title: The challenge of studying TiO2 nanoparticle bioaccumulation at environmental concentrations: crucial use of a stable isotope tracer.
abstract: The ecotoxicity of nanoparticles (NPs) is a growing area of research with many challenges ahead. To be relevant, laboratory experiments must be performed with well-controlled and environmentally realistic (i.e., low) exposure doses. Moreover, when focusing on the intensively manufactured titanium dioxide (TiO2) NPs, sample preparations and chemical analysis are critical steps to meaningfully assay NP's bioaccumulation. To deal with these imperatives, we synthesized for the first time TiO2 NPs labeled with the stable isotope (47)Ti. Thanks to the (47)Ti labeling, we could detect the bioaccumulation of NPs in zebra mussels (Dreissena polymorpha) exposed for 1 h at environmental concentrations via water (7-120 μg/L of (47)TiO2 NPs) and via their food (4-830 μg/L of (47)TiO2 NPs mixed with 1 × 10(6) cells/mL of cyanobacteria) despite the high natural Ti background, which varied in individual mussels. The assimilation efficiency (AE) of TiO2 NPs by mussels from their diet was very low (AE = 3.0 ± 2.7%) suggesting that NPs are mainly captured in mussel gut, with little penetration in their internal organs. Thus, our methodology is particularly relevant in predicting NP's bioaccumulation and investigating the factors influencing their toxicokinetics in conditions mimicking real environments.
authors.affiliation: CEA Saclay, DSM/IRAMIS/NIMBE/LIONS, UMR CEA-CNRS 3299, 91191 Gif-sur-Yvette, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Bourgeault
authors.forename: Cécile
authors.initials: C
authors.lastname: Cousin
authors.forename: Valérie
authors.initials: V
authors.lastname: Geertsen
authors.forename: Corinne
authors.initials: C
authors.lastname: Cassier-Chauvat
authors.forename: Franck
authors.initials: F
authors.lastname: Chauvat
authors.forename: Olivier
authors.initials: O
authors.lastname: Durupthy
authors.forename: Corinne
authors.initials: C
authors.lastname: Chanéac
authors.forename: Olivier
authors.initials: O
authors.lastname: Spalla
mesh_terms: D000818:Animals; D000458:Cyanobacteria; D049875:Dreissena / Q000187:drug effects / Q000378:metabolism*; D004781:Environmental Exposure / Q000032:analysis; D020387:Food Chain; D007553:Isotope Labeling; D007554:Isotopes / Q000032:analysis; D053758:Nanoparticles / Q000378:metabolism* / Q000633:toxicity; D014018:Tissue Distribution; D014025:Titanium / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics*; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics
chemical_list: D007554:Isotopes; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium