The main ingredients of Bullseye’s Thinfire are cellulose, aluminum hydroxide, fiber glass, and organic binders. It is predominately a nuisance dust and irritant.
Use a vacuum sweeper with a high efficiency filter and a bag rated for plaster dust. Also many vacuums with a HEPA filter system will be sufficient. Wrap the disposable bag in another -preferably paper - bag to avoid dispersing the dust when it goes into the rubbish.