Susana Loureiro, professor at the University of Aveiro ↗, has built her career at the intersection of ecotoxicology and environmental innovation. Fascinated by how chemicals interact with living organisms and ecosystems, she has become one of Europe’s leading voices on the opportunities and risks of nanomaterials. These materials, celebrated for their unique properties and growing range of applications, also raise complex questions about safety, bioaccumulation, and long-term ecological impact. In this interview, Loureiro explores the dual role of nanomaterials as both promising tools for sustainability and potential environmental stressors and explains how initiatives like PARC are working to close knowledge gaps, harmonise testing methods, and ensure that innovation in this field remains both safe and sustainable.

What sparked your interest in nanomaterials and their environmental impact? 

My background is in ecotoxicology, where we study how chemicals interact with organisms and ecosystems. Nanomaterials fascinated me because they represent a new frontier in chemistry: their special and specific properties give them unique behaviours that can be highly beneficial, with several applications, but also very bioactive, interacting with living entities. I was motivated to better understand how such novel materials behave once released into the environment and how we can ensure their safe use. 

Nanomaterials are being explored for environmental applications like pollution sensing and remediation. Where do you see the greatest environmental potential? 

I see great promise in their ability to support environmental monitoring and remediation. For example, nanosensors can detect pollutants at very low concentrations, helping us identify problems earlier. Nanomaterials can also play a role in water purification or soil decontamination, or even be used for slow release in agricultural practices as fertilisers or pesticides. If developed responsibly, they can contribute to more sustainable solutions to long-standing environmental challenges. One of the sensors we have been testing can provide early warning for corrosion in marine environments, and therefore bring huge benefits to society. They are slow-release nanomaterials, whose impact on the environment is reduced when compared to the application of other free compounds. They will help control time for improving maritime structures and therefore reduce costs and the need for new applications of other chemicals to these structures. 

But they also raise safety concerns. What are the main challenges in assessing environmental risks of these materials? 

Yes, indeed. In the first decade of the 2000s, the knowledge gaps on nanomaterials’ hazards were enormous, but research unveiled several aspects of their behaviour that also enable industry to tune them into safer and more sustainable forms.

The biggest challenge is their complexity. Nanomaterials are highly diverse in terms of size, shape, surface chemistry, and coatings — all of which influence how they behave in nature. Their transformations in the environment make it difficult to predict their fate and interactions with organisms. We have learned how they can be internalised in cells, but by changing slightly one of their characteristics, everything can change! Standard risk assessment frameworks were not designed with such dynamic materials in mind, so we need new approaches. 

What do we know so far about their effects on ecosystems, species and food chains? 

Research has shown that nanomaterials can be taken up by organisms, affect physiological processes, and, in some cases, transfer along food chains. However, effects vary greatly depending on the type of nanomaterial and the environmental conditions. For example, in one of the bioaccumulation studies we performed, we found that silver particles could not be internalised by the unicellular algae species we were using, and then we realised that this was a pattern for silver and microalgae, except for one or two species. With that, we could foresee that toxicity was driven by silver ions and a potential shadow effect from particles, and dissolution was key. We are now more able to understand patterns of bioaccumulation and toxicity, but there are still many gaps, especially when it comes to long-term, multigenerational (population) and ecosystem-level consequences. 

How is PARC helping to advance the methods used to detect, trace and assess nanomaterials in the environment? 

PARC provides a collaborative European platform to harmonise methods, develop advanced detection tools, and strengthen data sharing. For nanomaterials, this means improving analytical techniques to track them in complex environmental samples, refining models to predict exposure, and creating guidance that bridges the gap between research and regulatory needs. Here enters NAMs development, both for human health and the environment, which can help to tackle questions on Modes of Action, processes, or baseline toxicity, and enable the creation of Adverse Outcome Pathways (AOPs) to understand the mechanistic part of toxicity. The use of non-conventional endpoints can also be key to achieving this. Therefore, essential testing methods for human health and environmental hazard assessment of nanomaterials are still lacking. In addition, most new approach methodologies (NAMs) have yet to undergo validation, which limits their acceptance and integration into regulatory frameworks. 

Are current testing methods sensitive and standardised enough to capture real-world risks? 

In previous European projects, we aimed at harmonising methods that were developed for conventional chemicals. Along with stakeholders, in the NanoHarmony project, the White Paper From Science to Regulation ↗ was published and recommendations in key areas were highlighted to help improve the effectiveness of the TG development process. Additionally, another goal was to complement OECD Guidance Document 317 on Aquatic and Sediment Toxicological Testing of Nanomaterials by developing detailed annexes with technical recommendations for applying Test Guidelines 201 (algal growth inhibition), 202 (acute Daphnia immobilisation), and 203 (acute fish toxicity). While GD 317 already addresses these assays for nanomaterials, the annexes will provide more specific, practical guidance on protocols and procedures for both metallic and non-metallic nanomaterials, without revising other sections of the document. 

Are environmental regulators equipped with the necessary data and tools to manage the risks of nanomaterials? 

Not fully. While progress has been made, regulators still face significant gaps. Many analytical methods remain insufficiently sensitive to detect and characterise nanomaterials at environmentally relevant concentrations or in complex real-world matrices such as soil, water, and biological tissues. Laboratory methods exist, but translating them into standardised, validated tools that can be routinely used in regulatory monitoring is still a challenge.

Moreover, regulators often lack exposure assessment models tailored to nanoscale materials. Conventional chemical risk assessment frameworks are not always appropriate, since nanoscale properties such as surface area, shape, and coating can alter toxicity.

That said, there are encouraging developments. International initiatives such as the OECD Working Party on Manufactured Nanomaterials are creating shared databases and testing strategies. Advances in high-resolution imaging, single-particle ICP-MS, and omics-based methods are beginning to provide better insights.

However, regulatory readiness will also require stronger collaboration between governments, academia, and industry. Member states need to invest in monitoring infrastructure, data sharing, and training to build the technical capacity of regulators. 

What areas of research or regulation should be prioritised in the coming years to ensure the safe and sustainable use of nanomaterials in the environment? 

There are still several areas for improvement, but I will leave here four of them:

• Developing sensitive and standardised detection methods that work in real environmental matrices, especially more complex ones, like biological tissues, soils or sediments;
• Understanding long-term, low-dose effects within populations, revisiting multigenerational effects;
• Establishing regulatory guidance tailored to the specificities of nanomaterials;
• Promoting safe and sustainable-by-design approaches, so that sustainability and safety are built into innovation from the start and throughout the entire value chain of a product. 

How do you see your role as a chemical leader and what are PARC’s priorities? 

As a researcher and a professor, my role is to generate knowledge, train the next generation of scientists, and build bridges between academia, regulators, and society. Within PARC, our priority is to strengthen Europe’s capacity to anticipate and manage chemical risks, including emerging challenges like nanomaterials. By combining excellence in research with regulatory relevance, we can help ensure that innovation brings with it safety and sustainability.