Chemical and structural characterization of UICC amosite fibres from Penge mine (South Africa)

In the present work we report the full structural and spectroscopic characterization of an UICC amosite (fibrous gnmerite) standard sample from Penge mine (South Africa). The chemical composition was obtained by SEM-EDS and cation site partition was retrieved by complementing chemical, Mossbauer and X-ray powder diffraction data. Cell parameters, fractional coordinates, and site scattering for M(1), M(2), M(3), M(4) were refined using the Rietveld method. The retrieved crystal chemical formula (A)[Na-0.02](Sigma 0.02)(B)(Fe1.542+Mn0.29Na0.10Ca0.07)Sigma(C)(2.00)(Fe2.922+Mg1.93Fe0.153+)(Sigma 5.00)(T)(Si7.93Al0.07)(Sigma 8.00) O-22.00 (W)(OH2.00)(Sigma 2.00) is in reasonable agreement with reference data.Rietveld refinement results evidenced that Fe2+ is allocated in the octahedral layer following the site preferencesM(1)approximate to M(3)>M(2), whereas Mg preferentially is ordered at M(2). Refined cell parameters are: a=9.55264(17) angstrom, b=18.3069(3) angstrom, c=5.33487(8) angstrom, beta= 101 .840(3)degrees, V=913.11(3) angstrom(3). Quantitative Phase Analysis indicates about 10 wt.% of accessory phases including quartz, ankerite and minor stilpnomelane and biotite/annite. Obtained results are the basis for further studies aimed at investigating possible correlation between physico-chemical features of the fibres and their chemical reactivity and toxicity

Modelling the Fenton reaction of amphibole asbestos

In this work a sample of UICC crocidolite and a sample of fibrous tremolite were leached up to 1 week both in a simplified Gamble’s solution at acidic pH and in a phosphate buffered medium at neutral pH, in presence of H2O2. Surface chemical modifications were monitored by XPS spectroscopy. Subsequently, the generation of HO• radicals following reaction of both pristine and leached fibres with H2O2 (Fenton reaction) was investigated by spin trapping/EPR spectroscopy, with the aim of better clarifying the relationships between possible surface alteration occurring in vivo and chemical reactivity of amphibole asbestos. Moreover, the generation of HO• radicals was monitored on thermally treated fibres after leaching in phosphate buffered medium at neutral pH and in presence of H2O2 to investigate how chemical reactivity may be modulated by Fe oxidation state. Results showed that, for both amphibole asbestos, the surface alteration following incubation in the modified Gamble’s solution does not alter HO• radical generation. Interestingly, leaching in phosphate buffered solution in presence of H2O2 induced a progressive increase in HO• release for crocidolite fibres, whereas a strong reduction was observed for asbestos tremolite. This behaviour is likely due to the quicker alteration of the crocidolite surface due to the interaction with H2O2, as indicated by XPS analysis. In particular, the oxidation induced by H2O2 promotes the dissolution of the first atomic layer of the crocidolite structure and the following occurrence on its surface of new reactive Fe centres, particularly under the form of Fe(II), of which the bulk is richer than the oxidized surface. Accordingly, the heated samples showed a reduced, but not suppressed by thermal oxidation, chemical reactivity, with no significant evolution following incubation in phosphate buffered medium at neutral pH and in presence of H2O2

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 asbestoslike 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

Case report: Early-onset osteoporosis in a patient carrying a novel heterozygous variant of the WNT1 gene

Article presents a case study of a 35 year-old Caucasian woman who experienced multiple vertebral fractures two months after her second pregnancy. The results suggest a potential role of heterozygous WNT1 variants in the pathogenesis of early-onset osteoporosis. The authors suggest that teriparatide is one of the most appropriate available therapies for such cases

Biosolubility of high temperature insulation wools in simulated lung fluids

Abstract 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

Quantification of Tremolite in Friable Material Coming from Calabrian Ophiolitic Deposits by Infrared Spectroscopy

The aim of this study is to identify the infrared absorption band suitable for quantifying tremolite in three powdered samples (fine, medium, and large size classes) coming from a quarry of ophiolitic friable rocks in the western part of the Calabria region of Italy. Three IR bands were considered: OH stretching band between 3700 and 3650 cm−1, the stretching bands of the Si-O-Si linkage between 1200 and 900 cm−1, and the absorbance band at 756 cm−1 attributable to tremolite. The amount of tremolite in the test samples was quantified by using the curve parameters of the three analytical bands. The quantitative analysis of tremolite using the band due to OH stretchings (3700–3650 cm−1) and the bands attributed to the Si-O-Si stretchings (1200–900 cm−1) showed high values for all test samples. Their use overestimated the tremolite amount because both bands were affected at the interfering mineral silicates such as talc, kaolinite, chlorite, and serpentinites. The abundant presence of antigorite in studied samples mainly in medium size class sample had a key role in our findings. The band at 756 cm−1 was not affected at the interfering minerals and can be used for quantitative analysis of tremolite in sample coming from ophiolitic deposits

Airborne Asbestos Fiber Concentration in Buildings: Surveys Carried Out in Latium (Central Italy)

In Italy, use and production of asbestos and asbestos-containing materials (ACMs) were banned in 1992, however, the risk of exposure to asbestos still exists, because most ACMs are located in industrial and public buildings. A total of 111 Italian buildings with friable and non-friable ACMs were surveyed; 500 air samples were collected in the areas where contamination might have occurred. Airborne asbestos fiber concentration calculated from air samples was averaged for each building. Statistical analysis of the data showed no significant differences between the mean concentration measured in buildings with friable and non-friable ACMs (p = 0.258). The concentration values were below 2 f/L, the value stated by Italian regulation to ensure that the area is safe to reoccupy after asbestos removal. Samples of settled dust were also collected. The presence of asbestos fibers in the dust showed the occurrence of a release of asbestos from the material. Although the airborne asbestos fiber concentrations measured were low, current Italian regulation requires an asbestos management program. The Public Institution to which the authors of this work belong encourages asbestos removal as the preferred abatement method, in line with the asbestos-free future approach proposed by the European Commission

Airborne Asbestos Fiber Concentration in Buildings: Surveys Carried Out in Latium (Central Italy)

In Italy, use and production of asbestos and asbestos-containing materials (ACMs) were banned in 1992, however, the risk of exposure to asbestos still exists, because most ACMs are located in industrial and public buildings. A total of 111 Italian buildings with friable and non-friable ACMs were surveyed; 500 air samples were collected in the areas where contamination might have occurred. Airborne asbestos fiber concentration calculated from air samples was averaged for each building. Statistical analysis of the data showed no significant differences between the mean concentration measured in buildings with friable and non-friable ACMs (p = 0.258). The concentration values were below 2 f/L, the value stated by Italian regulation to ensure that the area is safe to reoccupy after asbestos removal. Samples of settled dust were also collected. The presence of asbestos fibers in the dust showed the occurrence of a release of asbestos from the material. Although the airborne asbestos fiber concentrations measured were low, current Italian regulation requires an asbestos management program. The Public Institution to which the authors of this work belong encourages asbestos removal as the preferred abatement method, in line with the asbestos-free future approach proposed by the European Commission