Occurrence and human health risk assessment of antibiotics and trace elements in Lactuca sativa amended with different organic fertilizers

Soil amendment with organic fertilizers is an effective approach to improve soil fertility. However, organic fertilizers may contain pollutants such as trace elements (TEs) and antibiotics (ABs), which, once deployed in arable soil, can be taken up by vegetables and have adverse effects on crops and human health. This study assesses the presence of 15 TEs and 16 ABs in lettuce grown in a greenhouse facility and amended with 3 different organic fertilizers (sewage sludge (SS), organic fraction of municipal solid waste (OFMSW), and swine manure (SM)) at 3 different fertilization doses. The results show that lettuces amended with SS resulted in the lowest content of TEs. Although 11 ABs were detected in the SM and SS fertilizers, only 3 ABs were detected in lettuce leaves. The concentrations of detected ABs in lettuce ranged from 0.67 ng/g fw (lincomycin) to 14.2 ng/g fw (ciprofloxacin) in SS. The organic fertilization dose did not affect the lettuce uptake of TEs or ABs. Moreover, the use of SS resulted in the highest lettuce yield of the organic amendments. The total hazard quotients (THQs) obtained for TEs and ABs were less than 1 for all the studied fertilization treatments. The highest THQs for TEs were observed in lettuce amended with SM (0.11-0.16), whereas the highest THQs for ABs were observed in SS treatments (0.06-0.09). The results thus suggest that consumption of lettuces amended with organic fertilizers would not pose a risk to human health due to the presence of studied TEs or ABs, but potentially harmful combined effects cannot ruled out.

The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Competitiveness through Project AGL2017-89518-R. Rui You gratefully acknowledges the fellowship from the China Scholarship Council

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