Titanium dioxide nanoparticles (TiO₂ NPs) are widely used engineered metallic nanomaterials, well known for their photocatalytic properties, bright white colour, bactericidal activity, and ability to block ultraviolet radiation. Their inexpensive synthesis makes them attractive to industry, and they are present in many consumer products, including personal care items. Given the perception that mineral-based sunscreens are safer and more effective, along with increasing awareness of the harmful effects of UV radiation, the use and environmental release of TiO₂ NPs are expected to continue rising.
TiO₂ NPs, as well as their primary element titanium, are unintentionally reaching the environment, potentially affecting organisms and aquatic ecosystems. Titanium has been detected in wastewater discharges and coastal waters, particularly during warmer months, mainly due to sunscreen usage. However, the levels of these environmental contaminants in Portuguese surface waters remain unknown. Furthermore, current legislation does not define maximum limits for nanoparticles, as acceptable levels have yet to be established. In addition, the ingestion of TiO₂ NPs through consumer products is receiving increasing attention, as their use as food additives for human and animal consumption is no longer considered safe.
The AQUATIDE project proposes a comprehensive and direct approach to assess the risks and implications of TiO₂ NP exposure in aquatic ecosystems, aiming to study their presence, effects on aquatic organisms, and impact on seafood quality. By developing faster, more sustainable, and ethically acceptable assessment tools, the project will advance methods for detecting the harmful effects of nanoparticles. To achieve this, five technical work packages (WPs) are proposed:
1. CIIMAR team members will test the hypothesis that TiO₂ NP concentrations are higher in aquatic environments subject to greater human pressure. To this end, environmental levels of TiO₂ NPs and titanium will be assessed across several ecosystems along the Portuguese coast.
2. CIIMAR team members will investigate the bioaccumulation of TiO₂ NPs along trophic chains. A model aquatic food chain will be used to evaluate trophic transfer risks in terms of toxicity and bioaccumulation. Environmentally relevant microalgae will serve as primary producers, the crustacean Artemia salina as a primary consumer, and fish as secondary consumers. Fish tissues obtained from these experiments will be used in subsequent work packages.
3. IPMA and CIIMAR team members will examine the effects of dietary exposure to TiO₂ NPs on fish nutritional quality. As previous studies have reported cellular structural changes, metabolic impairment, and lipid accumulation in fish exposed to TiO₂ NPs, this work will assess nutritional value and energy allocation among tissues, with potential implications for fisheries, aquaculture, and human health.
4. CIIMAR team members will investigate the biological processes affected by TiO₂ NP exposure in fish at molecular and cellular levels. This work package will focus on the metabolic consequences of dietary intake of TiO₂ NPs using multi-tissue and multi-omics approaches.
5. CIIMAR team members will conduct an in-depth analysis of affected molecular pathways to explore the interaction of TiO₂ NPs (and titanium) with different primary fish cell cultures. The goal is to develop non-invasive or alternative methods and identify new, cell-specific biomarkers, enabling rapid detection of the potential harmful effects of TiO₂ NPs.
Through environmental monitoring, experimental testing, and methodological innovation, AQUATIDE aims to develop cutting-edge nanotoxicology tools and procedures. The ultimate goal is to translate the project’s findings into practical solutions for mitigating the biological impacts of nanoparticle contaminants on the environment and consumers. AQUATIDE will benefit both society and the scientific community by advancing understanding of nanoparticle impacts on aquatic ecosystems, providing valuable data to support informed environmental policies and sustainable resource management practices.