Rice is not "dust" and sand is not "dust" by any stretch of parlance.
These things will fall on the ground and you'll hear them hit the floor in a quiet room.
These things will not float on windless air, suspended in a sunbeam.
They are not saw dust, either. They are not iron filings. They are not crushed slivers of glass. They are something more.
Look at the picture. Maybe relative to other implantable electronics, they are certainly very small. But qualitatively speaking, not soot, not smoke, not powder, not dust.
