A recent paper regarding toxicity from 3D printers has caught the attention of many, it would seem. It is an interesting topic, and certainly one that might come up as a concern if you are near a 3D printer that is melting filament close by on a regular basis. Generally just an odor is enough to cause concern. According to the aforementioned paper, however, moderation is key if you are using filaments like ABS—and if you are using PLA, you should be fine no matter what as it is a completely natural material—and harmless. All involved with research on this topic seem to agree however that more study is necessary. Read more at 3DPrint.com: http://3dprint.com/118194/makerbot-filaments-pla-safe/