Toxicity is only a matter of dosage. There are a lot of things that we used to think were only toxic from prolonged, extreme exposure, turns out that may not all be so true. I think its safe to say that the smoke from a ferro rod should be treated like any other metal smoke, avoid breathing it. the compounds in the smoke are going to be different than they are in the rod, and I don't know what all those might be. There is also the matter of contamination, I don't know the purity of the originating materials and what contaminants might be along for the ride.
Yes all of those materials are in your body in some amount, but its the form, and where that make the difference, smear zinc oxide on your skin, and you don't get sunburn, breath zinc oxide smoke from galv steel, and life is pretty miserable until it clears up. I would say that using the knife for food prep after striking a ferro-rod would be fairly safe. But this is based on nothing but looking at how chemicals get processed through the body. And that most people would clean the knife at least somewhat. If you knew you were going to burn up a bunch of a ferro-rod in practice, then it would be worth having a bit of wind and fresh air.
Rollintent, if you don't feel better in a few days, or if it gets worse, go in and see someone, they probably won't do much, but you never know. lung and throat conditions can also be psychosomatic, not saying that this is the case, but its possible. it might also be unrelated, I'd try an antihistamine for a couple of days. (I'm not a doctor, following my advice may be fatal) Also keep in mind, some people are more sensitive to some metals than others, so that might have played a part.
And from the old section of the thread, Dr. Oz is a moron, and nothing from his show should be taken as medical advice or opinion. He is dangerous and should not be trusted. About like me, but at least I'm honest about that part.
