Nanoparticles are increasingly common, with some considered safe and now widely used, but their long term safety is unclear. The risk seems to rise as the particle size decreases, and even silver nanoparticles have shown toxic effects. The presence of a metal or its oxides, however, does not mean that nanoparticles of those materials are present. They require particular conditions for their production, and in a normal atmosphere with only a normal butane torch there is no evidence that those conditions apply to the copper (or other metals) in any of our favourite torch powered vaporizers.