Well, I can taste iron with Kanthal even after an oxide scale is formed. So ...
Nothing is perfect in real life, is it?
According to Magaro, our metallurgist friend:
"Kanthal is designed to be protected by a continuous layer of aluminum oxide. If you oxidize Kanthal too much (or too many times), you can deplete the aluminum in the near surface region of the wire. Then the chromium in the alloy will preferentially migrate to the surface to oxidize, along with the iron. This new scale is, according to my quick first look at the technical literature, less adherent to the base metal and can spall off. Presumably then it could be inhaled. It would be nice to know where this occurs in the life of a coil for different styles of cleaning - dry burn vs not. It's not just about fresh coils, but how they age."
I've said if before and I'll say it again: the only right way to determine exact amounts of metals, acrolein, various aldehydes, and whatever other nasties we may worry about in vapor are direct measurements of vapor composition in real world settings. Everything else is just educated guessing.
Dr. Farsalinos promised to do a wire study. I hope he'll do it soon.