Virgin microplastics are not causing imminent harm to fish after dietary exposure

Area of Science:

• Environmental Toxicology
• Aquatic Ecology
• Marine Biology

Background:

• Fish are susceptible to microplastic ingestion due to visual cues and buoyancy.
• Previous studies used unrealistic microplastic concentrations, chemical contamination, or focused only on larval stages.
• Understanding microplastic effects on adult fish under realistic conditions is crucial.

Purpose of the Study:

• To investigate the effects of virgin microplastics on adult gilt-head seabream (Sparus aurata).
• To assess growth, blood biochemistry, histopathology, and microplastic accumulation/translocation.
• To determine the short- and long-term retention potential of microplastics in fish.

Main Methods:

• Adult gilt-head seabream were exposed to 6 common types of virgin microplastics at 0.1 µg/kg bodyweight/day for 45 days.
• Evaluated overall growth, performed blood biochemical analyses, and conducted histopathological examinations.
• Monitored microplastic accumulation in gastrointestinal organs, liver, and muscles, followed by a 30-day depuration period.

Main Results:

• No imminent harm, stress, altered growth, or pathology observed in adult gilt-head seabream after 45 days of exposure.
• Microplastic retention in the gastrointestinal tract was low, indicating effective elimination.
• Minimal accumulation in the gastrointestinal tract (near zero retention), but some large particles were found in 5.3% of analyzed livers.

Conclusions:

• Dietary exposure to common virgin microplastics does not induce significant stress or pathology in adult gilt-head seabream.
• Effective elimination of microplastics from the gastrointestinal tract suggests low long-term retention.
• While gut accumulation is minimal, some microplastic translocation to the liver warrants further investigation.