title: Nickel release and surface characteristics of fine powders of nickel metal and nickel oxide in media of relevance for inhalation and dermal contact.
abstract: Differences in surface oxide characteristics and extent of nickel release have been investigated in two thoroughly characterized micron-sized (mainly <4 μm) nickel metal powders and a nickel oxide bulk powder when immersed in two different synthetic fluids, artificial sweat (ASW-pH 6.5) and artificial lysosomal fluid (ALF-pH 4.5) for time periods up to 24h. The investigation shows significantly more nickel released from the nickel metal powders (<88%) compared to the NiO powder (<0.1%), attributed to differences in surface properties. Significantly more nickel was released from the nickel metal powder with a thin surface oxide predominantly composed of non-stoichiometric nickel oxide (probably Ni(2)O(3)), compared to the release from the nickel metal powder with a thicker surface oxide predominantly composed of NiO and to a lesser extent Ni(2)O(3) (88% and 25% release after 24 h in ALF, respectively). Significantly lower amounts of nickel were released from the nickel metal powders in ASW (2.2% and <1%, respectively). The importance of particle and surface characteristics for any reliable risk assessment is discussed, and generated data compared with literature findings on bioaccessibility (released fraction) of nickel from powders of nickel metal and nickel oxide, and massive forms of nickel metal and nickel-containing alloys.
authors.affiliation: KTH Royal Institute of Technology, Division of Surface and Corrosion Science, School of Chemical Science and Engineering, 100 44 Stockholm, Sweden.
authors.forename: Neda
authors.initials: N
authors.lastname: Mazinanian
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Hedberg
authors.forename: Inger
authors.initials: I
authors.lastname: Odnevall Wallinder
mesh_terms: D000818:Animals; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019570:Inhalation Exposure / Q000009:adverse effects; D008247:Lysosomes / Q000378:metabolism*; D009532:Nickel / Q000737:chemistry*; D010316:Particle Size; D011208:Powders; D018570:Risk Assessment / Q000379:methods; D012867:Skin / Q000378:metabolism; D013499:Surface Properties; D013542:Sweat / Q000378:metabolism*; D013997:Time Factors
chemical_list: D011208:Powders; D009532:Nickel; C028007:nickel monoxide