I haven’t looked for lab data, but certainly what appears to happen is that the swarf ends up suspended in the water. Some water will spray, which will be a bit messy, but mostly it will be in droplets that don’t stay in the air. (And presumably aren’t going to get to one’s lungs either.) And the majority of the swarf just stays in a puddle.

This is in contrast to cutting dry, which causes all the swarf to fly into the air.

So the exposure isn’t zero, but it’s low. It would be interesting to see if it registers on a particle counter (Plantower, etc).