title: Metrics, dose, and dose concept: the need for a proper dose concept in the risk assessment of nanoparticles.
abstract: In order to calculate the dose for nanoparticles (NP), (i) relevant information about the dose metrics and (ii) a proper dose concept are crucial. Since the appropriate metrics for NP toxicity are yet to be elaborated, a general dose calculation model for nanomaterials is not available. Here we propose how to develop a dose assessment model for NP in analogy to the radiation protection dose calculation, introducing the so-called "deposited and the equivalent dose". As a dose metric we propose the total deposited NP surface area (SA), which has been shown frequently to determine toxicological responses e.g. of lung tissue. The deposited NP dose is proportional to the total surface area of deposited NP per tissue mass, and takes into account primary and agglomerated NP. By using several weighting factors the equivalent dose additionally takes into account various physico-chemical properties of the NP which are influencing the biological responses. These weighting factors consider the specific surface area, the surface textures, the zeta-potential as a measure for surface charge, the particle morphology such as the shape and the length-to-diameter ratio (aspect ratio), the band gap energy levels of metal and metal oxide NP, and the particle dissolution rate. Furthermore, we discuss how these weighting factors influence the equivalent dose of the deposited NP.
authors.affiliation: Institute of Technology Assessment, Austrian Academy of Sciences, Strohgasse 45, Vienna 1030, Austria. Myrtill.Simko@ait.ac.at.
authors.forename: Myrtill
authors.initials: M
authors.lastname: Simkó
authors.affiliation: Department Radiation Protection and Health, Federal Office for Radiation Protection, Ingolstädter Landstr. 1, Oberschleißheim 85764, Germany. dnosske@bfs.de.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Nosske
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH) Ingolstädter Landstr. 1, Neuherberg/Munich 85764, Germany. kreyling@helmholtz-muenchen.de.
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Kreyling
mesh_terms: D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D006801:Humans; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000633:toxicity*; D008954:Models, Biological; D010087:Oxides / Q000008:administration & dosage* / Q000633:toxicity*; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D018570:Risk Assessment
chemical_list: D010087:Oxides
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