We asked ABC's Alan Sunderland for comment.
UPDATE: Right on cue ABC cover the story and no surprise they give prominence to activist opinions of a career environmental campaigner over the experts. In comments FOE's Louise Sales further misrepresents the results of the recent work and further exaggerates the risks of nano-particles.
We asked report author Simon James for more information. Here is his reply:
Here is some clarification about the current work; Zn is an essential nutrient, our bodies must have Zn in order to function (similar to iron or calcium). In 2013 the Therapeutic Goods Administration (TGA) released a review of the literature (attached) which concluded ZnO nanoparticles present in sunscreens pose no risk to consumers when used as intended. Our manuscript dose acknowledges previous work which demonstrated that a very, very small amount of Zn from ZnO nanoparticles present in sunscreen can penetrate the skin when used in the field (attached). I want to be very clear that this work showed that the Zn from ZnO nanoparticles made up less than 0.001% of the total Zn detected. This is not a level of Zn which is associated with any safety concerns (to be honest I am impressed the authors could even make such a precision measurement). However, given the limitations of doing a field studies the authors could not conclude whether the Zn made it into the body as part of intact nanoparticles or in some other form. Our study built on this finding by asking the question, “If the nanoparticles do penetrate the skin can a macrophage break these objects down?” We are not the first to try and answer this question, indeed our work is merely a single study adding to a much larger body of work but we were able to go further than other groups and show direct evidence for cell mediated breakdown of ZnO nanoparticles.