There's a TON of toxicological data out there supporting the supposition that once polymerized, urethanes in general present little to no difference in hazard than any other plastic in handling, sanding etc. But, you sure would do well to keep the mixed liquid off you while handling it, because 1) you can develop an allergy from skin exposure (not likely, but it does happen) and 2) it's tough to get off you when it kicks. Witness Great Stuff foam...clear coat not as messy, but still...yuck. BTW, you need a new respirator cartridge each day you spray; once opened, even the humidity in the air fills the adsorption sites in the activated charcoal.

Good lock and show us your project - My next one is this weekend or early next week and will actually be an old surfboard; shooting it with some single stage, catalyzed automotive urethane. Nasan, I believe. Never shot this brand.