Dissolution Reaction and Surface Modification of UICC Amosite in Mimicked Gamble's Solution: A Step towards Filling the Gap between Asbestos Toxicity and Its Crystal Chemical Features.

This study focuses on the dissolution process and surface characterization of amosite fibres following interaction with a mimicked Gamble's solution at a pH of 4.5 and T = 37 °C, up to 720 h. To achieve this, a multi-analytical approach was adopted, and the results were compared to those previously obtained on a sample of asbestos tremolite and UICC crocidolite, which were investigated under the same experimental conditions. Combining surface chemical data obtained by XPS with cation release quantified by ICP-OES, an incongruent behaviour of the fibre dissolution was highlighted for amosite fibres, similarly to asbestos tremolite and UICC crocidolite. In particular, a preferential release of Mg and Ca from the amphibole structure was observed, in agreement with their Madelung site energies. Notably, no Fe release from amosite fibres was detected in our experimental conditions (pH of 4.5 and atmospheric pO2), despite the occurrence of Fe(II) at the M(4) site of the amphibole structure, where cations are expected to be rapidly leached out during mineral dissolution. Moreover, the oxidation of both the Fe centres initially present on the fibre surface and those promoted from the bulk, because of the erosion of the outmost layers, was observed. Since biodurability (i.e., the resistance to dissolution) is one of the most important toxicity parameters, the knowledge of the surface alteration of asbestos possibly occurring in vivo may help to understand the mechanisms at the basis of its long-term toxicity.

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.

Toxicological evaluation of polycrystalline wools in human lung cells.

Aim: Polycrystalline wools (PCW) are included with Refractory ceramic fibers (RCF) in the alumino-silicates family of High Temperature Insulation Wools (HTIW). IARC includes PCW in the ceramic fibers group and considers them as possible human carcinogens (GROUP 2B). Since PCW toxicity is not yet clear, our aim was to evaluate their toxic and inflammatory effects and to compare them with the known RCF effects.Method: We exposed human bronchial (BEAS-2B) and alveolar (A549) cells to 2-100 µg/mL (2.4 × 103-1.2 × 105 fibers/mL; 2.51 × 103-1.26 × 105 fibers/cm2 of PCW and 7.4 × 103-3.7 × 105 fibers/mL; 7.75 × 103-3.87 × 105 fibers/cm2 of RCF) of the tested fibers to evaluate potential viability reduction, apoptosis, membrane damage, direct/oxidative DNA-damage, cytokine release.Results: In A549, PCW did not induce cytotoxicity and apoptosis but they induced significant dose-dependent DNA-damage, although lower than RCF; only RCF induced oxidative effects. PCW also induced an increase in IL-6 release at 100 µg/mL (1.2 × 105 fibers/mL; 1.26 × 105 fibers/cm2). In BEAS-2B, PCW did not induce cell-viability reduction RCF induced a dose-dependent cell-viability decrease. Both fibers show a dose-dependent increase of apoptosis. In BEAS-2B, PCW also induced dose-dependent DNA-damage, although lower than RCF, and slight oxidative effects similar to RCF. PCW also induced an increase of IL-6 release; RCF induced a decrease of IL-8. Summarizing, PCW induce direct-oxidative DNA-damage although to a lower extent than RCF observed by both mass-based and fiber number-based analysis.Conclusion: For the first time, the study shows the potential toxicity of PCW, usually considered safe, and suggests to perform further in vitro studies, also on other cell types, to confirm these findings.

Size characteristics of asbestiform fibers in lung tissue of animals that grazed in areas rich in ophiolitic outcrops in Central Calabria (Southern Italy).

In Calabria (Southern Italy) naturally occurring asbestos (NOA) mainly occurs in the ophiolitic sequences cropping in the Mount Reventino area. The most common type of asbestos detected was the amphibole tremolite; fibrous antigorite and minor chrysotile were also found. The development of asbestos-related diseases depends on, among other things, the morphological characteristics of fibers, length and width, affecting the durability of asbestos fibers in the lung. In this work fifteen lung samples of sheep, goats and wild boars, grazing around the Mount Reventino area were collected and asbestos fibers analysed. Observed fibers (357), of which 97 % were tremolite and 3 % antigorite fibers, were grouped according to species, grazing area and age of the animals. The aim of this work was to highlight any differences among the groupings and to compare our size results with data in literature related to exposed populations. Principal Component Analysis (PCA) highlighted a positive correlation between tremolite fiber length and width and revealed groupings in terms of animal age. The Kruskal-Wallis test showed statistically significant differences between fiber mean widths in young and old animals. 63 % observed asbestiform fibers were longer than 5 µm and 7 % of the fibers were longer than 20 µm (critical fiber length connected to the frustrated phagocytosis by the macrophage). Fibers conforming to the Stanton Hypothesis size (predictor of the carcinogenic potency of fibers) were 1 %. Our size parameters of fibers detected in the animal lungs were in fairly good agreement with literature data for human asbestos exposure to tremolite. These results confirmed that an animal-sentinel system could be used to monitor the natural background of the airborne breathable fibers exposure. In addition, the size correlation of animal-human breathed fibers could be useful to study their potential toxicity. Additional data are necessary for improving the agreement with human exposure data.

Asbestos containing materials in schools of Rome and surrounding area (Italy).

Despite Italy banning use and production of asbestos in 1992, it continues to represent a risk to human health due to its permanence in the places where it was located. The aim of this work is to estimate how many schools in Rome (Italy) have asbestos containing materials (ACM), and to assess whether the location, condition and nature of ACM can influence the level of risk for student health. 3,672 schools were contacted and 1,451 participated to asbestos survey. 692 bulk samples were collected and analyzed by optical and electron microscope and Fourier transform infrared spectrometer. About 16% of the surveyed schools had ACM. Most of the ACM were not accessible to students (water tanks, boiler thermal insulations). Asbestos-cement materials and vinyl floor tiles were the most common non-friable materials found in schools and equipment insulation linings and Bunsen burner gauze mats were the friable ACM found in science laboratories. Measures to prevent or reduce asbestos hazards were applied where necessary. This study allowed to develop the awareness of the asbestos health hazard among headteachers and the need to manage these hazards appropriately. It represents the beginning of a larger study leading to ACM national mapping in schools.

Biomonitoring of workers employed in a titanium dioxide production plant: Use of buccal micronucleus cytome assay as noninvasive biomarker to evaluate genotoxic and cytotoxic effects.

We aimed to evaluate whether TiO2 production process induces genotoxic and cytotoxic effects on the first target organ of inhalable particles by a sensitive and noninvasive biomarker of effect. Final aim was to find a useful and suitable tool to assess and manage the risk of TiO2 occupational exposure. We enrolled 40 workers employed in TiO2 production, 5 office workers, and 18 external controls. Buccal micronucleus cytome assay (BMCyt assay) was applied because it allows to evaluate micronucleus (MN), nuclear buds (NB), and broken eggs (BE) indicating the presence of chromosomal instability and gene amplification and binucleated cells (BIN), karyolytic cells (KL), and condensed chromatin (CC) indicating cytokinesis defect or arrest, cell death and apoptosis respectively. We characterized the exposure measuring inhalable and respirable particles by personal monitoring. BMCyt-assay showed in exposed workers compared with external controls a higher value of MN frequency (2.57 vs. 0.05‰, p < .001) and MN positivity, evaluated as percentage of subjects with MN frequency higher than a 1.5‰ cut-off value (52.5 vs. 0%). We also found in exposed workers higher frequency of BE + NB (2.41 vs. 0.22‰, p = .002), BIN (9.45 vs. 8.44‰, p = .047) and CC (1.80 vs. 0.21, p = .001) than in controls. Moreover, we found a relationship between personal monitoring results and presence of MN and other cellular anomalies. This study demonstrates induction of genotoxic and cytotoxic effects on buccal cells of workers involved in TiO2 production, suggesting the suitability of BMCyt assay as tool for risk assessment and management of TiO2 exposure.

Environmental contamination by naturally occurring asbestos (NOA): Analysis of sentinel animal lung tissue.

Ophiolites are known sources of naturally occurring asbestos (NOA). In Calabria (Southern Italy) NOA are mainly concentrated in the ophiolitic sequences cropping in the Mount Reventino area, in the southern part of the Sila massif, and along the Coastal Chain. The most common type of asbestos identified in the rocks of these areas belongs to the tremolite-actinolite series. Another identified asbestiform mineral is fibrous antigorite belonging to the serpentine mineral group with a minor amount of chrysotile. The purpose of the present study is to evaluate the diffusion of natural asbestiform fibers from NOA using sentinel animals. Fifteen lung samples of sheep, goats and wild boars from Mount Reventino area and two from an area free from NOA were collected. The lung samples were subjected to anatomopathological examination and lung fiber burden analysis by electron microscopy. Abundant tremolite and few antigorite fibers were detected in the lung samples coming from the NOA area. No corpuscle of asbestos was observed. No fiber was found in the two lung samples of sheet from the area free from NOA. These concentrations of fibers per gram of dry weight of lung tissue (f/gdw) ranged from 104 to 106 f/gdw. The asbestos fibers detected in the lungs of the examined animals reflect the geological features of the areas where they grazed and lived. The anatomopathological analysis showed that 60% of the examined animals had macroscopic lesions affecting their lungs. The presence of tremolite fibers in the lungs confirms the diffusion of mineral fibers in the environment and the real advantage of using animal populations in the study areas.

Biosolubility of high temperature insulation wools in simulated lung fluids.

OBJECTIVE: Biosolubility is an important parameter in the understanding of mechanisms involved in pulmonary toxicity of fibrous materials. It can be studied in vitro using models of simulated lung fluids and observing the loss of structural molecules, expressed as dissolution constant (Kdis). The aim of this paper was the study of dissolution behaviour of four wools belonging to high temperature insulation wools (HTIW) in saline solutions simulating lung fluids. METHODS: Four HTIW were studied in saline solutions at pH 7.4 (representative of the extracellular environment) and 4.5 (representative of the intracellular conditions): refractory ceramic fibers (RCF), two alkaline earth silicate wools (AES1 and AES2 with high calcium and magnesium content respectively), and polycrystalline wools (PCW). Size, morphological and chemical changes of fibers were observed by scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). RESULTS: RCF, AES2 and PCW did not show statistically significant diameter changes. AES1 size distribution shifted to a larger mean diameter suggesting that through dissolution there was a preferential loss of thin fibers at acid pH after 14 days of treatment.Both AES wools showed selective leaching of alkali/alkali earth oxides (incongruent dissolution) at pH 7.4: a fast and extensive selective leaching of calcium for AES1 with complete dissolution of fibers already after 14 days of treatment and a moderate selective leaching of magnesium for AES2. PCW showed some transversal breakage of the fibers in both pH environments (low congruent dissolution). For RCF, the treatment produced uncorroded fibers in both pH environments without chemical changes and fiber fragmentation (no dissolution).The estimated Kdis at physiological pH followed the sequence: AES1 > AES2 > PCW > RCF. All wools had a low Kdis at acid pH suggesting a low dissolution rate of short fibers. CONCLUSION: The leaching process and transverse fragmentation play an important role in the biopersistence mechanisms and pathogenicity of fibers and the Kdis estimate is undoubtedly useful as a preliminary toxicological screening of fibers, especially for developing fibers.

Alkaline earth silicate (AES) wools: Evaluation of potential cyto-genotoxic and inflammatory effects on human respiratory cells.

Biosoluble AES wools are increasingly used since considered not hazardous, however, few toxicity studies are available. We evaluated cytotoxic, genotoxic-oxidative and inflammatory effects of two differently soluble AES wools, AES1 (high MgO percentage) and AES2 (high CaO percentage), on alveolar (A549) and bronchial (BEAS-2B) cells. Fiber dimensions and dissolution in cell media were evaluated by SEM analysis. Cell viability, LDH release, direct/oxidative DNA damage (fpg-comet assay) and IL-6, IL-8 and TNF-α release (ELISA), were analysed after 24 h exposure to 2-200 µg/ml. On A549 cells AES1 induced LDH release, slight direct DNA damage and oxidative DNA damage with very high IL-6 release at 100 µg/ml; AES2 induced higher DNA damage than AES1 and slight oxidative DNA damage. On BEAS-2B cells we found direct DNA damage (higher for AES1) and slight oxidative DNA damage (associated to slight increased IL-6 and IL-8 release for AES1). The higher genotoxicity of more soluble AES2 on A549 cells could be explained by higher respirable fibers % and fiber number/µg found after 24 h in RPMI-medium at 100 µg/ml. The higher membrane damage, oxidative DNA damage and inflammation induced by AES1 in A549 cells could be due to the higher DLG and silica percentage. These findings suggest further investigations on AES toxicity.

Asbestiform minerals in ophiolitic rocks of Calabria (southern Italy).

Ophiolitic rocks cropping on Calabria territory, southern Italy, can hold asbestiform minerals potentially harmful for human health. The aim of this work was to detect the fibrous phases of ophiolites along the Coastal Chain of northern Calabria and southern part of the Sila massif. Above 220 massive samples were collected in the study areas and analyzed using optical and electron microscopy, X-ray diffractometry, and Fourier transform infra-red spectrometry. The main fibrous constituent belonged to tremolite-actinolite series followed by fibrous antigorite that becomes more abundant in the samples collected in Reventino Mount surroundings. Results highlighted that serpentinites samples mainly consisted of antigorite and minor chrysotile. Samples collected along the coastal chain of northern Calabria did not hold fibrous materials. The results will be useful for Italian natural occurrences of asbestos (NOA) mapping in order to avoid an unintentional exposition by human activity or weathering processes.

Evaluation of performance loss of paraffin oil loaded filtering facepieces.

Penetration measurements through commercially available filtering facepieces were performed with monodisperse DEHS aerosols ranging from 0.03 µm to 0.40 µm (either singly charged or neutralized), before and after 500 mg of paraffin oil loading. The distinct behavior of Coulomb and polarization capture efficiency is studied: as in the case of non loading also in the case of loading 500 mg of paraffin oil, the electrostatic capture mechanisms are mainly due to the Coulomb contribution up to aerosol particle diameter of about 0.10 µm, just when the polarization contribution becomes substantial. Both Coulomb and polarization capture mechanisms are influenced by the presence of 500 mg of paraffin oil, resulting less effective than the oil unloaded case of about 12% and 11%, respectively. By the occupational hygiene point of view, there is a degradation in the filter performance due to oil loading that the user does not realize because there is no remarkable variation in the breathing resistance.

Field comparison of two inhalable samplers used in Italy to measure the wood dust exposure.

BACKGROUND: Particle size affects the performance of personal air samplers used to measure dust exposure in the workplace. Few field studies have been conducted for comparing the performance of personal inhalable samplers. OBJECTIVE: To compare wood dust sampling with two inhalable samplers: IOM (Institute of Occupational Medicine) and Italian cone. METHODS: 136 Italian cone/IOM paired samples and 136 passive IOM samples were collected in 30 Italian woodworking industries. The valid number of sample pairs was 114. Ultra-large particles were collected by passive IOM. The sampling membranes were weighed and the size particles were measured. Mass differences in active and passive IOM samples were calculated (IOM-Δ). RESULTS: Statistical analysis of all 114 Italian cone/active IOM paired results showed a significant mass difference (P < 0.05) and no significant mass difference for sanding and cutting woodworking processes. The Italian cone/IOM-Δ paired results consistently showed no statistically significant mass differences in any woodworking processes. Both samplers performed similarly when ultra-large particles mass contribution was not considered. CONCLUSIONS: These findings confirm the presence of ultra-large particles in woodworking. The Italian cone and IOM samplers can be used interchangeably for personal wood dust exposure assessment, when the wood activities produce small-size particles.

Dissolution of glass wool, rock wool and alkaline earth silicate wool: morphological and chemical changes in fibers.

The behavior of alkaline earth silicate (AES) wool and of other biosoluble wools in saline solution simulating physiological fluids was compared with that of a traditional wool belonging to synthetic vitreous fibers. Morphological and size changes of fibers were studied by scanning electron microscopy (SEM). The elements extracted from fibers were analyzed by inductively coupled plasma atomic emission spectrometry. SEM analysis showed a larger reduction of length-weighted geometric mean fiber diameter at 4.5 pH than at 7.4 pH. At the 7.4 pH, AES wool showed a higher dissolution rate and a dissolution time less than a few days. Their dissolution was highly non-congruent with rapid leaching of calcium. Unlike rock wool, glass wool dissolved more rapidly at physiological pH than at acid pH. Dissolution of AES and biosoluble rock wool is accompanied by a noticeable change in morphology while by no change for glass wool. Biosoluble rock wool developed a leached surface with porous honeycomb structure. SEM analysis showed the dissolution for glass wool is mainly due to breakage transverse of fiber at pH 7.4. AES dissolution constant (Kdis) was the highest at pH 7.4, while at pH 4.5 only biosoluble rockwool 1 showed a higher Kdis.

A study on the transfer of heavy methals released by Chinese commercial products.

OBJECTIVES: Studies by The World trade Organization (WTO) and the Organization for the Economic Cooperation and Development (OECD) state that the trade on counterfeit goods corresponds to 10% of the global trade and it is worth 450 billion dollars. In this work we studied the transfer of toxic metals released by some Chinese watches causing significant allergic dermatitis. METHODS: Several samples of dust released from metal parts got collected. Such powders were observed at the Electron Microscope complete with EDAX spectrometer. RESULTS: In all the studied dust samples we identified the following chemical elements: Cu, Ni and Zn. The SEM analysis has identified two predominant phases such as pure nickel and brass alloy (Cu-Zn). CONCLUSIONS: The first metal subjected to cession and to corrosion phenomena is nickel. The main causes of corrosion in the studied materials were due to the presence of chloride ions. Among the ceased metals found in our study nickel is the most dangerous. Scientific evidence now agree that nickel and certain nickel compounds are toxic and highly harmful to human health they indeed cause allergic contact dermatitis (DAC).

Angiogenic effect induced by mineral fibres.

Due to the toxic effect of asbestos, other materials with similar chemical-physical characteristics have been introduced to substitute it. We evaluate the angiogenic effect of certain asbestos substitute fibres such as glass fibres (GFs), ceramic fibres (CFs) and wollastonite fibres (WFs) and then compare angiogenic responses to those induced by crocidolite asbestos fibres (AFs). An in vitro model using human endothelial cells in small islands within a culture matrix of fibroblasts (Angio-Kit) was used to evaluate vessel formation. The release of IL-6, sIL-R6, IL-8, VEGF-A and their soluble receptors, sVEGFR-1, sVEGFR-2, was determined in the conditioning medium of Angio-Kit system after fibre treatment. ROS formation and cell viability were evaluated in cultured endothelial cells (HUVEC). To evaluate the involvement of intracellular mechanisms, EGFR signalling, ROS formation and nuclear factor-κB (NFκB) pathway were then inhibited by incubating HUVEC cells with AG1478, NAC and PDTC respectively, and the cytokine and growth factor release was analyzed in the culture medium after 7 days of fibre incubation. Among the mineral fibres tested, WFs markedly induced blood vessel formation which was associated with release of IL-6 and IL-8, VEGF-A and their soluble receptors. ROS production was observed in HUVEC after WFs treatment which was associated with cell cytotoxicity. The EGFR-induced ERK phosphorylation and ROS-mediated NFκB activation were involved in the cytokine and angiogenic factor release. However, only the EGFR activation was able to induce angiogenesis. The WFs are potential angiogenic agents that can induce regenerative cytokine and angiogenic factor production resulting in the formation of new blood vessels.

Risk assessment of the decay of asbestos cement roofs.

OBJECTIVES: In an assessment of the risk of asbestos fibres release from asbestos cement materials, an important role is played by the assessment of the surface corrosion and by the disaggregation of asbestos cement. The aim of this work is to evaluate the differences among several methods used for the risk assessment that lead to a specific choice of abatement techniques. METHODS: The state of deterioration of 40 asbestos cement roofs was evaluated using two priority assessment algorithms elaborated in Italy, the 'pull-up test' described by the Italian Organization for Standardization and the indicators described in the Italian legislation coupled with the observation of a small sample, taken from each roof, by a stereomicroscope. RESULTS: The results obtained with the methods, proposed in this study, for the risk assessment of the decay of asbestos cement roofs show slight differences among them, only one deviates from the others in judgement on the state of conservation of the roof. CONCLUSIONS: It is very important to train the operator conducting the study since a completely subjectivity-free method does not exist. Whatever method is used will always be affected by the subjectivity linked to the competency and the training of the operator. Moreover, each method on its own cannot assess the risk of exposure to asbestos, but reliable assessment of asbestos-containing materials requires the use of more than one method, such as visual inspections, a pull-up test, and an assessment algorithm.

[Mount Reventino greenstone: assessment of tremolite fibre dispersion in the workplace]. / Le pietre verdi del Reventino: valutazione della dispersione di fibre di tremolite nelle attività lavorative.

BACKGROUND: Mount Reventino, a massif located in the Calabria Region of Italy, has several ophiolite outcrops of greenstone. These deposits are an important economical resource in the surrounding area. Some rock layers contain tremolite, a type of asbestos fibre. OBJECTIVES: The aim of this paper was to analyze the chemical and physical structure of the outcrops of Mount Reventino, and to assess and reduce the risk to workers associated with exposure to airborne fibres. METHODS: Personal and environmental samples were collected and analysed by Scanning Electron Microscopy equipped with energy-dispersive X-ray analysis. RESULTS: The analysis of samples showed a difference in mineralogical features not only between the quarries under study, but also between the two opposite sides of the mountain. Exploitation of the quarries produces a fibre dispersion that is higher than the natural emission. Occupational exposure to asbestos fibres during greenstone transformation was confirmed by by the results of analysis of the collected samples. CONCLUSIONS: This study made it possible to identify working activities with highest exposure to asbestos and establish the correct procedures to abate fibre dispersion, in order to reduce the correlated risk. Environmental samples collected in the urban area surrounding the quarries showed that the asbestos fibre concentrations were very low, however, further studies are needed in order to confirm these findings.

Differential in vitro cellular response induced by exposure to synthetic vitreous fibers (SVFs) and asbestos crocidolite fibers.

In this study, we analyzed the effects of synthetic vitreous fibers (SVFs) on a mesothelial (MeT5A) and a fibroblast cell line (NIH3T3), compared to those exerted by crocidolite asbestos fibers. SVFs (glass wool, rock wools) do not induce significant changes in cell mortality, whereas crocidolite asbestos fibers caused a dose-dependent cytotoxicity. We investigated the correlation between the fiber-induced cytotoxicity and the extent and type of interaction of the fibers with the cell surface, and we observed that SVFs, unlike crocidolite asbestos fibers, establish few and weak interactions. Moreover, after internalization, crocidolite asbestos fibers are often found free in the cytoplasm, whereas glass wool fibers are mainly localized inside cytoplasmic vacuoles. After treatments, we also detected signs of oxidative stress, revealed by an increased reactive oxygen species (ROS) production and by an induction of superoxide dismutase (SOD) activity. The lipoperoxidative damage was characterized by a decrease in polyunsaturated fatty acids (PUFA), an increase in the content of thiobarbituric reactive species (TBARS) and a consumption of vitamin E, as a lipophilic antioxidant. Furthermore, we investigated the effect of fiber exposure on cell proliferation. and it was found that, unlike crocidolite asbestos fibers, SVFs did not induce a significant increase in DNA synthesis.

Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line.

The introduction of man-made vitreous fibers (MMVFs) as a substitute for asbestos in industrial and residential applications raises concerns about their potential health hazards. The aim of our study was to assess cytotoxic and oxidative effects induced on a human mesothelial cell line (MeT-5A) by exposure to glass wool (GW), rock wool (RW) and refractory ceramic fibers (RCF) in comparison with crocidolite asbestos (CR). MeT-5A cells were exposed for 24 h to 2, 5 and 10 microg/cm2 of MMVF and crocidolite fibers and analysed by scanning electron microscope (SEM) for cell surface alterations. Cells were exposed for 2 h to 1, 2, 5 and 10 microg/cm2 of the same fibers and analysed by enzyme Fpg-modified comet test for direct and oxidative DNA damage. SEM revealed loss of microvilli in cells exposed to RCF and numerous blebs in cells exposed to higher doses of RW. Comet test showed significant direct DNA damage in cells exposed to RCF even at the lowest dose. Comet test with Fpg, that permits the detection of oxided DNA bases, showed significant oxidative DNA damage in cells exposed to higher doses of RW. The presence of DNA damage and alterations of cell surface induced by low doses of RCF and the presence of oxidative DNA damage and blebs on cell surface in cells exposed to higher dose of RW suggest possible cytotoxic, oxidative and genotoxic effects for these MMVFs.