Ecotoxicological Assessment and Biodegradation of Prednisone by Aquatic Microorganisms

Area of Science:

• Environmental Science
• Ecotoxicology
• Environmental Chemistry

Background:

• Pharmaceuticals in aquatic environments are a growing concern due to increased global consumption.
• Corticosteroids, like prednisone, are widely used and their environmental impact requires evaluation.

Purpose of the Study:

• To assess the ecotoxicity of prednisone on different trophic levels of aquatic organisms.
• To investigate the biodegradation potential of prednisone using cyanobacteria.

Main Methods:

• Ecotoxicity tests were performed on *Artemia salina*, *Aliivibrio fischeri*, and *Microcystis novacekii* at concentrations up to 100 mg/L.
• Biodegradation assays utilized *M. novacekii* under standardized protocols (ISO 11348-3, OECD 201).
• Standardized protocols (ABNT NBR 16530, ABNT NBR 15411-3, ISO 11348-3, OECD 201) ensured experimental rigor.

Main Results:

• Prednisone exhibited no significant toxic effects on any tested aquatic organisms up to 100 mg/L.
• EC50 values could not be determined as no toxicity was observed within the tested range.
• Prednisone concentration decreased during *M. novacekii* growth, correlating with increased medium pH.

Conclusions:

• Prednisone is considered non-toxic to aquatic organisms under the tested conditions, based on GHS criteria.
• Biodegradation of prednisone appears to be an indirect process mediated by pH alterations from cyanobacterial activity.
• Further research is needed to fully elucidate the environmental fate and indirect degradation pathways of prednisone.