Comment on Moon Rocks by jollyjack
I'm mostly sure if you try to breath while being coated in anything, it goes into your lungs.
If you assume he was present for the pulverizing process, that's true. But once in gel form it can't be aspirated, and I'd assume he wasn't ever a test subject so he wouldn't have absorbed it through his skin or mouth.
Ah... alright then. I think he WAS the pulverizing process, considering how broke Aperture was at the time.
On a related note, moon dust is probably as toxic as sand or other silicates, as it's made of the same stuff. However, there's next to no erosion on the moon, so fine particles have a lot of sharp edges which easily tear away at soft, squishy structures, like human lungs. So it probably has to be the dust to have any meaningful effect.
I actually think that maybe Moon dust as some carcinogenic effect.