Health effects of exposure to nano-TiO2: a meta-analysis of experimental studies

Titanium dioxide nanoparticles Disrupt ultrastructure and function of Rat thyroid tissue via oxidative stress

Nano-TiO2 is widely used in various fields such as industry, daily necessities, food and medicine. Previous studies have shown that it can enter mammalian tissues through the digestive tract or respiratory tract and have effects on various organs and systems. However, the effect of nano-TiO2 on the mammalian thyroid gland has not been reported. In this study, we fed SD rats with rutile nano-TiO2 at a dose of 5 mg/kg body weight for 3 weeks, and then examined the thyroid histology and thyroid function of the rats. In vitro experiments were conducted to determine the effects of nano-TiO2 on the viability, apoptosis, inflammatory factors, antioxidant enzymes, and oxidative stress of human thyroid follicular epithelial cells. Histological evidence showed abnormal morphology of rat thyroid follicles and organelle damage in follicular epithelial cells. Nano-TiO2 caused a decrease in the level of sodium/iodide symporter (NIS), an increase in the level of apoptotic protein cleaved-caspase 3, and an increase in the levels of pro-inflammatory factors IL-1β and TNF-α in rat thyroid tissue. Nano-TiO2 also resulted in increased serum FT4 and TPO-Ab levels. In in vitro experiments, nano-TiO2 reduced the viability of human thyroid follicular cells, downregulated the levels and activities of antioxidant enzymes CAT, GPX1 and SOD, and increased the levels of ROS and MDA caused by oxidative stress. These results indicate that nano-TiO2 damages the structure and function of thyroid follicular epithelial cells through oxidative stress. Long-term exposure to nano-TiO2 could be a potential risk factor for thyroid dysfunction.

Ultra-processed food consumption and risk of chronic respiratory diseases mortality among adults: evidence from a prospective cohort study

PURPOSE

The purpose of the study was to determine the relationships between ultra-processed food (UPF) consumption and risk of mortality due to chronic respiratory diseases (CRDs) overall, chronic obstructive pulmonary disease (COPD), and lung cancer.

METHODS

A total of 96,607 participants aged 55 years and over were included from the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer trial. Dietary intake was measured using food frequency questionnaire. Cox regression was fitted to estimate the risk of all-cause mortality and mortality due to CRDs overall, COPD and lung cancer associated with UPF intake. Competing risk regression was used to account for deaths from other causes and censoring.

RESULTS

During the follow-up of 1,379,655.5 person-years (median 16.8 years), 28,700 all-cause, 4092 CRDs, 2015 lung cancer and 1,536 COPD mortality occurred. A higher intake of UPF increased the risk of mortality from CRDs overall by 10% (HR 1.10; 95% CI 1.01, 1.22) and COPD by 26% (HR 1.26; 95% CI 1.06, 1.49) but not associated with lung cancer mortality risk (HR 0.97; 95% CI 0.84, 1.12). However, the risk of lung cancer increased by 16% (HR 1.16; 95% CI 1.01, 1.34) in the highest UPF intake after multiple imputation. Dose-response relationships existed for CRDs and COPD mortality but not lung cancer.

CONCLUSION

UPF consumption was associated with an increased risk of CRD mortality. The association between UPF consumption and lung cancer mortality is inconclusive and only significant when multiple imputation was applied.

Titanium dioxide nanoparticles oral exposure induce osteoblast apoptosis, inhibit osteogenic ability and increase lipogenesis in mouse

Titanium dioxide nanoparticles (TiO2-NPs) are widely used in food, paint, coating, cosmetic, and composite orthodontic material. As a common food additive, TiO2-NPs can accumulate in various organs of human body, but the effect and underlying mechanism of bone remain unclear. Here mice were exposed to TiO2-NPs by oral gavage, and histological staining of femoral sections showed that TiO2-NPs reduced bone formation and enhanced osteoclast activity and lipogenesis, contributing to decreased trabecula bone. Transmission electron microscope (TEM) as well as biochemical and flow cytometry analysis of osteoblast exhibited that TiO2-NPs accumulated in osteoblast cytoplasm and impaired mitochondria ultrastructure with increased reactive oxygen species (ROS) and lipid hyperoxide, resulting in osteoblast apoptosis. In terms of mechanism, TiO2-NPs treatment inhibited expression of AKT and then increased pro-apoptotic protein Bax expression which was failure to form heterodimers with decreased anti-apoptotic Bcl-2, activating downstream Caspase-9 and Caspase-3 and inducing apoptosis. Additionally, TiO2-NPs suppressed Wnt3a level and then activated anti-Glycogen synthesis kinase (GSK-3β) phosphorylation, and ultimately resulted in degradation of β-catenin which down-regulated Runt-related transcription factor 2 (Runx2) and Osterix, inhibiting expression of osteogenic related proteins. Together, these results revealed that exposure of TiO2-NPs induced apoptosis and inhibited osteoblast differentiation through suppressing PI3K/AKT and Wnt/β-catenin signaling pathways, resulting in reduction of trabecula bone.

Catching nano: Evaluating the fate and behaviour of nano-TiO2 in swimming pools through dynamic simulation modelling

Engineered titanium dioxide nanoparticles (nano-TiO2) in consumer products such as sunscreens widely used by swimmers in aquatic settings have raised concerns about their potential adverse impact on ecosystems and human health due to their small size and unique physicochemical properties. Therefore, this research paper aims to investigate the fate and behaviour of nano-TiO2 from sunscreens in swimming pools using System Dynamics Modelling. The study developed a dynamic simulation model that considers various factors, including weather conditions, sunscreen and pool usage behaviour, filtration efficacy, pool maintenance, water chemistry, pool chemicals, and TiO2 concentration levels, which can affect exposure levels for different scenarios. The study considered non-linear interdependent relationships, feedback structures, and temporal changes and dealt with parameter uncertainties through Monte Carlo analyses. The results reveal that the regular use of sunscreen leads to nano-TiO2 concentrations ranging from 0.001 to 0.05 mg/L within a year, reflecting seasonal and pool usage variations. The study also found that changes in the weight percentage of TiO2 in the sunscreen formulation and the filtration duration per day are the most sensitive factors affecting TiO2 concentrations. Scenario analyses exploring different nano-TiO2 removal strategies suggested that one daily turnover is necessary for sufficient removal. Regular manual pool maintenance and monthly use of a pool clarifier are recommended for enhanced and accelerated removal without substantial additional costs. The study is novel in its integrated approach, combining empirical work with dynamic simulations, resulting in a novel approach to model the environmental fate and behaviour of nano-TiO2. The study makes important methodological contributions to the field and has initiated an interdisciplinary collaboration to create more accurate models. This study is of great significance as it presents a pioneering analysis of the impact of sunscreen properties, user behaviour, and environmental stressors on the fate and behaviour of nano-TiO2 in swimming pools.

Inactivation of mammalian spermatozoa on the exposure of TiO2 nanorods deposited with noble metals

Titanium dioxide (TiO₂) nanorods (NRs) are well-known semiconducting and catalytic material that has been widely applied, but their toxicities have also attracted recent interest. In this study, we investigated and compared the toxic effects of TiO₂ NRs and TiO₂ NRs loaded with Ag or Au NPs on boar spermatozoa. As a result, sperm incubated with Ag-TiO₂ NRs showed lower motility than sperm incubated with controls (with or without TiO₂ NRs) or Au-TiO₂ NRs. In addition, sperm viability and acrosomal integrity were defective in the presence of Ag-TiO₂ NRs, and the generation of intracellular reactive oxygen species (ROS) increased significantly when spermatozoa were incubated with 20 μg/ml Ag-TiO₂ NRs. We discussed in depth the charge transfer mechanism between enzymatic NADPH and Ag-TiO₂ NRs in the context of ROS generation in spermatozoa. The effects we observed reflected the fertilization competence of sperm incubated with Ag-TiO₂ NRs; specifically sperm penetration and embryonic development rates by in vitro fertilization were reduced by Ag-TiO₂ NRs. To summarize, our findings indicate that exposure to Ag-TiO₂ NRs could affect male fertilization fecundity and caution that care be exercised when using these NRs.

Food processing groups and colorectal cancer risk in Morocco: evidence from a nationally representative case-control study

OBJECTIVE

The aim of this study was to investigate the association between the consumption of foods and drinks from different food processing categories using the NOVA classification and CRC risk among Moroccan adults.

METHODS

1453 cases and 1453 matched controls aged at least 18 years and recruited from the 5 greater Moroccan regions were interviewed by trained investigators about their habitual diet using a standardized food frequency questionnaire (FFQ). Foods were categorized according to their degree of processing by the NOVA classification. Intakes of each food processing group were categorized into tertiles based on the distribution of controls with the lowest tertile considered as the reference category. Multivariable conditional logistic regression models were used to assess the association between each group and CRC risk (Odds Ratio (OR) and 95% Confidence Intervals (CI)), taking relevant confounders into account.

RESULTS

High consumption of unprocessed or minimally processed foods (NOVA group 1) was significantly inversely (OR = 0.82, 95%CI = 0.72-0.93), while high consumption of ultra-processed foods and drink products (NOVA group 4) was significantly positively (OR = 1.40, 95% CI = 1.22-1.61) associated with CRC risk as compared to the lowest intake group. These results were similar for colon and rectum sub-sites.

CONCLUSION

This is the first study to evaluate the association between the NOVA classification groups and CRC risk in an African country. Our results suggest that the consumption of ultra-processed foods and drink products may be associated with an increased risk of developing CRC, but longitudinal studies are needed to confirm these results.

A comprehensive review on electrospun nanohybrid membranes for wastewater treatment

Electrospinning, being a versatile and straightforward method to produce nanofiber membranes, has shown significant advancement in recent years. On account of the unique properties such as high surface area, high porosity, mechanical strength, and controllable surface morphologies, electrospun nanofiber membranes have been found to have a great potential in many disciplines. Pure electrospun fiber mats modified with different techniques of surface modification and additive incorporation have exhibited enhanced properties compared to traditional membranes and are even better than the as-prepared electrospun membranes. In this review, we have summarized recently developed electrospun nanohybrids fabricated by the incorporation of functional specific nanosized additives to be used in various water remediation membrane techniques. The adsorption, filtration, photocatalytic, and bactericidal capabilities of the hybrid membranes in removing common major water pollutants such as metal ions, dyes, oils, and biological pollutants have been discussed. Finally, an outlook on the future research pathways to fill the gaps existing in water remediation have been suggested.

Rare earth doped metal oxide nanoparticles for photocatalysis: a perspective

Metal oxides are well-known materials that have been considered as the prominent photocatalysts. Photocatalysis is a promising way to address the environmental issues which are caused by fossil fuel the combustion and industrial pollutants. Lot of efforts such as doping of metal oxides with metals, non-metals have been made to enhance their photocatalytic activity. More specifically, in this review we have discussed detailed synthesis procedures of rare earth doped metal oxides performed in the past decades. The advantage of doping metal oxides with rare earth metals is that they readily combine with functional groups due to the 4f vacant orbitals. Moreover, doping rare earth metals causes absorbance shift to the visible region of the electromagnetic spectrum which results to show prominent photocatalysis in this region. The effect of rare earth doping on different parameters of metal oxides such as band gap and charge carrier recombination rate has been made in great details. In perspective section, we have given a brief description about how researchers can improve the photocatalytic efficiencies of different metal oxides in coming future. The strategies and outcomes outlined in this review are expected to stimulate the search for a whole new set of rare earth doped metal oxides for efficient photocatalytic applications.

Association of multi-metals exposure with intelligence quotient score of children: A prospective cohort study

BACKGROUND

Associations between most single metals and children's intelligence quotient (IQ) scores have been evaluated in previous studies. However, associations between multi-metal exposures and children's IQ scores have not been analyzed.

OBJECTIVES

To assess the joint effects of lead (Pb), manganese (Mn), antimony (Sb), tin (Sn) and titanium (Ti) co-exposure on children's IQ scores.

METHODS

A prospective cohort study was conducted in Shimen and Huayuan, Hunan Province, China. Urine metals levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) at baseline. Children's IQ scores were repeatedly measured at baseline and follow-up following the method of Raven's Standard Progressive Matrices (SPM) and standardized as z scores. We fitted linear regression models and Bayesian kernel machine regression (BKMR) models to investigate the associations of metal levels with children's IQ scores after adjusting for covariates.

RESULTS

A total of 633 participants aged 7-10 years completed the survey. Urinary Pb (β = -0.028, P = 0.022) and urinary Ti (β = -0.0003, P = 0.001) were inversely associated with children's IQ scores. The BKMR analyses revealed significant negative overall effects of the five metals on children's IQ scores when all the metals were above their median levels, while significant positive associations were shown when all the metal concentrations were below their median levels. The model also showed negative trends of Sn and Ti on children's IQ. Furthermore, Ti and Sn had a synergistic relationship, with a decline in IQ score when Sn exposure was relatively high. The urinary Sn concentration was significantly higher but the urinary Ti concentration was significantly lower in participants from the Shimen area than in those from the Huayuan area. Decreasing trends of the overall effects were observed in both the Shimen and Huayuan areas.

CONCLUSION

Our findings revealed that multi-metal exposures caused a decline in children's IQ scores according to traditional linear regression models and the BKMR model. Our results provide some evidence of the association between multi-metal exposure and children's IQ. Meanwhile, interactions between multi-metal exposures on children's IQ should be given more attention.

Influence of Titanium Dioxide Nanoparticles on Human Health and the Environment

Nanotechnology has enabled tremendous breakthroughs in the development of materials and, nowadays, is well established in various economic fields. Among the various nanomaterials, TiO₂ nanoparticles (NPs) occupy a special position, as they are distinguished by their high availability, high photocatalytic activity, and favorable price, which make them useful in the production of paints, plastics, paper, cosmetics, food, furniture, etc. In textiles, TiO₂ NPs are widely used in chemical finishing processes to impart various protective functional properties to the fibers for the production of high-tech textile products with high added value. Such applications contribute to the overall consumption of TiO₂ NPs, which gives rise to reasonable considerations about the impact of TiO₂ NPs on human health and the environment, and debates regarding whether the extent of the benefits gained from the use of TiO₂ NPs justifies the potential risks. In this study, different TiO₂ NPs exposure modes are discussed, and their toxicity mechanisms—evaluated in various in vitro and in vivo studies—are briefly described, considering the molecular interactions with human health and the environment. In addition, in the conclusion of this study, the toxicity and biocompatibility of TiO₂ NPs are discussed, along with relevant risk management strategies.

Synthesis, Characterization and Photoelectric Properties of Fe2O3 Incorporated TiO2 Photocatalyst Nanocomposites

In the present work we report the sol-gel synthesis of pure TiO2 and (TiO2)1−x(Fe2O3)x nanocomposites with different Fe2O3 contents (x = 0, 0.1, 0.5, and 1.0 for pure TiO2, Fe2O3 incorporated 0.1, 0.5, and pure Fe2O3 which are denoted as PT, 0.1F, 0.5F, and PF, respectively). The structural, morphological, optical, and surface texture of the prepared nanocomposites were characterized using various techniques. The structural studies confirm the strong influence of Fe2O3 contents on the crystallite sizes and dislocation values. The size of the crystallites was increased by the increase in Fe2O3 contents. The bandgap values elucidated from DRS analysis were decreased from 3.15 eV to 1.91 eV with increasing Fe2O3 contents. The N2-Physorption analysis has confirmed the mesoporous nature of the samples with a comparable specific surface area of 35 m2/g. The photoelectrochemical measurements (CV, CA and EIS) were performed to assess the photoelectric properties of the prepared materials. It was found that the PT samples have the highest catalytic activity and photocurrent response compared to other composites. The reduction in current density was as follows: 2.8, 1.65, 1.5 and 0.9 mA/cm2, while the photocurrent response was ca. 800, 450, 45, 35 µA/cm2 for PT, 0.1F, 0.5F and PF samples, respectively. The EIS results showed that the (TiO2)1−x(Fe2O3)x nanocomposites exhibit lower charge transfer resistance than pure titania and hematite samples.

Ultra-processed food intake and all-cause mortality: DRECE cohort study

OBJECTIVE

To determine the association between ultra-processed food (UPF) intake and all-cause mortality in a representative sample of Spanish population.

DESIGN

Prospective cohort design in which follow-up lasted from baseline (1991) to mortality date or 31 December 2017, whichever was first. Dietary information was collected using a validated frequency questionnaire and categorised following the NOVA classification according to the extent of food processing. The association between consumption of UPF and mortality was analysed using Cox models. Isoenergetic substitution models were constructed to compare the health effects of the NOVA groups.

SETTING

Cohort from the Diet and Risk of Cardiovascular Diseases (CVD) in Spain (DRECE) study, representative of the Spanish population.

PARTICIPANTS

Totally, 4679 subjects between 5 and 59 years old.

RESULTS

Average consumption of UPF was 370·8 g/d (24·4 % of energy intake). After a median follow-up of 27 years, 450 deaths occurred. Those who consumed the highest amount of UPF had higher risk of mortality. For every 10 % of the energy intake from UPF consumption, an increase of 15 % in the hazard of all-cause mortality was observed (HR 1·15; (95 % CI 1·03, 1·27); P-value = 0·012). Substitution of UPF with minimally processed foods was significantly associated with a decreased risk of mortality.

CONCLUSIONS

An increase in UPF consumption was associated with higher risk of all-cause mortality in a representative sample of the Spanish population. Moreover, the theoretical substitution of UPF with unprocessed or minimally processed foods leads to a decrease in mortality. These results support the need to promote diets based on unprocessed or minimally processed foods.

Titanium dioxide nanoparticles induced the apoptosis of RAW264.7 macrophages through miR-29b-3p/NFAT5 pathway

Titanium dioxide nanoparticles (TiO₂ NPs) are widely found in consumer and industrial products, contributing to their prevalent presence in our surroundings. In this study, several miRNAs in the immuno-related pathways were found to be dysregulated in RAW264.7 cells after 24-h exposure to TiO₂ NPs, including miR-29b-3p, which had not been previously found to be associated with the dysregulation of immunity after exposure to TiO₂ NPs. The KEGG pathway and GO enrichment analysis suggested that miR-29b-3p functioned both in the T and B cell receptor signaling pathways. The NFAT5 gene was predicted to regulate miR-29b-3p using the MiRDB online database. The expression of miR-29b-3p and NFAT5 was found to be inversely correlated using qRT-PCR and western blotting analysis. Dual-luciferase reporter gene assays demonstrated the precise regulatory relationship between miR-29b-3p and NFAT5. The upregulation of miR-29b-3p was found to reinforce the apoptosis of cells, while no changes were found in terms of the cell cycle or cell proliferation, using MTT, cell apoptosis, and cycle detection experiments. Our results demonstrate that miR-29b-3p is involved in the response of RAW264.7 cells to exposure to TiO₂, proving evidence for the further study of the toxicity and mechanisms of nano-TiO₂ exposure.

Oxidative Damage Induced by Nano-titanium Dioxide in Rats and Mice: a Systematic Review and Meta-analysis

Nano-titanium dioxide is a kind of widely used nanomaterial that exhibits various adverse outcomes. However, the role of oxidative stress in this regard remains controversial. This study aimed to evaluate whether oxidative stress is one of the toxicity mechanisms induced by nano-titanium dioxide in rats and mice model. In this meta-analysis, 64 relevant publications were included through detailed database search. The pooled results showed that nano-titanium dioxide exposure could promote the expression of oxidants, such as malonaldehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), superoxide anion (O₂^-), and hydrogen peroxide (H₂O₂). Meanwhile, the levels of antioxidant-related enzymes and molecules, such as superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), and catalase (CAT), were reduced. Subgroup analysis revealed that different intervention routes, exposure periods, exposure dosages, and sample sources could affect the oxidative stress when exposed to nano-titanium dioxide. It was worth noting that the levels of MDA, 8-OHdG, and GSH significantly increased (P < 0.05) when the particle size of nano-titanium dioxide was < 10 nm, whereas H₂O₂, SOD, and GPx showed the highest effect at 10-40 nm. This study indicated that nano-titanium dioxide could cause oxidative damage by affecting the levels of enzymes and molecules involved in oxidative stress in rats and mice. And these results could provide a reference for studies of the toxicity mechanism induced by nano-titanium dioxide in the future.

Genotoxicity of TiO2 Nanoparticles in Four Different Human Cell Lines (A549, HEPG2, A172 and SH-SY5Y)

Titanium dioxide nanoparticles (TiO2 NPs) have a wide variety of applications in many consumer products, including as food additives, increasing the concern about the possible hazards that TiO2 NPs may pose to human health. Although most previous studies have focused on the respiratory system, ingestion must also be considered as an important exposure route. Furthermore, after inhalation or ingestion, TiO2 NPs can reach several organs, such as the liver, brain or lungs. Taking this into consideration, the present study focuses on the uptake and potential genotoxicity (micronuclei induction) of TiO2 NPs on four human cell lines of diverse origin: lung cells (A549), liver cells (HepG2), glial cells (A172) and neurons (SH-SY5Y), using flow cytometry methods. Results showed a concentration-, time- and cell-type- dependent increase in TiO2 NPs uptake but no significant induction of micronuclei in any of the tested conditions. Data obtained reinforce the importance of cell model and testing protocols choice for toxicity assessment. However, some questions remain to be answered, namely on the role of cell culture media components on the agglomeration state and mitigation of TiO2 NPs toxic effects.

Assessment of strategies for the formation of stable suspensions of titanium dioxide nanoparticles in aqueous media suitable for the analysis of biological fluids

Due to their omnipresence in consumer products, there is a growing concern about the potential effects of nanoparticles on human health. Toxicological assessment and NP end-product studies require proper quantification of these materials in biological fluids. However, their quantifications in these media require stable predispersed NP solutions in aqueous media to enable the fortification in the matrices of interest or the preparation of calibration standards. In this study, a sample preparation scheme was developed by studying various dispersion media (polyvinylpyrrolidone and polyethylene glycol) and sonication strategies (bath and ultrasonic probe) to ensure homogeneous dispersion of titanium dioxide nanoparticles. Optimization of the various parameters was performed using SRM NIST 1898 NP reference material, composed of rutile and anatase phases. Number-based size distribution for titanium dioxide NPs was determined by dynamic light scattering and single-particle inductively coupled plasma mass spectrometry to evaluate the procedure efficiency. Changes in mean size and most frequent size distribution were also studied to determine if the agglomeration of nanoparticles occurs at the various dispersion conditions tested. Among the different dispersion parameters tested herein, the use of polyvinylpyrrolidone combined with a sonication process generated by a probe leads to a significant improvement in terms of suspension efficiency and stability over 72 h. The dispersion efficiency of the proposed methodology was assessed by single-particle inductively coupled plasma mass spectrometry with spiked biological fluids such as urine and blood. Graphical abstract.

Amelioration of titanium dioxide nanoparticle reprotoxicity by the antioxidants morin and rutin

The present study aimed to examine the ameliorative effects of morin and rutin on the reproductive toxicity induced by titanium dioxide nanoparticles (TiO₂NPs) in male rats. A total of seventy adult male Sprague-Dawley rats were randomly divided into seven groups, each comprising ten rats. Nanoreprotoxicity was induced by treating rats with TiO₂NPs at a dosage of 300 mg/kg body weight for 30 days. Morin (30 mg/kg body weight) and rutin (100 mg/kg body weight) were co-administered with or without TiO₂NPs to rats either individually or combined. Only distilled water was administered to the control group. The results showed that TiO₂NPs enhanced oxidative stress, indicated by reduced levels of antioxidants such as superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) in testicular tissues, and increased levels of the lipid peroxidation marker malondialdehyde (MDA). TiO₂NPs significantly reduced the levels of sex hormones (testosterone, FSH, and LH), reduced sperm motility, viability, and sperm cell count, and increased sperm abnormalities, in addition to damaging the testicular histological architecture. TiO₂NPs resulted in the downregulation of 17β-HSD and the upregulation of proapoptotic gene (Bax) transcripts in the testicular tissues. Conversely, morin and/or rutin had a protective effect on testicular tissue. They effectively counteracted TiO₂NP-induced oxidative damage and morphological injury in the testis by conserving the endogenous antioxidant mechanisms and scavenging free radicals. Thus, we suggest that morin and rutin could be used to alleviate the toxicity and oxidative damage associated with TiO₂NP intake.

A numerical investigation of the heat transfer characteristics of water-based mango bark nanofluid flowing in a double-pipe heat exchanger

In this study, the heat transfer characteristics of a new class of nanofluids made from mango bark was numerically simulated and studied during turbulent flow through a double pipe heat exchanger. A range of volume fractions was considered for a particle size of 100 nm. A two-phase flow was considered using the mixture model. The mixture model governing equations of continuity, momentum, energy and volume fraction were solved using the finite-volume method. The results showed an increase of the Nusselt number by 68% for a Reynolds number of 5,000 and 45% for a Reynolds number of 13 000, and the heat transfer coefficient of the nanofluid was about twice that of the base fluid. In addition, the Nusselt number decreased by an average value of 0.76 with an increase of volume fraction by 1%. It was also found that there was a range of Reynolds numbers in which the trend of the average heat transfer coefficient of the nanofluid was completely reversed, and several plots showing zones of higher heat transfer which if taken advantage of in design will lead to higher heat transfer while avoiding other zones that have low heat transfer. It is hoped that these results will influence the thermal design of new heat exchangers.

Study of mitochondrial swelling, membrane fluidity and ROS production induced by nano-TiO2 and prevented by Fe incorporation

The potential impact of TiO2 and Fe incorporated TiO2 nanoparticles at the organelle level has been reported. The toxicity of the samples on mitochondria isolated from chicken liver tissue has been examined through mitochondrial swelling, membrane fluidity, ROS generation capacity, and activity of complex II. The toxic effect of TiO2 was prevented by incorporating Fe into the TiO2 matrix at different concentrations. The activity of the succinate dehydrogenase enzyme complex was affected and permeabilization of the mitochondrial inner membrane to H+ and K+ and its alteration in membrane fluidity at 100 μg mL-1 of nano-TiO2 dosage were investigated, which showed significant changes in the anisotropy of DPH-labeled mitochondria. Fe incorporation into the TiO2 matrix makes it more biocompatible by changing its structure and morphology.

Effect of TiO2 and Fe doped TiO2 nanoparticles on mitochondrial membrane potential in HBL-100 cells

Titanium dioxide (TiO₂) nanoparticles (NPs) have made unbelievable progress in the field of nanotechnology and biomedical research. The proper toxicological assessment of TiO₂ NPs and the reduction of its cytotoxicity need to be addressed. Fe doping in TiO₂ has been investigated to reduce the toxic effects of TiO₂ NPs. Fe doped TiO₂ powder samples were synthesized by sol-gel methods. The prepared samples were characterized by x-ray diffractometer (XRD), transmission electron microscope (TEM), and Raman spectroscopy to study their structure, morphology, and molecular conformation. XRD results revealed the coexistence of anatase (A) and rutile (R) phases of TiO₂. The A-R transformation was observed with an increase in Fe doping along with the formation of α-Fe₂O₃ phase. TEM showed changes in morphology from spherical nanoparticles to elongated rod-shaped nanostructures with increasing Fe content. Shape variation of TiO₂ nanoparticles after incorporation of Fe is a key reason behind the toxicity reduction. The authors observed that the toxicity of TiO₂ nanoparticles was rescued upon Fe incorporation. The effect of NPs on the mitochondrial membrane potential (MMP) was assessed using flow cytometry. The MMP (%) decreased in TiO₂ treated cells and increased by 1% Fe doped TiO₂ NPs treated cells. Confocal imaging revealed the presence of functional mitochondria upon the exposure of Fe doped TiO₂ NPs. The goal of the present study was to decrease the toxic effects induced by TiO₂ NPs on mitochondrial potential and its prevention by Fe doping.

TiO2 particles induce ER stress and apoptosis in human hepatoma cells, HepG2, in a particle size-dependent manner

The cytotoxicity of TiO₂ nanoparticles are well-known, but the particle size-dependent induction of ER stress and apoptosis by TiO₂ in hepatocytes has not been elucidated clearly. In the present study, we investigated whether a fine TiO₂ particle and two types of TiO₂ nanoparticles induce ER stress and apoptosis differently in HepG2 cells. A particle size-dependent decrease in cell viability was observed after exposure to the TiO₂ particles. The levels of ER stress-related proteins (BiP, CHOP, ATF6α, and p-PERK) were increased with decreasing particle size. TiO₂ particles induced ER stress-mediated apoptosis in a particle size-dependent manner as seen by a decrease in the expression of Bcl-2, and increases in the expression of Bax, caspase-12, and cleaved caspase-3. These results indicated that the cytotoxicity produced by TiO₂ particles was related to particle size, with smaller TiO₂ nanoparticles producing greater toxic effects involving ER stress and apoptosis in the HepG2 cells.

Association Between Ultraprocessed Food Consumption and Risk of Mortality Among Middle-aged Adults in France

IMPORTANCE

Growing evidence indicates that higher intake of ultraprocessed foods is associated with higher incidence of noncommunicable diseases. However, to date, the association between ultraprocessed foods consumption and mortality risk has never been investigated.

OBJECTIVE

To assess the association between ultraprocessed foods consumption and all-cause mortality risk.

DESIGN, SETTING, AND PARTICIPANTS

This observational prospective cohort study selected adults, 45 years or older, from the French NutriNet-Santé Study, an ongoing cohort study that launched on May 11, 2009, and performed a follow-up through December 15, 2017 (a median of 7.1 years). Participants were selected if they completed at least 1 set of 3 web-based 24-hour dietary records during their first 2 years of follow-up. Self-reported data were collected at baseline, including sociodemographic, lifestyle, physical activity, weight and height, and anthropometrics.

EXPOSURES

The ultraprocessed foods group (from the NOVA food classification system), characterized as ready-to-eat or -heat formulations made mostly from ingredients usually combined with additives. Proportion (in weight) of ultraprocessed foods in the diet was computed for each participant.

MAIN OUTCOMES AND MEASURES

The association between proportion of ultraprocessed foods and overall mortality was the main outcome. Mean dietary intakes from all of the 24-hour dietary records available during the first 2 years of follow-up were calculated and considered as the baseline usual food-and-drink intakes. Mortality was assessed using CépiDC, the French national registry of specific mortality causes. Hazard ratios (HRs) and 95% CIs were determined for all-cause mortality, using multivariable Cox proportional hazards regression models, with age as the underlying time metric.

RESULTS

A total of 44 551 participants were included, of whom 32 549 (73.1%) were women, with a mean (SD) age at baseline of 56.7 (7.5) years. Ultraprocessed foods accounted for a mean (SD) proportion of 14.4% (7.6%) of the weight of total food consumed, corresponding to a mean (SD) proportion of 29.1% (10.9%) of total energy intake. Ultraprocessed foods consumption was associated with younger age (45-64 years, mean [SE] proportion of food in weight, 14.50% [0.04%]; P < .001), lower income (<€1200/mo, 15.58% [0.11%]; P < .001), lower educational level (no diploma or primary school, 15.50% [0.16%]; P < .001), living alone (15.02% [0.07%]; P < .001), higher body mass index (calculated as weight in kilograms divided by height in meters squared; ≥30, 15.98% [0.11%]; P < .001), and lower physical activity level (15.56% [0.08%]; P < .001). A total of 602 deaths (1.4%) occurred during follow-up. After adjustment for a range of confounding factors, an increase in the proportion of ultraprocessed foods consumed was associated with a higher risk of all-cause mortality (HR per 10% increment, 1.14; 95% CI, 1.04-1.27; P = .008).

CONCLUSIONS AND RELEVANCE

An increase in ultraprocessed foods consumption appears to be associated with an overall higher mortality risk among this adult population; further prospective studies are needed to confirm these findings and to disentangle the various mechanisms by which ultraprocessed foods may affect health.

Health hazards of nanoparticles: understanding the toxicity mechanism of nanosized ZnO in cosmetic products

In recent years, nanoparticles are being used extensively in personal healthcare products such as cosmetics, sunscreens, soaps, and shampoos. Particularly, metal oxide nanoparticles are gaining competence as key industrial constituents, progressing toward a remarkable rise in their applications. Zinc oxide and titanium oxide nanoparticles are the most commonly employed metal oxide nanoparticles in sunscreens, ointments, foot care, and over the counter topical products. Dermal exposure to these metal oxides predominantly occurs through explicit use of cosmetic products and airway exposure to nanoparticle dusts is primarily mediated via occupational exposure. There is a compelling need to understand the toxicity effects of nanoparticles which can easily enter the cells and induce oxidative stress. Consequently, these products have become a direct source of pollution in the environment and thereby greatly impact our ecosystem. A complete understanding of the toxicity mechanism of nano-ZnO is intended to resolve whether and to what extent such nanoparticles may pose a threat to the environment and to human beings. In this review article, we have discussed the characteristics of metal oxide nanoparticles and its applications in the cosmetic industry. We have also highlighted about their toxicity effects and their impact on human health.

Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort

OBJECTIVE

To assess the prospective associations between consumption of ultra-processed food and risk of cancer.

DESIGN

Population based cohort study.

SETTING AND PARTICIPANTS

104 980 participants aged at least 18 years (median age 42.8 years) from the French NutriNet-Santé cohort (2009-17). Dietary intakes were collected using repeated 24 hour dietary records, designed to register participants' usual consumption for 3300 different food items. These were categorised according to their degree of processing by the NOVA classification.

MAIN OUTCOME MEASURES

Associations between ultra-processed food intake and risk of overall, breast, prostate, and colorectal cancer assessed by multivariable Cox proportional hazard models adjusted for known risk factors.

RESULTS

Ultra-processed food intake was associated with higher overall cancer risk (n=2228 cases; hazard ratio for a 10% increment in the proportion of ultra-processed food in the diet 1.12 (95% confidence interval 1.06 to 1.18); P for trend<0.001) and breast cancer risk (n=739 cases; hazard ratio 1.11 (1.02 to 1.22); P for trend=0.02). These results remained statistically significant after adjustment for several markers of the nutritional quality of the diet (lipid, sodium, and carbohydrate intakes and/or a Western pattern derived by principal component analysis).

CONCLUSIONS

In this large prospective study, a 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increase of greater than 10% in risks of overall and breast cancer. Further studies are needed to better understand the relative effect of the various dimensions of processing (nutritional composition, food additives, contact materials, and neoformed contaminants) in these associations.

STUDY REGISTRATION

Clinicaltrials.gov NCT03335644.

Titania and Zinc Oxide Nanoparticles: Coating with Polydopamine and Encapsulation within Lecithin Liposomes—Water Treatment Analysis by Gel Filtration Chromatography with Fluorescence Detection

The interplay of metal oxide nanoparticles, environmental pollution, and health risks is key to all industrial and drinking water treatment processes. In this work we present a study using gel filtration chromatography for the analytical investigation of metal oxide nanoparticles in water, their coating with polydopamine, and their encapsulation within lecithin liposomes. Polydopamine prevents TiO2 and ZnO nanoparticles from aggregation during chromatographic separation. Lecithin forms liposomes that encapsulate the nanoparticles and carry them through the gel filtration column, producing an increase of peak area for quantitative analysis without any change in retention time to affect qualitative identification. To the best of our knowledge, this is the first report that demonstrates the potential application of lecithin liposomes for cleaning up metal oxide nanoparticles in water treatment. Encapsulation of graphene quantum dots by liposomes would allow for monitoring of nanoparticle-loaded liposomes to ensure their complete removal by membrane ultrafiltration from treated water.

Liver histopathological alteration after repeated intra-tracheal instillation of titanium dioxide in male rats

AIM

The present study designed to evaluate the toxic effect of anatase TiO2 NPs on BALF biochemical changes and liver alteration in rats.

BACKGROUND

Titanium dioxide (TiO2) nanoparticles (NPs) are utilized in food color additives and cosmetics worldwide. Humans uptake these nanoparticulate by different routes and may exhibit potential side effects, lags behind the rapid development of nanotechnology.

METHODS

Sixty-three mats rats were used. Included by the control group and the experimental groups treated twice a week with 0.5, 5, 50, 1.5, 15, 150 mg/kg of nano-TiO2 (size 21 nm), for four consecutive weeks. Animals were sacrificed at 4 days, a month and three months post-instillation. The levels of tumor necrosis factor - α (TNF-α) and macrophage inflammatory protein- 2 (MIP-2) were measured in the lung homogenate and in the bronchoalveolar lavage fluid (BALF) supernatants by enzyme-linked immunosorbent assay (ELISA) and histopathological examination of liver tissue was performed.

RESULTS

The results showed that TiO2 NP induces many alterations in the liver structure after 4 days, a month and reduced after 3 months from intratracheal instillation. This included liver heavy infiltration of inflammatory cells, an increase of collagen density in portal triads, beginning of fibrosis formation and Glisson capsule thickness increase and TiO2 NPs reached the liver tissue after a month from exposure at all doses especially low doses (0.5, 1.5, 5) mg/kg of TiO2 NPs.

CONCLUSION

The immune system was strongly responded in the groups treated with high doses (15, 50, 150) mg/kg of TiO2 NP leading to raising the concentration of α-TNF, and MIP-2 in BALF while they decrease in tissue homogenate.

Nano-Inclusions Applied in Cement-Matrix Composites: A Review

Research on cement-based materials is trying to exploit the synergies that nanomaterials can provide. This paper describes the findings reported in the last decade on the improvement of these materials regarding, on the one hand, their mechanical performance and, on the other hand, the new properties they provide. These features are mainly based on the electrical and chemical characteristics of nanomaterials, thus allowing cement-based elements to acquire "smart" functions. In this paper, we provide a quantitative approach to the reinforcements achieved to date. The fundamental concepts of nanoscience are introduced and the need of both sophisticated devices to identify nanostructures and techniques to disperse nanomaterials in the cement paste are also highlighted. Promising results have been obtained, but, in order to turn these advances into commercial products, technical, social and standardisation barriers should be overcome. From the results collected, it can be deduced that nanomaterials are able to reduce the consumption of cement because of their reinforcing effect, as well as to convert cement-based products into electric/thermal sensors or crack repairing materials. The main obstacle to foster the implementation of such applications worldwide is the high cost of their synthesis and dispersion techniques, especially for carbon nanotubes and graphene oxide.

Mass or total surface area with aerosol size distribution as exposure metrics for inflammatory, cytotoxic and oxidative lung responses in rats exposed to titanium dioxide nanoparticles

There is currently no consensus on the best exposure metric(s) for expressing nanoparticle (NP) dose. Although surface area has been extensively studied for inflammatory responses, it has not been as thoroughly validated for cytotoxicity or oxidative stress effects. Since inhaled NPs deposit and interact with lung cells based on agglomerate size, we hypothesize that mass concentration combined with aerosol size distribution is suitable for NP risk assessment. The objective of this study was to evaluate different exposure metrics for inhaled 5 nm titanium dioxide aerosols composed of small (SA < 100 nm) or large (LA > 100 nm) agglomerates at 2, 7, and 20 mg/m3 on rat lung inflammatory, cytotoxicity, and oxidative stress responses. We found a significant positive correlation ( r = 0.98, p < 0.01) with the inflammatory reaction, measured by the number of neutrophils and the mass concentration when considering all six (SA + LA) aerosols. This correlation was similar ( r = 0.87) for total surface area. Regarding cytotoxicity and oxidative stress responses, measured by lactate dehydrogenase and 8-isoprostane, respectively, and mass or total surface area as an exposure metric, we observed significant positive correlations only with SA aerosols for both the mass concentration and size distribution ( r > 0.91, p < 0.01), as well as for the total surface area ( r > 0.97, p < 0.01). These data show that mass or total surface area concentrations alone are insufficient to adequately predict oxidant and cytotoxic pulmonary effects. Overall, our study indicates that considering NP size distribution along with mass or total surface area concentrations contributes to a more mechanistic discrimination of pulmonary responses to NP exposure.

Genotoxicity Studies of Titanium Dioxide Nanoparticles (TiO2NPs) in the Brain of Mice

Titanium dioxide nanoparticles (TiO2NPs) are excessively used and represent one of the top five most commonly used nanoparticles worldwide. Recently, various studies referred to their toxic potential on various organs using different treatment route. Male Swiss Webster mice were orally administrated TiO2NPs (500 mg/kg b.w.) daily for five consecutive days and then animals were sacrificed at 24 h, 7 days, or 14 days after the last treatment. The present results report that exposure to TiO2NPs produces mild to moderate changes in the cytoarchitecture of brain tissue in a time dependent manner. Moreover, Comet assay revealed the apoptotic DNA fragmentation, while PCR-SSCP pattern and direct sequencing showed point mutation of Presenilin 1 gene at exon 5, gene linked to inherited forms of the Alzheimer's disease. Therefore, from these findings, the present study concluded that TiO2NPs is genotoxic and mutagenic to brain tissue which in turn might lead to Alzheimer's disease incidence.

Photoactivity of hierarchically nanostructured ZnO–PES fibre mats for water treatments

Brush-like ZnO nanorods shell grown by CBD onto electrospun PES fibres as photocatalytic membranes for water purification.

Markers of oxidative damage of nucleic acids and proteins among workers exposed to TiO2 (nano) particles

OBJECTIVE

The use of nanotechnology is growing enormously and occupational physicians have an increasing interest in evaluating potential hazards and finding biomarkers of effect in workers exposed to nanoparticles.

METHODS

A study was carried out with 36 workers exposed to (nano)TiO2 pigment and 45 controls. Condensate (EBC) titanium and markers of oxidation of nucleic acids (including 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU)) and proteins (such as o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr) and 3-nitrotyrosine (3-NOTyr)) were analysed from samples of their exhaled breath.

RESULTS

In the production workshops, the median total mass 2012 and 2013 TiO2 concentrations were 0.65 and 0.40 mg/m(3), respectively. The median numbers of concentrations measured by the scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) were 1.98 × 10(4) and 2.32 × 10(4) particles/cm(3), respectively; and about 80% of those particles were smaller than 100 nm in diameter. In the research workspace, lower aerosol concentrations (0.16 mg/m(3) and 1.32 × 10(4) particles/cm(3)) were found. Titanium in the EBC was significantly higher in production workers (p<0.001) than in research workers and unexposed controls. Accordingly, most EBC oxidative stress markers, including in the preshift samples, were higher in production workers than in the two other groups. Multiple regression analysis confirmed an association between the production of TiO2 and the levels of studied biomarkers.

CONCLUSIONS

The concentration of titanium in EBC may serve as a direct exposure marker in workers producing TiO2 pigment; the markers of oxidative stress reflect the local biological effect of (nano)TiO2 in the respiratory tract of the exposed workers.

Rethinking Meta-Analysis: Applications for Air Pollution Data and Beyond

Meta-analyses offer a rigorous and transparent systematic framework for synthesizing data that can be used for a wide range of research areas, study designs, and data types. Both the outcome of meta-analyses and the meta-analysis process itself can yield useful insights for answering scientific questions and making policy decisions. Development of the National Ambient Air Quality Standards illustrates many potential applications of meta-analysis. These applications demonstrate the strengths and limitations of meta-analysis, issues that arise in various data realms, how meta-analysis design choices can influence interpretation of results, and how meta-analysis can be used to address bias and heterogeneity. Reviewing available data from a meta-analysis perspective can provide a useful framework and impetus for identifying and refining strategies for future research. Moreover, increased pervasiveness of a meta-analysis mindset-focusing on how the pieces of the research puzzle fit together-would benefit scientific research and data syntheses regardless of whether or not a quantitative meta-analysis is undertaken. While an individual meta-analysis can only synthesize studies addressing the same research question, the results of separate meta-analyses can be combined to address a question encompassing multiple data types. This observation applies to any scientific or policy area where information from a variety of disciplines must be considered to address a broader research question.

Toxicity of titanium dioxide nanoparticles in central nervous system

Titanium dioxide nanoparticles (TiO2 NPs) have found many practical applications in industry and daily life. A widespread application of TiO2 NPs rises the question about safety of their use in the context of potential occupational, environmental and intentional exposure of humans and biota. TiO2 NPs easily enter the body through inhalation, cross blood-brain barrier and accumulate in the brain, especially in the cortex and hippocampus. Toxicity of these NPs and the molecular mechanisms of their action have been studied extensively in recent years. Studies showed that TiO2 NPs exposure resulted in microglia activation, reactive oxygen species production, activation of signaling pathways involved in inflammation and cell death, both in vitro and in vivo. Consequently, such action led to neuroinflammation, further brain injury. A spatial recognition memory and locomotor activity impairment has been also observed.

In vitro and in vivo study of hazardous effects of Ag nanoparticles and Arginine-treated multi walled carbon nanotubes on blood cells: application in hemodialysis membranes

One of the novel applications of the nanostructures is the modification and development of membranes for hemocompatibility of hemodialysis. The toxicity and hemocompatibility of Ag nanoparticles and arginine-treated multiwalled carbon nanotubes (MWNT-Arg) and possibility of their application in membrane technology are investigated here. MWNT-Arg is prepared by amidation reactions, followed by characterization by FTIR spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The results showed a good hemocompatibility and the hemolytic rates in the presence of both MWNT-Arg and Ag nanoparticles. The hemolytic rate of Ag nanoparticles was lower than that of MWNT-Arg. In vivo study revealed that Ag nanoparticle and MWNT-Arg decreased Hematocrit and mean number of red blood cells (RBC) statistically at concentration of 100 µg mL(-1) . The mean decrease of RBC and Hematocrit for Ag nanoparticles (18% for Hematocrit and 5.8 × 1,000,000/µL) was more than MWNT-Arg (20% for Hematocrit and 6 × 1000000/µL). In addition, MWNT-Arg and Ag nanoparticles had a direct influence on the White Blood Cell (WBC) drop. Regarding both nanostructures, although the number of WBC increased in initial concentration, it decreased significantly at the concentration of 100 µg mL(-1) . It is worth mentioning that the toxicity of Ag nanoparticle on WBC was higher than that of MWNT-Arg. Because of potent antimicrobial activity and relative hemocompatibility, MWNT-Arg could be considered as a new candidate for biomedical applications in the future especially for hemodialysis membranes.

Cellulose nanofiber–titania nanocomposites as potential drug delivery systems for dermal applications

Nanocomposites with potential for dermal drug delivery have been developed using nanotitania chemically grafted onto nanocellulose as an active ingredient for enhanced uptake and controlled release of model drug loads.