Health implications of engineered nanomaterials

With the development of nanotechnology, a growing number of people are expected to be exposed to its products, the engineered nanomaterials (ENMs). Some physico-chemical properties of ENMs, linked to their size in the nanoscale (1-100 nm), make them potentially more reactive, and therefore raise concern about possible adverse effects in humans. In this article, I discuss human diseases which may be predicted after exposure to ENMs, and how their pathogenetic mechanisms may be linked to exposure; in this regard, special emphasis has been given to the triad of oxidative stress/inflammation/genotoxicity and to the interaction of ENMs/proteins in different biological compartments. The analysis of possible adverse effects has been made on an organ-by-organ basis, starting from the skin, respiratory system and gastrointestinal tract. These sites are in fact not only those exposed to the highest amounts of ENMs, but are also the portals of entry to internal organs for possible systemic effects. Although the list and the relevance of possible human disorders linked to ENM exposure are at least as impressive as that of their direct or indirect beneficial effects for human health, we must be clear that ENM-linked diseases belong to the realm of possible risk (i.e. cannot be excluded, but are unlikely), whereas ENMs with proven beneficial effects are on the market. Therefore, the mandatory awareness about possible adverse effects of ENMs should in no way be interpreted as a motivation to disregard the great opportunity represented by nanotechnology.     

Ingested engineered nanomaterials: state of science in nanotoxicity testing and future research needs

Background

Engineered nanomaterials (ENM) are used extensively in food products to fulfill a number of roles, including enhancement of color and texture, for nutritional fortification, enhanced bioavailability, improved barrier properties of packaging, and enhanced food preservation. Safety assessment of ingested engineered nanomaterials (iENM) has gained interest in the nanotoxicology community in recent years. A variety of test systems and approaches have been used for such evaluations, with in vitro monoculture cell models being the most common test systems, owing to their low cost and ease-of-use. The goal of this review is to systematically assess the current state of science in toxicological testing of iENM, with particular emphasis on model test systems, their physiological relevance, methodological strengths and challenges, realistic doses (ranges and rates), and then to identify future research needs and priorities based on these assessments.

Methods

Extensive searches were conducted in Google Scholar, PubMed and Web of Science to identify peer-reviewed literature on safety assessment of iENM over the last decade, using keywords such as “nanoparticle”, “food”, “toxicity”, and combinations thereof. Relevant literature was assessed based on a set of criteria that included the relevance of nanomaterials tested; ENM physicochemical and morphological characterization; dispersion and dosimetry in an in vitro system; dose ranges employed, the rationale and dose realism; dissolution behavior of iENM; endpoints tested, and the main findings of each study. Observations were entered into an excel spreadsheet, transferred to Origin, from where summary statistics were calculated to assess patterns, trends, and research gaps.

Results

A total of 650 peer-reviewed publications were identified from 2007 to 2017, of which 39 were deemed relevant. Only 21% of the studies used food grade nanomaterials for testing; adequate physicochemical and morphological characterization was performed in 53% of the studies. All in vitro studies lacked dosimetry and 60% of them did not provide a rationale for the doses tested and their relevance. Only 12% of the studies attempted to consider the dissolution kinetics of nanomaterials. Moreover, only 1 study attempted to prepare and characterize standardized nanoparticle dispersions.

Conclusion

We identified 5 clusters of factors deemed relevant to nanotoxicology of food-grade iENM: (i) using food-grade nanomaterials for toxicity testing; (ii) performing comprehensive physicochemical and morphological characterization of iENM in the dry state, (iii) establishing standard NP dispersions and their characterization in cell culture medium, (iv) employing realistic dose ranges and standardized in vitro dosimetry models, and (v) investigating dissolution kinetics and biotransformation behavior of iENM in synthetic media representative of the gastrointestinal (GI) tract fluids, including analyses in a fasted state and in the presence of a food matrix. We discussed how these factors, when not considered thoughtfully, could influence the results and generalizability of in vitro and in vivo testing. We conclude with a set of recommendations to guide future iENM toxicity studies and to develop/adopt more relevant in vitro model systems representative of in vivo animal and human iENM exposure scenarios.

     

Partnership in research: Exposure assessment methods

The National Institute for Occupational Safety and Health (NIOSH), under the leadership of Dr. Linda Rosenstock, in conjunction with several partners and stakeholders, created and is implementing the National Occupational Research Agenda (NORA), a framework to guide occupational safety and health research into the next decade. NORA is actually a multitiered partnering agenda. This paper will address NORA in general and then, within the context of NORA, delve more deeply into the workings of one of the partnership teams, Exposure Assessment Methods.     

A facile method for the assessment of DNA damage induced by UV-activated nanomaterials

Fluorescent microscopy observation of gene-size DNA (T4 phage DNA or λ phage DNA) was used to assess DNA damage induced by UV irradiation in the presence of nanomaterials, such as QDs (quantum dots: CdSe/ZnS semiconductor nanoparticles), the water-soluble fullerene derivative C(60)(OH)(n) (n = 6-12) and titanium oxide nanoparticles of 25 nm in diameter. The magnitude of DNA damage could be simply evaluated based on the degree of shortening of the stretched DNA image. This method showed that DNA damage was amplified by the action of QDs under irradiation by C-band (λ(max) = 254 nm) or B-band (λ(max) = 303 nm) UV. Smaller QDs that emitted higher-energy fluorescence (λ = 565 nm) induced more severe damage than medium- and larger-size QDs that emitted longer-wavelength fluorescence (λ = 605 and 705 nm, respectively). The fullerene derivative and TiO(2) nanoparticles caused DNA damage even under irradiation by A-band UV (λ(max) = 365 nm) and showed more severe DNA damage than QDs under similar conditions.     

Cytotoxicity screening of 23 engineered nanomaterials using a test matrix of ten cell lines and three different assays

Background

The most common causes of granulomatous inflammation are persistent pathogens and poorly-degradable irritating materials. A characteristic pathological reaction to intratracheal instillation, pharyngeal aspiration, or inhalation of carbon nanotubes is formation of epithelioid granulomas accompanied by interstitial fibrosis in the lungs. In the mesothelium, a similar response is induced by high aspect ratio nanomaterials, including asbestos fibers, following intraperitoneal injection. This asbestos-like behaviour of some engineered nanomaterials is a concern for their potential adverse health effects in the lungs and mesothelium. We hypothesize that high aspect ratio nanomaterials will induce epithelioid granulomas in nonadherent macrophages in 3D cultures.

Results

Carbon black particles (Printex 90) and crocidolite asbestos fibers were used as well-characterized reference materials and compared with three commercial samples of multiwalled carbon nanotubes (MWCNTs). Doses were identified in 2D and 3D cultures in order to minimize acute toxicity and to reflect realistic occupational exposures in humans and in previous inhalation studies in rodents. Under serum-free conditions, exposure of nonadherent primary murine bone marrow-derived macrophages to 0.5 μg/ml (0.38 μg/cm²) of crocidolite asbestos fibers or MWCNTs, but not carbon black, induced macrophage differentiation into epithelioid cells and formation of stable aggregates with the characteristic morphology of granulomas. Formation of multinucleated giant cells was also induced by asbestos fibers or MWCNTs in this 3D in vitro model. After 7-14 days, macrophages exposed to high aspect ratio nanomaterials co-expressed proinflammatory (M1) as well as profibrotic (M2) phenotypic markers.

Conclusions

Induction of epithelioid granulomas appears to correlate with high aspect ratio and complex 3D structure of carbon nanotubes, not with their iron content or surface area. This model offers a time- and cost-effective platform to evaluate the potential of engineered high aspect ratio nanomaterials, including carbon nanotubes, nanofibers, nanorods and metallic nanowires, to induce granulomas following inhalation.     

Cytotoxicity screening of 23 engineered nanomaterials using a test matrix of ten cell lines and three different assays

Background  

Engineered nanomaterials display unique properties that may have impact on human health, and thus require a reliable evaluation of their potential toxicity. Here, we performed a standardized in vitro screening of 23 engineered nanomaterials. We thoroughly characterized the physicochemical properties of the nanomaterials and adapted three classical in vitro toxicity assays to eliminate nanomaterial interference. Nanomaterial toxicity was assessed in ten representative cell lines.     

An in vitro liver model - assessing oxidative stress and genotoxicity following exposure of hepatocytes to a panel of engineered nanomaterials

ABSTRACT: BACKGROUND: Following exposure via inhalation, intratracheal instillation or ingestion some nanomaterials(NM) have been shown to translocate to the liver. Since oxidative stress has been implicatedas a possible mechanism for NM toxicity this study aimed to investigate the effects of variousmaterials (five titanium dioxide (TiO2), two zinc oxide (ZnO), two multi-walled carbonnanotubes (MWCNT) and one silver (Ag) NM) on oxidative responses of C3A cell line as amodel for potential detrimental properties of nanomaterials on the liver. RESULTS: We noted a dose dependant decrease in the cellular glutathione content following exposure ofthe C3A cells to Ag, the ZnO and the MWCNTs. Intracellular ROS levels were alsomeasured and shown to increase significantly following exposure of the C3A to the lowtoxicity NMs (MWCNT and TiO2). The antioxidant Trolox in part prevented the detrimentaleffect of NMs on cell viability, and decreased the NM induced IL8 production after exposureto all but the Ag particulate. Following 4 hr exposure of the C3A cells to sub-lethal levels ofthe NMs, the largest amount of DNA damage was induced by two of the TiO2 samples (7 nmand the positively charged 10 nm particles). CONCLUSIONS: All ten NMs exhibited effects on the hepatocyte cell line that were at least in partROS/oxidative stress mediated. These effects included mild genotoxicity and IL8 productionfor all NM except the Ag possibly due to its highly cytotoxic nature.     

An integrated methodology for assessing the impact of food matrix and gastrointestinal effects on the biokinetics and cellular toxicity of ingested engineered nanomaterials

Background

Engineered nanomaterials (ENMs) are increasingly added to foods to improve their quality, sensory appeal, safety and shelf-life. Human exposure to these ingested ENMs (iENMS) is inevitable, yet little is known of their hazards. To assess potential hazards, efficient in vitro methodologies are needed to evaluate particle biokinetics and toxicity. These methodologies must account for interactions and transformations of iENMs in foods (food matrix effect) and in the gastrointestinal tract (GIT) that are likely to determine nano-biointeractions. Here we report the development and application of an integrated methodology consisting of three interconnected stages: 1) assessment of iENM-food interactions (food matrix effect) using model foods; 2) assessment of gastrointestinal transformations of the nano-enabled model foods using a three-stage GIT simulator; 3) assessment of iENMs biokinetics and cellular toxicity after exposure to simulated GIT conditions using a triculture cell model. As a case study, a model food (corn oil-in-water emulsion) was infused with Fe₂O₃ (Iron(III) oxide or ferric oxide) ENMs and processed using this three-stage integrated platform to study the impact of food matrix and GIT effects on nanoparticle biokinetics and cytotoxicity .

Methods

A corn oil in phosphate buffer emulsion was prepared using a high speed blender and high pressure homogenizer. Iron oxide ENM was dispersed in water by sonication and combined with the food model. The resulting nano-enabled food was passed through a three stage (mouth, stomach and small intestine) GIT simulator. Size distributions of nano-enabled food model and digestae at each stage were analyzed by DLS and laser diffraction. TEM and confocal imaging were used to assess morphology of digestae at each phase. Dissolution of Fe2O3 ENM along the GIT was assessed by ICP-MS analysis of supernatants and pellets following centrifugation of digestae. An in vitro transwell triculture epithelial model was used to assess biokinetics and toxicity of ingested Fe₂O₃ ENM. Translocation of Fe₂O₃ ENM was determined by ICP-MS analysis of cell lysates and basolateral compartment fluid over time.

Results

It was demonstrated that the interactions of iENMs with food and GIT components influenced nanoparticle fate and transport, biokinetics and toxicological profile. Large differences in particle size, charge, and morphology were observed in the model food with and without Fe₂O₃ and among digestae from different stages of the simulated GIT (mouth, stomach, and small intestine). Immunoflorescence and TEM imaging of the cell culture model revealed markers and morphology of small intestinal epithelium including enterocytes, goblet cells and M cells. Fe₂O₃ was not toxic at concentrations tested in the digesta. In biokinetics studies, translocation of Fe₂O₃ after 4 h was <1% and ~2% for digesta with and without serum, respectively, suggesting that use of serum proteins alters iENMs biokinetics and raises concerns about commonly-used approaches that neglect iENM – food-GIT interactions or dilute digestae in serum-containing media.

Conclusions

We present a simple integrated methodology for studying the biokinetics and toxicology of iENMs, which takes into consideration nanoparticle-food-GIT interactions. The importance of food matrix and GIT effects on biointeractions was demonstrated, as well as the incorporation of these critical factors into a cellular toxicity screening model. Standardized food models still need to be developed and used to assess the effect of the food matrix effects on the fate and bioactivity of iENMs since commercial foods vary considerably in their compositions and structures.

     

The unrecognized occupational relevance of the interaction between engineered nanomaterials and the gastro-intestinal tract: a consensus paper from a multidisciplinary working group

Background

There is a fundamental gap of knowledge on the health effects caused by the interaction of engineered nanomaterials (ENM) with the gastro-intestinal tract (GIT). This is partly due to the incomplete knowledge of the complex physical and chemical transformations that ENM undergo in the GIT, and partly to the widespread belief that GIT health effects of ENM are much less relevant than pulmonary effects.However, recent experimental findings, considering the role of new players in gut physiology (e.g. the microbiota), shed light on several outcomes of the interaction ENM/GIT. Along with this new information, there is growing direct and indirect evidence that not only ingested ENM, but also inhaled ENM may impact on the GIT. This fact, which may have relevant implications in occupational setting, has never been taken into consideration.This review paper summarizes the opinions and findings of a multidisciplinary team of experts, focusing on two main aspects of the issue: 1) ENM interactions within the GIT and their possible consequences, and 2) relevance of gastro-intestinal effects of inhaled ENMs. Under point 1, we analyzed how luminal gut-constituents, including mucus, may influence the adherence of ENM to cell surfaces in a size-dependent manner, and how intestinal permeability may be affected by different physico-chemical characteristics of ENM. Cytotoxic, oxidative, genotoxic and inflammatory effects on different GIT cells, as well as effects on microbiota, are also discussed.Concerning point 2, recent studies highlight the relevance of gastro-intestinal handling of inhaled ENM, showing significant excretion with feces of inhaled ENM and supporting the hypothesis that GIT should be considered an important target of extrapulmonary effects of inhaled ENM.

Conclusions

In spite of recent insights on the relevance of the GIT as a target for toxic effects of nanoparticles, there is still a major gap in knowledge regarding the impact of the direct versus indirect oral exposure. This fact probably applies also to larger particles and dictates careful consideration in workers, who carry the highest risk of exposure to particulate matter.

     

箱包用万能胶中丙酮和三氯甲烷的暴露评估及健康风险评价

为了解万能胶中丙酮和三氯甲烷对皮革箱包制造工人的潜在健康风险,从市售产品中收集了50份万能胶样品,并采用气相色谱-质谱联用法对样品中的丙酮、三氯甲烷含量进行了测定。针对检出样品的相关数据,采用美国环境保护局(EPA)的健康风险评价法建立了在皮革箱包小企业使用的万能胶中丙酮和三氯甲烷的暴露量计算模型,并对潜在的健康风险进行了评价。研究结果表明:万能胶中丙酮和三氯甲烷存在较高的非致癌风险(R~n1)和致癌风险(Rc10~(-4)),故丙酮和三氯甲烷在万能胶中的含量应引起有关部门的重视。     

Producing nanomaterials in combustion

This paper presents original results in the area of synthesis of fullerenes, carbon nanotubes, and superhydrophobic soot in hydrocarbon flames and data on the self-propagating hightemperature synthesis of nanomaterials obtained in recent years at the Institute of Combustion Problems.     

纳米材料的性质

编者按:纳米材料是近年来科学上的一项重大发现,已成为当今许多学科的研究热点.纳米材料是指颗粒尺寸在纳米量级(1～100 nm)的超细材料,其尺寸大于原子簇而小于通常的微粉,处在原子簇和宏观物体交界的过渡区域.正如美国著名物理学家、诺贝尔奖获得者R.P.Feynman所言:"如果我们得以在细微尺度上控制事物的话,毫无疑问,这将使材料所具有的物性范围大为扩充."纳米材料在结构、光电和化学性质等方面的诱人特征,正引起材料科学家的浓厚兴趣.纳米材料科学是凝聚态物理、胶体化学、配位化学、化学反应动力学、表面、界面等学科的交叉学科,是现代材料科学的重要组成部分.纳米材料的发展对于人们进一步认识固体材料的本质结构性能具有十分重要的价值,科学家们把这种材料誉为"21世纪最有前途的材料".因此,本刊拟开辟"纳米材料专栏",以期对纳米材料的性能、研制方法以及在各个领域的应用与发展作较为全面、系统的报道.欢迎专家学者投稿进行专题介绍与评述,也欢迎读者来信来函提出意见和建议.     

纳米材料在放射性废水处理中的应用进展

放射性污染会引起生态环境问题,安全高效地处理放射性废水是我国应对环境安全的迫切需求,因此,研发高效的放射性处理技术和材料具有重要意义。近年来,纳米材料因其独特的物化性质受到广泛关注,被尝试用于放射性废水处理,并表现出良好的应用潜力。本文综述了国内外研究者利用纳米材料处理放射性废水的研究进展,总结了纳米材料作为吸附剂和膜材料对水体放射性核素的处理性能和应用情况：一方面,高比表面积的纳米材料作为新型吸附剂,经适当化学处理后具有大量活性位点和纳米孔,可高效吸附处理放射性废水;另一方面,种类丰富的纳米材料可作为制膜材料和添加剂,增加膜材料种类和制备调控维度,改善传统膜对水体放射性核素的去除效果。最后,总结了处理放射性废水的纳米材料选择依据,并讨论了纳米材料在放射性废水处理中需要引起重视的几个问题。     

Engineered nanomaterials exposure in the production of graphene

The objective of this study was to obtain the multi-metric occupational exposure assessment to graphene family nanomaterials (GFNs) particles of workers engaged in the large-scale production of graphene. The study design consisted of the combination of (i) direct-reading instruments, used to evaluate the total particle number concentrations relative to the background concentration (time series with spatial approach) and the mean size-dependent characteristics of particles (mean diameter and surface-area concentration) and (ii) filter-based air sampling for the determination of size-resolved particle mass concentrations. The data obtained from direct reading measurement were then used to estimate the 8-h time weighted average (8-h TWA) exposure to GFNs particles for workers involved in different working tasks. Workers were generally exposed to 8-h TWA GFNs particle levels lower than the proposed reference value (40,000 particle/cm³). Furthermore, despite high short-term exposure conditions were present during specific operations of the production process, the possibility of significant exposure peaks is not likely to be expected. The estimated 8-h TWA concentration showed differences between the unexposed (<100 particle/cm³; <0.05 µg/m³) and exposed subjects (mean concentration ranging from 909 to 6438 particle/cm³ and from 0.38 to 3.86 µg/m³). The research outcomes can be of particular interest because the exposure of workers in real working conditions was assessed with a multi-metric approach; in this regard, the study suggests that workers who are directly involved in some specific working task (material sampling for quality control) have higher potential for occupational exposure than operators who are in charge of routine production work.

© 2016 American Association for Aerosol Research     

纳米材料的应用

１　工业催化纳米材料的比表面积大,表面活性中心多,为做催化剂提供了必要条件。同时纳米材料的表面效应和体积效应决定了它具有良好的催化活性和催化反应选择性。目前在高分子聚合物氧化、还原及合成反应中可直接用纳米态铂黑、银、氧化铝、氧化铁等做催化剂,大大提高了反应效率;利用纳米镍作为火箭固体燃料反应催化剂,燃烧效率可提高１００倍。纳米材料催化剂的催化反应选择性还表现出特异性,如用硅载体纳米镍催化剂对丙醛的氧化反应研究表明,镍粒径在５ｎｍ以下时,反应选择性发生急剧变化——醛分解得到控制,生成乙醇的选择性迅…     

蛋白质基纳米材料的研究进展

介绍了几类包装材料、蛋白质芯片、酶生物传感器、分子马达以及蛋白质矿化材料、纳米模板等蛋白质基纳米材料的制备、特性及其应用前景。