Mobility of crocidolite asbestos in sandy porous media mimicking aquifer systems.

Asbestos is widely recognized as being a carcinogen when dispersed in air, but very little is known about its exposure pathways in water and its subsequent effects on human health. Several studies have proved asbestos presence in groundwater but failed to assess its mobility in aquifer systems. This paper aims to fill this gap by studying the transport of crocidolite, an amphibole asbestos, through sandy porous media mimicking different aquifer systems. To this purpose, two sets of column test were performed varying the crocidolite suspension concentration, the quartz sand grain size distribution, and the physicochemical water parameters (i.e., pH). The results proved that crocidolite is mobile in quartz sand due to the repulsive interactions between fibres and porous media. The concentration of fibres at the outlet of the column were found to decrease when decreasing the grain size distribution of the porous medium, with a bigger impact on highly concentrated suspensions. In particular, 5-to-10-µm-long fibres were able to flow through all the tested sands while fibres longer than 10 µm were mobile only through the coarser medium. These results confirm that groundwater migration should be considered a potential exposure pathway while implementing human health risk assessment.

From field analysis to nanostructural investigation: A multidisciplinary approach to describe natural occurrence of asbestos in view of hazard assessment.

The environmental impact of natural occurrences of asbestos (NOA) and asbestos-like minerals is a growing concern for environmental protection agencies. The lack of shared sampling and analytical procedures hinders effectively addressing this issue. To investigate the hazard posed by NOA, a multidisciplinary approach that encompasses geology, mineralogy, chemistry, and toxicology is proposed and demonstrated here, on a natural occurrence of antigorite from a site in Varenna Valley, Italy. Antigorite is, together with chrysotile asbestos, one of the serpentine polymorphs and its toxicological profile is still under debate. We described field and petrographic analyses required to sample a vein and to evaluate the NOA-hazard. A combination of standardized mechanical stress and automated morphometrical analyses on milled samples allowed to quantify the asbestos-like morphology. The low congruent solubility in acidic simulated body fluid, together with the toxicity-relevant surface reactivity due to iron speciation, signalled a bio-activity similar or even greater to that of chrysotile. Structural information on the genetic mechanism of antigorite asbestos-like fibres in nature were provided. Overall, the NOA site was reported to contain veins of asbestos-like antigorite and should be regarded as source of potentially toxic fibres during hazard assessment procedure.

Waterborne asbestos: Good practices for surface waters analyses.

Asbestos occurrence has been mainly monitored in air so far and only limitedly considered in other matrices, such as water. Waterborne asbestos could originate from natural or anthropogenic sources, leading to non-conventional exposure scenarios. It could be a secondary source of airborne asbestos in case of water-to-air migration, particularly in case of surface moving water, such as in rivers and streams. The scarce attention dedicated to waterborne asbestos has led to a considerable fragmentation in regulatory approaches regarding the study of water samples possibly contaminated by mineral fibres. In this context, this study has been designed to test the reliability of an existing analytical method devoted to natural waters investigations. Following the operational protocol issued by the Piedmont (Italy) Environmental Protection Agency, Scanning Electron Microscopy analyses have been performed on a standard sample of waterborne chrysotile, mimicking stream water. The investigations have been performed by different operators and using different analytical setups, to verify whether the method applied has a good interlaboratory reproducibility and which could be the most error-prone analytical steps. Three data sets have been obtained on the same sample, showing a low reproducibility among each other. Possible reasons causing this discrepancy have been discussed in detail and good practices to perform reliable analyses on surface water samples containing asbestos have been proposed to help the regulatory organs to better define analytical protocols.

Asbestos burden in lungs of non-occupationally exposed women from Broni (Pavia, Italy): a postmortem SEM-EDS study.

Background: In Italy the incidence of malignant mesothelioma (MM) among women is remarkably high, due to the several contexts in which women had been exposed to asbestos. However, very few studies in literature focus on the inorganic lung content in women. The aim of this retrospective, observational study is to investigate the asbestos lung burden, in terms of concentration, dimensions and type of asbestos, in 42 women who died from MM and had been non-occupationally exposed to asbestos during the activity of the asbestos-cement plant located in Broni (Pavia, Northern Italy) where mainly chrysotile, crocidolite and amosite were used. Methods: Lung samples taken during forensic autopsies have been digested using sodium hypochlorite and filtered through a cellulose-ester membrane. The filter was examined using a scanning electron microscope and the chemical composition of the fibers was analyzed using an electron dispersive spectroscopy. The number of detected inorganic fibers, asbestos fibers and asbestos bodies (ABs) were normalized to 1 gram of dry tissue. Results: In six samples no asbestos has been detected. Overall, the most represented kind of asbestos was amosite, followed by crocidolite, tremolite/actinolite asbestos and chrysotile. The concentration of all inorganic fibers was significantly higher in women with environmental and household exposures compared with those with only environmental exposure (P=0.025), as well as the concentration of asbestos fibers (P=0.019) and ABs (P=0.049). We found a significant correlation between the concentration of asbestos fibers and the duration of exposure (rho =0.413, P=0.008), as well as with the latency of MM (rho =0.427, P=0.005). The distance of the residential address from the factory and the time spent daily in contact with asbestos did not influence the lung asbestos burden. Conclusions: These results suggest the relevance of the lung clearance of asbestos, regarding mainly chrysotile. As a consequence, although scanning electron microscopy -energy dispersive X-ray spectroscopy (SEM-EDS) is considered the most reliable tool for assessing previous exposure to asbestos, its results should be interpreted with caution, especially in a legal context. In addition, our data confirm the relevance of environmental and household exposure in determining asbestos concentration in lungs and highlight the importance of household exposure.

Asbestos and Other Hazardous Fibrous Minerals: Potential Exposure Pathways and Associated Health Risks.

There are six elongate mineral particles (EMPs) corresponding to specific dimensional and morphological criteria, known as asbestos. Responsible for health issues including asbestosis, and malignant mesothelioma, asbestos has been well researched. Despite this, significant exposure continues to occur throughout the world, potentially affecting 125 million people in the workplace and causing thousands of deaths annually from exposure in homes. However, there are other EMPS, such as fibrous/asbestiform erionite, that are classified as carcinogens and have been linked to cancers in areas where it has been incorporated into local building materials or released into the environment through earthmoving activities. Erionite is a more potent carcinogen than asbestos but as it is seldom used for commercial purposes, exposure pathways have been less well studied. Despite the apparent similarities between asbestos and fibrous erionite, their health risks and exposure pathways are quite different. This article examines the hazards presented by EMPs with a particular focus on fibrous erionite. It includes a discussion of the global locations of erionite and similar hazardous minerals, a comparison of the multiple exposure pathways for asbestos and fibrous erionite, a brief discussion of the confusing nomenclature associated with EMPs, and considerations of increasing global mesothelioma cases.

Chrysotile asbestos migration in air from contaminated water: An experimental simulation.

In Naturally Occurring Asbestos (NOA) rich areas, water flows through asbestos bearing rocks and soils and generates waterborne fibres that may migrate in air and become a risk for humans. Research on the migration and dispersion after water vaporisation has been so far only marginally evaluated. This study investigates the migration in air of asbestos from a set of suspensions contaminated by chrysotile from Balangero (Italy), under controlled laboratory conditions. We evaluated i) the morphological modifications that might occur to chrysotile during migration from water to air, and ii) the amount of airborne chrysotile mobilised from standardised suspensions. Morphological alteration of asbestos fibres occurred during water-air migration and impacted on the analytical response of electron microscopy. Waterborne asbestos concentration higher than 40 ∙ 106 f/L generates in air concentration higher than 1 fibre per litre [f/L], the alarm threshold limit set by World Health Organization for airborne asbestos. A possible correlation between the waterborne fibre concentration as mass or number of fibres per volume unit [µg/L or f/L] was observed.

Evaluation of Deposition and Clearance of Asbestos (Detected by SEM-EDS) in Lungs of Deceased Subjects Environmentally and/or Occupationally Exposed in Broni (Pavia, Northern Italy).

Biodurability is one of the main determinants of asbestos hazardousness for human health. Very little is known about the actual persistence of asbestos in lungs and its clearance, nor about differences in this regard between the different mineralogical types of asbestos. The aim of the present study was to evaluate the amount, the dimensional characteristics and the mineralogic kinds of asbestos in lungs (measured using SEM-EDS) of a series of 72 deceased subjects who were certainly exposed to asbestos (mainly crocidolite and chrysotile) during their life. Moreover, we investigated possible correlations between the lung burden of asbestos (in general and considering each asbestos type), as well as their dimension (length, width, and l/w ratio) and the duration of exposure, the latency- in case of malignant mesothelioma (MM), the survival and the time since the end of exposure. In 62.5% of subjects, asbestos burden in lungs was lower that the threshold considered demonstrative for occupational exposure. In 29.1% of cases no asbestos was found. Chrysotile was practically not detected. The mean length of asbestos fibers and the length to width ratio were significantly related to the duration of exposure to asbestos. No other statistically significant correlations were found between the amount and dimensional characteristics of asbestos (nor with the relative amount of each asbestos type) and the other chronological variables considered. In conclusion, it was pointed out that chrysotile can be completely removed from human lungs in <8 years and, instead, amphiboles persist much more time. The present results suggest, as well, that the finding of no asbestos in lungs cannot rule out the attribution of MM to asbestos (in particular, chrysotile) inhaled in an occupational setting. This point is of crucial importance from a legal point of view.

Reply to Mirabelli et al. Is Mesothelioma Unrelated to the Lung Asbestos Burden? Comment on "Visonà et al. Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples. Int. J. Environ. Res. Public Health 2021, 18, 2053".

We appreciate very much the interest of Mirabelli et al. [...].

Asbestos bodies count and morphometry in bulk lung tissue samples by non-invasive X-ray micro-tomography.

The number of the Asbestos Bodies (AB), i.e. asbestos that developed an iron-protein coating during its permanence in biological tissues, is one of the most accessible markers of asbestos exposure in individuals. The approaches developed to perform AB count in biological tissues are based on the manual examination of tissue digests or histological sections by means of light or electron microscopies. Although these approaches are well established and relatively accessible, manual examination is time-consuming and can be reader-dependent. Besides, approximations are applied because of the limitations of 2D readings and to speed up manual counts. In addition, sample preparation using tissue digests require an amount of tissue that can only be obtained by invasive surgery or post-mortem sampling. In this paper, we propose a new approach to AB counting based on non-destructive 3D imaging, which has the potential to overcome most of the limitations of conventional approaches. This method allows automating the AB count and determining their morphometry distribution in bulk tissue samples (ideally non-invasive needle biopsies), with minimal sample preparation and avoiding approximations. Although the results are promising, additional testing on a larger number of AB-containing biological samples would be required to fully validate the method.

Chemo-physical properties of asbestos bodies in human lung tissues studied at the nano-scale by non-invasive, label free x-ray imaging and spectroscopic techniques.

In the lungs, asbestos develops an Fe-rich coating (Asbestos Body, AB) that becomes the actual interface between the foreign fibers and the host organism. Conventional approaches to study ABs require an invasive sample preparation that can alter them. In this work, a novel combination of x-ray tomography and spectroscopy allowed studying unaltered lung tissue samples with chrysotile and crocidolite asbestos. The thickness and mass density maps of the ABs obtained by x-ray tomography were used to derive a truly quantitative elemental analysis from scanning x-ray fluorescence spectroscopy data. The average mass density of the ABs is compatible with that of highly loaded ferritin, or hemosiderin. The composition of all ABs analyzed was similar, with only minor differences in the relative elemental fractions. Silicon concentration decreased in the core-to-rim direction, indicating a possible partial dissolution of the inner fiber. The Fe content in the ABs was higher than that possibly contained in chrysotile and crocidolite. This finding opens two opposite scenarios, the first with Fe coming from the fiber bulk and concentrating on the surface as long as the fiber dissolves, the second where the Fe that takes part to the formation of the AB originates from the host organism Fe-pool.

Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples.

Increased mortality due to malignant mesothelioma has been demonstrated by several epidemiologic studies in the area around Broni (a small town in Lombardy, northern Italy), where a factory producing asbestos cement was active between 1932 and 1993. Until now, the inorganic fiber burden in lungs has not been investigated in this population. The aim of this study is to assess the lung fiber burden in 72 individuals with previous occupational and/or anthropogenic environmental exposure to asbestos during the activity of an important asbestos cement factory. Inorganic fiber lung burden was assessed in autoptic samples taken from individuals deceased from asbestos-related diseases using a scanning electron microscope equipped with an energy-dispersive spectrometer. Significant differences in the detected amount of asbestos were pointed out among the three types of exposure. In most lung samples taken from patients who died of mesothelioma, very little asbestos (or, in some cases, no fibers) was found. Such subjects showed a significantly lower median amount of asbestos as compared to asbestosis. Almost no chrysotile was detected in the examined samples. Overall, crocidolite was the most represented asbestos, followed by amosite, tremolite/actinolite asbestos, and anthophyllite asbestos. There were significant differences in the amount of crocidolite and amosite fibers according to the kind of exposure. Overall, these findings provide novel insights into the link between asbestos exposure and mesothelioma, as well as the different impacts of the various types of asbestos on human health in relation to their different biopersistences in the lung microenvironment.

Malignant peritoneal mesothelioma in a boar who lived in Calabria (Italy): Wild animal as sentinel system of human health.

Mesothelioma is a tumor of the serosal membranes described both in human and veterinary medicine. While in humans the relationship between mesothelioma and exposure to asbestos and some other asbestiform minerals is well known, in animals it is still difficult to establish. In this paper a case of malignant peritoneal mesothelioma probably related to asbestos exposure in a wild boar is described. At post-mortem evaluation the peritoneum, diaphragm and serosal surface of liver and kidneys showed isolated to coalescent multiple nodular lesions. Samples from diaphragm, liver and lung were collected to perform microbiological and histological investigations. To assess the presence of asbestos and/or other asbestiform minerals, SEM-EDS investigations were performed on organs and soil samples collected from the area where the wild boar lived. Microbiological investigations were negative for Mycobacterium species. Gross and histological examination were compatible with a biphasic mesothelioma, with nodules composed of epithelioid and sarcomatoid elements with high pleomorphism. Immunohistochemistry revealed only multifocal scattered positivity for WT-1 and D2-40. Asbestos fibres were detected in all samples (organs and soil) by SEM-EDS, demonstrating a potential relationship between the neoplasia and the exposure to naturally occurring asbestos (NOA). In conclusion, the results of the present study are further confirmation that wild animals, such as the boar, are suitable sentinels to indicate the risk of environmental exposure to asbestos for human populations.

Asbestos fibre burden in gallbladder: A case study.

The methods conventionally used to determine the burden of asbestos fibres inhaled/incorporated in lung require chemical digestion of the biological matrix before counting/characterising the inorganic fibrous phases under scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS). Asbestos fibres can also be present in extra-pulmonary organs, and we set out to quantify the fibres in gallbladder. Although the standardised procedure requires approximately 5 × 10-1 g of wet tissue, this amount of tissue is not always available. We applied the procedure on about 9 × 10-4 g of gallbladder from a patient with known environmental and workplace exposure to asbestos. The patient died of malignant pleural mesothelioma and was also affected by severe bile-tract problems. The traditional procedure of digesting tissue samples in NaClO and filtering the resulting suspension was carried out. The filter was then examined under SEM/EDS using two methods 1. following the standardised procedure to assess the fibre burden in lung by investigating only 2 mm2 of the filter (660 microscopic fields), and 2. analysing all the microscopic fields in one-quarter of the filter (about 82 mm2). In parallel, histological sections (prepared in the usual way for medical diagnosis) were analysed without digestion or manipulation of the sample using variable pressure SEM/EDS. The fibre counts obtained using the two methods were of the same order of magnitude, i.e., ∼105 fibres/g of wet tissue. We showed that the counting of fibres in human tissue may be successfully carried out even when a limited amount of tissue is available. We also found that, when exposure to asbestos is considerable, the number of asbestos fibres accumulating in the gallbladder may be significant.

New insights on the biomineralisation process developing in human lungs around inhaled asbestos fibres.

Once penetrated into the lungs of exposed people, asbestos induces an in vivo biomineralisation process that leads to the formation of a ferruginous coating embedding the fibres. The ensemble of the fibre and the coating is referred to as asbestos body and is believed to be responsible for the high toxicological outcome of asbestos. Lung tissue of two individuals subjected to prolonged occupational exposure to crocidolite asbestos was investigated using synchrotron radiation micro-probe tools. The distribution of K and of elements heavier than Fe (Zn, Cu, As, and Ba) in the asbestos bodies was observed for the first time. Elemental quantification, also reported for the first time, confirmed that the coating is highly enriched in Fe (~20% w/w), and x-ray absorption spectroscopy indicated that Fe is in the 3+ oxidation state and that it is present in the form of ferritin or hemosiderin. Comparison of the results obtained studying the asbestos bodies upon removing the biological tissue by chemical digestion and those embedded in histological sections, allowed unambiguously distinguishing the composition of the asbestos bodies, and understanding to what extent the digestion procedure altered their chemical composition. A speculative model is proposed to explain the observed distribution of Fe.

Trace elements in hazardous mineral fibres.

Both occupational and environmental exposure to asbestos-mineral fibres can be associated with lung diseases. The pathogenic effects are related to the dimension, biopersistence and chemical composition of the fibres. In addition to the major mineral elements, mineral fibres contain trace elements and their content may play a role in fibre toxicity. To shed light on the role of trace elements in asbestos carcinogenesis, knowledge on their concentration in asbestos-mineral fibres is mandatory. It is possible that trace elements play a synergetic factor in the pathogenesis of diseases caused by the inhalation of mineral fibres. In this paper, the concentration levels of trace elements from three chrysotile samples, four amphibole asbestos samples (UICC amosite, UICC anthophyllite, UICC crocidolite and tremolite) and fibrous erionite from Jersey, Nevada (USA) were determined using inductively coupled plasma mass spectrometry (ICP-MS). For all samples, the following trace elements were measured: Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Sb, Cs, Ba, La, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U. Their distribution in the various mineral species is thoroughly discussed. The obtained results indicate that the amount of trace metals such as Mn, Cr, Co, Ni, Cu and Zn is higher in anthophyllite and chrysotile samples, whereas the amount of rare earth elements (REE) is higher in erionite and tremolite samples. The results of this work can be useful to the pathologists and biochemists who use asbestos minerals and fibrous erionite in-vitro studies as positive cyto- and geno-toxic standard references.

Diagnosis of Asbestos-Related Diseases: The Mineralogist and Pathologist's Role in Medicolegal Field.

Because asbestos diseases represent a complex pattern of legal, social, and political issue, the involvement of the mineralogist and pathologist for a multidisciplinary assessment of its diagnosis helps investigate the relationship between mesothelioma or lung cancer and occupational or environmental asbestos exposure.In the present study, we consider the concentrations of asbestos bodies (ABs) detected by optical microscopy (OM) and scanning electron microscopy (SEM) and the burden of different kinds of mineral fibers (among which is asbestos) identified by SEM combined with an energy dispersive spectrometer (EDS), in 10 lung tissue samples of subjects with occupational and nonoccupational exposure to asbestos.In all subjects with occupational exposure to asbestos, more than 1000 ABs per gram of dry weight were detected both with OM and SEM; this concentration is internationally accepted as suggesting high probability of past occupational exposure to asbestos.In 9 lung samples of the 10 investigated by SEM-EDS different inorganic fibers were found. Asbestos fibers have been identified too, and more than 100,000 fibers per gram of dry weight were detected in subjects with occupational exposure; this concentration is internationally accepted as suggesting high probability of past occupational exposure to asbestos.Instead, when the ABs burden is low or moderate (such as in subjects with absent or probable asbestos exposure), the correlation between ABs concentration determined by OM and those determined by SEM is lost. Therefore, when the ABs value in OM is borderline, the SEM investigation became essential. Furthermore, the mineralogical analysis by SEM-EDS (identification and quantification of inorganic fibers in general and asbestos in particular) of the fibers detected in the lung tissues is very useful, if not necessary, to complete the pathological diagnosis of asbestos-related malignancies in medicolegal field.

Urinary asbestos fibers and inorganic particles in past asbestos workers.

To assess the validity of the procedure as a test of asbestos exposure, we compared urinary asbestos fibers with occupational and environmental exposure data in a random sample of 48 subjects with high past asbestos exposure. Occupational and environmental exposure was estimated on questionnaire, pleural plaques were diagnosed with computed tomography, and inorganic fibers and particles were identified by scanning electron microscope with an energy-dispersive spectrometry. Few urinary asbestos fibers (in 15% of workers and 17% of cases with pleural plaques) and high amount of urinary silicate (particularly nonfibrous particles) were detected. Asbestos undergoes dissolution in lung tissues, but the secondary minerals are largely unknown. These materials, possibly nonfibrous silicates or metals, could be excreted with urine. Therefore, another study including a control group is warranted to discriminate the occupational origin of minerals in the urine.

The wild rat as sentinel animal in the environmental risk assessment of asbestos pollution: a pilot study.

Asbestos has been banned in many countries, including Italy. However, sources of exposure may still exist, due to asbestos in-situ or past disposal of asbestos-containing waste. In an urban area with past high environmental exposure, like Casale Monferrato, the lung fiber burden in sentinel animals may be useful to identify such sources. A pilot study was conducted to assess the feasibility of its determination in wild rats, a suitable sentinel species never used before for environmental lung asbestos fiber burden studies. Within the framework of pest control campaigns, 11 adult animals from 3 sites in the urban area of Casale Monferrato and 3 control rats from a different, unexposed town were captured. Further, 3 positive and 3 negative control lung samples were obtained from laboratories involved in breeding programs and conducting experimental studies on rats. Tissue fiber concentration was measured by scanning electron microscopy with energy dispersive spectrometry. Asbestos (chrysotile and crocidolite) was identified in the lungs from rats from Casale Monferrato, but not in control rats and in negative control lung samples. Asbestos grunerite at high concentration was found in positive control lung samples. Measurement of the lung fiber burden in wild rats has proved feasible: it was possible not only to detect, but also to characterize asbestos fibers both qualitatively and quantitatively. The pilot study provides the rationale for using wild rats as sentinels of the soil contamination level in Casale Monferrato, to identify areas with the possible presence of previously unrecognized asbestos sources.

Post-occupational health surveillance of asbestos workers.

BACKGROUND: Italian law requires an extensive health surveillance of workers after cessation of their employment status in the case of occupational exposure to carcinogens, including asbestos. Nonetheless, Italian law does not specify the timeframe of these clinical checks, nor who has financial and organizational responsibility for this surveillance. A literature search confirmed a lack of consensus around the objectives and methods to follow up workers with past occupational exposure to asbestos. OBJECTIVES: To develop an updated evidence-based methodology for an appropriate health surveillance programme. METHODS: We present an overview of the field experience developed by the Veneto Region from 2000 to 2011, and new studies that could contribute to establishing a national policy for the medical surveillance of workers with past asbestos exposure. RESULTS: There were three specific topics: (1) definition of a reliable method to identify asbestos workers (through multiple sources and procedures that meet current confidentiality regulations); (2) detection of asbestos fibres in biological media (to support the etiological diagnosis of asbestos-related diseases); (3) creation of a national protocol of health surveillance (through the assessment of policies developed by other Regions in this field, and recruiting from these regions a cohort of past-exposed workers: the epidemiological study should offer relevant suggestions for specific surveillance approaches, based on either estimated cumulative asbestos exposure or detection of x-ray patterns of pleural plaques and/or asbestosis). CONCLUSIONS: These studies will support the Regions in setting up health care policies directed at workers with past asbestos exposure.

Cytotoxicity induced by exposure to natural and synthetic tremolite asbestos: an in vitro pilot study.

Mineral fibers are potential carcinogens to humans. In order to help clarify the etiology of the pathological effects of asbestos, cellular reactions to natural and synthetic asbestos fibers were compared using a lung alveolar cancer cell line (A549 epithelial cells), considered the first target of inhaled micro-environmental contaminants. Natural asbestos tremolite (NAT) fibers were collected from rocks in NW Italy. Synthetic asbestos tremolite (SAT) was iron-free and therefore considered as standard tremolite. Both fibers, subjected to mineralogical characterization by X-ray powder diffractometry, electron microscopy and energy dispersive spectrometry, fell within the definition of respirable and potentially carcinogenic fibers. Several signs of functional and structural cell damage were found after treatment with both fibers, documented by viability, motility, and morphological perturbations. Phalloidin labeling showed irregular distribution of cytoskeletal F-actin, whereas immunohistochemical investigations showed abnormal expression of VEGF, Cdc42, ß-catenin, assessed as risks indicators for cancer development. Both fibers caused significant loss of viability, even compared to UICC crocidolite, but, while SAT fibers exerted a more direct cytotoxic effect, survival of damaged cells expressing high VEGF levels was detected after NAT contact. This in vitro pilot study outlines potential health risks of NAT fibers in vivo related to their iron content, which could trigger signaling networks connected with cell proliferation and neoplastic transformation.