Oxidative Stress and Toxicological Responses of Eisenia fetida Exposed to Superparamagnetic Iron Oxide Nanoparticles in Soil

Dye pollution in aquatic systems is a significant environmental concern, prompting the use of nanocomposites for wastewater treatment. However, these materials may subsequently accumulate in soil through sludge disposal or irrigation with treated water, making soil a potential secondary sink of contamination. Therefore, assessing their impact on soil organisms is essential. Eisenia fetida is widely used as a sensitive bioindicator due to its ability to accumulate contaminants and reflect soil health. The aim of the present study was to utilize earthworms as biological indicators of iron oxide nanoparticles (IONPs) in soil. A green approach was used to make IONPs, which were then dried. Flaxseed extract was used in the method. We used X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and magnetic susceptibility tests to look at the nanoparticles' optical, structural, and dimensional features. After that, earthworms were exposed to IONPs in soil at levels of 0, 100, 200, 300, and 400 mg/kg for 7 days in a row. Exposure to IONPs had a big effect on the biochemical levels in earthworms. Light microscopy revealed histological damage in the body wall, longitudinal section, nephridium, and gut of earthworms subjected to IONPs. Furthermore, the front, ventral, and anal areas displayed morphological alterations post-exposure, as evidenced by scanning electron microscopy. The results suggested that earthworms exposed to IONPs demonstrated antioxidant depletion and histological alterations, especially at elevated nanoparticle concentrations. The necessity to evaluate the environmental safety of nanocomposites utilized in water treatment is highlighted by the physiological and histological alterations noted in earthworms after exposure to IONPs.