Researchers at Missouri University of Science and Technology suggest that when exposed to sunlight, zinc oxide, a common ingredient in sunscreens, undergoes a chemical reaction that may release unstable molecules known as free radicals. Free radicals seek to bond with other molecules, but in the process, they can damage cells or the DNA contained within those cells.

Silver nanoparticles cause more damage to testicular cells than titanium dioxide nanoparticles, according to a recent study by the Norwegian Institute of Public Health. However, the use of both types may affect testicular cells with possible consequences for fertility.

In February 2012, experts from Europe and the USA exchanged knowledge at the "Conference on Nanosilver" organised by the Federal Institute for Risk Assessment. Apart from toxicological aspects, the discussions covered the possible development of silver resistances in pathogenic germs as well as analytical procedures for the detection of nanosilver in various matrices such as foods, sprays and consumer products and its release from such matrices.

More than three in five Australians are concerned enough about the health implications of nanoparticles in sunscreens to want to know more about their impact. And while the initial scientific information released suggests little cause for alarm, it does justify the community's confusion. That's the message that emerges from a survey and three research papers on nanoparticles in sunscreens presented at the 2012 ICONN, held recently in Perth.