Toxicological and hygienic safety assessment of the aqueous suspension of nano-dispersed silicon dioxide, synthesized using liquid-crystal templating

Abstract

Abstract.Experimental research has shown that after intragastric administration of a water suspension of nanodispersed silicon dioxide particles synthesized by the method of templating the tested product falls in hazard class 3 by criteria LD50. A number of morphological changes were detected in the least researched dose of 500 mg/kg, in particular, gross changes in the blood circulatory system in the form of vascular distention, kidney, liver, and thymus. Other changes included lymphoid and macrophage proliferation and degenerative changes in the liver, kidney, splenic cords and lungs. After administration of a microdispersed analogue by the same method, no deaths of experimental animals were recorded (hazard class 4). A number of morphological changes were detected in dose 500 mg/kg including moderate vascular changes in liver, lymphoid proliferation, and lymphoid infiltration in the tissues of the esophagus, liver, kidney, large intestine, and gastric tissues.

Toxicity Evaluation of Nanostructured Silica Orally Administered to Rats: Influence on Immune System Function

“…However, the performance of the immune system in this study has not been investigated. It can be assumed that the main reason for the discrepancy in results [6,7] and [3,4], was the difference in the properties of the SiO 2 preparations used. It should be noted that all types of nanostructured SiO 2 studied in [2][3][4][5][6][7] are not used in consumer goods, including food.…”

“…It can be assumed that the main reason for the discrepancy in results [6,7] and [3,4], was the difference in the properties of the SiO 2 preparations used. It should be noted that all types of nanostructured SiO 2 studied in [2][3][4][5][6][7] are not used in consumer goods, including food. The study of subacute oral toxicity of NPs with a primary particle size of 5-30 nm showed the absence of noticeable signs of toxic effects when NM was administered for three months at a dose of up to 100 mg/kg bw daily by integral indicators, including weight gain, and permeability of the intestinal barrier to macromolecules.…”

“…Based on the data listed, it may be concluded that the oral toxicity of silica nanoparticles is relatively low. At the same time, in works [3,4], mice in an acute experiment were injected intragastrically with "monodisperse" SiO 2 NPs obtained by the method of the liquid crystal templating using cetyltrimethylammonium bromide as a template. The SiO 2 particles used in these studies were elliptical in size of approximately (50~70) × (20~30) nm.…”

“…Toxicity of nanostructured amorphous SiO 2 at the inhalation route of intake can be significant [2,3], whereas results that have been obtained with its oral route of intake do not coincide with each other. Hence, in particular, even a single administration to rats of monodisperse SiO 2 NPs results in a series of both local and systemic toxic effects which are evident at a dose of less than 1000 mg/kg of body weight (bw) [4,5]. However, in the study [6] only marginal toxic effects of SiO 2 nanoparticles manifested at a dose of 2500 mg/kg bw or more with repeated intragastric administration, and another study [7] did not reveal any adverse effects for both nanoparticles and microparticles of amorphous silica.…”