Q: Are nanoparticle-containing sunscreens and cosmetics dangerous? Can the nanoparticles penetrate our skin?
A: 2015 it was concluded [Naess, 2015] that none of the existing studies on skin penetration of nano titanium dioxide and nano zinc oxide (both common components of sunscreen, especially nano titanium dioxide) reported any evidence of skin penetration – except for one case, in which the person studied had dermal wounds. Based on the (rather limited) amount of research that up to this day have been conducted on the matter, a lot speaks for that the skin, as long as intact, is a very effective barrier of nanoparticles.
Q: How do you study the potential hazard of a nanoparticle?
A: The risk of an engineered nanoparticle is estimated based upon two factors: 1) the toxicity of the particle, and 2) how exposed we are to these particles. Factor 1 is assessed by toxicological studies. These studies are generally conducted by animal exposures or cell culture exposures. In principal, cell studies give us information of the biological mechanisms behind a toxic effect, and animal studies give us causality (dose-response). Factor 2 is investigated by doing exposure measurements or exposure estimates, which can be the basis of epidemiological studies (where large groups of persons are followed for a long time). When it comes to engineered nanoparticles, we still do not have very much information on either of these two factors, we need more studies.
Q: Can studies of other, ”normal”, nanoparticles help us to understand the hazard of engineered nanoparticles?
A: There are still many knowledge gaps concerning the potential health effects of engineered nanoparticles. We do, however, know that inhaled common particles in nanosize (eg. From vehicle emissions or industrial air pollution) cause a wide range of health effects. There are several very well established connections between nanosized air pollution particles (and their agglomerates) and coronary heart diseases (eg. ischemia and myocardial infarction), stroke, intracranial hemorrhage, respiratory infections (eg. acute bronchitis and pneumonia), lung cancer, and COPD. Other more recently discovered connections are diabetes, autism, dementia, pre-tern birth, and preeclampsia. There is every reason to see if we can learn from these studies, and such work is beginning to emerge, for example comparisons between nanosized diesel emission particles and engineered nanoparticles.