Haven't had any problems with cocobolo yet. However, I used to use wenge a good deal. Had been using it for power lams and riser lams for about a month when one day, wham!, got sensitized. All my exposed skin developed a rash/dermatitis. Needless to say I immediately got rid of all the wenge I had. Breathing the dust of any wood is bad, but especially the exotics. I'm very much hoping I don't become sensitized to further woods...really like the look of many of the exotics!