just use extreme caution when using it on something you may later heat up really hot, like trying to clean/degrease something you plan to weld... even if it sits and airs out till dry, it is a hazard. I cleaned some parts I wanted to zap together with my mig, they were dry so I thought, but when I struck the first arc I got one single whiff, and stopped...knowing something was not good. I washed the parts in hot soapy water, and blew them dry prior to finishing the weld, and that was fine.
2 hours later both hands went claw like into excruciating muscle locked spasms, and I was feeling very uncomfortable... I decided to research this, and found i had just exposed myself to phosgene gas created by the reaction...that ain't funny, I had repeated issues with muscle spasms for 6 years after that 1 second whiff.
http://www.crcindustries.com/faxdocs/msds/5089.pdfthe cautions about not smoking around the stuff ain't for flammability, but because if it's in the air, when you puff on a cig, you are drawing that chemical in, and directly inhaling the resultant toxin once it converts...
I believe this was why I had such bad effects from it, bad stuff Maynard...