title: Electron microscopic investigation and elemental analysis of titanium dioxide in sun lotion.
abstract: OBJECTIVE
  The objective of this research was to determine the size, shape and aggregation of titanium dioxide (TiO2) particles which are used in sun lotion as UV-blocker.
  
  
  METHODS
  Overall, six sunscreens from various suppliers and two reference substances were analysed by electron microscopy (EM) techniques in combination with energy dispersive X-ray spectroscopy (EDS). Because of a high fat content in sun lotion, it was impossible to visualize the TiO2particles without previous EM sample preparation. Different defatting methods for TiO2from sun screens were tested. A novel sample preparation method was developed which allowed the characterization of TiO2particles with the help of EM and EDS.
  
  
  RESULTS
  Aggregates of titanium dioxide with the size of primary particles varying between 15 and 40 nm were observed only in five products. In the sun lotion with the highest SPF, only few small aggregates were found. In the sun screen with the lowest SPF, the largest aggregates of TiO2particles were detected with sizes up to 1.6 μm. In one of the sun lotions, neither TiO2nor ZnO was found in spite of the labelling. Instead, approx. 500 nm large diamond-shaped particles were observed. These particles are composed of an organic material as only carbon was detected by EDS.
  
  
  CONCLUSIONS
  A novel defatting method for sample preparation of titanium dioxide nanoparticles used in sun cosmetics was developed. This method was applied to six different sun lotions with SPF between 30 and 50+. TiO2particles were found in only five sunscreens. The sizes of the primary particles were below 100 nm and, according to the EU Cosmetic Regulation, have to be listed on the package with the term 'nano'.
authors.affiliation: Department of Chemical Safety and Toxicology, Bavarian Health and Food Safety Authority, Pfarrstraße 3, Munich, DE-80538, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Sysoltseva
authors.affiliation: Department of Chemical Safety and Toxicology, Bavarian Health and Food Safety Authority, Pfarrstraße 3, Munich, DE-80538, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Winterhalter
authors.affiliation: Ludwig-Maximilians-Universität, Butenandtstraße 11, Munich, DE-81377, Germany.
authors.forename: A S
authors.initials: AS
authors.lastname: Wochnik
authors.affiliation: Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, Düsseldorf, DE-40237, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Scheu
authors.affiliation: Department of Chemical Safety and Toxicology, Bavarian Health and Food Safety Authority, Pfarrstraße 3, Munich, DE-80538, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Fromme
mesh_terms: D000818:Animals; D006801:Humans; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D013052:Spectrometry, X-Ray Emission; D013473:Sunscreening Agents / Q000737:chemistry*; D014025:Titanium / Q000032:analysis*
chemical_list: D013473:Sunscreening Agents; C009495:titanium dioxide; D014025:Titanium
keywords: chemical analysis; claim substantiation; formulation sunscreen; sunscreen; titanium dioxide