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Silver nanoparticles are increasingly used in consumer products, such as clothing and personal care products, in the medical and pharmaceutical industry and in the food industry. This is why their presence should increase in the environment where they can have harmful effects on the organisms. The UPV / EHU Cell Biology in Environmental Toxology research group analyzed adult zebrafish to determine the long-term effects of these silver particles in freshwater.
Among the main conclusions of the study, it should be noted that the form of metal (soluble or nanoparticles) that silver absorbs into water influences the distribution of the metal in fish organs. At the same time, soluble silver has also been found to cause short-term (three-day) alterations and long-term alterations of nanoparticles (21 days); and that in both cases, the animals purified themselves of the accumulated silver in their bodies after spending six months in clean water, although gill inflammation remained after being exposed to the metal.
In the study, led by Amaia Orbea, three groups of 50-60 adult zebrafish were used in three aquariums. Silver nitrate was added to the first reservoir to produce silver soluble in water; Silver nanoparticles at 20 nm (NP Ag) were added in the second; clean water was added to the third which served as a control. The groups in the contaminated reservoirs remained exposed to both metal forms for 21 days before spending six more months in clean water to study the consequences of a long – term exposure to water. money. An environmentally significant metal concentration has been used, in other words a concentration that could be found in nature, for example at the sewage treatment plant outlet. The accumulation of a substance is the first step for intoxication to occur.
three and 21 days of exposure to silver and after six months in clean water, various chemical and biological analyzes were performed on the gills, liver and intestines of the fish. The research team has selected the gills because it is the main route of entry of contaminants. the liver as it is the main organ of metabolism and detoxification; and the intestine, because silver nanoparticles can be absorbed by food.
It can be deduced from the analyzes that fish accumulate similar concentrations of metals after exposure to soluble silver and silver nanoparticles. And that after 6 months in clean water, the initial concentrations of metal were recovered. The conclusions differed when fish organs were analyzed. The distribution of silver in the liver and intestines depended on the type of metal used in the treatment, but both treatments resulted in inflammation of the gills in the fish, an effect that remained even after six months in the first year. clean water.
In addition, liver transcriptome analysis revealed a strong impact of exposure to money. The effect of soluble silver was more intense after three days of exposure when changes were detected in the expression levels of a total of 410 gene sequences. In the case of silver nanoparticles, the alteration was detected 21 days later and affected 799 sequences.
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Material provided by University of the Basque Country. Note: Content can be changed for style and length.
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