I was way off on the standard...it's ANSI Z87.1. You have to pay for standards (unless you own it yourself or your company does) but here's a bit of an outline on Z87.1:
So only the basic rating is a 1" steel ball dropped from 50 inches, it would appear. This doesn't seem like much energy or momentum at impact to me but I'll crunch the numbers later and compare it with BB's.
There's also a Milspec and CSA standard related to safety eyewear also (I don't remember the standard numbers) if people wanted to look those up as well.