The material type and the resolution are usually two independent things.
I know you can use PETG for medical and food applications (approved by FDA) so it shouldnt be toxic. You could try using PLA (non toxic as it’s based on corn starch).
You should also know that with all FDM prints there will be microbial growth overtime because of the small crevices in between the layers of the printed object.
For 50microns resolution (smallest possible on FDM printers) you should get a 0.1mm nozzle.