Strain it to remove the dust and smaller particles, and then rinse it (do this outside, trust me). That should do the trick. I've mixed MG perlite with a better brand cactus mix, and it's worked fine.

It should be on the label what % of NPK is in it; is it? I wonder if they use slow release fertilizer?

It is very good idea to sift perlite (a kitchen sieve could be used) to get rid of all dust, and then rinse. I didn't even know they 'enrich' the perlite...

Rufflife - Miracle Gro Perlite is 0.07-0.07-0.07. The concentration is so low I wouldn't worry about it or really consider that it's there at all.

Thanks everyone for your quick replies. I'll pick some up, sift it and rinse it and add it to my gravel and soil.