Occurrence and risk assessment of antibiotics in water and lettuce in Ghana

Hospital wastewater and effluents from waste stabilization ponds in Kumasi, Ghana, are directly discharged as low quality water into nearby streams which are eventually used to irrigate vegetables. The presence of 12 com monly used antibiotics in Ghana (metronidazole, ciprofloxacin, erythromycin, trimethoprim, ampicillin, cefuroxime, sulfamethoxazole, amoxicillin, tetracycline, oxytetracycline, chlortetracycline and doxycycline) were investigated in water and lettuce samples collected in three different areas in Kumasi, Ghana. The water samples were from hospital wastewater, wastewater stabilization ponds, rivers and irrigation water, while the lettuce samples were from vegetable farms and market vendors. Antibiotics in water samples were extracted using SPE while antibiotics in lettuce samples were extracted using accelerated solvent extraction followed by SPE. All extracted antibiotics samples were analyzed by HPLC-MS/MS. All studied compounds were detected in concentrations significantly higher (p = 0.01) in hospital wastewater than in the other water sources. The highest concentration found in the present study was 15 μg/L for ciprofloxacin in hospital wastewater. Irrigation water samples analyzed had consent but effective means of removing antibiotics with removal efficiency up to 95% recorded in this study. However, some chemicals are still found in levels indicating medium to high risk of antibiotics resistance devel opment in the environment. The total concentrations of antibiotics detected in edible lettuce tissues from vege table farms and vegetable sellers at the markets were in the range of 12.0–104 and 11.0–41.4 ng/kg (fresh weight) respectively. The antibiotics found with high concentrations in all the samples were sulfamethoxazole, erythromycin, ciprofloxacin, cefuroxime and trimethoprim. Furthermore, our study confirms the presence of seven antibiotics in lettuce from irrigation farms and markets, suggesting an indirect exposure of humans t
This article is published by Elseviere,2017 and is also available at https://doi.org/10.1016/j.scitotenv.2017.11.287
Science of the Total Environment 622–623 (2018) 293–305