People have been worrying about what dangers nanoparticles may pose to humans as nanotechnology evolves.
Last week, an Australian research study was made public that implied that certain laser printers (including models popular in the US) release ultrafine particles hazardous to our health.
Lidia Morawska of the Queensland University of Technology, along with colleagues in Australia, reported in the August 1 issue of Environmental Science & Technology that some laser printers release ultrafine particles of toner-like material into the air. If people inhale these particles into their lungs, they may pose a health hazard. The researchers looked at 62 printers and classified 17 as "high particle emitters." They think the ultrafine particles come from the toner, which is an ultrafine powder used instead of liquid ink. One of the printers released particles into an experimental chamber at a rate similar to that of a cigarette smoker.
See the ZDNet posting by David Berlind on HP's response: