I've wondered about this too with steels containing a high amount of cobalt.
My concern is not at all related to 'Cobalt 60 and radioactivity', but that it is well established that two known sources of cobalt toxicity in humans are from the grinding and fabricating of tungsten parts in industrial environments, and the minute particles released from cobalt containing steels in metal-on-metal wear in hip replacements.
Sharpening obviously leaves minute particles of cobalt containing alloy dust on the knife blade and the stone or rod you are abrading the steel against.
My laymans understanding of the danger involved in breathing in cobalt containing metal dust, is that it probably needs to happen in large quantities over a long time in an industrial environment, but I'm not a doctor.
Similarly I don't know anything about the type of cobalt content in the alloys used for hip replacements, but it would seem that the fine particles released from metal-on-metal wear are also locked into an alloy composition that may contain similar amounts of cobalt to steels like Maxamet.
Now just to be clear, I'm not concerned about the odd bit of Maxamet dust getting in your food or on your fingers, by doing a few swipes on the Sharpmaker and then slicing up something to eat.
What I'm asking about is, say you were using your Maxamet knife as your primary EDC over years, doing the normal amounts of reprofiling and sharpening which many of us do - should we exercise a more stringent cleaning of the abraded metal dust particles on the blade, stones and fingers as a basic safety measure?
I don't know, but I can tell you I do wash my Maxamet Para 3 blade off after any sharpening or touch up honing, and wash my hands, and clean the stones off and rinse away the water after use. Maybe this is way overkill, but I guess it doesn't hurt, and it's not bad practice for sharpening anyway. After washing, I give a few light passes on clean leather to pick up any residual dust. I also always use the stones and Sharpmaker rods with water on them to prevent breathing in of metal dust.
I'm sure this is all a bit excessive, but I still use my knife on food, and intend to keep using this amazing steel for years.
I know we'll all have opinions
on this matter, but I'd be curious to hear the thoughts of a medical professional.
http://toxicology.imedpub.com/cobalt-po ... ?aid=10377
https://www.mja.com.au/journal/2011/194 ... prostheses