Oh, well that's totally different. Short answer: we don't. You breath enough smoke, it kills you, you die in part because these nano-particles (soot) are clogg

Oh, well that's totally different. Short answer: we don't. You breath enough smoke, it kills you, you die in part because these nano-particles (soot) are clogging up your lungs (Along with the CO2/lack of O2). Carbon particles in your food are carcinogenic and can accumulate in your body. Everything around you is constantly killing you by inches. Your body is pretty good at just ignoring anything that isn't causing immediate system shocks and allowing you to function. Which is to say, the fact that toxic particles are being spewed by your 3D printer might not be any worse than working next to a grill. That's not to say that either is good, and you should probably minimize contact to prevent accumulation. We haven't "adapted" to natural chemicals, it's more that different chemicals are different degrees of problematic to the body.