Quantitative human health risk assessment along the lifecycle of nano-scale copper-based wood preservatives

Learning from Safe-by-Design for Safe-and-Sustainable-by-Design: Mapping the current landscape of Safe-by-Design reviews, case studies, and frameworks

With the introduction of the European Commission's "Safe and Sustainable-by-Design" (SSbD) framework, the interest in understanding the implications of safety and sustainability assessments of chemicals, materials, and processes at early-innovation stages has skyrocketed. Our study focuses on the "Safe-by-Design" (SbD) approach from the nanomaterials sector, which predates the SSbD framework. In this assessment, SbD studies have been compiled and categorized into reviews, case studies, and frameworks. Reviews of SbD tools have been further classified as quantitative, qualitative, or toolboxes and repositories. We assessed the SbD case studies and classified them into three categories: safe(r)-by-modeling, safe(r)-by-selection, or safe(r)-by-redesign. This classification enabled us to understand past SbD work and subsequently use it to define future SSbD work so as to avoid confusion and possibilities of "SSbD-washing" (similar to greenwashing). Finally, the preexisting SbD frameworks have been studied and contextualized against the SSbD framework. Several key recommendations for SSbD based on our analysis can be made. Knowledge gained from existing approaches such as SbD, green and sustainable chemistry, and benign-by-design approaches needs to be preserved and effectively transferred to SSbD. Better incorporation of chemical and material functionality into the SSbD framework is required. The concept of lifecycle thinking and the stage-gate innovation model need to be reconciled for SSbD. The development of high-throughput screening models is critical for the operationalization of SSbD. We conclude that the rapid pace of both SbD and SSbD development necessitates a regular mapping of the newly published literature that is relevant to this field.

The Effects of Gluconacin on Bacterial Tomato Pathogens and Protection against Xanthomonas perforans, the Causal Agent of Bacterial Spot Disease

As agricultural practices become more sustainable, adopting more sustainable practices will become even more relevant. Searching for alternatives to chemical compounds has been the focus of numerous studies, and bacteriocins are tools with intrinsic biotechnological potential for controlling plant diseases. We continued to explore the biotechnological activity of the bacteriocin Gluconacin from Gluconacetobacter diazotrophicus, PAL5 strain, by investigating this protein's antagonism against important tomato phytopathogens and demonstrating its effectiveness in reducing bacterial spots caused by Xanthomonas perforans. In addition to this pathogen, the bacteriocin Gluconacin demonstrated bactericidal activity in vitro against Ralstonia solanacearum and Pseudomonas syringae pv. tomato, agents that cause bacterial wilt and bacterial spots, respectively. Bacterial spot control tests showed that Gluconacin reduced disease severity by more than 66%, highlighting the biotechnological value of this peptide in ecologically correct formulations.

A Decision Support System for preclinical assessment of nanomaterials in medical products: the REFINE DSS

The application of nanomaterials in medicine has led to novel pharmaceuticals and medical devices that have demonstrated a strong potential for increasing the efficacy/performance and safety of therapeutic and diagnostic procedures to address a wide range of diseases. However, the successful translation of these technologies from their inception (proof-of-concept) to clinical practice has been challenged by substantial gaps in the scientific and technical capacity of R&D companies, especially SMEs, to keep up with the ever-evolving regulatory expectations in the emerging area of nanomedicine. To address these challenges, the EU Horizon 2020 project REFINE has developed a Decision Support System (DSS) to support developers of nanotechnology-enabled health products in bringing their products to the clinic. The REFINE DSS has been developed to support experts, innovators, and regulators in the implementation of intelligent testing strategies (ITS) for efficient preclinical assessment of nanotechnology-enabled health products. The DSS applies logical rules provided by REFINE experts which generate prioritized lists of assays to be performed (i.e. ITSs) for physicochemical characterisation and for immunotoxicological endpoints. The DSS has been tested against several case studies and was validated by internal project experts as well as external ones.

A methodology for the automatic evaluation of data quality and completeness of nanomaterials for risk assessment purposes

This manuscript proposes a methodology to assess the completeness and quality of physicochemical and hazard datasets for risk assessment purposes. The approach is also specifically applicable to similarity assessment as a basis for grouping of (nanoforms of) chemical substances as well as for classification of the substances according to the Classification, Labeling and Packaging regulation. The unique goal of this approach is to assess data quality in such a way that all the steps are automatized, thus reducing reliance on expert judgment. The analysis starts from available (meta)data as provided in the data entry templates developed by the NanoSafety community and used for import into the eNanoMapper database. The methodology is implemented in the templates as a traffic light system-the providers of the data can see in real time the completeness scores calculated by the system for their datasets in green, yellow, or red. This is an interactive feedback feature that is intended to provide an incentive for anyone inserting data into the database to deliver more complete and higher quality datasets. The users of the data can also see this information both in the data entry templates and on the database interface, which enables them to select better datasets for their assessments. The proposed methodology has been partially implemented in the eNanoMapper database and in a Weight of Evidence approach for the regulatory classification of nanomaterials. It was fully implemented in a publicly available online R tool.

Occupational risk of nano-biomaterials: Assessment of nano-enabled magnetite contrast agent using the BIORIMA Decision Support System

The assessment of the safety of nano-biomedical products for patients is an essential prerequisite for their market authorization. However, it is also required to ensure the safety of the workers who may be unintentionally exposed to the nano-biomaterials (NBMs) in these medical applications during their synthesis, formulation into products and end-of-life processing and also of the medical professionals (e.g., nurses, doctors, dentists) using the products for treating patients. There is only a handful of workplace risk assessments focussing on NBMs used in medical applications. Our goal is to contribute to increasing the knowledge in this area by assessing the occupational risks of magnetite (Fe₃O₄) nanoparticles coated with PLGA-b-PEG-COOH used as contrast agent in magnetic resonance imaging (MRI) by applying the software-based Decision Support System (DSS) which was developed in the EU H2020 project BIORIMA. The occupational risk assessment was performed according to regulatory requirements and using state-of-the-art models for hazard and exposure assessment, which are part of the DSS. Exposure scenarios for each life cycle stage were developed using data from literature, inputs from partnering industries and results of a questionnaire distributed to healthcare professionals, i.e., physicians, nurses, technicians working with contrast agents for MRI. Exposure concentrations were obtained either from predictive exposure models or monitoring campaigns designed specifically for this study. Derived No-Effect Levels (DNELs) were calculated by means of the APROBA tool starting from in vivo hazard data from literature. The exposure estimates/measurements and the DNELs were used to perform probabilistic risk characterisation for the formulated exposure scenarios, including uncertainty analysis. The obtained results revealed negligible risks for workers along the life cycle of magnetite NBMs used as contrast agent for the diagnosis of tumour cells in all exposure scenarios except in one when risk is considered acceptable after the adoption of specific risk management measures. The study also demonstrated the added value of using the BIORIMA DSS for quantification and communication of occupational risks of nano-biomedical applications and the associated uncertainties.

Transformation and release of micronized Cu used as a wood preservative in treated wood in wetland soil

Micronized Cu (μ-Cu) is used as a wood preservative, replacing toxic chromated copper arsenate (CCA). Micronized Cu is malachite [Cu₂CO₃(OH)₂] that has been milled to micron/submicron particles, with many particle diameters less than 100 nm, mixed with biocides and then used to treat wood. In addition to concerns about the fate of the Cu from μ-Cu, there is interest in the fate of the nano-Cu (n-Cu) constituents. We examined movement of Cu from μ-Cu-treated wood after placing treated-wood stakes into model wetland ecosystems. Release of Cu into surface and subsurface water was monitored. Surface water Cu reached maximum levels 3 days after stake installation and remained elevated if the systems remained inundated. Subsurface water Cu levels were 10% of surface water levels at day 3 and increased gradually thereafter. Sequential filtering indicated that a large portion of the Cu in solution was associating with soluble organics, but there was no evidence for n-Cu in solution. After 4 months, Cu in thin-sections of treated wood and adjacent soil were characterized with micro X-ray absorption fine structure spectroscopy (μ-XAFS). Localization and speciation of Cu in the wood and adjacent soil using μ-XAFS clearly indicated that Cu concentrations decreased over time in the treated wood and increased in the adjacent soil. However, n-Cu from the treated wood was not found in the adjacent soil or plant roots. The results of this study indicate that Cu in the μ-Cu-treated wood dissolves and migrates into adjacent soil and waters primarily in ionic form (i.e., Cu²⁺) and not as nano-sized Cu particles. A reduced form of Cu (Cu₂S) was identified in deep soil proximal to the treated wood, indicating strong reducing conditions. The formation of the insoluble Cu₂S effectively removes some portion of dissolved Cu from solution, reducing movement of Cu²⁺ to the water column and diminishing exposure.

Silica Particles Trigger the Exopolysaccharide Production of Harsh Environment Isolates of Growth-Promoting Rhizobacteria and Increase Their Ability to Enhance Wheat Biomass in Drought-Stressed Soils

In coming decades, drought is expected to expand globally owing to increased evaporation and reduced rainfall. Understanding, predicting, and controlling crop plants’ rhizosphere has the potential to manipulate its responses to environmental stress. Our plant growth-promoting rhizobacteria (PGPR) are isolated from a natural laboratory, ‘The Evolution Canyon’, Israel, (EC), from the wild progenitors of cereals, where they have been co-habituating with their hosts for long periods of time. The study revealed that commercial TM50 silica particles (SN) triggered the PGPR production of exopolysaccharides (EPS) containing D-glucuronate (D-GA). The increased EPS content increased the PGPR water-holding capacity (WHC) and osmotic pressure of the biofilm matrix, which led to enhanced plant biomass in drought-stressed growth environments. Light- and cryo-electron- microscopic studies showed that, in the presence of silica (SN) particles, bacterial morphology is changed, indicating that SNs are associated with significant reprogramming in bacteria. The findings encourage the development of large-scale methods for isolate formulation with natural silicas that ensure higher WHC and hyperosmolarity under field conditions. Osmotic pressure involvement of holobiont cohabitation is also discussed.

Untapped potentials of hazardous nanoarchitectural biopolymers

The First Industrial Revolution began when manual labour transitioned to machines. Fossil fuels and steam eventually replaced wood and water as an energy source used predominantly for the mechanized production of textiles and iron. The emergence of the required numerous enormous factories gave rise to smoke pollution due to the immense growth in coal consumption. The manufactured gas industry produced highly toxic effluent that was released into sewers and rivers polluting the water. Many pieces of legislation were introduced to overcome this issue, but with varying degrees of effectiveness. Alongside our growth in world population, the problems that we had with waste remained, but together with our increase in number the waste produced has also increased additionally. The immense volume of waste materials generated from human activity and the potentially detrimental effects on the environment and on public health have awakened in ourselves a critical need to embrace current scientific methods for the safe disposal of wastes. We are informed daily that our food waste must be better utilized to ensure enough food is available to feed the world's growing population in a sustainable way (Thyberg and Tonjes, 2016). Some things are easy, like waste food and cellulose products can be turned into compost, but how do we recycle sheep's wool? Or shrimp shells? Despite the fact that both these substances are hazardous, and have caused environmental and economic impact from being incinerated; but we anticipate that those substances may have the potential to convert into added value applications.We have been working in this area for over 15 years, working towards managing them and seeking their added value applications. We take the biological products, process (reconstitute) and engineer them into added value products such as functional and nanostructure materials including edible films, foams and composites including medical devices useful in the human body. Anything that we can ingest, should not cause an immune response in the human system. Natural biomacromolecules display the inherent ability to perform very specific chemical, mechanical or structural roles. Specifically, protein- and polysaccharide-based biomaterials have come to light as the most promising candidates for many biomedical applications due their biomimetic and nanostructured arrangements, their multi-functional features, and their capability to function as matrices that are capable of facilitating cell-cell and cell-matrix interactions.

Impact of copper oxide particle dissolution on lung epithelial cell toxicity: response characterization using global transcriptional analysis

The in vitro and in vivo toxicity of copper oxide nanoparticles (CuO NPs) is attributed to both particle and dissolved copper ion species. However, a clear understanding of (1) the specific cellular responses that are modulated by the two species and (2) the temporal dynamics in toxicity, as the proportional amount of particulate and ionic forms change over time, is lacking. In the current study, in vitro responses to microparticulate CuO (CuO MPs), CuO NPs, and dissolved Cu²⁺ were characterized in order to elucidate particle and ion-induced kinetic effects. Particle dissolution experiments were carried out in a relevant cell culture medium, using CuO NPs and MPs. Mouse lung epithelial cells were exposed for 2-48 h with 1-25 µg/mL CuO MPs, CuO NPs, or 7 and 54 µg/mL CuCl₂. Cellular viability and genome-wide transcriptional responses were assessed. Dose and time-dependent cytotoxicity were observed in CuO NP exposed cells, which was delayed and subtle in CuCl₂ and not observed in CuO MPs treated cells. Analyses of differentially expressed genes and associated pathway perturbations showed that dissolved ions released by CuO NPs in the extracellular medium are insufficient to account for the observed potency and cytotoxicity. Further organization of gene expression results in an Adverse Outcome Pathway (AOP) framework revealed a series of key events potentially involved in CuO NPs toxicity. The AOP is applicable to toxicity induced by metal oxide nanoparticles of varying solubility, and thus, can facilitate the development of in vitro alternative strategies to screen their toxicity.

Iron-Doping of Copper Oxide Nanoparticles Lowers Their Toxic Potential on C6 Glioma Cells

Copper oxide nanoparticles (CuO-NPs) are well known for their cytotoxicity which in part has been attributed to the release of copper ions from CuO-NPs. As iron-doping has been reported to reduce the susceptibility of CuO-NPs to dissolution, we have compared pure CuO-NPs and CuO-NPs that had been doped with 10% iron (CuO-Fe-NPs) for copper release and for their toxic potential on C6 glioma cells. Physicochemical characterization revealed that dimercaptosuccinate (DMSA)-coated CuO-NPs and CuO-Fe-NPs did not differ in their size or zeta potential. However, the redox activity and liberation of copper ions from CuO-Fe-NPs was substantially slower compared to that from CuO-NPs, as demonstrated by cyclic voltammetry and by the photometric quantification of the copper ion-bathocuproine complex, respectively. Exposure of C6 cells to these NPs caused an almost identical cellular copper accumulation and each of the two types of NPs induced ROS production and cell toxicity. However, the time- and concentration-dependent loss in cell viability was more severe for cells that had been treated with CuO-NPs compared to cells exposed to CuO-Fe-NPs. Copper accumulation and toxicity after exposure to either CuO-NPs or CuO-Fe-NPs was prevented in the presence of copper chelators, while neutralization of the lysosomal pH by bafilomycin A1 prevented toxicity without affecting cellular copper accumulation or ROS production. These data demonstrate that iron-doping does not affect cellular accumulation of CuO-NPs and suggests that the intracellular liberation of copper ions from CuO-NPs is slowed by the iron doping, which in turn lowers the cell toxic potential of iron-doped CuO-NPs.

Controlling the risks of nano-enabled products through the life cycle: The case of nano copper oxide paint for wood protection and nano-pigments used in the automotive industry

The widespread use of engineered nanomaterials (ENMs) in consumer products and the overwhelming uncertainties in their ecological and human health risks have raised concerns regarding their safety among industries and regulators. There has been an ongoing debate over the past few decades on ways to overcome the challenges in assessing and mitigating nano-related risks, which has reached a phase of general consensus that nanotechnology innovation should be accompanied by the application of the precautionary principle and best practice risk management, even if the risk assessment uncertainties are large. We propose a quantitative methodology for selecting the optimal risk control strategy based on information about human health and ecological risks, efficacy of risk mitigation measures, cost and other contextual factors. The risk control (RC) methodology was developed in the European FP7 research project SUN and successfully demonstrated in two case studies involving real industrial nano-enabled products (NEPs): nano-scale copper oxide (CuO) and basic copper carbonate (Cu₂(OH)₂CO₃) used as antimicrobial and antifungal coatings and impregnations for the preservation of treated wood, and two nanoscale pigments used for colouring plastic automotive parts (i.e. red organic pigment and carbon black). The application of RC for human health risks showed that although nano-related risks could easily be controlled in automotive plastics case study with modifications in production technology or specific type of engineering controls, nano-related risks due to sanding and sawing copper oxide painted wood were non-acceptable in the use lifecycle stage and would need the identification of a more effective risk control strategy.

Guiding the development of sustainable nano-enabled products for the conservation of works of art: proposal for a framework implementing the Safe by Design concept

Nanotechnology provides innovative and promising solutions for the conservation of cultural heritage, but the development and application of new nano-enabled products pose concerns regarding their human health and environmental risks. To address these issues, we propose a sustainability framework implementing the Safe by Design concept to support product developers in the early steps of product development, with the aim to provide safer nano-formulations for conservation, while retaining their functionality. In addition, this framework can support the assessment of sustainability of new products and their comparison to their conventional chemical counterparts if any. The goal is to promote the selection and use of safer and more sustainable nano-based products in different conservation contexts. The application of the proposed framework is illustrated through a hypothetical case which provides a realistic example of the methodological steps to be followed, tailored and iterated along the decision-making process.

Source specific exposure and risk assessment for indoor aerosols

Poor air quality is a leading contributor to the global disease burden and total number of deaths worldwide. Humans spend most of their time in built environments where the majority of the inhalation exposure occurs. Indoor Air Quality (IAQ) is challenged by outdoor air pollution entering indoors through ventilation and infiltration and by indoor emission sources. The aim of this study was to understand the current knowledge level and gaps regarding effective approaches to improve IAQ. Emission regulations currently focus on outdoor emissions, whereas quantitative understanding of emissions from indoor sources is generally lacking. Therefore, specific indoor sources need to be identified, characterized, and quantified according to their environmental and human health impact. The emission sources should be stored in terms of relevant metrics and statistics in an easily accessible format that is applicable for source specific exposure assessment by using mathematical mass balance modelings. This forms a foundation for comprehensive risk assessment and efficient interventions. For such a general exposure assessment model we need 1) systematic methods for indoor aerosol emission source assessment, 2) source emission documentation in terms of relevant a) aerosol metrics and b) biological metrics, 3) default model parameterization for predictive exposure modeling, 4) other needs related to aerosol characterization techniques and modeling methods. Such a general exposure assessment model can be applicable for private, public, and occupational indoor exposure assessment, making it a valuable tool for public health professionals, product safety designers, industrial hygienists, building scientists, and environmental consultants working in the field of IAQ and health.

Risk Governance of Nanomaterials: Review of Criteria and Tools for Risk Communication, Evaluation, and Mitigation

Nanotechnologies have been increasingly used in industrial applications and consumer products across several sectors, including construction, transportation, energy, and healthcare. The widespread application of these technologies has raised concerns regarding their environmental, health, societal, and economic impacts. This has led to the investment of enormous resources in Europe and beyond into the development of tools to facilitate the risk assessment and management of nanomaterials, and to inform more robust risk governance process. In this context, several risk governance frameworks have been developed. In our study, we present and review those, and identify a set of criteria and tools for risk evaluation, mitigation, and communication, the implementation of which can inform better risk management decision-making by various stakeholders from e.g., industry, regulators, and the civil society. Based on our analysis, we recommend specific methods from decision science and information technologies that can improve the existing risk governance tools so that they can communicate, evaluate, and mitigate risks more transparently, taking stakeholder perspectives and expert opinion into account, and considering all relevant criteria in establishing the risk-benefit balance of these emerging technologies to enable more robust decisions about the governance of their risks.