Peculiarities of bioaccumulation and toxic effects produced by nanoparticles of molybdenum (VI) oxide under multiple oral exposure of rats: examination and comparative assessment.

Abstract

Molybdenum (VI) oxide nanoparticles (MoO3 NPs) are widely used in various economic activities. This creates elevated risks of exposure to this nanomaterial for workers and population in general and, consequently, there can be an increased number of developing pathological changes caused by exposure to MoO3 NPs. To examine and comparatively assess peculiarities of bioaccumulation and toxic effects produced by MoO NPs under multiple oral introductions. We evaluated sizes of analyzed particles by scanning electronic microscopy; specific surface area was calculated by the method of Brunauer, Emmett and Taylor; the total pore volume, by Barrett, Joyner and Halenda. Rats were exposed as per the scheme introduced by Lim with colleagues. We examined biochemical and hematological blood indicators, molybdenum concentrations and pathomorphological changes in tissues of various organs 24 hours after the last exposure. The study involved comparison with effects produced by MoO3 microparticles. The tested MoO3 sample was established to be a nanomaterial as per the whole set of its physical properties. 50% of animals in the exposed group died on the 16th day in the experiment after the total exposure dose of MoO3 NPs reached 6500 mg/kg of body weight. Having analyzed blood plasma, we determined the following. There was a growth in quantity of leukocytes and a share of segmented neutrophils and monocytes, which were by 1.76-3.50 times higher than in the control group. Activity of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase, alpha-amylase, and lactate dehydrogenase, and concentrations of urea, crude and direct bilirubin were higher by 1.61-22.86 times. Decrease in the number of platelets, plateletcrit, the relative number of lymphocytes, the number and proportion of large platelets by 1.31-2.71 times. We detected elevated molybdenum concentrations in the lungs, heart, liver, kidneys, brain and blood under exposure to MoO3 NPs in an amount exceeding the control values by 12.10-361.75 times. Rats exposed to MoO3 NPs had liver parenchymal steatosis, inflammatory changes, hemorrhagic infarctions and hyperplasia in the lungs. MoO3 NPs have a more apparent ability to bioaccumulate and produce toxic effects in comparison with their microdispersed analogue under multiple oral introductions into the body.