Fine particulate matter like ground salt or pepper is usually not a good thing to keep around camera equipment. The individual granules work their way into every nook and cranny and clog and scratch what was never meant to be clogged and scratched. However, camera lenses are not the only thing designed to be twisted and turned; salt and pepper grinders and mills also share that same atribute.
The Camera Lens Pepper Mill Grinder from Nuop is okay with small particles. In fact, it wants to help. Fill with peppercorns, twist and season. Taking care of camera equipment never tasted so good.