Wear gloves, eye protection, and an appropriate mask if you’re going to do any sanding. Carbon fiber is a great material, but if you breathe in the particulates from sanding, it could cause lung damage. I would imagine there is similar risk if it gets in your eyes (hence eye protection). The gloves suggestion was there because you feel concerned about skin contact.

The standard, “print only in well ventilated areas” always applied, because heat + polymers = noxious gases.

Here’s some good info that may give you what you’re looking good for:

https://www.osha.gov/otm/section-3-health-hazards/chapter-1#6

It's perfectly fine to handle. Carbon fiber in FDM 3D printing is largely a lie. It's not that there isn't carbon fiber in there, it's just that it's chopped up so finely that it's practically pointless by the time it's printed. At best, all it does is destroy any printer not set up to handle it. It's basically like printing sandpaper. Honestly, I'd avoid it entirely; same goes for glow-in-the-dark. Only reputable supplier I know for GITD is Das Filament, which ball-grinds their glow powder before inclusion into the stock.

If you're interested in real carbon fiber in FDM prints, the only people to really see are Markforged.

For the record, chopped strand fiber in a fdm printer doesn’t significantly increase strength- especially along layer lines.

It might increase tensile strength of the load is parallel to the layers, but that’s about it. In every other direction, the fiber doesn’t cross layers, and delaminating is the primary failure mode.

The strands would be more like glass fiber than asbestos- you wouldn’t want it in your lungs, but then it shouldn’t really be airborne.

A better option might be graphite filled, which will still get you that look, and help lighten the part without losing strength. Still would not want to sand it without ppe, though.

In theory it should be mostly fine to touch, idk much about it either unfortunately. it might be a good idea to put some sort of spray on sealer if you will be touching it regularly and are concerned about it at all.

It is definitely dangerous to sand or cut with a saw or something, definitely want to do that outside with gloves and a respirator because then you're getting loose fibers both on you and airborne.

I can't find much literature about it, did find this safe handling procedures from UNSW Sydney if interested. I'd say if you're concerned, don't use it. The fibres themselves to me are a concern when out of the polymer, so take precautions when sanding or cutting, glove up and wear a mask + eye protection, probably should consider wet sanding too to reduce airborn dust. Print in an enclosure with ventilation, same precautions you'd take for abs and nylon, you don't want to be around that when it's printing. As I said though, if you do have any concerns, don't use it, there are matte finished filaments if thats the look you're going for.

What was CNC kitchen's concerns? As above, personally I'd be concerned while disturbing the plastic through printing, cutting, sanding etc, just handling it wouldn't be on the top of my list unless the plastic has degraded or been damaged in some way, pretty much how I'd treat anything with fine fibres or particles in it.

At the end of it, I'm just some guy on the internet, if you have concerns, don't risk it. If you do decide to use it, treat it with respect like you would anything with fine particles or fibres.

Not sure, but I think it also benefits from ventilation. Hopefully someone more knowledgeable than both of us chimes in!