Understanding the chemical and mineralogical composition of commercial henna and jagua tattoos and dyes-a multi-analytical approach.

Temporary tattoos and dyes constitute a great analytical challenge in relation to the regulatory control of their ingredients. Most of these commercial products are not labeled according to their content and their chemical nature is highly diverse. Therefore, it is necessary to analyze these complex samples to evaluate the potential presence of metallic impurities, to ensure the safety of cosmetic products contributing to health protection. This study proposes a multi-analytical methodology, which includes handheld X-ray fluorescence (h-XRF) and X-ray diffraction (XRD), complemented by variable pressure scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (VP-SEM-EDS) to fully characterize 34 commercial samples of jagua and henna tattoos and dyes. The approach allowed the identification of the main constituents providing complementary compositional data and differences between sample types were established. In addition, information on the degree of natural pigments homogeneity was also obtained. The results' discussion considering the current European cosmetics regulation may be useful to support the drafting of safety requirements and specific regulation.

Nanoplastics and Arsenic Co-Exposures Exacerbate Oncogenic Biomarkers under an In Vitro Long-Term Exposure Scenario.

The increasing accumulation of plastic waste and the widespread presence of its derivatives, micro- and nanoplastics (MNPLs), call for an urgent evaluation of their potential health risks. In the environment, MNPLs coexist with other known hazardous contaminants and, thus, an interesting question arises as to whether MNPLs can act as carriers of such pollutants, modulating their uptake and their harmful effects. In this context, we have examined the interaction and joint effects of two relevant water contaminants: arsenic and polystyrene nanoplastics (PSNPLs), the latter being a model of nanoplastics. Since both agents are persistent pollutants, their potential effects have been evaluated under a chronic exposure scenario and measuring different effect biomarkers involved in the cell transformation process. Mouse embryonic fibroblasts deficient for oxidative DNA damage repair mechanisms, and showing a cell transformation status, were used as a sensitive cell model. Such cells were exposed to PSNPLs, arsenic, and a combination PSNPLs/arsenic for 12 weeks. Interestingly, a physical interaction between both pollutants was demonstrated by using TEM/EDX methodologies. Results also indicate that the continuous co-exposure enhances the DNA damage and the aggressive features of the initially transformed phenotype. Remarkably, co-exposed cells present a higher proportion of spindle-like cells within the population, an increased capacity to grow independently of anchorage, as well as enhanced migrating and invading potential when compared to cells exposed to arsenic or PSNPLs alone. This study highlights the need for further studies exploring the long-term effects of contaminants of emerging concern, such as MNPLs, and the importance of considering the behavior of mixtures as part of the hazard and human risk assessment approaches.

Cost-effectiveness of on-site musculoskeletal ultrasound in an outpatient rheumatology clinic.

OBJECTIVE: To evaluate the impact of the routine use of musculoskeletal ultrasound (MSUS) in rheumatology clinics by comparing one clinic with on-site MSUS (REU 1) and four clinics without this resource, which need to refer patients for the MSUS exams (REU 2-5). METHODS: The electronic medical records of all new patients at five rheumatology clinics during a 12-month period were reviewed. The impact of MSUS was analysed by comparing the percentage of direct discharges of patients from the different clinics, as an outcome of effectiveness, and the number and cost of radiology referrals for imaging exams (MSUS and MRI), as an outcome of cost-saving. RESULTS: The medical records of 4923 patients were included in the study, distributed as follows: REU 1, 1464 (29.7%); REU 2, 1042 (21.2%); REU 3, 1089 (22.1%); REU 4, 579 (11.8%); and REU 5, 749 (15.2%). There were more direct discharges from REU 1 (34.4%) than from REU 2-5 (15.6%) (P<0.001). REU 1 made radiological referrals for X-rays, MRIs or MSUS exams in 773 (52.8%) patients, compared with 2626 (75.9%) patients in REU 2-5 (P<0.001). An estimation of costs for the clinical assessment of 1000 new patients revealed a cost-saving in REU 1 of €21 413 in MSUS and of €877 in MRI exams. CONCLUSION: The implementation of on-site MSUS in a new-patient rheumatology clinic is cost-effective, facilitating the direct discharge of patients and reducing the number and cost of radiological referrals for imaging exams.

Autoimmune biomarkers in porto-sinusoidal vascular disease: Potential role in its diagnosis and pathophysiology.

BACKGROUND AND AIMS: Porto-sinusoidal vascular disease (PSVD) is a rare disease that requires excluding cirrhosis and other causes of portal hypertension for its diagnosis because it lacks a specific diagnostical test. Although it has been occasionally associated with autoimmune diseases, the pathophysiology of PSVD remains unknown. The aim of this study was to evaluate the potential role of autoimmunity in the pathophysiology and diagnosis of PSVD. METHODS: Thirty-seven consecutive patients with PSVD and 39 with cirrhosis matched by gender, signs of portal hypertension and liver function were included (training set). By using Indirect Immunofluorescence, ELISA and slot-blot methods data 22 autoantibodies were identified in patients with PSVD and cirrhosis. Presence of anti-endothelial cells antibodies (AECA) was assayed by a cell-based ELISA. Thirty-one PSVD, 40 cirrhosis patients, 15 patients with splenomegaly associated with haematological disease and 14 healthy donors were included in a validation set. FINDINGS: The proportion of patients with at least one positive antibody was statistically significantly higher in patients with PSVD compared with cirrhosis (92% vs 56%; P < .01). Specifically, AECA were significantly more frequent in PSVD than in cirrhosis (38% vs 15%; P = .013). Results were confirmed in the validation set. In the overall population, presence of AECA had a 63% positive predictive value for diagnosing PSVD and a 71% negative predictive value, with a specificity of 94% when the 1/16 level is used as cut-off. AECA positive serum samples react with a 68-72 kDa protein of human liver endothelial sinusoidal cells.

Effects of hesperidin in orange juice on blood and pulse pressures in mildly hypertensive individuals: a randomized controlled trial (Citrus study).

PURPOSE: To assess the sustained and acute effects, as well as the influence of sustained consumption on the acute effects, of orange juice (OJ) with a natural hesperidin content and hesperidin-enriched OJ (EOJ) on blood (BP) and pulse (PP) pressures in pre- and stage-1 hypertensive individuals. METHODS: In a randomized, parallel, double-blind, placebo-controlled trial, participants (n = 159) received 500 mL/day of control drink, OJ, or EOJ for 12 weeks. Two dose-response studies were performed at baseline and after 12 weeks. RESULTS: A single EOJ dose (500 mL) reduced systolic BP (SBP) and PP, with greater changes after sustained treatment where a decrease in diastolic BP (DBP) also occurred (P < 0.05). SBP and PP decreased in a dose-dependent manner relative to the hesperidin content of the beverages throughout the 12 weeks (P < 0.05). OJ and EOJ decreased homocysteine levels at 12 weeks versus the control drink (P < 0.05). After 12 weeks of EOJ consumption, four genes related to hypertension (PTX3, NLRP3, NPSR1 and NAMPT) were differentially expressed in peripheral blood mononuclear cells (P < 0.05). CONCLUSION: Hesperidin in OJ reduces SBP and PP after sustained consumption, and after a single dose, the chronic consumption of EOJ enhances its postprandial effect. Decreases in systemic and transcriptomic biomarkers were concomitant with BP and PP changes. EOJ could be a useful co-adjuvant tool for BP and PP management in pre- and stage-1 hypertensive individuals.

Synthesis, characterization and biological evaluation of octyltrimethylammonium tetrathiotungstate.

Octyltrimethylammonium tetrathiotungstate salt (ATT-C8) was synthesized and its ability to chelate copper was evaluated. The biological and toxic aspects were evaluated by in vitro and in vivo assays, using bovine aorta endothelial cells (BAEC) and zebrafish (Danio rerio) embryos. The obtained results suggest that ATT-C8 has better biocompatibility, showing a significantly lower lethal concentration 50 (LC50) value in comparison to ammonium tetrathiotungstate (ATT). Zebrafish embryos assay results indicate that both tetrathiotungstate salts at the studied concentrations increase the hatching time. Even more, an in vivo assay showed that synthesized materials behave as copper antagonists and have the ability to inhibit its toxicological effects. Also, both materials were found to be active for the in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The characterization of the materials was carried out using the following spectroscopic techniques: Ultraviolet-Visible (UV-Vis), Fourier Transform Infrared (FTIR) and proton nuclear magnetic resonance (1H-NRM).

Multi-Target Strategy to Uncover Unexpected Compounds in Rinse-Off and Leave-On Cosmetics.

The wide range and complexity of cosmetic formulations currently available on the market poses a challenge from an analytical point of view. In addition, during cosmetics manufacture, impurities coming from raw materials or formed by reaction of different organic compounds present in the formulation may be present. Their identification is mandatory to assure product quality and consumer health. In this work, micro-matrix solid-phase dispersion (µMSPD) is proposed as a multi-target sample preparation strategy to analyze a wide number of unexpected families of compounds including polycyclic aromatic hydrocarbons (PAHs), pesticides, plasticizers, nitrosamines, alkylphenols (APs), and alkylphenol ethoxylates (APEOs). Analytical determination was performed by gas chromatography-mass spectrometry (GC-MS) for the determination of 51 target compounds in a single run, whereas liquid chromatography tandem mass spectrometry (LC-MS/MS) was employed for the analysis of six APs and APEOs. Both methodologies were successfully validated in terms of linearity, accuracy, and precision in leave-on and rinse-off cosmetics. Limits of detection (LODs) were calculated in the low ng g-1, showing their suitability to determine trace levels of impurities and banned compounds with different chemical natures, providing useful tools to cosmetic control laboratories and companies.

Potential adverse health effects of ingested micro- and nanoplastics on humans. Lessons learned from in vivo and in vitro mammalian models.

In recent years, increasing global attention has focused on "microplastics" (MPs) and "nanoplastics" (NPs) resulting in many studies on the effects of these compounds on ecological and environmental aspects. These tiny particles (<5000 µm), predominantly derived from the degradation of plastics, pollute the marine and terrestrial ecosystems with the ability to enter into the food chain. In this manner, human consumption of food contaminated with MPs or NPs is unavoidable, but the related consequences remain to be determined. The aim of this review is to complement previous reviews on this topic by providing new studies related to exposure, absorption, and toxicity in mammalian in vivo and in vitro systems. With respect to novel information, gaps and limitations hindering attainment of firm conclusions as well as preparation of a reliable risk assessment are identified. Subsequently, recommendations for in vivo and in vitro testing methods are presented in order to perform further relevant and targeted research studies.

Interactions of polystyrene nanoplastics with in vitro models of the human intestinal barrier.

The universal presence of micro-nanoplastics (MNPLs) and its relative unknown effects on human health is a concern demanding reliable data to evaluate their safety. As ingestion is one of the main exposure routes for humans, we have assessed their hazard using two in vitro models that simulate the human intestinal barrier and its associated lymphoid system. Two different coculture models (differentiated Caco-2/HT29 intestinal cells and Caco-2/HT29 + Raji-B cells) were exposed to polystyrene nanoparticles (PSNPs) for 24 h. Endpoints such as viability, membrane integrity, NPS localization and translocation, ROS induction, and genotoxic damage were evaluated to have a comprehensive view of their potentially harmful effects. No significant cytotoxic effects were observed in any of the analyzed systems. In addition, no adverse effects were detected in the integrity or in the permeability of the barrier model. Nevertheless, confocal microscopy analysis showed that MNPLs were highly uptaken by both of the barrier model systems, and that translocation across the membrane occurred. Thus, MNPLs were detected into Raji-B cells, placed in the basolateral compartment of the insert. The internalization followed a dose-dependent pattern, as assessed by flow cytometry. Nonetheless, no genotoxic or oxidative DNA damage induction was detected in either case. Finally, no variations in the transcription of oxidative and stress genes could be detected in any of the in vitro barrier models. Our results show that MNPLs can enter and cross the epithelial barrier of the digestive system, as demonstrated when Raji-B cells were included in the model, but without exerting apparent hazardous effects.

Gastrointestinal bleeding due to a primary aortoenteric fistula.

We present the case of a 80 years-old male patient who underwent a CT angiogram due to hematemesis and hypovolemic shock. An upper gastrointestinal endoscopy revealed a large clot that closed the antrum and abundant red blood in the pyloric-antrum region. Sclerosis was performed blindly and the bleeding origin was not identified and the success of the sclerosis could not be evaluated. A primary aorta-duodenal fistula was observed by CT angiography, which was treated with an endograft and femoro-femoral bypass. The patient was discharged 14 days after admission.

Protein translation associated to PERK arm is a new target for regulation of metainflammation: A connection with hepatocyte cholesterol.

Endoplasmic reticulum stress is a cellular phenomenon that has been associated with metabolic disorders, contributing to the development of obesity, fatty liver disease, and dyslipidemias. Under metabolic overload conditions, in cells with a high protein-secretory activity, such as hepatocytes and Langerhans ß cells, the unfolded protein response (UPR) is critical in to maintain protein homeostasis (proteostasis). UPR integrated by a tripartite signaling system, through activating transcription factor 6, protein kinase R-like endoplasmic reticulum kinase (PERK), and inositol-requiring enzyme 1, regulates gene transcription and translation to resolve stress and conserve proteostasis. In the current study, we demonstrated in hepatocytes under metabolic overload by saturated palmitic and stearic fatty acids, through activation of PERK signaling and CCAAT-enhancer-binding protein homologous protein (CHOP) transcription factor, an association with the expression of cyclooxygenase 2. More important, isolated exosomes from supernatants of macrophages exposed to lipopolysaccharides can also induce a metainflammation phenomenon, and when treated on hepatocytes, induced a rearrangement in cholesterol metabolism through sterol regulatory element-binding protein 2 (SREBP2), low-density lipoprotein receptor (LDLR), apolipoprotein A-I, and ABCA1. Moreover, we demonstrate the cellular effect of terpene-derived molecules, such as cryptotanshinone, isolated of plant Salvia brandegeei, regulating metainflammatory conditions through PERK pathway in both hepatocytes and ß cells. Our data suggest the presence of a modulatory mechanism on specific protein translation process. This effect could be mediated by eukaryotic initiation factor-4A, evaluating salubrinal as a control molecule. Likewise, the protective mechanisms of unsaturated fatty acids, such as oleic and palmitoleic acid were confirmed. Therefore, modulation of metainflammation suggests a new target through PERK signaling in cells with a high secretory activity, and possibly the regulation of cholesterol in hepatocytes is promoted via exosomes.

Receptor-ligand and parasite protein-protein interactions in Plasmodium vivax: Analysing rhoptry neck proteins 2 and 4.

Elucidating receptor-ligand and protein-protein interactions represents an attractive alternative for designing effective Plasmodium vivax control methods. This article describes the ability of P. vivax rhoptry neck proteins 2 and 4 (RON2 and RON4) to bind to human reticulocytes. Biochemical and cellular studies have shown that two PvRON2- and PvRON4-derived conserved regions specifically interact with protein receptors on reticulocytes marked by the CD71 surface transferrin receptor. Mapping each protein fragment's binding region led to defining the specific participation of two 20 amino acid-long regions selectively competing for PvRON2 and PvRON4 binding to reticulocytes. Binary interactions between PvRON2 (ligand) and other parasite proteins, such as PvRON4, PvRON5, and apical membrane antigen 1 (AMA1), were evaluated and characterised by surface plasmon resonance. The results revealed that both PvRON2 cysteine-rich regions strongly interact with PvAMA1 Domains II and III (equilibrium constants in the nanomolar range) and at a lower extent with the complete PvAMA1 ectodomain and Domains I and II. These results strongly support that these proteins participate in P. vivax's complex invasion process, thus providing new pertinent targets for blocking P. vivax merozoites' specific entry to their target cells.

Safer-by-design flame-sprayed silicon dioxide nanoparticles: the role of silanol content on ROS generation, surface activity and cytotoxicity.

BACKGROUND: Amorphous silica nanoparticles (SiO2 NPs) have been regarded as relatively benign nanomaterials, however, this widely held opinion has been questioned in recent years by several reports on in vitro and in vivo toxicity. Surface chemistry, more specifically the surface silanol content, has been identified as an important toxicity modulator for SiO2 NPs. Here, quantitative relationships between the silanol content on SiO2 NPs, free radical generation and toxicity have been identified, with the purpose of synthesizing safer-by-design fumed silica nanoparticles. RESULTS: Consistent and statistically significant trends were seen between the total silanol content, cell membrane damage, and cell viability, but not with intracellular reactive oxygen species (ROS), in the macrophages RAW264.7. SiO2 NPs with lower total silanol content exhibited larger adverse cellular effects. The SAEC epithelial cell line did not show any sign of toxicity by any of the nanoparticles. Free radical generation and surface reactivity of these nanoparticles were also influenced by the temperature of combustion and total silanol content. CONCLUSION: Surface silanol content plays an important role in cellular toxicity and surface reactivity, although it might not be the sole factor influencing fumed silica NP toxicity. It was demonstrated that synthesis conditions for SiO2 NPs influence the type and quantity of free radicals, oxidative stress, nanoparticle interaction with the biological milieu they come in contact with, and determine the specific mechanisms of toxicity. We demonstrate here that it is possible to produce much less toxic fumed silicas by modulating the synthesis conditions.

Successful aging in Spanish older adults: the role of psychosocial resources.

ABSTRACTBackground:Psychological and social resources such as extraversion, optimism, social support, or social networks contribute to adaptation and to successful aging. Building on assumptions derived from successful aging and from the developmental adaptation models, this study aims to analyze the joint impact of different psychosocial resources, such as personality, social relations, health, and socio-demographic characteristics on life satisfaction in a group of people aged 65 years-old and older from Spain. METHOD: A cross-sectional survey using non-proportional quota sampling was carried out. The sample comprised 406 community-dwelling older adults (M = 74.88, SD = 6.75). In order to collect the data, face-to-face interviews were individually conducted. A structural equation model (SEM) was carried out using the PLS software. RESULTS: The results of the SEM model showed that, within this sample, psychosocial variables explain 47.4% of the variance in life satisfaction. Social relations and personality, specifically optimism, were strongly related with life satisfaction, while health status and socio-demographic characteristics were modestly associated with life satisfaction. CONCLUSIONS: Findings support the view that psychosocial resources are important for successful aging and therefore should be included in successful aging models. Furthermore, interventions aimed at fostering successful aging should take into account the role of psychosocial variables.

Extreme cosmetics and borderline products: an analytical-based survey of European regulation compliance.

The cosmetic industry currently focuses on products with magnified or exaggerated effects or extremely long-lasting characteristics. There are also a number of related commercial products for which the regulatory framework is far from clear; they are called 'borderline', and the European authorities only recommend which regulations they need to comply with. In any case, all these products must be safe under reasonable conditions of use in accordance with the applicable laws in force in the European Union (EU) framework. In this context, adequate analytical methodology is needed to evaluate the degree of compliance. Ultrasound Assisted Extraction (UAE) procedures for the analysis of 70 cosmetic ingredients have therefore been developed in this work. Moreover, for cosmetics with plastic applicators, a Supported-UAE (Sup-UAE) method was also opportunely optimized to check if a partial transfer of plasticizers to the cosmetics-and thereby to the consumers-could happen. In a survey of 50 commercial products (30 'extreme' and 20 'borderline'), the methods afforded mean recoveries of about 100% and RSD values lower than 5% for UAE and 10% for Sup-UAE, and with detection limits far below the legal requirements, for all the target compounds, thereby demonstrating their analytical suitability. Results are discussed in detail for phthalates, fragrances (musks and allergens) and some frequent preservatives. Additionally, a labelling study was performed to check if the consumer is correctly and fully informed. Graphical abstract ᅟ.

Extroversion, social support and life satisfaction in old age: a mediation model.

OBJECTIVES: The aim of this study was twofold: on the one hand to analyze whether extroversion predicts social support in older people, and on the other hand to determine if different types of social support mediate the effect that extroversion has on older people's life satisfaction. METHOD: The sample comprised 406 community-dwelling older adults (M = 74.88, SD = 6.75) from urban areas of Granada, southern Spain. RESULTS: Extroversion was positively correlated with emotional (r = .23) and with affectionate support (r = .30). Extroversion and all types of social support also positively correlated with life satisfaction. The multiple mediation analysis revealed that when age, gender, marital status and loneliness were controlled, extroversion predicted emotional (B = .008, p < .01) and affectionate support (B = .015, p < .01) and emotional and affectionate support mediated the association between extroversion and life satisfaction (total effect: B = .034, SE = .0024, p < .001, r2 = .295). Results from this study highlight the fact supportive social relations are crucial for older people's life satisfaction. Also emotional and affectionate support constitutes important explanatory mechanisms of the indirect effect of extroversion on life satisfaction. CONCLUSION: Personality traits should be considered when interventions aimed at promoting life satisfaction in old age and successful aging are designed.

Coping strategies in Spanish older adults: a MIMIC model of socio-demographic characteristics and activity level.

OBJECTIVES: The aim of this study was to analyze the combined effect of socio-demographic characteristics and activity level on coping strategies and to test which of these variables has a greater impact on coping. METHOD: A sample of 243 men and women aged 55-99 years old was selected from different elderly activity centers in Granada, Spain, using a convenience sampling. Associations between eight coping strategies measured by Coping Strategies Inventory and the above mentioned variables were examined using a Multiple Indicator and Multiple Causes model. RESULTS: Age was negatively related with problem solving, express emotions and social support. Activity level was positively related with problem solving, cognitive restructuring, express emotions and social support and it was negatively associated with social withdrawal. Gender only predicted the scores in self-criticism and living alone was related with higher emotional expression. Participation in creative activities, attending University for the third age and practicing physical exercise were related with differences in the use of several coping strategies. CONCLUSIONS: There is a complex relationship between socio-demographic characteristics, activity level and the coping strategies used by the elderly. It is important to understand this relationship in order to identify older adults who use ineffective coping, and to subsequently include them in intervention programs to improve their coping abilities.

Development of high throughput, high precision synthesis platforms and characterization methodologies for toxicological studies of nanocellulose.

Cellulose is one of the most abundant natural polymers, is readily available, biodegradable, and inexpensive. Recently, interest is growing around nanoscale cellulose due to the sustainability of these materials, the novel properties, and the overall low environmental impact. The rapid expansion of nanocellulose uses in various applications makes the study of the toxicological properties of these materials of great importance to public health regulators. However, most of the current toxicological studies are highly conflicting, inconclusive, and contradictory. The major reasons for these discrepancies are the lack of standardized methods to produce industry-relevant reference nanocellulose and relevant characterization that will expand beyond the traditional cellulose characterization for applications. In order to address these issues, industry-relevant synthesis platforms were developed to produce nanocellulose of controlled properties that can be used as reference materials in toxicological studies. Herein, two types of nanocellulose were synthesized, cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) using the friction grinding platform and an acid hydrolysis approach respectively. The nanocellulose structures were characterized extensively regarding their physicochemical properties, including testing for endotoxins and bacteria contamination.

Perceived health status and life satisfaction in old age, and the moderating role of social support.

OBJECTIVES: The aim of this study was on one hand to examine the associations between health impairment and life satisfaction, as well as social support and life satisfaction, and on the other, to analyze the moderating effect of social support with regard to health impairment and life satisfaction in a sample of community-dwelling older adults from urban areas of Granada, southern Spain. METHOD: This was a cross-sectional survey in which a sample of 406 older adults with ages between 65 and 99 years old (Mage = 74.88, SD = 6.75) was selected. Multiple stepwise regression analysis was used to assess the impact of health impairment and perceived social support on life satisfaction. Moderation analysis was performed using the bias-corrected and accelerated bootstrapping approach. RESULTS: Significant differences in life satisfaction scores were found by number and type of disease, restrictions in daily life activities and subjective health. Perceived health and perceived social support predicted life satisfaction. Besides global social support, emotional and affectionate support moderated the link between perceived health and life satisfaction. CONCLUSIONS: Older people who do not rate their health status positively and indicate low levels of social support have a higher risk of being dissatisfied with their lives and due to this they should receive special attention from gerontologists.

Multi-walled carbon nanotubes (NM401) induce ROS-mediated HPRT mutations in Chinese hamster lung fibroblasts.

Although there is an important set of data showing potential genotoxic effects of nanomaterials (NMs) at the DNA (comet assay) and chromosome (micronucleus test) levels, few studies have been conducted to analyze their potential mutagenic effects at gene level. We have determined the ability of multi-walled carbon nanotubes (MWCNT, NM401), to induce mutations in the HPRT gene in Chinese hamster lung (V79) fibroblasts. NM401, characterized in the EU NanoGenotox project, were further studied within the EU Framework Programme Seven (FP7) project NANoREG. From the proliferation assay data we selected a dose-range of 0.12 to 12µg/cm(2) At these range we have been able to observe significant cellular uptake of MWCNT by using transmission electron microscopy (TEM), as well as a concentration-dependent induction of intracellular reactive oxygen species. In addition, a clear concentration-dependent increase in the induction of HPRT mutations was also observed. Data support a potential genotoxic/ carcinogenic risk associated with MWCNT exposure.