PATHOMORPHOLOGICAL CHANGES IN THE INTERNAL ORGANS OF RATS UNDER EXPOSURE TO SUSPENDED ULTRAFINE PARTICLES OF INDUSTRIAL AEROSOL

Abstract

Introduction. The investigation of nanoparticles, materials with unique physicochemical properties, and their effects on the bodies of experimental animals and humans is a key focus of contemporary toxicology. Particular concern arises from the formation of ultrafine particles (<100 nm) during various industrial processes, as these particles can behave like engineered nanoparticles and may pose potential health risks to exposed workers. Objective. To assess the pathomorphological changes in the internal organs of rats exposed to ultrafine particles generated in the workplace environment of a metal smelting facility. Materials and methods. During the experiment, subchronic intoxication with ultrafine particles collected at the workplace of the metal smelter was simulated in Wistar rats. The animals were being administered a colloidal solution of ultrafine particles intraperitoneally for 6 weeks at a dose of 1 ml per 100 g of body weight (quantitative concentration of 142358 particles/cm3). Structural changes in internal organs were studied at the 6th and the 2th weeks of the experiment using the morphometry program Videotest Morphology 5.2.0.158.axis and the Axio Scope A1 microscope “Carl Zeiss” (Germany) with a Jenoptik Progres gryphax® SUBRA series camera (Germany). Results. By the 12th week of the experiment, pathomorphological changes were observed in all internal organs, exhibiting varying degrees of severity. In the lungs, distal acinar emphysema was noted, characterized by thinning of the interalveolar septa and a reduction in the capillary network. Additionally, areas of septal thickening with lympho-macrophage infiltration were identified, along with dystrophic changes in the bronchial epithelium, including focal desquamation and inflammatory infiltration of the bronchial submucosa. In the liver, an increased number of hepatocytes with optically clear cytoplasm was observed, along with sinusoidal narrowing and evidence of pleurisy, suggesting edema or blood stasis. Moderate vacuolization and granularity of hepatocytes were also present. In the spleen, an increased number of destructively altered cells was found in lymphoid structures, accompanied by red pulp pleurisy, the appearance of young lymphoid cells within vessels, and a rise in reticular cell count. Myocardial changes were limited to isolated foci, showing uneven cytoplasmic staining in cardiomyocytes, nuclear alterations, karyopyknosis, and partial loss of transverse striation. In the kidneys, most glomeruli maintained normal architecture, though some displayed a moderate increase in mesangial cells without clustering. The tubular structures remained largely unaffected. In the brain, single foci of pyknotic neurons with intense staining were observed, along with stasis in small capillaries. Parenchymal compactness was preserved, and no signs of edema were detected. Conclusion. In experimental rats exposed to suspended ultrafine particles over a 12-week period, sclerotic, dystrophic, dyscirculatory, and inflammatory changes were observed in the internal organs. These alterations were most pronounced in the lung tissue, spleen, and liver parenchyma, and to a lesser extent in the myocardium, kidneys, and brain. The pathomorphological changes identified in these organs indicate a clear toxic effect of ultrafine particles generated during the metal smelting process.