Comparative Assessment of the Effects of Short-Term Inhalation Exposure to Nickel Oxide Nanoparticles and Microdispersed Nickel Oxide

The biological effects of nickel oxide nanoparticles (Nickel (II) oxide, CAS number 1313-99-1, product number 637130) produced by Sigma-Aldrich (United States)) have been analyzed. The nanomaterial that was investigated consists of spherical particles with a hydrodynamic size of 17–40 nm; that is, the particle size is 9- to 38-fold less than the size of the particles of the microdispersed analog (150–1500 nm). CL50 of the samples investigated was higher than 5000 mg/m3 for BALB/C mice; therefore, the substances are classified as low-risk (class 4 hazardous substances). The capacity of nickel oxide nanoparticles used at the absolute concentration of 140194 ± 27768 particles/dm3 (equivalent to 1.34 ± 0.07 mg/dm3 nickel oxide) to accumulate in the lungs and blood after 4 h of inhalation exposure is higher than that of the microdispersed analog (39.27 times higher for accumulation in the lungs and 13.71 times higher for accumulation in blood); therefore, the nanoparticles are assumed to be more toxic than the microdispersed analog. This assumption is confirmed by the detection of morphological alterations that include the formation of focal perivascular and peribronchial lymphoid infiltrates with small amounts of macrophages and eosinophils in the lung tissue of BALB/C mice. The microdispersed analog applied at the same actual concentration does not induce the effect described above.