After Australian researchers delivered a damning report claiming that HP's printers were at the top of the heap for expelling dangerous, potentially cancer-causing, ultra-fine particles, the company responded with a lengthy press release which essentially "debunked" the study's findings -- and now the researchers have fired back to the Australian press. The printer-maker claimed that the study of ultra-fine particles was a "new" science, to which Lidia Morawska, head of the project, says simply isn't true. According to her, the European Commission has added a particle number limit to its emissions standards for light vehicles, which Morawska claims is a normally "lengthy" process. Additionally, she says that there is "considerable toxicological evidence of potential detrimental effects of ultra-fine particles on human health," based on the current World Health Organization's Air Quality Guidelines. The scientist further refutes HP's claims that the particles "cannot be accurately characterised by analytical technology," by stating that the study found plenty of printer models which carried no dangerous emissions at all, suggesting clear differences in the variety of particle output. Obviously this debate is just getting started, though we'll be avoiding superfluous laser printing while the jury is out... just to be safe.