Uptake and accumulation of erythromycin in leafy vegetables and induced phytotoxicity and dietary risks

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. Two leafy vegetables, pakchoi (Brassica rapa subsp. chinensis) and water spinach (Ipomoea aquatica Forsk.), were grown in laboratory-constructed soil or hydroponic systems to investigate the dynamic accumulation of ERY in edible plants. Results indicate ¹⁴C-ERY could be absorbed by water spinach and pakchoi in both systems. Autoradiographic imaging and concentration data of plant tissues suggested that ERY had limited translocation from roots to shoots in these two vegetables. 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 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 negligible risks of consuming vegetables with roots exposed to ERY at environmentally relevant levels. In addition, ERY was found to cause growth inhibition and oxidative stress 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 risks of ERY to vegetables and human health.