also been noted after transplantation surgery, mostly associated with hip and knee replacements and in dental procedures. Cobalt can also be found in cosmetics, hair dyes and inks.
It is a metallic element and important constituent of vitamin B12, so it may also often be found in B12 supplements.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Cobalt.php
The allergy resources page for cobalt covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with cobalt .
There is also regularly updated links to useful websites specifically for cobalt allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.