As far as I can see, no FDM 3D-printed model is food-safe: they all contain little holes where food rests can accumulate, and bacteria can get a good grip, so you can't wash them out.
I think the printer nozzles are not going to be the problem: they operate at +200°C: not much bacteria are going to survive that. And the wear is very low, otherwise there would not be a nozzle at all anymore after a few meters of printing filament...
Wood-filled material is even going to be much worse than unfilled plain PLA, obviously, due to its porosity and natural materials which can be eaten by bacteria and fungi. There is a reason why people do not recommend cutting meat on a wood plate, or why doctors discard the wood spatulas after they used it in a patient's mouth.
If you want to use food-safe materials for printing toys, just to make sure the kids won't get poisoned by ingesting cadmium or poisonous plastics, when they accidentally bite in it, then PLA and PET would be "safe enough", I guess. If you want to make drinking cups, spoons, forks, dish plates, and similar stuff for repeated use in the mouth, nothing is going to be safe.
kmanstudiosBecoming an expertLevel: 51 Points: 2243 Posts: 1308Location: United States
Ultimaker 3 Extended
There are food safe filaments, but the act of printing will not let it be food safe unless you have a science level clean room to print and seal it with. The sealant would have to be food safe as well. All materials would have to be contained and handled in a sterilized way and area.
Once that container is open, it is fair game to airborne pathogens and sneeze stuff, etc as well as what is floating around inside the build area.
So, even if the hotend cooks out the organisms, then there is a lot of secondary ways of being contaminated.
Also, most food safe filaments do not really stand up to the cleaning temps needed to keep it clean without softening.
I think the label of food safe applies to prior 3D printing. After 3D printing I don't think anything can still be considered foodsafe for multiple use. If you use a foodsafe materioal only once fairly fast after it was printed I think it should be fine (however 'official' legislation may not agree). If you want to use it multiple times, you probably have to post process it, so the material is sealed. In that case, it probably doesn't matter which material you use, since it will be sealed.