1-s2.0-S1352231013005086-main.pdf (470201Bytes)
Well, here is some scientific support (see attached pdf) to why your 3D printer might try to at very least harm you!
The study only incides over particle emission, and not the chemical nature of the emitted particles and yet it can be scary enough. That, added with my reported symptons after going on a 3D (ABS) printing binge: persistant chest pains/disconfort should be enough to keep you on your toes.
So you better ventilate/filtrate if you're into this messy business.