Exploring the environmental impacts of nanomaterials and their effects on biodiversity through the lens of nanotoxicology
Imagine a material so small that 100,000 particles could fit across the width of a single human hair, yet so potent it can penetrate the most fundamental barriers of life—from cell membranes to organ systems. This is the paradoxical world of nanomaterials, substances measuring 1-100 nanometers in at least one dimension 1 .
By January 2022, the Nanodatabase counted 5,224 products containing nanoparticles available on the European market alone 1 .
The emerging field of nanotoxicology examines the potential harmful effects of nanomaterials while balancing their beneficial applications 2 .
Nanomaterials are created through various synthesis methods, potentially releasing particles during production.
Products containing nanomaterials are used daily, with potential release during application or wear.
End-of-life disposal leads to nanomaterials entering waste streams and potentially the environment.
Nanomaterials move through air, water, and soil systems, potentially accumulating in organisms.
Nanomaterials possess extraordinary properties that differ dramatically from their bulk counterparts, primarily due to their high surface area-to-volume ratio and quantum effects that emerge at the nanoscale 3 .
A nanoparticle's small size enables it to cross biological barriers that would normally block larger particles. Studies have shown that nanomaterials can cross cell membranes, the blood-testis barrier, and even the placenta barrier in pregnant mice, potentially causing neurotoxicity in offspring .
Visual representation of nanomaterial scale compared to common objects
Smaller particles typically have higher surface area, increasing their reactivity and potential toxicity 7 . Size also determines whether particles can enter cells or cross biological barriers.
Surface charge, chemistry, and reactivity govern how nanomaterials interact with biological systems 7 . Positively charged particles often show higher toxicity.
Some nanomaterials like silver nanoparticles can dissolve, releasing toxic ions that contribute to their toxicity profile 7 .
Nanomaterials enter the environment throughout their life cycle—from manufacturing and use to disposal. Once released, they can travel through air, water, and soil, potentially accumulating in organisms and moving up food chains 5 .
In aquatic environments, nanomaterials often undergo sedimentation due to increased ionic strength, increasing their bioavailability to bottom-dwelling organisms 9 .
Marine ecosystems face particular concern as they represent the ultimate sink for many contaminants. Research has shown that nanomaterials can exert toxic effects on marine species across trophic levels, including fish, zooplankton, marine bivalves, and phytoplankton—the base of the marine food web that accounts for approximately 50% of primary productivity on Earth 9 .
As nanotechnology advances, scientists are increasingly developing multi-component nanomaterials (MCNMs) that combine different elements to achieve specific functions 5 .
While these sophisticated materials offer enhanced control over properties, they also present greater complexity for toxicity assessment. With thousands of possible nanomaterial variations, traditional testing methods that rely on laboratory experiments cannot keep pace with innovation 5 .
To address this challenge, researchers have turned to computational approaches. In a 2025 study published in Environmental Science: Nano, scientists developed a novel classification structure-activity relationship (SAR) framework to predict the ecotoxicity of MCNMs 5 .
Compiled 652 half-maximal concentration measurements for 214 metal and metal oxide MCNMs.
Identified hydration enthalpy and energy difference as key descriptors.
Developed classification models using these descriptors.
Validated models against experimental data across diverse organisms.
The study revealed that just two descriptors could effectively classify MCNMs based on their ecotoxicity across diverse organisms 5 . This breakthrough suggests that fundamental material properties can predict biological impacts, even for complex multi-component nanomaterials.
| Target Organism | Classification Accuracy | Most Influential Descriptor |
|---|---|---|
| E. coli | High | Hydration enthalpy |
| S. aureus | High | Hydration enthalpy |
| D. rerio (zebrafish) | Moderate | Energy difference |
| D. magna (water flea) | Moderate | Energy difference |
| C. albicans | High | Hydration enthalpy |
| MCNM Type | Toxicity Classification | Primary Mechanism |
|---|---|---|
| Doped metal oxides | Variable | Depends on doping element |
| Composite metal oxides | Often toxic | Electron transfer capability |
| Bimetallic nanoparticles | Often toxic | Ion release potential |
| Surface-loaded metal oxides | Variable | Surface reactivity |
The ocean faces an era of unprecedented change, characterized by warming, acidification, and pollution 9 . Research examining nanomaterial ecotoxicity in this context reveals that environmental conditions significantly alter how nanomaterials interact with marine life.
A concerning finding is that ocean warming can enhance the toxicity of some nanomaterials. Experiments with the green alga Dunaliella tertiolecta showed that silver nanoparticles caused greater decreases in photosynthetic performance at 31°C compared to 25°C 9 .
Similarly, the diatom S. costatum suffered greater adverse effects from zinc oxide nanoparticles when temperatures increased 9 .
| Stressor Combination | Organism | Biological Effect | Severity |
|---|---|---|---|
| Silver NPs + warming | Green alga | Decreased photosynthetic performance | Enhanced at higher temperature |
| Zinc oxide NPs + warming | Diatom | Growth inhibition, oxidative stress | Enhanced at higher temperature |
| Titanium dioxide NPs + acidification | Mussels | Altered immune response, oxidative damage | Material-dependent |
| Nanomaterials + co-contaminants | Various | Altered bioavailability, mixture toxicity | Variable |
Nanomaterials don't affect all species equally, creating potential disruptions to ecological balance:
Experience growth inhibition, oxidative stress, and reduced photosynthetic efficiency 9 .
Understanding nanomaterial impacts requires sophisticated approaches spanning experimental and computational methods.
| Tool/Method | Function | Environmental Relevance |
|---|---|---|
| In vitro systems | Cell-based assays for mechanistic studies and high-throughput screening | Limited environmental relevance but useful for initial screening 1 |
| In vivo testing | Whole-organism studies using standard model species | Higher relevance but ethical concerns and resource-intensive 1 3 |
| Advanced models | Co-cultures, 3D models, organoids that better mimic real tissues | Improved prediction of in vivo effects 1 |
| Computational toxicology | QSAR, QNTR, and other in silico prediction models | Enables high-throughput safety assessment 3 5 |
| Characterization techniques | SEM, AFM, XPS for analyzing size, shape, surface properties | Essential for linking properties to toxicity 3 |
| Omics technologies | Genomics, proteomics, metabolomics for mechanistic insights | Reveals molecular-level interactions and pathways 2 |
| Mesocosm studies | Intermediate-scale experiments simulating natural environments | Bridge between laboratory and field conditions |
Each method offers distinct advantages and limitations, highlighting the need for integrated approaches that combine multiple techniques to comprehensively assess nanomaterial impacts 1 .
As nanotechnology continues to evolve, the field of nanotoxicology faces both challenges and opportunities. The enormous variety of nanomaterials and their potential transformations in the environment make case-by-case testing impractical . Instead, researchers are working toward predictive toxicology that can forecast material behavior based on fundamental properties 5 .
The concept of Safe-by-Design represents a promising approach where safety considerations are integrated into nanomaterial development from the earliest stages 2 5 . This proactive strategy, supported by computational predictions like the SAR framework described earlier, could help maximize benefits while minimizing potential harms.
That better reflect real-world exposure scenarios .
That consider nanomaterials in combination with other environmental stressors 9 .
To understand impacts across generations .
That move beyond individual species to community and ecosystem dynamics .
The invisible world of nanomaterials presents both extraordinary potential and significant responsibility. As we continue to harness the power of nanotechnology, understanding its interface with environmental health and biodiversity becomes increasingly crucial.
Through sophisticated computational approaches, carefully designed experiments, and a growing understanding of environmental context, scientists are developing the knowledge needed to guide sustainable nanotechnology development. The challenge ahead lies in balancing innovation with precaution, ensuring that the remarkable benefits of nanomaterials don't come at the cost of environmental integrity or biodiversity.