Dermal toxicity of Colloidal Nanosilver in Albino Rabbit: A New Approach to Physicochemical Properties

Silver nanoparticles have been widely used as new potent antimicrobial agents in cosmetic and hygienic products, as well as in new medical devices. Serious concerns have been expressed on the potential health risks of dermal applications of nanosilver containing consumer products (AgNPs), therefore regulatory health risk assessment has become necessary for the safe usage of AgNPs in biomedical products with special emphasis to their dermal toxicity potentials. We aimed in the present study to compare the dermal toxicity of three different AgNP containing disinfectantsin an albino rabbit model and tried to determine the role of size and other physicochemical properties on their possible dermal toxicity. After the characterization of all three samples by transmission electron microscopy (TEM), X-Ray Diffraction (XRD) and Dynamic Light Scattering (DLS) , corrosive and irritant potentials  of AgNPs in three different sizes of three colloidal AgNPs were scored by the OECD 404 guideline with necessary modifications and were applied under the specified concentrations via nanosilver skin patches on the shaved skin of young female albino rabbits. All skin reactions were recorded in 3 min as well as in 1, 4, 24, 48 and 72 hours from the application and compared with the control group and followed up for 14 days. Although short-term observations didn’t show any significant changes in the weight of animals and macroscopic  variables, long-term histopathological abnormalities were seen in the skin of all test groups, which was not associated with the size and other physicochemical properties of AgNP samples. The toxicity manifestations were dry skin, scaling in doses lower than 100 ppm and erythema in higher doses up to 4000 ppm which was reversed. This finding creates a new issue in the possible dermal effects of all colloidal AgNPs, containing nano health products, which should be considered in future studies by focusing on other physicochemical properties of AgNPs and possible underlying mechanisms of toxicity by conducting cellular models.