I think they are both lethal and I do worry about how it's affecting my health with all the stuff I have to handle for 26 animals - I always breathe through my nose rather than my mouth, try not to talk, blow my nose after (yuk - sorry peeps :lol: ) and hold my breath when I'm filling trays with megazorb. I haven't dusted the piggy room for ages and the very sticky (odd) thick yellow dust is megazorb, so I dread to think what it does to your lungs.