Disposabl tips, do they go in sharps bin?

Hi,
When I was at college I was told that anything that was sharp enough to pierce the clinical waste bag should go in the sharps bin.

I was recently told all our application tips, the ones that go on the end of etch, composite flow etc should be disposed of in sharps bin. I was quite surprised and did as I was told but I'm sure there are sharper items I use that don't go in the bin.
Is this a requirement, and where is the proof? Thanks xx