I remember from my days working in a research lab at Pfizer, that SO2 was labeled as an "insidious poison" because as it works on you, the first thing that happens is that you can no longer smell it and continuous exposure can kill you. It is something that should be worked with under a good ventilation hood. It's just not something that I associate, nor would want to, with cooking.
HC
As @Duvel correctly points out below, I was thinking of hydrogen Sulfide, sorry for the mix up!!!!