Emerging contaminants adsorbed onto microplastics: Integrated assessment of behavioral and molecular effects in a transgenerational analysis in zebrafish

• Grant number: 25/15685-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: February 01, 2026
• End date: January 31, 2028
• Field of knowledge: Health Sciences - Pharmacy - Toxicological Analysis
• Principal Investigator: Danielle Palma de Oliveira
• Grantee: Bianca de Arruda Leite
• Host Institution: Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

This project aims to investigate the ecotoxicological effects of co-exposure to polystyrene microplastics (PS-MPs) and two emerging contaminants, the repellent icaridin (IC) and UV filter octocrylene (OC), in zebrafish (Danio rerio), focusing on behavioral alterations, oxidative stress, epigenetic mechanisms, and potential transgenerational effects. The presence of these contaminants in aquatic environments has been well-documented, with concentrations ranging from 2 to 280,000 ng/L for IC and 1.2 to 3,510 ng/L for OC. Due to their lipophilic properties, these compounds can adsorb to MPs, increasing their persistence and bioavailability to aquatic organisms and humans. However, the impacts of this interaction, particularly in chronic and multigenerational exposures, remain poorly understood. The study will be conducted in multiple phases. Initially, zebrafish embryos will be exposed to PS-MPs (50 µm), IC, and OC, both individually and in combination, at environmentally relevant concentrations validated by the Fish Embryo Toxicity test (FET - OECD 236). Lethal and sublethal parameters will be assessed, including malformations, hatching rate, and organ development. Subsequently, exposed larvae will undergo behavioral tests evaluating motor activity, novel tank exploration, social preference, spatial memory (Y-maze), and light/dark preference. At the molecular level, markers of oxidative stress, endocrine disruption, and epigenetic changes will be analyzed using RT-qPCR and RNA-Seq techniques. Tissue samples (brain, liver, and gonads) will be collected for transcriptomic and metabolomic analyses to identify affected biological pathways. To assess transgenerational effects, exposed adults (F0 generation) will be bred to produce the F1 generation, which will be analyzed for potential inheritance of behavioral and molecular alterations despite no direct exposure. Additionally, adsorption and desorption assays will be conducted to quantify MPs' capacity to transport and release IC and OC under simulated environmental conditions, using kinetic models such as Langmuir and Freundlich. The results will provide essential data to understand how MPs may modulate these contaminants' toxicity. Expected outcomes include identifying combined toxicity mechanisms, elucidating potential transgenerational effects, and generating evidence to support public policies related to chemical safety and aquatic ecosystem protection. The project aligns with the UN Sustainable Development Goals (SDGs 3, 6, 12, and 14) and benefits from international collaboration for advanced analyses, enhancing its scientific relevance and applicability. (AU)