Edit: I have had bad reactions from chechen burl. I was cutting some up for inlay slabs and my eyes became a little swollen and very irritated for a couple of days.
I remembered that time when I read the title for this thread, and still feel bad about It. I remember It irritating you pretty bad. Funny how different woods can effect people differently.
That same stuff did not effect me, but I have had respiratory issues from Coco, although the first few times I used It no problems, that just seemed to get worse each time I worked with It. I did not have major skin reactions like some do, although My knuckles may turn a little red, nothing major though. It can screw My sinuses up pretty bad though, so I have to at a minimum where a paper mask. Last time I worked with It I wore a chemical mask, because It got to where the smell of it alone was irritating My sinuses, so maybe there is some kind of gas produced. not sure, but the stuff seemed to kind of sneak up on me the more I worked with It. It depends on how much dust I'm making though, small amounts have no real effect, It's the hard cuts that get to Me.
Greg