PLA in a dishwasher greatly distorts the print, because it has a glass transition temperature of 60C (I tried).

3D printed materials do have crevices that contain bacteria, so it is wise to take extra care and avoid prolonged food exposure.
SLS nylon is porous and after about 6 months used in contact with water starts growing black mold in my experience which can be dangerous.

I am researching which materials are food-graded and will post an update soon.