Its been on my mind lately, and wanted to start a thread about safety regarding our various resins we use with hard baits. I personally have developed a sensitivity to certain resins and upon further research I fault myself for not using better precautions. The fastest way to end one's lure making days is to develop a sensitivity to one of the chemicals used in bait making so I will give my lessons learned with safety and encourage others to give their lessons learned.
First, polyurethanes use a toxic chemical known as methylene diphenyl diisocyanate (MDI) which is usually the yellow or darked tinted liquid in two part mixes. The clear liquid is usually a diol compound similar to antifreeze and is less toxic. Studies have found nearly everyone can eventually become sensitized to MDI with enough time. 2-8 years of low chronic exposure to MDI will result in 25% or higher likelihood of sensitization. Of those sensitized, 60% will retain the symptoms of sensitization for life, even when permanently removed for ALL exposure. Recently it has been learned that dermal contact with isocyanates can be as dangerous or even more dangerous than inhalation. You may not have realized that spraying an auto clear without a mask is as dangerous as spilling uncured resin on your skin.
Second, epoxies usually contain triamines and/or formaldehyde and have caused even worse sensitizations than with isocyanates in studies with Guinea Pigs. Everything above applies but even more severe.
Third, microballoons are borosilicate glass and when inhaled chronically can cause silicosis (permanent scarring of the lungs). I work in the abrasives/grinding industry and have personally viewed ceramic dust under a SEM, and have seen many particles often as small as 1 micron by 4 microns. Hence, your dust mask and/or filter is not removing them. When you sand microballoon filled resin your dust mask is not enough.
To protect yourself when pouring resins, at a minimum, you should:
 Work in a well ventilated area
 Wear nitrile gloves and long sleeve shirt (no exposed skin)
 Use a vent hood when pouring/sanding/mixing resins or use a full air supplied respirator
 Never heat any resin without industrial equipment designed for such a purpose
 Forget about "it won't happen to me" because it will, given enough chronic exposure
 Remember that even organic respirators do not remove isocyanate vapors
Any other stories/suggestions?