Is It Dangerous
Dangerous is fairly hard to define. I remember a time when Doctors recommended their patients smoke cigarettes for health reasons. I remember a time when a large American corporation said their cigarettes with asbestos in the filter were a healthy choice. If you drink enough water, just plain water, nothing special, it will lower electrolytes causing swelling of cells, including your brain, and kill you. If you do not get enough water that will kill you. DiHydrogen MonOxide is a dangerous chemical and we are all balanced on a knife edge and if we get too much or too little we could easily be dead in a week.
Even if you know everything some risks are worth it. In the time I have been alive I have had over a 1% chance of dying in an automobile accident. I, and almost everyone in the US, drive almost every day.
PLA is, as far as we know now (See the doctors and smoking stuff) safe. All PLA filament has stuff in it. Stuff to give it nice colors and stuff to make it print better. Most companies will not tell you what that stuff is and if it is known to be safe to ingest.
Brass has no lead in it. During manufacture of most brass stuff lead is used as a lubricant and some of it ends up on the thing they are making. Your bras nozzle probably has lead on it. Some of that lead comes off the nozzle and ends up on the plastic. Some probably ends up in the air for you to breath. Some probably is brushed off by the filament moving through it.
Some plastics give off Volatile Organic Compounds when they are heated. An enclosed hobbyist printer is not sealed well enough to keep them all in.
A HEPA filter may help. HEPA is just a designation for how small a particle it will remove. VOCs are not particles. Some particles of plastic are smaller that what a HEPA filter is designed to remove. HEPA filters do not remove 100% of the particles they are intended to remove. HEPA filters perform worse over time as they are used and should be replaced regularly.
Activated carbon, carbon with more nooks and crannies opened up, will absorb VOCs. It does not absorb 100%, it loses effectiveness as it absorbs stuff and should be replaced regularly.
When you print tiny bits of plastic end up in the air. There is some scientific disagreement on how dangerous these are. Some particles are smaller than a HEPA filter is designed to remove and some particles a HEPA filter is designed to remove make it through.
Food Safe
Some PLA is labeled food safe by corporations, see the asbestos thing above. Also see the added stuff above. See all the other stuff above. Let’s assume it’s perfectly fine as it comes off the printer.
Bacteria grow on almost any surface if there is water. If something is in contact with food it is in contact with water.
Bacteria on surfaces is killed by heat, if the heat is high enough to kill bacteria it is hot enough to deform PLA. Bacteria is killed by radiation. If you have enough radiation to kill bacteria it will degrade the PLA and, unless you take far more precautions than I do, it will kill you. Some chemicals kill bacteria. A chemical that will kill bacteria and not degrade the plastic is probably not in your home.
So, if the PLA is in contact with food it will grow bacteria that you can not easily kill without degrading the PLA.
What Should I Do
I certainly would not tell you how to live your life. I can only tell you what I do.
I am NOT a doctor. Nor do I play one on TV. I am a random dude on the Internet. You would be a FOOL if you took medical advice from me. I would be a FOOL if I offered you medical advice. I certainly am not offering you any. I am just telling you what I do.
I have an enclosed printer. I have it because when I got it the company only had one printer, the enclosed one. I don’t own it for any health reasons. It has a fan on the back that some people have exhausted outside. My printer just blows air out the back and into my living room (Did you know this room used to be called the parlor, where funeral parlor comes from, and during the early 20th century it was a bummer to have the death room in the house, so the name got changed to living room). There is a small filter, particle and VOC, but I have not changed it in the almost two years I have had the printer. If I were getting a printer today I probably would get an open one.
I don’t print stinky filament. No matter what I did a little bit of the smell escaped, I did not like it, and I found other options. It’s not a health thing for the VOCs. I don’t like the way they smell.
I have some PLA that is in contact with water. It’s plain water so I tell myself there is no food for the bacteria, probably wrong.
Plastics could kill me tomorrow, or make me sick, or help other stuff kill me, or I could live forever, highly unlikely. I live my daily life doing a bunch of things that are bad for me, I am overweight, that may shorten my life more that the plastics, I don’t know. Jim Fixx was a runner, seriously low body fat percentage, he keeled over from a heart attack when he was 20 years younger than I am now.
Like most things, it’s a balancing act. If a study comes out tomorrow that makes a great case for 3D printing stuff killing me, I probably would stop 3D printing. The way things stand now, I will continue pretty much as I am now.
I tried to keep opinion out. If I have any of the facts wrong please let me know. I checked and you should be careful you are not letting your prejudice color things. I only said bacteria will grow on most things in the presence of water, I did not say it was good or bad.
In the what do I do part I tried to say what I did and not give a reason. I use plastic in contact with water, I did not say it made me feel bad and I probably would die before the week was out or it tastes like cherry clouds and unicorns fly out my but whenever I use it.
A pair of lovely stories that have little to do with 3D printers. I researched them a little and, as far as I know, they are true. The Supreme Court of the United States ruled that the tomato, a fruit, is a vegetable. A woman, I don’t remember her name, in New Jersey ended up in a coma and was kept alive by machines. The joke at the time was that she was the state vegetable of New Jersey, not what I consider a story. The Indiana legislature thought the whole pi being 3.1415926… was a pain and it should be 3. The mnemonic device “may I have a large container of coffee” will get you 7 decimal digits of pi. Add a please to the end and you are only off by 1 in the 8th decimal place and if you get your coffee from Ralph you are right on.