The introduction of heavy metals into water or soil is a significant global issue affecting environmental health and food security. Potentially toxic elements (PTEs), such as chromium (Cr), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb), are non-biodegradable and toxic to living organisms. In contrast, essential elements, such as copper (Cu), zinc (Zn), or selenium (Se), can cause harm due to their deficit or excess. The exposure of an organism to such substances increases the concentration of them at a higher level of the trophic chain, a process known as biomagnification. Pollution of farmlands, coasts, or water bodies in agriculture is a major concern. The increase in the use of nanotechnologies, such as nanomaterials in agriculture, has introduced such substances into the environment and into the food chain. The consumption of products that contain PTEs can cause harm to human health, including neurotoxicity, genotoxicity, and several types of cancer. The aim of this research is to present the current advances regarding biomagnification in aquatic and terrestrial food chains of PTEs and metal-based nanomaterials in order to understand the data related to biomagnification, to find the routes of exposure to these substances, and, finally, to establish and monitor the risk assessment for human health.

In recent years, the acceleration of climate change and the growing demand for higher-quality food to meet the needs of an expanding population have become pressing challenges. Nanotechnology has emerged as a promising tool in agriculture, particularly through the application of nanoparticles (NPs). Recent studies highlight their potential to enhance plant performance, improve resistance to environmental stresses, and act as eustressors—stimuli that activate beneficial adaptive responses. Nanoparticles have been shown to stimulate plant defense systems (elicitation), promote growth and productivity, and improve crop quality by modulating physiological and biochemical pathways. Their role in enhancing adaptive capacity under diverse stress conditions makes them valuable candidates for sustainable agricultural strategies. However, a critical knowledge gap remains: the definition of eustress dose intervals. Establishing these thresholds is essential for maximizing the positive effects of NPs while minimizing risks. Finally, the need to define safe eustress dose intervals is highlighted as a critical step toward maximizing agricultural benefits while minimizing ecological and health risks.

Nanotechnology has emerged as a promising approach to enhance agricultural productivity; in this context, the effects of nanoparticles (NPs) on plants depend strongly on their size, composition, and concentration. We evaluated the influence of titanium dioxide (TiO₂) and silver-doped titanium dioxide (Ag-TiO₂) nanoparticles on seed germination, early growth, metabolite production, and antioxidant responses in alfalfa (Medicago sativa L.). Nanoparticles were synthetized via sol–gel; titanium isopropoxide was used as precursor and isopropanol as organic solvent, silver nitrate was used as dopant. Seeds were treated with nanoparticle suspensions at 0, 1, 5, 10, and 15 ppm. Morphological parameters (germination rate, radicle length, fresh weight, leaf morphology, and chlorophyll index), total phenols, flavonoids, and antioxidant capacity (DPPH and ABTS assays) were evaluated. Results showed a concentration-dependent response in morphological characteristics. TiO₂ promoted radicle elongation at 10 ppm (16%) and increased chlorophyll index along all concentrations (from 7% to 17%) but inhibited leaf growth at both 1 and 15 ppm (from 49% to 59%). In contrast, Ag-TiO₂ enhanced germination percentage by up to 95% and phenolic accumulation at 5 and 15 ppm (p < 0.05), although leaf length was consistently reduced across all concentrations (from 11% to 17%). Flavonoid levels increased by up to 116% at concentration of 15 ppm (p < 0.05). Antioxidant activity exhibited a contrasting pattern: TiO₂ reduced radical scavenging capacity when applied at 10 and 15 ppm, against the control group, from 48.62% to 17.72% and 13.96%, respectively, while Ag-TiO₂ maintained the antioxidant capacity when applied at 1 ppm. These findings suggest that nanoparticles in fact influence the germination process and have a noticeable effect on the morphological characteristics of alfalfa’ sprouts.