Cytotoxicity and Genotoxicity of Sulfur-Vegetable Oil Polymers and Urea‑Loaded Composites Evaluated by the Allium Cepa Test

This study evaluated the cytotoxicity and genotoxicity of a sulfur vegetable oil biopolymer (p-SF) and its urea-loaded biocomposites using the Allium cepa L. assay. Urea was incorporated at different loadings 79 mg and 92 mg per g of biopolymer (p-SF-79U, p-SF-92U) to obtain controlled-release biocomposites for potential agricultural applications. After 72 h exposure, root growth increased by up to 63% in p-SF-92U compared with − 2.6% in the negative control, without visible signs of citotoxicity. Mitotic index values remained comparable to the control (5.93%), ranging from 4.27% to 6.66%, while the positive control (H₂O₂) completely inhibited mitosis. Microscopic analyses aloe to determinate that chromosomal aberrations were consistently low (< 2.9%) in treated cells, even below the control (3.67%), confirming the absence of genotoxicity. Moreover, all mitotic phases in treated groups, and severe chromosomal damage induced by H₂O₂ were observed. These findings demonstrate that the evaluated biopolymers and biocomposites are non-cytotoxic and non-genotoxic to eukaryotic cells, while promoting root development. Overall, the Allium cepa assay proved to be a reliable, low-cost tool for preliminary toxicological assessment, and the results support the safe application of sulfur oil biocomposites as sustainable encapsulation matrices for urea, offering an eco-friendly strategy to improve fertilizer efficiency and minimize environmental risks.