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Micro- and nanoplastics (MNPs) are ubiquitous environmental pollutants representing a concern for human health. MNPs have been detected in human placentas, indicating that during pregnancy maternal exposure may lead to placental transfer and foetal exposure, with potential for adverse effects on early-life development. However, a comprehensive risk assessment (RA) framework, specific to early-life is lacking. Here, we propose a novel roadmap to assist the development of an early-life health RA of MNPs. This roadmap is designed based on established chemical, mixture, particle, and MNP assessment strategies aligned with standard RA components (problem formulation, hazard identification, hazard characterisation, exposure assessment, risk characterisation). We systematically work through these stages to identify what is needed to progress a RA for the early-life impacts of MNPs, including what information is missing, and what may be used in the interim. While challenges such as complex physicochemical properties of MNPs, limited toxicity data at relevant exposure levels, and uncertainties related to characterising complex exposures have been described elsewhere, our work discusses how these challenges specifically impact early-life stages such as the significance of MNP presence in biological samples and factors influencing bioaccumulation and placental transfer. Additionally, we introduce the development of new technology readiness levels for methods used in the detection of MNPs in complex matrices. Importantly, this review integrates a broad scope of relevant information into one comprehensive document, providing a unified resource. We highlight specific requirements and areas for targeted research, including the development of dose-response relationships specific to early-life stages and novel strategies for assessing bioaccumulation and placental transfer of MNPs. By addressing these gaps, our roadmap aims to advance the development of a robust framework, ultimately enhancing the understanding and mitigation of risks associated with early-life exposure to MNPs. [ABSTRACT FROM AUTHOR]

Toxicity evaluation of engineered nanomaterials is challenging due to the ever increasing number of materials and because nanomaterials (NMs) frequently interfere with commonly used assays. Hence, there is a need for robust, high-throughput assays with which to assess their hazard potential. The present study aimed at evaluating the applicability of a genotoxicity assay based on the immunostaining and foci counting of the DNA repair protein 53BP1 (p53-binding protein 1), in a high-throughput format, for NM genotoxicity assessment. For benchmarking purposes, we first applied the assay to a set of eight known genotoxic agents, as well as X-ray irradiation (1 Gy). Then, a panel of NMs and nanobiomaterials (NBMs) was evaluated with respect to their impact on cell viability and genotoxicity, and to their potential to induce reactive oxygen species (ROS) production. The genotoxicity recorded using the 53BP1 assay was confirmed using the micronucleus assay, also scored via automated (high-throughput) microscopy. The 53BP1 assay successfully identified genotoxic compounds on the HCT116 human intestinal cell line. None of the tested NMs showed any genotoxicity using the 53BP1 assay, except the positive control consisting in (CoO)(NiO) NMs, while only TiO2 NMs showed positive outcome in the micronucleus assay. Only Fe3O4 NMs caused significant elevation of ROS, not correlated to DNA damage. Therefore, owing to its adequate predictivity of the genotoxicity of most of the tested benchmark substance and its ease of implementation in a high throughput format, the 53BP1 assay could be proposed as a complementary high-throughput screening genotoxicity assay, in the context of the development of New Approach Methodologies. [ABSTRACT FROM AUTHOR]

Background: Toxicity assessment for regulatory purposes is starting to move away from traditional in vivo methods and towards new approach methodologies (NAM) such as high-throughput in vitro models and computational tools. For materials with limited hazard information, utilising quantitative Adverse Outcome Pathways (AOPs) in a testing strategy involving NAM can produce information relevant for risk assessment. The aim of this work was to determine the feasibility of linking in vitro endpoints to in vivo events, and moreover to key events associated with the onset of a chosen adverse outcome to aid in the development of NAM testing strategies. To do this, we focussed on the adverse outcome pathway (AOP) relating to the onset of pulmonary fibrosis. Results: We extracted in vivo and in vitro dose–response information for particles known to induce this pulmonary fibrosis (crystalline silica, specifically α-quartz). To test the in vivo–in vitro extrapolation (IVIVE) determined for crystalline silica, cerium dioxide nanoparticles (nano-CeO2) were used as a case study allowing us to evaluate our findings with a less studied substance. The IVIVE methodology outlined in this paper is formed of five steps, which can be more generally summarised into two categories (i) aligning the in vivo and in vitro dosimetry, (ii) comparing the dose–response curves and derivation of conversion factors. Conclusion: Our analysis shows promising results with regards to correlation of in vitro cytokine secretion to in vivo acute pulmonary inflammation assessed by polymorphonuclear leukocyte influx, most notable is the potential of using IL-6 and IL-1β cytokine secretion from simple in vitro submerged models as a screening tool to assess the likelihood of lung inflammation at an early stage in product development, hence allowing a more targeted investigation using either a smaller, more targeted in vivo study or in the future a more complex in vitro protocol. This paper also highlights the strengths and limitations as well as the current difficulties in performing IVIVE assessment and suggestions for overcoming these issues. [ABSTRACT FROM AUTHOR]

Chemicals containing Volatile Organic Compounds (VOCs) are commonly used in the machine carpet production. 1,3-butadiene and styrene are main components of the carpenter's glue used in carpet factories. Exposition to these chemicals can lead to a number of adverse health effects. This is the first study of the human health risk assessment due to inhalational exposure to 1,3-butadiene (BD) and styrene (ST) performed among workers in the carpet factories in Kashan city, Iran. The importance of the study was related with the fact of high popularity of carpet production in the South Asia countries. Inhalation exposure to BD and ST were measured based on the National Institute for Occupational Safety and Health (NIOSH) 1024 and 1501 methods, respectively. The cancerogenic risk (CR) and non-cancerogenic risk described as Hazard Quotient (HQ) values were calculated based on the United States Environmental Protection Agency (USEPA) method. The sensitivity and uncertainty analysis were performed by the Monte Carlo simulation (MCS) technique. The average concentration measured of BD and ST during work shifts of employees were 0.039 mg m−3 (0.017 ppm) and 12.108 mg m−3 (2.84 ppm), respectively. The mean ± SD value of estimated cancerogenic risk in inhalation exposure to BD and ST were equal to 5.13 × 10–3 ± 3.85 × 10–4 and 1.44 × 10–3 ± 2.36 × 10–4, respectively exceeding the acceptable risk level of 10–6 defined by USEPA. The average non-carcinogenic risk (HQ) values of BD and ST were equal to 8.50 × 100 and 5.13 × 100, respectively exceeding the acceptable risk level of 1. As the results of our studies exceeded both cancerogenic and non-carcinogenic risk values it indicates that adverse health effects due to inhalational exposure to BD and ST for workers in the machine carpet industry are very likely. To avoid negative health effects protective measures for employees in the factories should be introduced immediately and furher detailed research are recommended. [ABSTRACT FROM AUTHOR]

There is an urgent need to apply effective, data-driven approaches to reliably predict engineered nanomaterial (ENM) toxicity. Here we introduce a predictive computational framework based on the molecular and phenotypic effects of a large panel of ENMs across multiple in vitro and in vivo models. Our methodology allows for the grouping of ENMs based on multi-omics approaches combined with robust toxicity tests. Importantly, we identify mRNA-based toxicity markers and extensively replicate them in multiple independent datasets. We find that models based on combinations of omics-derived features and material intrinsic properties display significantly improved predictive accuracy as compared to physicochemical properties alone. Nanomaterials have a range of potential applications, however, toxicity remains a concern, limiting application and requiring extensive testing. Here, the authors report on a predictive framework made using a range of tests linking materials properties with toxicity, allowing the prediction of toxicity from physiochemical and biological properties. [ABSTRACT FROM AUTHOR]

Hazard studies for nanomaterials (NMs) commonly assess whether they activate an inflammatory response. Such assessments often rely on rodents, but alternative models are needed to support the implementation of the 3Rs principles. Zebrafish (Danio rerio) offer a viable alternative for screening NM toxicity by investigating inflammatory responses. Here, we used non-protected life stages of transgenic zebrafish (Tg(mpx:GFP)i114) with fluorescently-labeled neutrophils to assess inflammatory responses to silver (Ag) and zinc oxide (ZnO) NMs using two approaches. Zebrafish were exposed to NMs via water following a tail fin injury, or NMs were microinjected into the otic vesicle. Zebrafish were exposed to NMs at 3 days post-fertilization (dpf) and neutrophil accumulation at the injury or injection site was quantified at 0, 4, 6, 8, 24, and 48 h postexposure. Zebrafish larvae were also exposed to fMLF, LTB4, CXCL-8, C5a, and LPS to identify a suitable positive control for inflammation induction. Aqueous exposure to Ag and ZnO NMs stimulated an enhanced and sustained neutrophilic inflammatory response in injured zebrafish larvae, with a greater response observed for Ag NMs. Following microinjection, Ag NMs stimulated a time-dependent neutrophil accumulation in the otic vesicle which peaked at 48 h. LTB4 was identified as a positive control for studies investigating inflammatory responses in injured zebrafish following aqueous exposure, and CXCL-8 for microinjection studies that assess responses in the otic vesicle. Our findings support the use of transgenic zebrafish to rapidly screen the pro-inflammatory effects of NMs, with potential for wider application in assessing chemical safety (e.g. pharmaceuticals). [ABSTRACT FROM AUTHOR]

Exposure to engineered nanomaterials (ENM) poses a potential health risk to humans through long-term, repetitive low-dose exposures. Currently, this is not commonplace within in vitro lung cell cultures. Therefore, the purpose of this study was to consider the optimal exposure approach toward determining the stability, sensitivity and validity of using in vitro lung cell mono- and co-cultures to determine ENM hazard. A range of exposure scenarios were conducted with DQ12 (previously established as a positive particle control) (historic and re-activated), TiO2 (JRC NM–105) and BaSO4 (JRC NM–220) on both monocultures of A549 cells as well as co-cultures of A549 cells and differentiated THP-1 cells. Cell cultures were exposed to either a single, or a repeated exposure over 24, 48- or 72-hours at in vivo extrapolated concentrations of 0–5.2 µg/cm2, 0-6 µg/cm2 and 0-1µg/cm2. The focus of this study was the pro-inflammatory, cytotoxic and genotoxic response elicited by these ENMs. Exposure to DQ12 caused pro-inflammatory responses after 48 hours repeat exposures, as well as increases in micronucleus frequency. Neither TiO2 nor BaSO4 elicited a pro-inflammatory response at this time point. However, there was induction of IL-6 after 24 hours TiO2 exposure. In conclusion, it is important to consider the appropriateness of the positive control implemented, the cell culture model, the time of exposure as well as the type of exposure (bolus or fractionated) before establishing if an in vitro model is appropriate to determine the level of response to the specific ENM of interest. [ABSTRACT FROM AUTHOR]

Assessment of nanomaterial (NM) induced inflammatory responses has largely relied on rodent testing via measurement of leukocyte accumulation in target organs. Despite observations that NMs activate neutrophil driven inflammatory responses in vivo, a limited number of studies have investigated neutrophil responses to NMs in vitro. We compared responses between the human neutrophil-like HL-60 cell line and human primary neutrophils following exposure to silver (Ag), zinc oxide (ZnO), copper oxide (CuO) and titanium dioxide (TiO2) NMs. NM cytotoxicity and neutrophil activation were assessed by measuring cellular metabolic activity, cytokine production, respiratory burst, and release of neutrophil extracellular traps. We observed a similar pattern of response between HL-60 cells and primary neutrophils, however we report that some neutrophil functions are compromised in the cell line. Ag NMs were consistently observed to stimulate neutrophil activation, with CuO NMs inducing similar though weaker responses. TiO2 NMs did not induce a neutrophil response in either cell type. Interestingly, ZnO NMs readily induced activation of HL-60 cells but did not appear to activate primary cells. Our findings are relevant to the development of a tiered testing strategy for NM hazard assessment which promotes the use of non-rodent models. Whilst we acknowledge that HL-60 cells may not be a perfect substitute for primary cells and require further investigation regarding their ability to predict neutrophil activation, we recommend their use for initial screening of NM-induced inflammation. Primary human neutrophils can then be used for more focused assessments of neutrophil activation before progressing to in vivo models where necessary. [ABSTRACT FROM AUTHOR]

There is an urgent need for safe and effective approaches to combat COVID-19. Here, we asked whether lessons learned from nanotoxicology and nanomedicine could shed light on the current pandemic. SARS-CoV-2, the causative agent, may trigger a mild, self-limiting disease with respiratory symptoms, but patients may also succumb to a life-threatening systemic disease. The host response to the virus is equally complex and studies are now beginning to unravel the immunological correlates of COVID-19. Nanotechnology can be applied for the delivery of antiviral drugs or other repurposed drugs. Moreover, recent work has shown that synthetic nanoparticles wrapped with host-derived cellular membranes may prevent virus infection. We posit that nanoparticles decorated with ACE2, the receptor for SARS-CoV-2, could be exploited as decoys to intercept the virus before it infects cells in the respiratory tract. However, close attention should be paid to biocompatibility before such nano-decoys are deployed in the clinic. [ABSTRACT FROM AUTHOR]

Societies worldwide are investing considerable resources into the safe development and use of nanomaterials. Although each of these protective efforts is crucial for governing the risks of nanomaterials, they are insufficient in isolation. What is missing is a more integrative governance approach that goes beyond legislation. Development of this approach must be evidence based and involve key stakeholders to ensure acceptance by end users. The challenge is to develop a framework that coordinates the variety of actors involved in nanotechnology and civil society to facilitate consideration of the complex issues that occur in this rapidly evolving research and development area. Here, we propose three sets of essential elements required to generate an effective risk governance framework for nanomaterials. (1) Advanced tools to facilitate risk-based decision making, including an assessment of the needs of users regarding risk assessment, mitigation, and transfer. (2) An integrated model of predicted human behavior and decision making concerning nanomaterial risks. (3) Legal and other (nano-specific and general) regulatory requirements to ensure compliance and to stimulate proactive approaches to safety. The implementation of such an approach should facilitate and motivate good practice for the various stakeholders to allow the safe and sustainable future development of nanotechnology. [ABSTRACT FROM AUTHOR]

Assessing the safety of engineered nanomaterials (NMs) is paramount to the responsible and sustainable development of nanotechnology, which provides huge societal benefits. Currently, there is no evidence that engineered NMs cause detrimental health effects in humans. However, investigation of NM toxicity usingin vivo, in vitro, in chemico, andin silicomodels has demonstrated that some NMs stimulate oxidative stress and inflammation, which may lead to adverse health effects. Accordingly, investigation of these responses currently dominates NM safety assessments. There is a need to reduce reliance on rodent testing in nanotoxicology for ethical, financial and legislative reasons, and due to evidence that rodent models do not always predict the human response. We advocate thatin vitromodels and zebrafish embryos should have greater prominence in screening for NM safety, to better align nanotoxicology with the 3Rs principles. Zebrafish are accepted for use by regulatory agencies in chemical safety assessments (e.g. developmental biology) and there is growing acceptance of their use in biomedical research, providing strong foundations for their use in nanotoxicology. We suggest that investigation of the response of phagocytic cells (e.g. neutrophils, macrophages)in vitroshould also form a key part of NM safety assessments, due to their prominent role in the first line of defense. The development of a tiered testing strategy for NM hazard assessment that promotes the more widespread adoption of non-rodent, alternative models and focuses on investigation of inflammation and oxidative stress could make nanotoxicology testing more ethical, relevant, and cost and time efficient. [ABSTRACT FROM AUTHOR]

Tuberculosis kills more people worldwide than any other infectious disease. Treatment requires multiple drug therapy administered over long periods (6-24 months). The emergence of multidrug-resistant strains is a major problem, and with few new drugs in the pipeline, a novel modus operandi is urgently required. Solid drug nanoparticles (SDNs), a new development in nanomedicine, offer a fresh therapeutic approach. Here, we show that SDNs are more effective (50-fold) at killing pathogenic mycobacteria than aqueous forms of the same drug and can target mycobacteria internalised by macrophages, where bacilli reside. We demonstrate synthesis of dual and triple drug loaded SDNs, facilitating combination tuberculosis therapy. Our results suggest that by employing SDNs of existing antibiotics, it may be possible to improve drug delivery and therefore reduce drug dosage to lessen side effects and fight drug resistance. [ABSTRACT FROM AUTHOR]

A first European Conference on Computational Nanotoxicology, CompNanoTox, was held in November 2015 in Benahavís, Spain with the objectives to disseminate and integrate results from the European modeling and database projects (NanoPUZZLES, ModENPTox, PreNanoTox, MembraneNanoPart, MODERN, eNanoMapper and EU COST TD1204 MODENA) as well as to create synergies within the European NanoSafety Cluster. This conference was supported by the COST Action TD1204 MODENA on developing computational methods for toxicological risk assessment of engineered nanoparticles and provided a unique opportunity for cross fertilization among complementary disciplines. The efforts to develop and validate computational models crucially depend on high quality experimental data and relevant assays which will be the basis to identify relevant descriptors. The ambitious overarching goal of this conference was to promote predictive nanotoxicology, which can only be achieved by a close collaboration between the computational scientists (e.g. database experts, modeling experts for structure, (eco) toxicological effects, performance and interaction of nanomaterials) and experimentalists from different areas (in particular toxicologists, biologists, chemists and material scientists, among others). The main outcome and new perspectives of this conference are summarized here. [ABSTRACT FROM PUBLISHER]

Nanoparticles (NP) have a tendency to agglomerate after dispersion in physiological media, which can be prevented by the addition of serum. This may however result in modification of the toxic potential of particles due to the formation of protein corona. Our study aimed to analyze the role of serum that is added to improve the dispersion of 10 nm TiO NPs on in vitro and in vivo effects following the exposure via the respiratory route. We characterized NP size, surface charge, sedimentation rate, the presence of protein corona and the oxidant-generating capacity after NP dispersion in the presence/absence of serum. The effect of serum on NP internalization, cytotoxicity and pro-inflammatory responses was assessed in a human pulmonary cell line, NCI-H292. Serum in the dispersion medium led to a slower sedimentation, but an enhanced cellular uptake of TiO NPs. Despite this greater uptake, the pro-inflammatory response in NCI-H292 cells was lower after serum supplementation (used either as a dispersant or as a cell culture additive), which may be due to a reduced intrinsic oxidative potential of TiO NPs. Interestingly, serum could be added 2 h after the NP treatment without affecting the pro-inflammatory response. We also determined the acute pulmonary and hepatic toxicity in vivo 24 h after intratracheal instillation of TiO NPs in C57BL/6N mice. The use of serum resulted in an underestimation of the local acute inflammatory response in the lung, while a systemic response on glutathione reduction remained unaffected. In conclusion, serum as a dispersion agent for TiO NPs can lead to an underestimation of the acute pro-inflammatory response in vitro and in vivo. To avoid potential unwanted effects of dispersants and medium components, we recommend that the protocol of NM preparation should be thoroughly tested, and reflect as close as possible realistic exposure conditions. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is a serious problem. Nanotechnology offers enormous potential in medicine, yet there is limited knowledge regarding the toxicity of nanoparticles (NP) for mycobacterial species that cause serious human diseases (e.g. tuberculosis (TB) and leprosy). Mycobacterial diseases are a major global health problem; TB caused byMycobacterium tuberculosis(Mtb) kills up to 2 million people annually and there are over 200 000 leprosy cases each year caused byMycobacterium leprae(M. leprae). Few drugs are effective against these mycobacteria and increasing antibiotic resistance exacerbates the problem. As such, alternative therapies are urgently needed but most current assays used to assess the effectiveness of therapeutics against mycobacteria are slow and expensive. This study aimed to develop a rapid, low-cost assay which can be used for screening the antimicrobial properties of compounds against pathogenic mycobacteria and to assess the toxicity of three NP (silver [Ag], copper oxide [Cu(II)O], and zinc oxide [ZnO]) against a green fluorescent protein reporter strain ofMycobacterium aviumsubspeciesparatuberculosis, a slow growing, pathogenic mycobacterial species causing paratuberculosis in ruminants. Fluorescence was used to monitor mycobacterial growth over time, with NP concentrations of 6.25–100 μg/mL tested for up to 7 days, and a method of data analysis was designed to permit comparison between results. Mycobacterial sensitivity to the NP was found to be NP composition specific and toxicity could be ranked in the following order: Ag > Cu(II)O > ZnO. [ABSTRACT FROM AUTHOR]

ENPRA was one of the earlier multidisciplinary European Commission FP7-funded projects aiming to evaluate the risks associated with nanomaterial (NM) exposure on human health across pulmonary, cardiovascular, hepatic, renal, and developmental systems. The outputs from this project have formed the basis of this review. A retrospective interpretation of the findings across a wide range of in vitro and in vivo studies was performed to identify the main highlights from the project. In particular, focus was placed on informing what advances were made in the hazard assessment of NM, as well as offering some suggestions on the future of “nanotoxicology research” based on these observations, shortcomings, and lessons learned from the project. A number of issues related to the hazard assessment of NM are discussed in detail and include use of appropriate NM for nanotoxicology investigations; characterization and dispersion of NM; use of appropriate doses for all related investigations; need for the correct choice of experimental models for risk assessment purposes; and full understanding of the test systems and correct interpretation of data generated from in vitro and in vivo systems. It is hoped that this review may assist in providing information in the implementation of guidelines, model systems, validation of assessment methodology, and integrated testing approaches for risk assessment of NM. It is vital to learn from ongoing and/or completed studies to avoid unnecessary duplication and offer suggestions that might improve different aspects of experimental design. [ABSTRACT FROM PUBLISHER]

Workers involved in producing nanomaterials or using nanomaterials in manufacturing plants are likely to have earlier and higher exposure to manufactured/engineered nanomaterials ( ENM) than the general population. This is because both the volume handled and the probability of the effluence of 'free' nanoparticles from the handled volume are much higher during a production process than at any other stage in the lifecycle of nanomaterials and nanotechnology-enabled products. Risk assessment (RA) techniques using control banding ( CB) as a framework for risk transfer represents a robust theory but further progress on implementing the model is required so that risk can be transferred to insurance companies. Following a review of RA in general and hazard measurement in particular, we subject a Structural Alert Scheme methodology to three industrial case studies using ZrO2, TiO2, and multi-walled carbon nanotubes ( MWCNT). The materials are tested in a pristine state and in a remediated (coated) state, and the respective emission and hazard rates are tested alongside the material performance as originally designed. To our knowledge, this is the first such implementation of a CB RA in conjunction with an ENM performance test and offers both manufacturers and underwriters an insight into future applications. WIREs Nanomed Nanobiotechnol 2015, 7:839-855. doi: 10.1002/wnan.1340 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editors discuss various papers within the issue on topics including the NanoTEST project, biological impact of nanoparticles in nanomedicine, safety aspects of the use of nanomaterials in medicine, and cytotoxicity and genotoxicity of certain nanomaterials.

Nanogenotoxicity is a crucial endpoint in safety testing of nanomaterials as it addresses potential mutagenicity, which has implications for risks of both genetic disease and carcinogenesis. Within the NanoTEST project, we investigated the genotoxic potential of well-characterised nanoparticles (NPs): titanium dioxide (TiO2) NPs of nominal size 20 nm, iron oxide (8 nm) both uncoated (U-Fe3O4) and oleic acid coated (OC-Fe3O4), rhodamine-labelled amorphous silica 25 (Fl-25 SiO2) and 50 nm (Fl-50 SiO) and polylactic glycolic acid polyethylene oxide polymeric NPs - as well as Endorem® as a negative control for detection of strand breaks and oxidised DNA lesions with the alkaline comet assay. Using primary cells and cell lines derived from blood (human lymphocytes and lymphoblastoid TK6 cells), vascular/central nervous system (human endothelial human cerebral endothelial cells), liver (rat hepatocytes and Kupffer cells), kidney (monkey Cos-1 and human HEK293 cells), lung (human bronchial 16HBE14o cells) and placenta (human BeWo b30), we were interested in which in vitro cell model is sufficient to detect positive (genotoxic) and negative (non-genotoxic) responses. All in vitro studies were harmonized, i.e. NPs from the same batch, and identical dispersion protocols (for TiO2 NPs, two dispersions were used), exposure time, concentration range, culture conditions and time-courses were used. The results from the statistical evaluation show that OC-Fe3O4 and TiO2 NPs are genotoxic in the experimental conditions used. When all NPs were included in the analysis, no differences were seen among cell lines - demonstrating the usefulness of the assay in all cells to identify genotoxic and non-genotoxic NPs. The TK6 cells, human lymphocytes, BeWo b30 and kidney cells seem to be the most reliable for detecting a dose-response. [ABSTRACT FROM AUTHOR]

Comparative hazard identification of nanomaterials (NMs) can aid in the prioritisation for further toxicity testing. Here, we assessed the acute lung, systemic and liver responses in C57BL/6N mice for three NMs to provide a hazard ranking. A silver (Ag), non-functionalised zinc oxide (ZnO) and a triethoxycaprylylsilane functionalised ZnO NM suspended in water with 2% mouse serum were examined 24 hours following a single intratracheal instillation (I.T.). An acute pulmonary inflammation was noted (marked by a polymorphonuclear neutrophil influx) with cell damage (LDH and total protein) in broncho-alveolar lavage fluid (BALF) after administration of both non-functionalised and functionalised ZnO. The latter also induced systemic inflammation measured as an increase in blood neutrophils and a decrease in blood lymphocytes. Exposure to Ag NM was not accompanied by pulmonary inflammation or cytotoxicity, or by systemic inflammation. A decrease in glutathione levels was demonstrated in the liver following exposure to high doses of all three nanomaterials irrespective of any noticeable inflammatory or cytotoxic effects in the lung. By applying benchmark dose (BMD) modeling statistics to compare potencies of the NMs, we rank functionalised ZnO ranked the highest based on the largest number of affected endpoints, as well as the strongest responses observed after 24 hours. The non-functionalised ZnO NM gave an almost similar response, whereas Ag NM did not cause an acute response at similar doses. [ABSTRACT FROM AUTHOR]

Substantial limitations and uncertainties hinder the exposure assessment of engineered nanomaterials (ENMs). The present deficit of reliable measurements and models will inevitably lead in the near term to qualitative and uncertain exposure estimations, which may fail to support adequate risk assessment and management. Therefore it is necessary to complement the current toolset with user-friendly methods for near-term nanosafety evaluation. This paper proposes an approach for relative exposure screening of ENMs. For the first time, an exposure model explicitly implements quantitative weight of evidence (WoE) methods and utilises expert judgement for filling data gaps in the available evidence-base. Application of the framework is illustrated for screening of exposure scenarios for nanoscale titanium dioxide, carbon nanotubes and fullerenes, but it is applicable to other nanomaterials as well. The results show that the WoE-based model overestimates exposure for scenarios where expert judgement was substantially used to fill data gaps, which suggests its conservative nature. In order to test how variations in input data influence the obtained results, probabilistic Monte Carlo sensitivity analysis was applied to demonstrate that the model performs in stable manner. [ABSTRACT FROM AUTHOR]

Background To assess the risk of all nanomaterials (NMs) on a case-by-case basis is challenging in terms of financial, ethical and time resources. Instead a more intelligent approach to knowledge gain and risk assessment is required. Methods A framework of future research priorities was developed from the accorded opinion of experts covering all major stake holder groups (government, industry, academia, funders and NGOs). It recognises and stresses the major topics of physicochemical characterisation, exposure identification, hazard identification and modelling approaches as key components of the current and future risk assessment of NMs. Results The framework for future research has been developed from the opinions of over 80 stakeholders, that describes the research priorities for effective development of an intelligent testing strategy (ITS) to allow risk evaluation of NMs. In this context, an ITS is a process that allows the risks of NMs to be assessed accurately, effectively and efficiently, thereby reducing the need to test NMs on a case-by-case basis. For each of the major topics of physicochemical characterisation, exposure identification, hazard identification and modelling, key-priority research areas are described via a series of stepping stones, or hexagon diagrams structured into a time perspective. Importantly, this framework is flexible, allowing individual stakeholders to identify where their own activities and expertise are positioned within the prioritisation pathway and furthermore to identify how they can effectively contribute and structure their work accordingly. In other words, the prioritisation hexagon diagrams provide a tool that individual stakeholders can adapt to meet their own particular needs and to deliver an ITS for NMs risk assessment. Such an approach would, over time, reduce the need for testing by increasing the reliability and sophistication of in silico approaches. The manuscript includes an appraisal of how this framework relates to the current risk assessment approaches and how future risk assessment could adapt to accommodate these new approaches. A full report is available in electronic format (pdf) at www.its-nano.eu. Conclusion ITS-NANO has delivered a detailed, stakeholder driven and flexible research prioritisation (or strategy) tool, which identifies specific research needs, suggests connections between areas, and frames this in a time-perspective. [ABSTRACT FROM AUTHOR]

PARTICLE_RISK was one of the first multidisciplinary projects funded by the European Commission's Framework Programme that was responsible for evaluating the implications of nanomaterial (NM) exposure on human health. This project was the basis for this review which identifies the challenges that exist within the assessment of NM risk. We have retrospectively reflected on the findings of completed nanotoxicology studies to consider what progress and advances have been made within the risk assessment of NMs, as well as discussing the direction that nanotoxicology research is taking and identifying the limitations and failings of existing research. We have reflected on what commonly encountered challenges exist and explored how these issues may be resolved. In particular, the following is discussed (i) NM selection (ii) NM physico-chemical characterisation; (iii) NM dispersion; (iv) selection of relevant doses and concentrations; (v) identification of relevant models, target sites and endpoints; (vi) development of alternatives to animal testing; and (vii) NM risk assessment. These knowledge gaps are relatively well recognised by the scientific community and recommendations as to how they may be overcome in the future are provided. It is hoped that this will help develop better defined hypothesis driven research in the future that will enable comprehensive risk assessments to be conducted for NMs. Importantly, the nanotoxicology community has responded and adapted to advances in knowledge over recent years to improve the approaches used to assess NM hazard, exposure and risk. It is vital to learn from existing information provided by ongoing or completed studies to avoid unnecessary duplication of effort, and to offer guidance on aspects of the experimental design that should be carefully considered prior to the start of a new study. [ABSTRACT FROM AUTHOR]

In 1987 the International Agency for Research on Cancer (IARC) classified crystalline silica (CS) as a probable carcinogen and in 1997 reclassified it as a Group 1 carcinogen, i.e., that there was sufficient evidence for carcinogenicity in experimental animals and sufficient evidence for carcinogenicity in humans. The Working Group noted that 'carcinogenicity in humans was not detected in all industrial circumstances studied, carcinogenicity may be dependent on inherent characteristics of the crystalline silica or on external factors affecting its biological activity or distribution of its polymorphs.' This unusual statement that the physicochemical form of the CS influences its carcinogenicity is well understood at the toxicological level and arises as a consequence of the fact that CS activity depends on the reactivity of the CS surface, which can be blocked by a number of agents. We reviewed the literature on CS genotoxicity that has been published since the 1997 monograph, with special reference to the mechanism of CS genotoxicity. The mechanism of CS genotoxicity can be primary, a result of direct interaction of CS with target cells, or indirect, as a consequence of inflammation elicited by quartz, where the inflammatory cell-derived oxidants cause the genotoxicity. The review revealed a number of papers supporting the hypothesis that the CS genotoxic and inflammatory hazard is a variable one. In an attempt to attain a quantitative basis for the potential mechanism, we carried out analysis of published data and noted a 5-fold greater dose required to reach a threshold for genotoxic effects than for proinflammatory effects in the same cell line in vitro. When we related the calculated threshold dose at the proximal alveolar region for inflammation in a published study with the threshold dose for genotoxicity in vitro, we noted that a 60-120-fold greater dose was required for direct genotoxic effects in vitro. These data strongly suggests that inflammation is the driving force for genotoxicity and that primary genotoxicity of deposited CS would play a role only at very high, possibly implausible, exposures and deposited doses. Although based on rat studies and in vitro studies, and therefore with caveats, the analysis supports the hypothesis that the mechanism of CS genotoxicity is via inflammation-driven secondary genotoxicity. This may have implications for setting of the CS standard in workplaces. During the writing of this review (in May 2009), IARC undertook a review of carcinogenic substances, including CS. The Working Group met to reassess 10 separate agents including CS. This was not a normal monograph working group published as a large single monograph, but was published as a two-page report. This review group reaffirmed the carcinogenicity of 'silica dust, crystalline in the form of quartz or cristobalite' as a Group 1 agent, with the lung as the sole tumor site. Of special relevance to the present review is that the cited 'established mechanism events' for CS are restricted to the words 'impaired particle clearance leading to macrophage activation and persistent inflammation.' The lack of mention of direct genotoxicity is in line with the conclusions reached in the present review. [ABSTRACT FROM AUTHOR]

In assessing hazard for human health posed by newly engineered nanomaterials (ENM), approaches such as Weight of Evidence (WOE) and expert judgment are required to develop conclusions about the hazard of ENM. This is because all factors affecting hazard are not currently well defined and are often subject to different interpretation. Here we report the application of a WOE procedure to assess the potential of ENM to cause harm for human health, by integrating and combining physicochemical properties of NM and toxicity data obtained within the EU-funded Particle Risk project. The procedure was applied to carbon black (CB), single-walled carbon nanotubes (SWNT), C60 fullerene and quantum dots (QD) ENM tested during the Particle Risk project. The results show that some of the investigated ENM present a relatively higher hazardousness level on the basis of the integration of their physicochemical properties and toxicological effects, and that their hazard may be ranked as follow: QD >> C60 > SWNT > CB. This case study shows the utility of WOE approach to obtain a hazard ranking of ENM. [ABSTRACT FROM AUTHOR]

There is evidence that nanoparticles (NP) can enter the bloodstream following deposition in the lungs, where they may interact with platelets. Polystyrene latex nanoparticles (PLNP) of the same size but with different surface charge—unmodified (umPLNP), aminated (aPLNP), and carboxylated (cPLNP)—were used as model NP to study interactions with human blood and platelets. Both the cPLNP and the aPLNP caused platelet aggregation, whereas the umPLNP did not. Whereas cPLNP caused aggregation by classical upregulation of adhesion receptors, aPLNP did not upregulate adhesion receptors and appeared to act by perturbation of the platelet membrane, revealing anionic phospholipids. Neither oxidative stress generation by particles nor metal contamination was responsible for these effects, which were a result of differential surface derivatization. The study reveals that NP composed of insoluble low-toxicity material are significantly altered in their potency in causing platelet aggregation by altering the surface chemistry. The two surface modifications, aminated and carboxylated, that did cause aggregation did so by different mechanisms. The study highlights the fundamental role of surface chemistry on bioactivity of NP in a platelet activation model. [ABSTRACT FROM PUBLISHER]

Nanotechnology has become the focus of a large amount of scientific, political, and financial interest. Limited information on the exposure to nanomaterials is available, with only a few occupational exposure studies having been performed. While laboratory animal studies on the biological effects of some nanomaterials have been published, no epidemiological studies have been reported to date. This lack of data on exposure and human health effects hinders risk assessment of these materials. As the use of nanomaterials increases rapidly, it is of vital importance that the risk assessment community understands the complexities of the issues surrounding the manufacture, use and disposal of nanomaterials, the potential of environmental and occupational exposure to human populations, as well as adverse health outcomes. For this to happen, it is in many ways necessary for the scientific community to also understand what questions risk assessors need to ask, and what research will best answer them. Risk management of nanomaterials requires more information as to the human and ecological effects of exposure to various nanomaterials. At this time, there are no specific regulations for nanomaterials, but a few efforts to include nanomaterials under existing environmental regulations have begun. The purpose of this article is to describe the potential regulations for nanomaterials, and the current issues related to the risk assessment of nanomaterials. WIREs Nanomed Nanobiotechnol 2010 2 130-137 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

Envirox is a scientifically and commercially proven diesel fuel combustion catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel consumption, greenhouse gas emissions (CO2), and particulate emissions when added to diesel at levels of 5 mg/L. Studies have confirmed the adverse effects of particulates on respiratory and cardiac health, and while the use of Envirox contributes to a reduction in the particulate content in the air, it is necessary to demonstrate that the addition of Envirox does not alter the intrinsic toxicity of particles emitted in the exhaust. The purpose of this study was to evaluate the safety in use of Envirox by addressing the classical risk paradigm. Hazard assessment has been addressed by examining a range of in vitro cell and cell-free endpoints to assess the toxicity of cerium oxide nanoparticles as well as particulates emitted from engines using Envirox. Exposure assessment has taken data from modeling studies and from airborne monitoring sites in London and Newcastle adjacent to routes where vehicles using Envirox passed. Data have demonstrated that for the exposure levels measured, the estimated internal dose for a referential human in a chronic exposure situation is much lower than the no-observed-effect level (NOEL) in the in vitro toxicity studies. Exposure to nano-size cerium oxide as a result of the addition of Envirox to diesel fuel at the current levels of exposure in ambient air is therefore unlikely to lead to pulmonary oxidative stress and inflammation, which are the precursors for respiratory and cardiac health problems. [ABSTRACT FROM AUTHOR]

We compared the effects of a single acute dose, or chronic fetal exposure, to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the male reproductive system of the Wistar(Han) rat. Tissue samples were taken from dams on gestation day (GD)16 and GD21, and from offspring on postnatal days (PND)70 and 120. Steady-state concentration of TCDD was demonstrated in the chronic study: body burdens were comparable in both studies. Fetal TCDD concentrations were comparable after acute and chronic exposure, and demonstrate more potent toxicity after chronic versus acute dosing. In maternal liver, cytochrome P450 (CYP)1A1 and CYP1A2 RNA were induced. In fetus, there was induction of both CYP1A1 and CYP1A2 RNA at medium and high doses, but inadequate evidence for induction at low dose in either study. The low level induction of CYP1A1 RNA at low dose in fetus argues against AhR activation in fetus as a mechanism of toxicity of TCDD in causing delay in balanopreputial separation (BPS), and the greater induction of CYP1A1 RNA in PND70 offspring liver from chronically-dosed dams suggests that lactational transfer of TCDD is crucial to this toxicity. These data characterize the maternal and fetal disposition of TCDD, induction of CYP1A1 RNA as a measure of AhR activation, and suggest that lactational transfer of TCDD determines the difference in delay in BPS between the two studies. [ABSTRACT FROM PUBLISHER]

Objective: Rats exposed to high airborne mass concentrations of low-solubility low-toxicity particles (LSLTP) have been reported to develop lung disease such as fibrosis and lung cancer. These particles are regulated on a mass basis in occupational settings, but mass might not be the appropriate metric as animal studies have shown that nanoparticles (ultrafine particles) produce a stronger adverse effect than fine particles when delivered on an equal mass basis. Methods: This study investigated whether the surface area is a better descriptor than mass of LSLTP of their ability to stimulate pro-inflammatory responses in vitro. In a human alveolar epithelial type II-like cell line, A549, we measured interleukin (IL)-8 mRNA, IL8 protein release and glutathione (GSH) depletion as markers of pro-inflammatory effects and oxidative stress after treatment with a range of LSLTP (fine and nanoparticles) and DQ12 quartz, a particle with a highly reactive surface. Results: In all the assays, nanoparticle preparations of titanium dioxide (TiO2-np) and of carbon black (CB-np) produced much stronger pro-inflammatory responses than the same mass dose of fine TiO2 and CB. The results of the GSH assay confirmed that oxidative stress was involved in the response to all the particles, and two ultra-fine metal dusts (cobalt and nickel) produced GSH depletion similar to TiO2·np, for similar surface-area dose. As expected, DQ12 quartz was more inflammatory than the low toxicity dusts, on both a mass and surface-area basis. Conclusion: Dose-response relationships observed in the in vitro assays appeared to be directly comparable with dose-response relationships in viva when the doses were similarly standardised. Both sets of data suggested a threshold in dose measured as surface area of particles relative to the surface area of the exposed cells, at around 1-10 cm²/cm². These findings are consistent with the hypothesis that surface area is a more appropriate dose metric than mass for the pro-inflammatory effects of LSLTP in vitro and in vivo, and consequently that the high surface area of nanoparticles is a key factor in their inflammogenicity. [ABSTRACT FROM AUTHOR]

Different particle types cause excessive lung inflammation that is thought to play a role in the various types of pathology they produce. Recently attention has been focused on nanoparticles due to their presence in environmental particulate air pollution, their use and exposure in occupational settings, and their potential use in nanotechnology and novel therapeutics. We have shown previously that the surface area metric drives the overload response. We have instilled a number of low-toxicity dusts of various particle sizes and assessed neutrophil influx into the lung at 18-24 h postinstillation. The extent of inflammation was demonstrated as being a function not of the mass dose instilled but interestingly of the surface area dose instilled. Since low-toxicity nanoparticles present a "special" case of high surface area, they are relatively inflammogenic. We tested whether we could use this approach to model the reactivity of highly toxic dusts. Rats were instilled with either DQ12 quartz or aluminum lactate-treated DQ12 and, as anticipated, the high specific surface toxicity of DQ12 meant that it was much more inflammogenic (63 times more) than the surface area alone would have predicted. By contrast, aluminum lactate-treated DQ12 fell into the line of "low-toxicity" dusts. In addition, as an in vitro testing alternative to that of in vivo testing, interleukin (IL)-8 production in A549 cells exposed to the panel of various particles clearly demonstrated the ability to also identify a relationship between surface area dose and reactivity. These approaches present the possibility of modelling potential toxicity of nanoparticles and nuisance dusts based on the inflammatory response of a given instilled surface area dose. [ABSTRACT FROM AUTHOR]

The celebrated physicist and Nobel laureate Richard Feynman was the first to predict the opportunities presented by the manipulation of matter at the level of individual atoms and molecules. Today, almost 50 years after his classic lecture on the wonders of the small world, the evolving nanotechnologies have the potential to bring about major changes in the lives of citizens. However, the very same properties that make engineered nanomaterials so promising from a technological perspective, such as their high degree of reactivity and the ability to cross biological barriers, could also make these novel materials harmful to human health and the environment. Therefore, exploitation of the full potential of the nanotechnologies requires close attention to safety issues. The 1st Nobel Forum mini-symposium on nanotoxicology was recently held in Stockholm, Sweden, and the program was devoted to the topic of definitions and standardization in nanotoxicological research, as well as nano-specific risk assessment and regulatory/legislative issues. Examples of recent and ongoing studies of carbon-based nanomaterials, including single-walled carbon nanotubes, using a wide range of in vitro and in vivo model systems were also presented. The current review will provide some highlights and conclusions from this exciting meeting. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT) are an important new class of technological materials that have numerous novel and useful properties. The forecast increase in manufacture makes it likely that increasing human exposure will occur, and as a result, CNT are beginning to come under toxicological scrutiny. This review seeks to set out the toxicological paradigms applicable to the toxicity of inhaled CNT, building on the toxicological database on nanoparticles (NP) and fibers. Relevant workplace regulation regarding exposure is also considered in the light of our knowledge of CNT. CNT could have features of both NP and conventional fibers, and so the current paradigm for fiber toxicology, which is based on mineral fibers and synthetic vitreous fibers, is discussed. The NP toxicology paradigm is also discussed in relation to CNT. The available peer-reviewed literature suggests that CNT may have unusual toxicity properties. In particular, CNT seem to have a special ability to stimulate mesenchymal cell growth and to cause granuloma formation and fibrogenesis. In several studies, CNT have more adverse effects than the same mass of NP carbon and quartz, the latter a commonly used benchmark of particle toxicity. There is, however, no definitive inhalation study available that would avoid the potential for artifactual effects due to large mats and aggregates forming during instillation exposure procedures. Studies also show that CNT may exhibit some of their effects through oxidative stress and inflammation. CNT represent a group of particles that are growing in production and use, and therefore, research into their toxicology and safe use is warranted. [ABSTRACT FROM AUTHOR]

This review considers the molecular toxicology of combustion-derived nanoparticles (CDNP) following inhalation exposure. CDNP originate from a number of sources and in this review we consider diesel soot, welding fume, carbon black and coal fly ash. A substantial literature demonstrates that these pose a hazard to the lungs through their potential to cause oxidative stress, inflammation and cancer; they also have the potential to redistribute to other organs following pulmonary deposition. These different CDNP show considerable heterogeneity in composition and solubility, meaning that oxidative stress may originate from different components depending on the particle under consideration. Key CDNP-associated properties of large surface area and the presence of metals and organics all have the potential to produce oxidative stress. CDNP may also exert genotoxic effects, depending on their composition. CDNP and their components also have the potential to translocate to the brain and also the blood, and thereby reach other targets such as the cardiovascular system, spleen and liver. CDNP therefore can be seen as a group of particulate toxins unified by a common mechanism of injury and properties of translocation which have the potential to mediate a range of adverse effects in the lungs and other organs and warrant further research. [ABSTRACT FROM AUTHOR]

Following the classification of quartz as a human carcinogen by the IARC, many standard-setting committees are currently trying to convert this hazard into their national or EU standards. Since human data to set a safe exposure limit for quartz are limited, we hypothesized that lung burden data on quartz in coal miners’ lungs after lifetime exposure could be used to set a non-carcinogenic lung burden of quartz, and that this might be valid for other groups occupationally exposed to quartz. A review of data shows that lungs of coal miners with simple coal workers’ pneumoconiosis (sCWP) typically contain up to 30 g of dust, and in one specific study lung burdens between 0.7 and 1.7 g of quartz were associated with macules only, and no sCWP. Assuming independent actions of coal and quartz and no clearance of quartz, and sCWP as a prerequisite for lung cancer due to quartz exposure in coal mine dust, a simple kinetic approach was applied. A no observed adverse effect level (NOAEL) for quartz of between 0.03 and 0.13 mg/m3 (40 yr exposure) is derived, but it is concluded that more refined physiologically based pharmacokinetic modelling is needed for a better estimate, also including interindividual differences in lung clearance. Considering the independent effects of, and the well-known interaction between coal and quartz, these data could be important to other workplaces with usual mixed-dust exposure. [ABSTRACT FROM PUBLISHER]

Engineered nanomaterials are potentially very useful for a variety of applications, but studies are needed to ascertain whether these materials pose a risk to human health. Here, we studied three benchmark nanomaterials (Ag nanoparticles, TiO2 nanoparticles, and multi-walled carbon nanotubes, MWCNTs) procured from the nanomaterial repository at the Joint Research Centre of the European Commission. Having established a sub-lethal concentration of these materials using two human cell lines representative of the immune system and the lungs, respectively, we performed RNA sequencing of the macrophage-like cell line after exposure for 6, 12, and 24 h. Downstream analysis of the transcriptomics data revealed significant effects on chemokine signaling pathways. CCR2 was identified as the most significantly upregulated gene in MWCNT-exposed cells. Using multiplex assays to evaluate cytokine and chemokine secretion, we could show significant effects of MWCNTs on several chemokines, including CCL2, a ligand of CCR2. The results demonstrate the importance of evaluating sub-lethal concentrations of nanomaterials in relevant target cells. [ABSTRACT FROM AUTHOR]

As the use of nanoparticles (NPs) is increasing, the potential toxicity and behavior of NPs in living systems need to be better understood. Our goal was to evaluate the developmental toxicity and bio-distribution of two different sizes of fluorescently-labeled SiO2 NPs, 25 and 115 nm, with neutral surface charge or with different surface functionalization, rendering them positively or negatively charged, in order to predict the effect of NPs in humans. We performed a zebrafish embryo toxicity test (ZFET) by exposing the embryos to SiO2 NPs starting from six hours post fertilization (hpf). Survival rate, hatching time, and gross morphological changes were assessed at 12, 24, 36, 48, 60, and 72 hpf. We evaluated the effect of NPs on angiogenesis by counting the number of sub-intestinal vessels between the second and seventh intersegmental vessels and gene expression analysis of vascular endothelial growth factor (VEGF) and VEGF receptors at 72 hpf. SiO2 NPs did not show any adverse effects on survival rate, hatching time, gross morphology, or physiological angiogenesis. We found that SiO2 NPs were trapped by the chorion up until to the hatching stage. After chemical removal of the chorion (dechorionation), positively surface-charged SiO2 NPs (25 nm) significantly reduced the survival rate of the fish compared to the control group. These results indicate that zebrafish chorion acts as a physical barrier against SiO2 NPs, and removing the chorions in ZFET might be necessary for evaluation of toxicity of NPs. [ABSTRACT FROM AUTHOR]

An introduction to the special issue is presented which discusses topics related genotoxicity of engineered nanomaterials (ENM), such as problems with genotoxicity testing and genotoxic mechanisms to support improved testing.

The authors reflect on the alleged indiscriminate usage of the term "nanoparticles" in the titles of scientific studies and in statements to the press. They examine a study conducted by Song and colleagues regarding the association of nanoparticles to serious cases of occupational lung and pleural injury in China, and explain why the inclusion of the term "nanoparticles" in the title of the paper is misleading. They discuss the implications of the study on issues about nanoparticle toxicity.

A response by Eileen D. Kuempel, Lang Tran, Vincent Castranova, and John Bailer to a letter to the editor about their article "Lung Dosimetry and Risk Assessment of Nanoparticles: Evaluating and Extending Current Models in Rats and Humans" issue is presented.