Respiratory effects of manufactured nanoparticles

Understanding the role of biomolecular coronas in human exposure to nanomaterials

Nanomaterials (NMs) are increasingly used in medical treatments, electronics, and food additives. However, nanosafety-the possible adverse effects of NMs on human health-is an area of active research. This review provides an overview of the influence of biomolecular coronas on NM transformation following various exposure routes. We discuss potential exposure pathways, including inhalation and ingestion, describing the physiology of exposure routes and emphasising the relevance of coronas in these environments. Additionally, we review other routes to NM exposure, such as synovial fluid, blood (translocation and injection), dermal and ocular exposure, as well as the dose and medium impact on NM interactions. We emphasize the need for an in-depth characterisation of coronas in different biological media, highlighting the need and opportunity to study lung and gastric fluids to understand NM behaviour and potential toxicity. Future research aims to predict better in vivo outcomes and address the complexities of NM interactions with biological systems.

Assessing the in vitro toxicity of airborne (nano)particles to the human respiratory system: from basic to advanced models

Several studies have been conducted to address the potential adverse health risks attributed to exposure to nanoscale materials. While in vivo studies are fundamental for identifying the relationship between dose and occurrence of adverse effects, in vitro model systems provide important information regarding the mechanism(s) of action at the molecular level. With a special focus on exposure to inhaled (nano)particulate material toxicity assessment, this review provides an overview of the available human respiratory models and exposure systems for in vitro testing, advantages, limitations, and existing investigations using models of different complexity. A brief overview of the human respiratory system, pathway and fate of inhaled (nano)particles is also presented.

Regulating Nanomaterials: A Case for Hybrid Governance

Despite their growing usage in commercial and industrial applications, nanomaterials have yet to be been thoroughly researched as to their potential health, safety, and environmental risk to human life after incorporation into new product improvement, development, design, and manufacturing processes. Identifying the appropriate governance framework for effective risk assessment analysis of toxicological risk to human beings—specifically manufacturing employees and consumers—and other living organisms, resulting from the development and application of these nanotechnology-based products, has yet to be scientifically determined. With major regulatory gaps in the public regulation framework at national and international levels of governance, a proposed private governance framework is needed to assist the existing public regulatory framework with the proliferation of products and manufacturing processes utilizing nanomaterials. There are three distinct (yet complimentary) approaches available to develop a private governance framework to complement existing national public regulatory frameworks: responsible innovation, risk management, and voluntary guidelines/industry standards. The case for supporting a hybrid governance framework, combining public and private governance mechanisms, for nanotechnology is reflective of the current public policy environment that has emerged to best address health, safety, and environmental risk assessment issues concerning nanotechnology and nanomaterials.

Evaluation of the effect of time on the distribution of zinc oxide nanoparticles in tissues of rats and mice: a systematic review

To evaluate the time effect on the distribution of zinc oxide nanoparticles (ZnO NPs) in tissues from rats and mice, a search on the PubMed, Embase, SpringerLink, Scopus, Science Direct, Cochrane, CNKI, Wanfang, and vip databases up to September 2014 was performed, followed by screening, data extraction, and quality assessment. Thirteen studies were included. At 24 h, Zn content was mainly distributed in the liver, kidney, and lung. At ≥7 days, Zn content was mainly distributed in the liver, kidney, lung, and brain. ZnO NPs are readily deposited in tissues. Furthermore, as time increases, Zn content decreases in the liver and kidney, but increases in the brain.

Incomplete lung recovery following sub-acute inhalation of combustion-derived ultrafine particles in mice

Background

Particulate matter (PM) is one of the six criteria pollutant classes for which National Ambient Air Quality Standards have been set by the United States Environmental Protection Agency. Exposures to PM have been correlated with increased cardio-pulmonary morbidity and mortality. Butadiene soot (BDS), generated from the incomplete combustion of 1,3-butadiene (BD), is both a model PM mixture and a real-life example of a petrochemical product of incomplete combustion. There are numerous events, including wildfires, accidents at refineries and tank car explosions that result in sub-acute exposure to high levels of airborne particles, with the people exposed facing serious health problems. These real-life events highlight the need to investigate the health effects induced by short-term exposure to elevated levels of PM, as well as to assess whether, and if so, how well these adverse effects are resolved over time. In the present study, we investigated the extent of recovery of mouse lungs 10 days after inhalation exposures to environmentally-relevant levels of BDS aerosols had ended.

Methods

Female BALB/c mice exposed to either HEPA-filtered air or to BDS (5 mg/m³ in HEPA filtered air, 4 h/day, 21 consecutive days) were sacrificed immediately, or 10 days after the final BDS exposure. Bronchoalveolar lavage fluid (BALF) was collected for cytology and cytokine analysis. Lung proteins and RNA were extracted for protein and gene expression analysis. Lung histopathology evaluation also was performed.

Results

Sub-acute exposures of mice to hydrocarbon-rich ultrafine particles induced: (1) BALF neutrophil elevation; (2) lung mucosal inflammation, and (3) increased BALF IL-1β concentration; with all three outcomes returning to baseline levels 10 days post-exposure. In contrast, (4) lung connective tissue inflammation persisted 10 days post-exposure; (5) we detected time-dependent up-regulation of biotransformation and oxidative stress genes, with incomplete return to baseline levels; and (6) we observed persistent particle alveolar load following 10 days of recovery.

Conclusion

These data show that 10 days after a 21-day exposure to 5 mg/m³ of BDS has ended, incomplete lung recovery promotes a pro-biotransformation, pro-oxidant, and pro-inflammatory milieu, which may be a starting point for potential long-term cardio-pulmonary effects.

Perspectives in Biological Monitoring of Inhaled Nanosized Particles

Given the results of experimental studies, occupational or environmental exposures to manufactured nanoparticles or to unintentionally produced ultrafine particles may result in health effects or diseases in humans. In this review, we synthesize published data of experimental studies on the distribution of inhaled nanoparticles and the first case reports to discuss the potential usefulness of their biological monitoring for clinical purposes. Toxicokinetic studies suggest that nanoparticles may be absorbed predominantly by respiratory and oral routes with possible systemic translocation, leading to accumulation in the peripheral organs or excretion in feces or urine. Some methods used in these studies may be applied successfully in retrospective evaluation of exposure or in follow-up of occupational exposure in the workplace. Biological monitoring of nanoparticles should be based on imaging methods that are essential to confirm their presence and to characterize them in tissue associated with analytical quantitative methods. The first case reports reviewed emphasize the urgent need for the development of standardized procedures for the preparation and analysis of biological samples with a view to characterizing and quantifying nanoparticles.

Opportunities and challenges of nanotechnology in the green economy

In a world of finite resources and ecosystem capacity, the prevailing model of economic growth, founded on ever-increasing consumption of resources and emission pollutants, cannot be sustained any longer. In this context, the "green economy" concept has offered the opportunity to change the way that society manages the interaction of the environmental and economic domains. To enable society to build and sustain a green economy, the associated concept of "green nanotechnology" aims to exploit nano-innovations in materials science and engineering to generate products and processes that are energy efficient as well as economically and environmentally sustainable. These applications are expected to impact a large range of economic sectors, such as energy production and storage, clean up-technologies, as well as construction and related infrastructure industries. These solutions may offer the opportunities to reduce pressure on raw materials trading on renewable energy, to improve power delivery systems to be more reliable, efficient and safe as well as to use unconventional water sources or nano-enabled construction products therefore providing better ecosystem and livelihood conditions.However, the benefits of incorporating nanomaterials in green products and processes may bring challenges with them for environmental, health and safety risks, ethical and social issues, as well as uncertainty concerning market and consumer acceptance. Therefore, our aim is to examine the relationships among guiding principles for a green economy and opportunities for introducing nano-applications in this field as well as to critically analyze their practical challenges, especially related to the impact that they may have on the health and safety of workers involved in this innovative sector. These are principally due to the not fully known nanomaterial hazardous properties, as well as to the difficulties in characterizing exposure and defining emerging risks for the workforce. Interestingly, this review proposes action strategies for the assessment, management and communication of risks aimed to precautionary adopt preventive measures including formation and training of employees, collective and personal protective equipment, health surveillance programs to protect the health and safety of nano-workers. It finally underlines the importance that occupational health considerations will have on achieving an effectively sustainable development of nanotechnology.

[Physio-pathological impacts of inhaled nanoparticles]

Nanomaterials are defined as materials with any external dimension in the nanoscale or having an internal structure or surface structure in the nanoscale, approximately 1 nm to 100 nm. They exhibit new or reinforced properties as compared to the same material at the micrometric scale, providing a benefit in numerous technological applications. However, their specific surface properties in addition to their shape, composition, size are suspected to elicit adverse responses from biological systems, underlining the need for a thorough hazard assessment. Increasing use of nanomaterials in industrial as well as consumer products extends the possibilities of environmental and occupational human exposures. During all their life cycle, from their production to their destruction through their use, engineered nanoparticles can be released and the respiratory route is one of the main unintentional routes of exposure. Although the respiratory tract is equipped with efficient clearance mechanisms, there is increasing evidence that nanoparticles exhibit an ability to cross biological barriers, getting access to the bloodstream and secondary target organs. Different features of nanomaterials (size, form, surface reactivity...) contribute to their internalization and translocation through the respiratory barrier. Short term inhalation exposure to nanoparticles induces pulmonary inflammation the extent of which is dependent on the type of nanoparticles according to shape, size, solubility...Oxidative stress is considered as a major toxicity pathway triggered by nanomaterials as they can intrinsically produce reactive oxygen species or induced the intracellular production of reactive oxygen species or anti-oxidant depletion upon interaction with cells. Alternative mechanisms are suspected, related to the ability of nanoparticles to interact with proteins. As they get in contact with biological fluids, nanoparticles are covered by a protein corona that modifies their interactions with cells, their fate and their effects. There is still a need to increase our mechanistic understanding of the toxicological events triggered by nanomaterials in order to provide relevant data for risk assessment as well as in helping to develop nanomaterials with a safer design.

Nanoparticles and Pop-off Technique for Electron Microscopy

Because of the size of the nanoparticles, their detection and exact anatomical localization in tissue samples are very difficult. Consequently, suitable methods are needed to prove their presence, especially co-localized to histological lesions. Therefore, the aim of this study was to investigate whether nanoparticles were detectable in specimens after reprocessing samples from glass slides using the pop-off technique. Tissue slides containing agglomerates of titanium dioxide nanoparticles already visible on a light microscopic level and amorphous silicium dioxide (SiO2) particles not observable in tissue slides were reprocessed. Furthermore, cytospots of bronchoalveolar lavage acquired from rats that previously inhaled carbon nanotubes were used. After reprocessing the samples, they were investigated using transmission electron microscopy. In all the reprocessed samples, the respective nanoparticles were detectable. Even the light microscopically invisible amorphous SiO2 particles were observed as electron dense structures. Titanium and silicium were additionally confirmed in the respective nanoparticles by energy-dispersive X-ray spectroscopy (EDX). In summary, the pop-off technique represents a fast and easy way to detect nanoparticles in histological sections. This enables further characterization of these particles by additional techniques such as EDX, and their direct correlation with light microscopic lesions at exactly the same location is investigated.

Tracking and quantification of single-walled carbon nanotubes in fish using near infrared fluorescence

Detection of SWCNTs in complex matrices presents a unique challenge as common techniques lack spatial resolution and specificity. Near infrared fluorescence (NIRF) has emerged as a valuable tool for detecting and quantifying SWCNTs in environmental samples by exploiting their innate fluorescent properties. The objective of this study was to optimize NIRF-based imaging and quantitation methods for tracking and quantifying SWCNTs in an aquatic vertebrate model in conjunction with assessing toxicological end points. Fathead minnows (Pimephales promelas) were exposed by single gavage to SWCNTs and their distribution was tracked using a custom NIRF imaging system for 7 days. No overt toxicity was observed in any of the SWCNT treated fish; however, histopathology observations from gastrointestinal (GI) tissue revealed edema within the submucosa and altered mucous cell morphology. NIRF images showed strong SWCNT-derived fluorescence signals in whole fish and excised intestinal tissues. Fluorescence was not detected in other tissues examined, indicating that no appreciable intestinal absorption occurred. SWCNTs were quantified in intestinal tissues using a NIRF spectroscopic method revealing values that were consistent with the pattern of fluorescence observed with NIRF imaging. Results of this work demonstrate the utility of NIRF imaging as a valuable tool for examining uptake and distribution of SWCNTs in aquatic vertebrates.

Carbon nanotubes enhance metastatic growth of lung carcinoma via up-regulation of myeloid-derived suppressor cells

Metastatic establishment and growth of Lewis lung carcinoma is promoted by single-walled carbon nanotubes (SWCNT) in C57BL6/J mice. The effect is mediated by increased local and systemic accumulation of myeloid-derived suppressor cells (MDSC), as their depletion abrogated pro-tumor activity in vivo. These data are important for the design of novel theranostics platforms with modules capable of depleting or functionally suppressing MDSC to ensure effective immunosurveillance in the tumor microenvironment.