When it is a nanohazard of course….
The increasingly confused and nanotech obsessed ETC group have launched a competition to design a “Nano-Hazard Symbol” with the prize on offer being that “the winning entry will be submitted to international standard-setting bodies responsible for hazard characterisation, to international governmental organisations and to national governments as a proposed symbol for nanotechnology hazards.”
It is more of a PR stunt than a serious attempt to design a new logo, as hazardous substances are already clearly labelled, and toxic means toxic at whatever scale.
The whole issue of labelling really depends on what the general public understand about by the label, for example nuclear magnetic resonance imaging has dropped the nuclear to become just MRI as the general public associates the word nuclear with weapons rather than taking it as a general term relating to the nucleus of an atom.
Unfortunately for science, bad news sells newspapers, while good news might find a niche on the science page.