Toxicological Effects of Zinc Oxide Nanoparticles in Aquatic Organisms

Zinc oxide nanoparticles (ZnO-NPs) are increasingly detected in freshwater and marine environments due to their widespread use in cosmetics, sunscreens and industrial processes. Once released, these particles undergo aggregation, dissolution and surface modification, leading to a dynamic interplay between particulate and ionic zinc species. In algae and diatoms, ZnO-NPs can impair photosynthesis and alter gene expression through both mechanical shading and the release of Zn2+. In invertebrates and fish, exposure during embryonic or larval stages often results in reduced hatching rates, developmental deformities, pericardial and yolk-sac oedema, and impaired growth. Biochemical assays consistently reveal elevated reactive oxygen species and lipid peroxidation alongside depressed antioxidant enzyme activities, indicating oxidative stress as a central mechanism of toxicity. Environmental parameters such as salinity, temperature and organic matter further modulate nanoparticle behaviour, influencing aggregation, ion release and bioavailability. Chronic or sublethal exposures may disrupt lipid metabolism, provoke inflammatory responses in hepatic tissues and affect energy homeostasis. Conversely, dietary interventions with bioactive microalgae have shown promise in mitigating ZnO-NP-induced hepatic inflammation and metabolic disturbances. The global significance of this body of work lies in informing regulatory thresholds for nanoparticle emissions, guiding wastewater treatment strategies and identifying resilient species and ecological contexts where ZnO-NP risks may be amplified or attenuated.

Research from Nature Portfolio

Investigations into the combined effects of temperature and salinity on ZnO-NP toxicity to the marine diatom Thalassiosira pseudonana have revealed that higher temperatures and salinities promote particle aggregation, reduce Zn2+ release and thereby lessen growth inhibition. However, when the temperature approached the upper thermal tolerance of the diatom, nanoparticle toxicity increased despite reduced ion dissolution, highlighting the importance of organismal thermal limits in risk assessment. Moreover, comparative analyses demonstrated that ZnO-NPs and dissolved zinc induced different transcriptional profiles, suggesting distinct molecular pathways of toxicity for particulate and ionic forms under varying physicochemical regimes.

Toxicological Effects of Zinc Oxide Nanoparticles in Aquatic Organisms publication trend

The graph below shows the total number of articles in toxicological effects of zinc oxide nanoparticles in aquatic organisms across all publications each year (not limited to Nature Index journals).

Technical terms

Aggregation: Clustering of nanoparticles into larger assemblies, affecting bioavailability and ion release.

Dissolution: Release of metal ions (Zn2+) from nanoparticles into the aqueous phase.

Oxidative stress: Imbalance between production of reactive oxygen species and antioxidant defences.

Pericardial oedema: Fluid accumulation around the heart in developing fish embryos.

Bioavailability: Extent to which organisms can absorb and accumulate dissolved or particulate contaminants.

References

1. Ecological Risks of Zinc Oxide Nanoparticles for Early Life Stages of Obscure Puffer (Takifugu obscurus). Toxics (2024).
2. Salinity Moderated the Toxicity of Zinc Oxide Nanoparticles (ZnO NPs) towards the Early Development of Takifugu obscurus. International Journal of Environmental Research and Public Health (2023).
3. Influences of temperature and salinity on physicochemical properties and toxicity of zinc oxide nanoparticles to the marine diatom Thalassiosira pseudonana. Scientific Reports (2017).
4. Dunaliella salina Microalga Restores the Metabolic Equilibrium and Ameliorates the Hepatic Inflammatory Response Induced by Zinc Oxide Nanoparticles (ZnO-NPs) in Male Zebrafish. Biology (2022).