CAUTION! The dust from MOP and abalone is harmful, precautions should be taken. It is not “toxic” per se but lodges in the alveloi of the lungs causing damage in a manner very similar to asbestos.
I’ve done inlay work with shell for 50 years. I cut pieces versus using it as dust. Wear a mask if doing bulk work, wet sand when possible. When milling on the Nomad I place the MOP in an acrylic reservoir and cut under water. Many instrument makers who do this by hand set up miniture vacuum systems to exhaust the dust outside the shop as they cut with a jeweler’s saw.
Here’s just one link if you’re skeptical: https://www.banjohangout.org/archive/215343
Search “dangers of shell dust” for many more references.