Effects of a biodegradable nanoformulation of herbicide on non-target organisms: Toxicity, Physiological Parameters, and Bioaccumulation

• Grant number: 24/13166-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2025
• End date: February 29, 2028
• Field of knowledge: Agronomical Sciences - Agronomy
• Principal Investigator: Valdemar Luiz Tornisielo
• Grantee: Ítallo Cristian da Silva de Oliveira
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Nanotechnology is a rapidly expanding area of science that can offer potential solutions for sustainable agriculture, including increasing the efficiency of active ingredients for target organisms and reducing environmental impacts. However, for these technologies to reach the global market, they must be evaluated for environmental, human risks, and their final fate. Quantitative and semi-quantitative ecotoxicological studies are used for this purpose. This project aims to evaluate the acute and chronic toxicity of a biodegradable polymeric nanoformulation of metribuzin (nanoMTZ) in Oreochromis niloticus (Nile Tilapia). The nanoMTZ will be prepared by the nanoprecipitation method and characterized according to methodologies already established in the literature. Initially, preliminary tests will be conducted to assess the organisms' health. Subsequently, acute and chronic toxicity tests will be conducted, where the fish will be exposed to various concentrations of the nanoformulation. Behavioral effects and survival will be monitored over time to determine the LC50. For chronic effects, the fish will be exposed to sublethal concentrations of nanoMTZ. After exposure, the fish will be captured, anesthetized, and blood will be collected for analysis of genotoxic biomarkers, including micronucleus (MN), erythrocytic nuclear abnormalities (ENA), and comet assay. Biochemical biomarkers will be analyzed through the activity of antioxidant enzymes such as glutathione S-transferase (GST) and catalase (CAT) in liver tissue. Histological analyses of the gills, liver, and kidney will be performed to assess histopathological biomarkers and verify tissue alterations. It is worth noting that nanoMTZ will be compared to conventional MTZ in all assays. The project also includes experiments on bioaccumulation and depletion of nanoMTZ in fish. These results may contribute to the development and safe use of herbicide nanoformulations, a promising technique that can improve the behavior of herbicides in environmental systems. Thus, obtaining these data will provide sufficient information to discuss the favorable and unfavorable aspects of implementing nanoformulations in agriculture. Moreover, it will contribute to the proposal of regulatory public policies that promote the effective and safe use of these nanoherbicides in aquatic ecosystems.