News media around the globe found a study from Australia linking particulate emissions from laser printers with potential health impacts to be good copy. A Google search yielded literally hundreds of stories (“Warning: Laser Printers Could Be a Health Hazard”), some of them with lists of specific printers deemed by the authors emitters or non-emitters.

Several reporters found Berkeley Lab environmental scientists in the fields of indoor air pollution and health risk assessment to be valued sources and give their stories context. Going beyond the headlines, Lab researchers warned that the study in the American Chemical Society's journal Environmental Science and Technology, while interesting, was far from definitive in terms of relating printer emissions to health problems.

Hugo Destaillats, who with colleague Randy Maddalena is studying how the chemical particles are produced from laser printers and computers and what the particles and gas-phase emissions are made of, said the Australian results are difficult to translate into any relevant exposure metrics and are “insufficient to draw any conclusion about possible health effects.”

“The part (of the study) on monitoring indoor and outdoor particles for 48 hours in an office used just one sampling location indoors and one outdoors,” Destaillats said. “Except for the spikes (presumably during printing), most indoor particle concentration data are lower or similar to the outdoor data. The intensity of those particle spikes depends strongly on the proximity of the printers to the sampling equipment.”

He also noted that “emissions are very much influenced by not only the printer itself (and its "history," in the case of aged equipment), but also by the quality of the toner and even the quality of the paper. All these variables were not accounted for in the characterization of high and low emitters” in the Australian study. This factor may explain why, by the study’s own admission, printers can be unreliable particle sources (the same model was found to act as both a non-emitter and a high emitter).

He concluded that the article shows interesting features of ultrafine particulate emissions by laser printers measured under controlled environmental chamber conditions, but that further study will be required to fully assess human exposures and health risk.

EETD colleague Rich Sextro agreed. “What we don't know is what (the findings in the study) mean,” he said. “Certainly our expectation is that exposures to lots of ultrafine particles probably isn't a very good thing, but we have no idea at the moment what that translates into in the real world.  Exposures to lots of contaminants in indoor air can be bad -- but the effects are often related to exposure amount, duration and toxicity of the materials in question, and we clearly don't know that here.”

"It's certainly a concern," said Mark Mendell to Scientific American. "The smaller (the particle) the worse, (and) the more likely they are to get deep into the lungs and possibly into the bloodstream." But showing that printers produce pollutants "is not the same thing as knowing that it causes certain health effects," he added.

Tom McKone told the same publication that it is good to be aware of the potential danger but that consumers should not fret too much—at least not yet. "Fine particles alone are not enough to worry about," he said, pointing to other potential indoor sources of ultrafine particles, including home cooking, candles and fires.