{"id":33,"date":"2008-07-22T07:20:53","date_gmt":"2008-07-22T15:20:53","guid":{"rendered":"http:\/\/blogs.edf.org\/nanotechnology\/2008\/07\/22\/nano-on-a-hot-tin-roof\/"},"modified":"2024-02-12T11:00:21","modified_gmt":"2024-02-12T16:00:21","slug":"nano-on-a-hot-tin-roof","status":"publish","type":"post","link":"https:\/\/blogs.edf.org\/health\/2008\/07\/22\/nano-on-a-hot-tin-roof\/","title":{"rendered":"Nano On A Hot Tin Roof"},"content":{"rendered":"

<\/em>Cal Baier-Anderson, Ph.D.<\/em>, is a Health Scientist.<\/em><\/p>\n

Andrew Maynard, of the Project on Emerging Nanotechnologies, recently blogged<\/a> about an Australian study<\/a> that documented an odd effect of sunscreens containing nanoscale titanium dioxide (TiO2).\u00a0 The study was prompted by the observation that installers of metal roofs who used these sunscreens inadvertently transferred the product onto the roofs. In places where the workers\u2019 skin had touched the painted metal surfaces, the paint showed accelerated weathering. Why?\u00a0 Because the particular type of nanoscale TiO2 in the sunscreen (the anatase crystal form) is photoactive<\/em> \u2013 when it absorbs UV light, it releases free radicals that speed up the oxidation of the underlying paint.<\/p>\n

<\/p>\n

So it\u2019s only fair to ask whether the use of such sunscreens could accelerate the weathering of our skin.\u00a0 Andrew says not necessarily.\u00a0 While the observed damage to roof paint raises a red flag, for harm to our skin to occur would require that the free radicals penetrate down to the living layers of the skin.\u00a0 That step has not (yet) been observed to occur.<\/p>\n

Researchers from DuPont<\/a> noted that some but not all forms of nanoscale TiO2 exhibit such photoactivity.\u00a0 And reactivity can be decreased (or increased) by introducing special treatments and surface coatings to either \u201cpassify\u201d or activate such materials.<\/p>\n

One might have expected that sunscreen formulators would choose to use the less-reactive nanoscale TiO2.\u00a0 So why do some of these sunscreens exhibit increased photoactivity?\u00a0 Does this demonstrate a lack of understanding on the part of formulators, or are treatments used to reduce reactivity breaking down over time?\u00a0\u00a0 And is the government watching?<\/p>\n

So let\u2019s review what we know and don\u2019t know:
\n\u2022\u00a0We know that some forms of nanoscale TiO2 are more reactive than others.
\n\u2022\u00a0We know that nanoscale TiO2 can be modified to reduce reactivity.
\n\u2022\u00a0We know that some sunscreens that contain the more reactive form of nanoscale TiO2 can damage painted metal roofs.<\/p>\n

But:
\n\u2022\u00a0We don\u2019t know if frequent use of sunscreens containing the more reactive form of nanoscale TiO2 poses a greater health (or environmental) risk than the less reactive form.
\n\u2022\u00a0We don\u2019t know what type of nanoscale TiO2 is present in any given sunscreen we may purchase (in fact we may not even know if the TiO2 is nanoscale or not).
\n\u2022\u00a0There\u2019s still a lot more research needed to determine whether each of the various forms of nanoscale TiO2 can or cannot penetrate skin, including actively flexed or damaged (e.g., sunburned) skin.<\/p>\n

Meanwhile, be careful climbing on that roof!<\/p>\n","protected":false},"excerpt":{"rendered":"

Cal Baier-Anderson, Ph.D., is a Health Scientist. Andrew Maynard, of the Project on Emerging Nanotechnologies, recently blogged about an Australian study that documented an odd effect of sunscreens containing nanoscale titanium dioxide (TiO2).\u00a0 The study was prompted by the observation that installers of metal roofs who used these sunscreens inadvertently transferred the product onto the …<\/p>\n","protected":false},"author":101,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5009,56087],"tags":[5019,39201,5022],"coauthors":[],"class_list":["post-33","post","type-post","status-publish","format-standard","hentry","category-health-science","category-nanotechnology","tag-consumer-products","tag-dupont","tag-worker-safety"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t