Potential hazzard of nanomaterials in food systems: Implications for soil, plant, environment, and human health

Nanotechnology has emerged as a promising frontier in agricultural innovation, with applications ranging from nanofertilizers and nanopesticides to smart delivery systems and biosensors.

These technologies are designed to improve input efficiency, reduce losses, and enhance crop performance. Metal and metal oxide nanoparticles such as zinc oxide, titanium dioxide, silver, iron oxide , and cerium oxide (CeO₂) are increasingly incorporated into agrochemical formulations. Despite rapid scientific and commercial interest, the environmental and health implications of nanomaterials remain inadequately addressed. Unlike conventional agrochemicals, nanoparticles possess unique physicochemical properties such as high mobility, large surface area, and Brownian motion that allow them to interact more aggressively with soil, plants, microorganisms, and human tissues. The long-term consequences of these interactions, particularly through food systems, raise serious concerns regarding agroecological sustainability and public health.

Soil as the primary receptor of Nanomaterials: Soil is the first and most critical environmental compartment exposed to nanomaterials applied through fertilizers, pesticides, irrigation water, or atmospheric deposition. Once introduced, nanoparticles may persist, transform, or accumulate due to their small size and strong surface reactivity. Numerous studies have shown that nanoparticles can disrupt soil structure by altering aggregation, porosity, and water-holding capacity. Their large surface area facilitates adsorption of organic matter and nutrients, potentially changing soil chemical equilibria. Additionally, nanoparticles may catalyze harmful chemical reactions, leading to contamination and degradation of soil ecosystems. Soil biota are particularly vulnerable. Nanoparticles such as ZnO, TiO₂, and Ag have been reported to reduce microbial biomass, inhibit enzyme activity, and alter microbial community composition. Earthworms, a keystone species in soil ecosystems, show reduced growth, survival, and reproduction upon exposure to nanoparticles. Bioaccumulation of ZnO nanoparticles in earthworms has been linked to DNA damage and impaired digestive function, indicating serious implications for soil fertility and ecosystem services.

Phytotoxicity and crop performance: Plants represent a critical interface between soil contamination and food-chain transfer. Nanoparticles can enter plants through roots or foliar surfaces and subsequently translocate to edible tissues. Phytotoxicity depends on multiple factors, including nanoparticle size, concentration, chemical composition, plant species, and developmental stage. Smaller nanoparticles (<20 nm) are generally more toxic due to higher reactivity and easier cellular penetration. Studies have shown that ZnO nanoparticles readily dissolve in soil and are efficiently taken up by plants, while TiO₂ nanoparticles tend to accumulate in soil and adhere to plant cell walls. Both have been associated with reduced biomass, inhibited root elongation, and impaired photosynthesis in crops such as wheat and rice. Silver nanoparticles have been reported to damage plant cell walls and membranes during penetration, leading to structural and physiological disruptions. Concentration is another critical determinant; nanoparticles of the same size may exhibit drastically different toxic effects at varying doses. For instance, ZnO nanoparticles can stimulate growth at low concentrations but cause severe inhibition of root growth and biomass at higher levels.

Impacts on aquatic ecosystems: Nanoparticles released from agricultural fields through runoff, leaching, or atmospheric deposition can contaminate surface and groundwater systems. Aquatic organisms are particularly sensitive to nanomaterial exposure due to direct contact and high uptake efficiency. Metal-based nanoparticles such as Ag, Cu, TiO₂, Al, and Ni have demonstrated pronounced toxicity to algae, daphnids, and fish. TiO₂ nanoparticles can reduce light penetration in water, impairing photosynthesis and algal growth. Silver and copper nanoparticles are among the most toxic, causing oxidative stress, membrane damage, and mortality across multiple trophic levels. Studies on zebrafish have revealed that nanoparticles can increase embryo mortality, delay hatching, reduce heart rate, and disrupt normal development. These effects are often irreversible and raise concerns about biodiversity loss and ecosystem stability. Importantly, soluble forms of nanoparticles tend to be more toxic than their bulk or aggregated counterparts, emphasizing the role of particle chemistry and dissolution behavior.

Food-chain transfer and bioaccumulation: One of the most critical risks associated with nanomaterials in agriculture is their potential to move through the food chain. Nanoparticles can accumulate in soil organisms, plants, animals, and ultimately humans. Due to their small size and mobility, nanoparticles may bypass biological barriers that typically limit the transfer of larger contaminants. Bioaccumulation has been observed in earthworms, fish, and plant tissues, suggesting a high likelihood of trophic transfer. Continuous exposure, even at low concentrations, may lead to chronic toxicity and long-term ecological consequences. The difficulty in detecting and monitoring nanoparticle contamination further complicates risk management.

Human health risks and exposure pathways: Human exposure to nanomaterials occurs primarily through inhalation, ingestion, and dermal contact. In agricultural contexts, ingestion through contaminated food and water represents the most significant pathway. Nanoparticles smaller than 50 nm can cross gastrointestinal barriers and enter systemic circulation, reaching organs such as the liver, spleen, bone marrow, and brain. Inhaled nanoparticles can deposit deep in the lungs, increasing respiratory and cardiovascular risks, and may even reach the brain via the olfactory nerve. Dermal exposure, particularly through damaged skin, also poses risks. Very small nanoparticles (<10 nm) can penetrate the epidermis, causing inflammation, oxidative stress, and tissue damage. Chronic exposure has been linked to respiratory diseases, cardiovascular disorders, and potential carcinogenic effects.

Status of Nanotechnology in Bangladesh Policy: In Bangladesh, nanotechnology in agriculture and food systems is at an early regulatory stage. The Food Safety Act, 2013 provides a general science-based framework for food safety but lacks explicit provisions on nanomaterials. The National Agriculture Policy (NAP) 2018, under Article 3.3.3, acknowledges the potential of nanotechnology for crop disease diagnosis, crop-specific nutrient management, soil quality monitoring through nanosensors, and improving input use efficiency via nano-based fertilizers and pesticides, including heavy metal mitigation. However, current policies emphasize innovation and productivity, with limited attention to nanoparticle risk assessment, environmental fate, food-chain transfer, and long-term human health impacts.

Alignment with FAO/WHO–Codex Perspective: Consistent with FAO and WHO guidance, the use of nanotechnology in food and agriculture should follow a precautionary, science-based, and risk-informed approach. Codex principles emphasize that novel technologies must undergo rigorous safety assessment, considering exposure pathways, toxicity, bioaccumulation, and long-term effects. Bangladesh's current policy framework partially aligns with innovation goals but requires harmonization with international standards on nanomaterial risk evaluation, labeling, and consumer protection.

Global overview of nano-regulation in food and agriculture: Across the world, regulation of nanomaterials in food and food-contact applications is evolving with a strong focus on safety. The European Union leads with mandatory labeling of nano-ingredients and requires separate safety approval for nano-forms of existing additives. The United States (FDA) treats nanomaterials as potentially novel, demanding case-by-case scientific data without assuming safety or risk. Canada and Taiwan require pre-market notification and safety assessment for engineered nanomaterials, including nano-packaging. Australia and New Zealand emphasize risk-based assessment and transparent communication. In Asia—including China, Japan, South Korea, and India—countries are gradually developing nano-specific guidelines, prioritizing safety evaluation, risk management, and, in some cases, labeling.

Regulatory and knowledge gaps: Despite rapid advances in nanotechnology, regulatory frameworks governing nanomaterial use in agriculture remain fragmented and insufficient. Most safety assessments rely on short-term toxicity studies and fail to capture chronic, low-dose, and multi-generational effects. Standardized protocols for evaluating nanoparticle toxicity in soil–plant–water–human systems are urgently needed. Risk assessment must consider particle size, shape, surface chemistry, concentration, and environmental transformations. Without robust regulation, the widespread adoption of nanotechnology in food systems may pose unintended and irreversible risks.

Why nanotechnology in food systems poses unique safety concerns

In countries like Bangladesh, nanotechnology in food systems raises heightened safety concerns due to unintentional, lifelong oral exposure through food and packaging within densely populated settings. Limited consumer awareness, weak monitoring capacity, and informal or abusive application of inputs increase exposure risks. Engineered nanoparticles may cross intestinal barriers, accumulate in organs, and cause oxidative stress, while long-term toxicity data under local dietary and environmental conditions are scarce. Regulatory frameworks, testing facilities, and enforcement mechanisms remain inadequate, making food-chain exposure more concerning than tightly regulated nanomedicine or controlled engineering applications.

The way forward

Nanotechnology holds significant promise for improving agricultural productivity and resource-use efficiency. However, the current body of evidence clearly indicates that nanomaterials can exert harmful effects on soil health, plant growth, aquatic ecosystems, and human health, particularly when applied without adequate understanding of their long-term behavior and toxicity. The level of nanotoxicity is strongly dependent on composition, particle size (<20 nm), and concentration (>100 ppm). Therefore, precautionary principles must guide the development and deployment of nano-enabled agricultural inputs. Future research should prioritize long-term, system-level studies, establish non-toxic thresholds, and integrate ecological and human health perspectives.

An intelligent, regulated, and risk-informed use of nanotechnology supported by green chemistry and agroecological principles may help achieve food security while safeguarding environmental sustainability and public health.