Antibiotics residues in inland and transitional sediments

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Analytical Chemistry

Background:

• Antibiotic contamination in aquatic environments is a growing global concern.
• Sediments act as sinks for various environmental contaminants, including pharmaceuticals.
• Understanding antibiotic levels in sediments is crucial for assessing ecological risks.

Purpose of the Study:

• To quantify a range of antibiotics in Irish riverine and transitional sediments.
• To identify potential pollution sources and assess environmental risks.
• To compare Irish antibiotic levels with international data and investigate partitioning behavior.

Main Methods:

• Quantification of 12 macrolide, fluoroquinolone, sulphonamide, and diaminopyrimidine antibiotics.
• Analysis of 80 surficial sediment samples from diverse locations in Ireland.
• Calculation of risk quotients using sediment Predicted No-Effect Concentrations (PNECs).

Main Results:

• Clarithromycin was the most frequently detected antibiotic (∼90% of samples) with the highest mean concentration (6.65 ng/g).
• Ireland shows lower overall antibiotic concentrations compared to international studies, except for clarithromycin.
• Higher antibiotic levels were found near wastewater emission points; moderate levels linked to wastewater, aquaculture, or agriculture.

Conclusions:

• Most quantified antibiotics in Irish sediments pose a low ecotoxicological risk.
• Clarithromycin presents a moderate environmental risk, and ciprofloxacin a high risk in a single instance, warranting further monitoring.
• Antibiotic partitioning between water and sediment varies, influencing monitoring strategies.