Uptake and Accumulation of Soil- and Water-Borne Erythromycin in Leafy Vegetables and Induced Phytotoxicity

Erythromycin (ERY), a widely used macrolide antibiotic, is omnipresent in soil and aquatic environments, which may potentially contaminate food crops but remains to be explored. Pakchoi and water spinach, two leafy vegetables, were grown in laboratory-constructed soil or hydroponic systems to investigate the dynamic uptake and transport of ERY by edible plants. Results indicate 14C-ERY could be uptaken by water spinach and pakchoi in both systems. The radioautographic imaging and the concentration data of plant tissues suggested that ERY had limited translocation from roots to shoots. The accumulation level of ERY was similar between the two vegetables in the soil system; but in the hydroponic system, pakchoi had a higher ERY accumulation than water spinach, with the bioconcentration factor of 2.74–25.98 and 3.65–11.67 L kg-1, respectively. The level of ERY intake via vegetable consumption was 0.01–2.17 ng kg-1 day-1, which was much lower than the maximum acceptable daily intake (700 ng kg-1 day-1), indicating the negligible risk that ERY posed on humans at environmentally relevant levels. In addition, ERY was found to cause growth inhibition and oxidative damages to pakchoi, even at low concentrations (7 and 22 μg L-1). This work contributes to a better understanding of plant uptake and translocation of ERY in soils and water, and has important implications for the reasonable evaluation of the implied risk of ERY to vegetables and human health