Environmental fate and pharmacokinetics of sulphamethazine in Fenneropenaeus chinensis shrimp production systems after oral administration

The antimicrobial sulphamethazine is widely used in aquaculture for the prevention and treatment of bacterial diseases. Residues of sulphamethazine have been detected in aquatic environments and in edible tissues of aquaculture fish and shrimps at relatively low, but detectable concentrations. Detailed information on the environmental fate and pharmacokinetics of sulphamethazine in aquaculture species is essential to predict possible ecological risks and to provide recommendations on appropriate dosages and withdrawal periods. In this study we investigated the distribution of sulphamethazine in water and sediments of Fenneropenaeus chinensis shrimp ponds treated with 50, 100 and 150 mg kg^?1·bw of sulphamethazine for 5 days and measured the uptake and elimination dynamics of sulphamethazine in different shrimp organs and tissues. Results of the HPLC analysis showed highest sulphamethazine concentrations in shrimp tissues, followed by sediments and water. The rank order of the mean concentrations of sulphamethazine in shrimp tissues and organs was hepatopancreas> plasma≈ stomach> muscle≈ gill≈ intestine> carapace. The results also demonstrated a significant dose‐dependent accumulation of sulphamethazine in the different biological and environmental compartments. Sulphamethazine decreased gradually with the time in all of the three compartments. The mean half‐life of sulphamethazine in sediment and water was 2.15 and 2.17 days respectively. A withdrawal period of 10 days or more is proposed for F. chinensis orally treated with sulphamethazine in order to meet the current food safety standards.