The effects of serum on the toxicity of manufactured nanoparticles

The aim of the present study was to assess the effects of the presence and absence of serum in NP suspension media in relation to their cytotoxicity, as well as their potential to cause oxidative stress and stimulate pro-inflammatory cytokine release from J774.A1 murine ‘macrophage-like’ cells. Different sized (20 nm and 200 nm) carboxylated, fluorescent, model polystyrene beads (PBs) at concentrations from 12.5 μg ml⁻¹ to 100 μg ml⁻¹ were used. Both 20 nm and 200 nm PBs, independent of the suspension media, were observed to cause limited, yet significant (p < 0.05) cytotoxicity over 48 h up to 100 μg ml⁻¹. Significant differences (p > 0.05) were also found between NP size and serum content of the suspension media used. The smaller sized PBs were found to affect intracellular glutathione (GSH) levels, causing a significant loss (p < 0.05) in GSH when suspended in the presence of serum. Subsequent analysis also showed significant (p < 0.05) increases in tumour necrosis factor-α production after 48 h when the 20 nm PBs were suspended in both the presence and absence of serum, compared to the affects observed by the larger, 200 nm sized PBs. In conclusion, the results of the present study show that the interaction of NPs with serum can significantly affect their resultant toxicity in vitro.     

Prospects of using nanotechnology for food preservation,safety, and security

The rapid development of nanotechnology has transformed many domains of food science, especially those that involve the processing, packaging, storage, transportation, functionality, and other safety aspects of food. A wide range of nanostructured materials (NSMs), from inorganic metal, metal oxides, and their nanocomposites to nano-organic materials with bioactive agents, has been applied to the food industry. Despite the huge benefits nanotechnology has to offer, there are emerging concerns regarding the use of nanotechnology, as the accumulation of NSMs in human bodies and in the environment can cause several health and safety hazards. Therefore, safety and health concerns as well as regulatory policies must be considered while manufacturing, processing, intelligently and actively packaging, and consuming nano-processed food products. This review aims to provide a basic understanding regarding the applications of nanotechnology in the food packaging and processing industries and to identify the future prospects and potential risks associated with the use of NSMs.     

Toxicity assessment of manganese oxide micro and nanoparticles in Wistar rats after 28 days of repeated oral exposure

In the near future, nanotechnology is envisaged for large‐scale use. Hence health and safety issues of nanoparticles (NPs) should be promptly addressed. Twenty‐eight‐day oral toxicity, genotoxicity, biochemical alterations, histopathological changes and tissue distribution of nano and microparticles (MPs) of manganese oxide (MnO₂) in Wistar rats was studied. Genotoxicity was assessed using comet, micronucleus and chromosomal aberration assays. The results demonstrated a significant increase in DNA damage in leukocytes, micronuclei and chromosomal aberrations in bone marrow cells after exposure of MnO₂‐NPs at 1000, 300 mg kg^–1 bw per day and MnO₂‐MPs at the dose of 1000 mg kg^–1 bw per day. Our findings showed acetylcholinestrase inhibition at 1000 as well as at 300 mg kg^–1 bw per day in blood and with all the doses in the brain indicating the toxicity of MnO₂‐NPs. Further, the doses significantly inhibited different ATPases in the brain P₂ fraction. Significant changes were observed in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in the liver, kidney and serum in a dose‐dependent manner. MnO₂‐MPs at 1000 mg kg^–1 bw per day were found to induce significant alterations in biochemical enzymes. A significant distribution was found in all the tissues in a dose‐dependent manner. MnO₂‐NPs showed a much higher absorptivity and tissue distribution as compared with MnO₂‐MPs. A large fraction of MnO₂‐NPs and MnO₂‐MPs was cleared by urine and feces. Histopathological analysis revealed that MnO₂‐NPs caused alterations in liver, spleen, kidney and brain. The MnO₂‐NPs induced toxicity at lower doses compared with MnO₂‐MPs. Further, this study did not display gender differences after exposure to MnO₂‐NPs and MnO₂‐MPs. Therefore, the results suggested that prolonged exposure to MnO₂ has the potential to cause genetic damage, biochemical alterations and histological changes. Copyright © 2013 John Wiley & Sons, Ltd.     

Differences in allergenic potential of food extracts following oral exposure in mice reflect differences in digestibility: potential approaches to safety assessment.

An animal model for food allergy is needed to assess genetically modified food crops for potential allergenicity. The ideal model must produce allergic antibody (IgE) to proteins differentially according to known allergenicity before being used to accurately identify potential allergens among novel proteins. The oral route is the most relevant for exposure to food antigens, and a protein's stability to digestion is a current risk assessment tool based on this natural route. However, normal laboratory animals do not mount allergic responses to proteins administered orally due to oral tolerance, an immunologic mechanism which specifically suppresses IgE. To circumvent oral tolerance and evoke differential IgE responses to a panel of allergenic and nonallergenic food extracts, female C3H/HeJ mice were exposed subcutaneously or orally with cholera toxin as an adjuvant. All foods elicited IgE by the subcutaneous route. Oral exposure, however, resulted in IgE to allergens (peanut, Brazil nut, and egg white) but not to nonallergens (spinach and turkey), provided that the dose and exposures were limited. Additionally, in vitro digestibility assays demonstrated the presence of digestion-stable proteins in the allergenic food extracts but not in the nonallergenic foods. Our results suggest that the subcutaneous route is inadequate to distinguish allergens from nonallergens, but oral exposure under the appropriate experimental conditions will result in differential allergic responses in accordance with known allergenicity. Moreover, those foods containing digestion-resistant proteins provoke allergic responses in this model, supporting the current use of pepsin resistance in the decision tree for potential allergenicity assessment.     

Use of computational tools in the field of food safety

In this article we give an overview of how computational methods are currently used in the field of food safety by national regulatory bodies, international advisory organisations and the food industry. Our results show that currently the majority of stakeholders in the field of food safety do not apply computational methods on a routine basis, mainly because of a lack of in-house expertise. Some organisations, however, are very experienced in their use and have developed specialised in-house approaches. Despite this variable situation, computational tools are widely perceived to be a useful tool to support regulatory assessments and decision making in the field of food safety. Recognized, however, is a widespread need to develop guidance documents and software tools that will promote and harmonise the use of computational methods, together with appropriate training.     

Perspective on recent developments of nanomaterial based fluorescent sensors: Applications in safety and quality control of food and beverages

As the highly toxic pollutants will seriously harm human health, it is particularly important to establish the analysis and detection technology of food pollutants. Compared with the traditional detection methods, fluorescent detection techniques based on nanomaterials trigger wide interesting because of reduced detection time, simple operation, high sensitivity and selectivity, and economic. In this review, the application of fluorescent sensors in food pollutants detection is presented. Firstly, conventional fluorescent nanomaterials including metal-based quantum dots, carbon dots, graphene quantum dots and metal nanoclusters were summarized, with emphasis on the photoluminescence mechanism. Then, the fluorescence sensors based on these nanomaterials for food pollutants detection were discussed, involving in the established methods, sensor mechanisms, sensitivity, selectivity, and practicability of fluorescence sensors. The selected analytes focus on five types of higher toxic food pollutants, including mycotoxins, foodborne pathogens, pesticide residues, antibiotic residues, and heavy metal ions. Finally, outlook on the future and potential development of fluorescence detection technology in the field of food science were proposed, including green synthesis and reusability of fluorescence probes, large-scale industrialization of sensors, nondestructive testing of samples and degradation of harmful substances.     

Toxicological review and oral risk assessment of terephthalic acid (TPA) and its esters: A category approach

Polyethylene terephthalate, a copolymer of terephthalic acid (TPA) or dimethyl terephthalate (DMT) with ethylene glycol, has food, beverage, and drinking water contact applications. Di-2-ethylhexyl terephthalate (DEHT) is a plasticizer in food and drinking water contact materials. Oral reference doses (RfDs) and total allowable concentrations (TACs) in drinking water were derived for TPA, DMT, and DEHT. Category RfD and TAC levels were also established for nine C₁–C₈ terephthalate esters. The mode of action of TPA, and of DMT, which is metabolized to TPA, involves urinary acidosis, altered electrolyte elimination and hypercalciuria, urinary supersaturation with calcium terephthalate or calcium hydrogen terephthalate, and crystallization into bladder calculi. Weanling rats were more sensitive to calculus formation than dams. Calculi-induced irritation led to bladder hyperplasia and tumors in rats fed 1000?mg/kg-day TPA. The lack of effects at 142?mg/kg-day supports a threshold for urine saturation with calcium terephthalate, a key event for calculus formation. Chronic dietary DMT exposure in rodents caused kidney inflammation, but not calculi. Chronic dietary DEHT exposure caused general toxicity unrelated to calculi, although urine pH was reduced suggesting the TPA metabolite was biologically-active, but of insufficient concentration to induce calculi. Respective oral reference doses of 0.5, 0.5, and 0.2?mg/kg-day and total allowable drinking water concentrations of 3, 3, and 1?mg/L were derived for TPA, DMT, and DEHT. An oral RfD of 0.2?mg/kg-day for the terephthalate category chemicals corresponded to a drinking water TAC of 1?mg/L.     

In vitro evaluation of SiC nanoparticles impact on A549 pulmonary cells: Cyto-, genotoxicity and oxidative stress

Silicon carbide (SiC) is considered a highly biocompatible material, consequently SiC nanoparticles (NPs) have been proposed for potential applications in diverse areas of technology. Since no toxicological data are available for these NPs, the aim of this study was to draw their global toxicological profile on A549 lung epithelial cells, using a battery of classical in vitro assays. Five SiC-NPs, with varying diameters and Si/C ratios were used, and we show that these SiC-NPs are internalized in cells where they cause a significant, though limited, cytotoxic effect. Cell redox status is deeply disturbed: SiC-NP exposure cause reactive oxygen species production, glutathione depletion and inactivation of some antioxidant enzymes: glutathione reductase, superoxide dismutase, but not catalase. Finally, the alkaline comet assay shows that SiC-NPs are genotoxic. Taken together, these data prove that SiC-NPs biocompatibility should be revisited.     

Cellular uptake and intracellular fate of engineered nanoparticles: A review on the application of imaging techniques

Abstract

The use of imaging tools to probe nanoparticle-cell interactions will be crucial to elucidating the mechanisms of nanoparticle-induced toxicity. Of particular interest are mechanisms associated with cell penetration, translocation and subsequent accumulation inside the cell, or in cellular compartments. The objective of the present paper is to review imaging techniques that have been previously used in order to assess such interactions, and new techniques with the potential to be useful in this area. In order to identify the most suitable techniques, they were evaluated and matched against a list of evaluation criteria. We conclude that limitations exist with all of the techniques and the ultimate choice will thus depend on the needs of end users, and their particular application. The state-of-the-art techniques appear to have the least limitations, despite the fact that they are not so well established and still far from being routine. For example, super-resolution microscopy techniques appear to have many advantages for understanding the details of the interactions between nanoparticles and cells. Future research should concentrate on further developing or improving such novel techniques, to include the development of standardized methods and appropriate reference materials.     

Combined hydroxypropyl-β-cyclodextrin and poly(anhydride) nanoparticles improve the oral permeability of paclitaxel

The aim of this work was to study the effect of the combination between 2-hydroxypropyl-β-cyclodextrin (HPCD) and bioadhesive nanoparticles on the encapsulation and intestinal permeability of paclitaxel (PTX). In this context, a solid inclusion complex between PTX and HPCD was prepared by an evaporation method. Then, the complex was incorporated in poly(anhydride) nanoparticles by a solvent displacement method. The resulting nanoparticles, PTX–HPCD NP, displayed a size of about 300 nm and a drug loading of about 170 μg/mg (500-fold higher than in the absence of HPCD). The effect of these nanoparticles on the permeability of intestinal epithelium was investigated using the Ussing chamber technique. The apparent permeability (P_app) of PTX was found to be 12-fold higher when formulated as PTX–HPCD NP than when formulated as Taxol^® (control). Furthermore, when interaction between nanoparticles and the mucosa was avoided, the permeability of PTX significantly decreased. In summary, the association between PTX–HPCD and poly(anhydride) nanoparticles would induce a positive effect over the intestinal permeability of paclitaxel, being the bioadhesion a mandatory condition in this phenomena.     

Polybrominated diphenyl ethers in food and human dietary exposure: a review of the recent scientific literature

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs) used to protect people from fires by reducing the flammability of combustible materials. In recent years, PBDEs have become widespread environmental pollutants, while body burden in the general population has been increasing. A number of studies have shown that, as for other persistent organic pollutants, dietary intake is one of the main routes of human exposure to PBDEs. The most recent scientific literature concerning the levels of PBDEs in foodstuffs and the human dietary exposure to these BFRs are here reviewed. It has been noted that the available information on human total daily intake through food consumption is basically limited to a number of European countries, USA, China, and Japan. In spite of the considerable methodological differences among studies, the results show notable coincidences such as the important contribution to the sum of total PBDEs of some congeners such as BDEs 47, 49, 99 and 209, the comparatively high contribution of fish and seafood, and dairy products, and the probably limited human health risks derived from dietary exposure to PBDEs. Various issues directly related to human exposure to PBDEs through the diet still need investigation.     

The impact of different nanoparticle surface chemistry and size on uptake and toxicity in a murine macrophage cell line

This study investigated the uptake, kinetics and cellular distribution of different surface coated quantum dots (QDs) before relating this to their toxicity. J774.A1 cells were treated with organic, COOH and NH₂ (PEG) surface coated QDs (40 nM). Model 20 nm and 200 nm COOH-modified coated polystyrene beads (PBs) were also examined (50 μg ml^− 1). The potential for uptake of QDs was examined by both fixed and live cell confocal microscopy as well as by flow cytometry over 2 h. Both the COOH 20 nm and 200 nm PBs were clearly and rapidly taken up by the J774.A1 cells, with uptake of 20 nm PBs being relatively quicker and more extensive. Similarly, COOH QDs were clearly taken up by the macrophages. Uptake of NH₂ (PEG) QDs was not detectable by live cell imaging however, was observed following 3D reconstruction of fixed cells, as well as by flow cytometry. Cells treated with organic QDs, monitored by live cell imaging, showed only a small amount of uptake in a relatively small number of cells. This uptake was insufficient to be detected by flow cytometry. Imaging of fixed cells was not possible due to a loss in cell integrity related to cytotoxicity. A significant reduction (p < 0.05) in the fluorescent intensity in a cell-free environment was found with organic QDs, NH₂ (PEG) QDs, 20 nm and 200 nm PBs at pH 4.0 (indicative of an endosome) after 2 h, suggesting reduced stability. No evidence of exocytosis was found over 2 h. These findings confirm that surface coating has a significant influence on the mode of NP interaction with cells, as well as the subsequent consequences of that interaction.     

A critical review of the literature to conduct a toxicity assessment for oral exposure to methyl salicylate

Methyl salicylate is the predominant constituent of oil of wintergreen and is used as a pesticide, a denaturant, an external analgesic, a fragrance ingredient, and a flavoring agent in products such as chewing gum, baked goods, syrups, candy, beverages, ice cream, and tobacco products; and it occurs naturally in some vegetables and berries. Methyl salicylate is of interest to the tobacco industry as oil of wintergreen is used as a flavorant in tobacco products. The purpose of this investigation was to conduct a critical review of the available literature for oral exposure to methyl salicylate, incorporating an analysis of the quality of the studies available and the current understanding of the mode of action. Following a review of all of the available literature, the most appropriate data sets for dose-response modeling were reported by Gulati et al. in which significant changes in reproductive/development endpoints were reported to occur after exposure to 500?mg/kg/d of methyl salicylate in male and female mice. Benchmark dose modeling was performed and the most sensitive endpoint, the number of litters per mating pair, was associated with a BMDL of 220?mg/kg/d. This BMDL was chosen as the point of departure and adjusted by a body weight scaling factor to derive a human equivalent dose. Based on the uncertainty factor analysis, the POD for methyl salicylate was adjusted by a UF of 3 for interspecies uncertainty to derive an allowable daily intake of 11?mg/kg/d.     

The potential exposure and hazards of copper nanoparticles: A review

Copper is an essential element for metabolism in plants and animals. In its nanoform, copper has found various applications, thus increasing potential environmental exposure. Released nanoparticles in the environment undergo various transformation processes while bioaccumulation and toxicity of copper nanoparticles have been demonstrated in plants and animals. This toxicity is thought to be a combined effect of intracellular particles and the release of dissolved copper ions. Oxidative stress responses have been studied in copper nanoparticle induced effects as well as other pathways to cytotoxicity. The antimicrobial potential of copper nanoparticles makes them excellent components for application in biomedicine and more recently, they have been investigated for applications as drug delivery agents in cancer therapy. These properties of copper nanoparticles necessitate a thorough review and understanding of toxic mechanisms of action and the associated implications of exposure to human and environmental health.     

Ecotoxicity of engineered nanoparticles to aquatic invertebrates: a brief review and recommendations for future toxicity testing

Based on a literature review and an overview of toxic effects of engineered nanoparticles in aquatic invertebrates, this paper proposes a number of recommendations for the developing field of nanoecotoxicology by highlighting the importance of invertebrates as sensitive and relevant test organisms. Results show that there is a pronounced lack of data in this field (less than 20 peer-reviewed papers are published so far), and the most frequently tested engineered nanoparticles in invertebrate tests are C(60), carbon nanotubes, and titanium dioxide. In addition, the majority of the studies have used Daphnia magna as the test organism. To date, the limited number of studies has indicated acute toxicity in the low mg l(-1) range and higher of engineered nanoparticles to aquatic invertebrates, although some indications of chronic toxicity and behavioral changes have also been described at concentrations in the high microg l(-1) range. Nanoparticles have also been found to act as contaminant carriers of co-existing contaminants and this interaction has altered the toxicity of specific chemicals towards D. magna. We recommend that invertebrate testing is used to advance the level of knowledge in nanoecotoxicology through standardized short-term (lethality) tests with invertebrates as a basis for investigating behaviour and bioavailability of engineered nanoparticles in the aquatic environment. Based on this literature review, we further recommend that research is directed towards invertebrate tests employing long-term low exposure with chronic endpoints along with more research in bioaccumulation of engineered nanoparticles in aquatic invertebrates.     

Toxicity of ZnO nanoparticles (NPs) to A549 cells and A549 epithelium in vitro: Interactions with dipalmitoyl phosphatidylcholine (DPPC)

Once inhaled, nanoparticles (NPs) will first interact with lung surfactant system, which may influence the colloidal aspects of NPs and consequently the toxic potential of NPs to pulmonary cells. In this study, we investigated the effects of dipalmitoyl phosphatidylcholine (DPPC), the major component in lung surfactant, on stability and toxicity of ZnO NPs. The presence of DPPC increased the UV–vis spectra, hydrodynamic size, Zeta potential and dissolution rate of ZnO NPs, which indicates that DPPC might interact with NPs and affect the colloidal stability of NPs. Exposure to ZnO NPs induced cytotoxicity associated with increased intracellular Zn ions but not superoxide in A549 cells. In A549 epithelium model, exposure to ZnO NPs induced cytotoxicity and decreased the release of interleukin 6 (IL-6) without a significant effect on epithelial permeability rate. Co-exposure of A549 cells or A549 epithelium model to DPPC and ZnO NPs induced a higher release of lactate dehydrogenase (LDH) and interleukin-6 (IL-6) compared with the exposure of ZnO NPs alone. We concluded that the presence of DPPC could influence the colloidal stability of ZnO NPs and increase the damage of NPs to membrane probably due to the increased positive surface charge.     

Drug interaction between oral atorvastatin and verapamil in healthy subjects: effects of atorvastatin on the pharmacokinetics of verapamil and norverapamil

Aim It has been reported that verapamil and atorvastatin are inhibitors of both P-glycoprotein (P-gp) and microsomal cytochrome P450 (CYP) 3A4, and verapamil is a substrate of both P-gp and CYP3A4. Thus, it could be expected that atorvastatin would alter the absorption and metabolism of verapamil. Methods The pharmacokinetic parameters of verapamil and one of its metabolites, norverapamil, were compared after oral administration of verapamil (60 mg) in the presence or absence of oral atorvastatin (40 mg) in 12 healthy volunteers. Results Pharmacokinetics of verapamil were significantly altered by the coadministration of atorvastatin compared with those of without atorvastatin. For example, the total area under the plasma-concentration time curve to the last measured time, 24 h, in plasma (AUC_{0−24 h}) of verapamil increased significantly by 42.8%. Thus, the relative bioavailability increased by the same magnitude with atorvastatin. Although the AUC_{0−24 h} of norverapamil was not significantly different between two groups of humans, the AUC_{0−24 h, norverapamil}/ AUC_{0−24 h, verapamil} ratio was significantly reduced (27.5% decrease) with atorvastatin. Conclusion The above data suggest that atorvastatin could inhibit the absorption of verapamil via inhibition of P-gp and/or the metabolism of verapamil by CYP3A4 in humans.     

Taiwan food scandal: The illegal use of phthalates as a clouding agent and their contribution to maternal exposure

In 2011 the Taiwan Food and Drug Administration reported that plasticizers di(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP), endocrine disruptors, were illegally added to clouding agents used in foods and beverages. 965 products were found contaminated, of which 206 were exported to 22 countries. This study’s purpose was to obtain English names for 28 contaminated products for which DEHP levels were reported, calculate estimated average daily intake (mg/kg/day) for a 50 kg woman consuming one portion, and compare to U.S. and E.U. guidelines for daily intake. We found that drinking just one bottle (500 ml) of sports drinks would result in an average DEHP intake of 0.14 mg/kg bw/day (range 0.091–0.341), which exceeds by several fold government guidelines (0.02–0.06 mg/kg bw/day). One (2 g) serving from 4/14 samples of contaminated dietary supplements exceeds the guideline of 0.02 mg/kg bw/day. In conclusion, consuming even one portion of tainted drinks and some powders would lead to daily intake of DEHP that greatly exceeds established safety guidelines, raising concerns about potential adverse effects, particularly reproductive tract development in the male fetus. Global distribution of DEHP-contaminated and other adulterated products should prompt governments to become proactive in food safety regulations and chemical testing.     

Oxidative stress and NFkappaB activation in the lungs of rats: a synergistic interaction between soot and iron particles

Particulate matter (PM) has been associated with a variety of adverse health effects primarily involving the cardiopulmonary system. However, the precise biological mechanisms to explain how exposure to PM exacerbates or directly causes adverse effects are unknown. Particles of varying composition may play a critical role in these effects. To study such a phenomenon, a simple, laminar diffusion flame was used to generate aerosols of soot and iron particles in the ultrafine size range. Exposures of healthy adult rats were for 6 h/day for 3 days. Conditions used included exposure to soot only, iron only, or a combination of soot and iron. We found animals exposed to soot particles at 250 microg/m3 had no adverse respiratory effects. Exposure to iron alone at a concentration of 57 microg/m3 also had no respiratory effects. However, the addition of 45 microg/m3 of iron to soot with a combined total mass concentration of 250 microg/m3 demonstrated significant pulmonary ferritin induction, oxidative stress, elevation of IL-1beta, and cytochrome P450s, as well as activation of NFkappaB. These findings suggest that a synergistic interaction between soot and iron particles account for biological responses not found with exposure to iron alone or to soot alone.     

A comparison of the toxicity to laboratory mice and pipistrelle bats Pipistrellus pipistrellus of exposure to remedially-treated timber

Many species of bats roost in roof spaces and can come into contact with pesticides used to treat roof timbers against rot. As part of a study to develop a test with laboratory mice which could be used to predict the likely toxicity of pesticides to bats, the toxic effects on pipistrelle bats Pipistrellus pipistrellus and laboratory mice (CFLP outbred-strain) of exposure to dieldrin-treated timber were compared. Dose (amount of dieldrin applied to the wood surface) — response (mortality) studies demonstrated that pipistrelle bats were 30 times more sensitive to dieldrin-treated wood than laboratory mice. However, dieldrin residues in the brain and liver of animals which had been poisoned were significantly higher in bats than mice. These residue data suggest that bats may be inherently less sensitive to dieldrin poisoning than mice and so it is likely that the 30-fold greater sensitivity of bats than mice to dieldrin-treated timber was a result of greater rate of uptake, per gram body weight, of the active ingredient from the wood surface and/or slower clearance from the body. The importance of differences in exposure and the reliability of residue data as an indicator of differences in inherent sensitivity to a chemical are discussed in terms of their importance when considering inter-species variation in toxic response.