Ecotoxicity of the Antimicrobials Methylparaben and Propylparaben in Mixture to Plants

Methylparaben (MPB) and propylparaben (PPB) are produced in high volumes worldwide and constantly released into the environment. They are found in the soil mainly due to the incorporation of urban sewage sludge into agricultural soils and the use of wastewater in irrigation. No studies were found on the impact assessment of parabens in mixture in soil organisms. The main objective of this study was to assess the ecotoxicity of MPB and PPB in mixture to plants. MPB and PPB were evaluated separately at concentrations 0.1, 1, 10, and 100 ng/L, and in combinations MPB 0.1 × PPB 0.1, MPB 1 × PPB 1, MPB 10 × PPB 10, and MPB 100 × PPB 100. Individually, the two parabens were not phytotoxic and cytogenotoxic. In mixture, MPB and PPB caused a significant reduction in root elongation in seeds of A. cepa, C. sativus, L. esculentum, and L. sativa. In A. cepa bulbs, the interaction of MPB and PPB reduced root elongation by inhibiting cell division and causing disturbances to the mitotic spindle and chromosomal compaction in meristematic cells. Such disorders were triggered because MPB and PPB in combination inhibit the cells’ defense system, leading to excess hydrogen peroxide in root meristems. Therefore, there was a phytotoxic, cytotoxic, and genotoxic synergy between MPB and PPB in plants, from the MPB 0.1 × PPB 0.1 combination, demonstrating that these compounds in a mixture can negatively impact crop productivity and the development non-cultivated plants.