Effect of polyethylene particles on dibutyl phthalate toxicity in lettuce (Lactuca sativa L.)

Highlights: • Polyethylene decrease DBP and monobutyl phthalate content in the roots and leaves. • Polyethylene aggravated the separation of the cell wall in roots treated with DBP. • Polyethylene decreased DBP transport from the culture solution to the roots. • The combined effects of DBP and PE toxicity on lettuce depend on the variety. The effects of dibutyl phthalate (DBP) on the toxicity and edible quality (e.g., soluble proteins, soluble sugars, and vitamin C) of green and purple lettuce in the presence of polyethylene (PE) fragments were evaluated. The results revealed that PE treatment for 28 days decreased DBP and monobutyl phthalate content in lettuce roots and leaves, but enhanced the inhibitory effects of DBP on root growth and activity, reduced soluble protein and sugar content in lettuce leaves, and increased vitamin C content in lettuce leaves. Scanning and transmission electron microscopies revealed that PE only adhered to the root surface and did not enter the lettuce roots. Moreover, separation of the cell wall was aggravated in lettuce roots treated with DBP+PE, but not in lettuce treated with individual DBP or PE, and even led to the expansion of endoplasmic reticulum vesicles and cell rupture. Gaussian analysis indicated that PE interacted with DBP molecules through van der Waals interactions, which decreased DBP transport from the culture solution into the lettuce roots. In addition, purple lettuce was more sensitive to exogenous pollutants than green lettuce. This study provides new insights for food safety related to DBP fate and toxicity under PE stress.