title: Human in vivo and in vitro studies on gastrointestinal absorption of titanium dioxide nanoparticles.
abstract: The study was designed to conduct human in vivo and in vitro studies on the gastrointestinal absorption of nanoparticles, using titanium dioxide as a model compound, and to compare nanoparticle behaviour with that of larger particles. A supplier's characterisation data may not fully describe a particle formulation. Most particles tested agreed with their supplied characterisation when assessed by particle number but significant proportions of 'nanoparticle formulations' were particles >100nm when assessed by particle weight. Oral doses are measured by weight and it is therefore important that the weight characterisation is taken into consideration. The human volunteer studies demonstrated that very little titanium dioxide is absorbed gastrointestinally after an oral challenge. There was no demonstrable difference in absorption for any of the three particle sizes tested. All tested formulations were shown to agglomerate in simulated gastric fluid, particularly in the smaller particle formulations. Further agglomeration was observed when dispersing formulations in polymeric or elemental foods. Virtually no translocation of titanium dioxide particles across the cell layer was demonstrated. This study found no evidence that nanoparticulate titanium dioxide is more likely to be absorbed in the gut than micron-sized particles.
authors.affiliation: Health & Safety Laboratory, Harpur Hill, Buxton SK17 9JN, UK. Electronic address: kate.jones@hsl.gsi.gov.uk.
authors.forename: Kate
authors.initials: K
authors.lastname: Jones
authors.affiliation: Health & Safety Laboratory, Harpur Hill, Buxton SK17 9JN, UK.
authors.forename: Jackie
authors.initials: J
authors.lastname: Morton
authors.affiliation: Health & Safety Laboratory, Harpur Hill, Buxton SK17 9JN, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Smith
authors.affiliation: Oxford University, Begbroke Science Park, Sandy Lane, Yarnton, Oxford OX5 1PF, UK.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Jurkschat
authors.affiliation: Health & Safety Laboratory, Harpur Hill, Buxton SK17 9JN, UK.
authors.forename: Anne-Helen
authors.initials: AH
authors.lastname: Harding
authors.affiliation: Health & Safety Laboratory, Harpur Hill, Buxton SK17 9JN, UK.
authors.forename: Gareth
authors.initials: G
authors.lastname: Evans
mesh_terms: D000328:Adult; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D065569:Gastrointestinal Absorption; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D010316:Particle Size; D012995:Solubility; D014025:Titanium / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: C009495:titanium dioxide; D014025:Titanium
keywords: Gastrointestinal absorption; Human volunteer study; In vitro; Nanoparticles; Oral dose; Titanium dioxide