Antimicrobial Residues in a Key Cerrado River: Distribution, Persistence, and Effects on Zebrafish Embryo-Larval...

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Aquatic Science

Background:

• Antimicrobial contamination in aquatic environments is a growing concern.
• Understanding the fate and effects of these compounds is crucial for ecosystem health.

Purpose of the Study:

• To quantify specific antimicrobials in Cerrado river water and sewage treatment plant effluents.
• To determine the environmental persistence (half-lives) of detected antimicrobials.
• To assess the ecotoxicity of these antimicrobials on zebrafish embryos and larvae.

Main Methods:

• High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for antimicrobial detection.
• pySiRC tool for predicting antimicrobial half-lives in aqueous media.
• Zebrafish embryo-larval toxicity assay to evaluate ecotoxicity.

Main Results:

• Metronidazole (MTZ) and sulfamethoxazole (SX) were detected, with concentrations ranging from 0.1 to 45.5 ng/L and 0.1 to 502.7 ng/L, respectively.
• Estimated half-lives for MTZ and SX were 14-139 days and 9-88 days, indicating significant persistence.
• MTZ exposure caused cardiotoxicity and developmental abnormalities in zebrafish larvae. Both MTZ and SX induced morphometric and behavioral changes.

Conclusions:

• MTZ and SX are persistent contaminants in the studied aquatic environment.
• These antimicrobials exhibit significant ecotoxicological effects on aquatic organisms, even at environmentally relevant concentrations.
• The findings highlight the need for monitoring and managing antimicrobial pollution in freshwater ecosystems.