Man-made Vitreous Fibers Research Articles

Initial evaluation of USP apparatus 4 for measuring dissolution profile of man-made vitreous fibers

We report the successful evaluation of a US Pharmacopeia Apparatus 4 (USP-4) system in measuring the dissolution profiles of man-made vitreous fibers (MMVF)11Man-made vitreous fibers (MMVF) is the terminology commonly used in the European Union to refer to mineral wool fibers, it is also the terminology used in the classification entries for these materials in Regulation (EC) No 1272/2008 classification, labelling and packaging of substances and mixtures as the term synthetic vitreous fibers (SVF) is also used in literature and other jurisdictions to refer to mineral wool fibers.. Glass and stone wool fibers with different (high- and low-) solubility profiles were tested in closed-loop configuration using a sodium/potassium phosphate buffer solution or an acetate buffer, respectively. Results confirm a need to operate in diluted conditions to avoid silicon saturation in the simulant solution and suppression of fiber dissolution. A clear fiber-to-fiber differentiation with good cell-to-cell reproducibility was achieved. These findings support the continued development of a USP-4 protocol for MMVF in vitro acellular testing.

Exposure to MMVF in residential and commercial buildings: A literature review and quantitative synthesis.

Man-made vitreous fibers (MMVF) are a class of inorganic fibrous materials that include glass and mineral wools, continuous glass filaments, and refractory ceramic fibers valued for their insulative properties in high temperature applications. Potential health effects from occupational exposure to MMVF have been investigated since the 1970s, with focus on incidence of respiratory tract cancer among MMVF-exposed production workers. The general population may experience exposure to MMVF in residential and/or commercial buildings due to deterioration, construction, or other disruption of materials containing these fibers. Numerous studies have characterized potential exposures that may occur during material disruption or installation; however, fewer have aimed to measure background MMVF concentrations in residential and commercial spaces (i.e., non-production settings) to which the general population may be exposed. In this study, we reviewed and synthesized peer-reviewed studies that evaluated respirable MMVF exposure levels in non-production, indoor environments. Among studies that analyzed airborne respirable MMVF concentrations, 110-fold and 1.5-fold differences in estimated concentrations were observed for those studies utilizing phase contrast optical microscopy (PCOM) versus transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. A positive correlation was observed between respirable air concentrations of MMVF and total surface concentrations of MMVF in seldom-cleaned areas. Ultimately, available evidence suggests that both ambient air and surface concentrations of MMVF in indoor environments are consistently lower than exposure limits developed to prevent negative health outcomes among sensitive populations.

Assessment of screening mineral wool waste from market by using handheld X‐ray fluorescence

AbstractStone wool from construction, renovation, demolition and horticultural applications is reclaimed for reuse and recycling. Variation of chemical composition of reclaimed material creates a challenge, especially with increasing quantities from construction and demolition sectors. Therefore, an assessment of handheld/portable X‐ray fluorescence (XRF) spectrometer was carried out with the objective to quickly discriminate various type of man‐made vitreous fibres (MMVF). The evaluation concerned mainly light element analysis. Therefore, the effect of disturbing factors, such as moisture, organic matter, surface roughness and sample density were evaluated. Direct measurement on mineral wool product or granulate gives a precision of ±1.5% for Al2O3 and ±2.1% for SiO2 after calibration. Precision is enhanced by preparing pressed pellets, resulting in precision down to ±0.9% for Al2O3 and ±1.5% for SiO2 after correction. Provided correctly calibrated, handheld XRF analysis gives a quick indication, though not necessarily conclusive, whether the reclaimed material applies to so called “old wool,” manufactured prior to the EU legislation requiring increased bio‐solubility. A quick indication is very relevant for the renovation and demolition sector and subsequent re‐use or recycling of mineral wool because it affects transport and handling requirements. In case the analysis is not obviously discriminative, desktop analysis is still required. Presence of moisture and organic matter influence the detection of lighter elements, which especially affects analysis of horticultural recycling substrate granulate.

Recycling the Product of Thermal Inertization of Man-Made Vitreous Fibres for the Manufacture of Stoneware Tiles

Recycling the Product of Thermal Inertization of Man-Made Vitreous Fibres for the Manufacture of Stoneware Tiles

Transport and deposition of inhaled man‐made vitreous and asbestos fibers in realistic human respiratory tract models: An in silico study

AbstractParticles longer than 5 μm and with a length/diameter ratio >3 are defined as fibers. Asbestos or other fibers are still identified in residential environments due to the emission from asbestos‐used building materials. The respiratory system is the primary route of asbestos exposure; under a longer residence time, asbestos‐related adverse health effects are inevitable. Currently, asbestos fibers have been replaced with man‐made vitreous fibers (MMVFs); however, studies have revealed some similar biological effects of MMVFs with asbestos. Therefore, MMVFs‐induced diseases need to be determined by analyzing their deposition characteristics and foci in human respiratory tracts. In this study, we used computational fluid dynamics method to investigate fibers' airflow and deposition patterns in two realistic human respiratory models. Two drag models were used to predict the deposition of uniform 1 μm (asbestos) and 3.66 μm (carbon fiber‐CF) diameter, 15–300 μm long fibers. Two drag models provided comparable results with the experimental data. Comparatively, asbestos deposition was independent of fiber length, while CF deposition increased proportionally to fiber length. The highest level of local deposition was detected in the anterior nasal cavity. The results obtained from this study can extend current knowledge of human vitreous fiber exposure‐related lung diseases.

Critical Choices in Predicting Stone Wool Biodurability: Lysosomal Fluid Compositions and Binder Effects.

The hazard potential, including carcinogenicity, of inhaled man-made vitreous fibers (MMVFs) is correlated with their biodurability in the lung, as prerequisite for biopersistence. Abiotic dissolution testing serves to predict biodurability. We re-analyzed the International Agency for Research on Cancer Monograph on MMVFs and found that the correlation between in vivo biopersistence and abiotic dissolution presented therein confounded different simulant fluids and further confounded evaluation of leaching vs structural elements. These are critical choices for abiotic dissolution testing, as are binder removal and the rate of the flow that removes ions during testing. Therefore, we experimentally demonstrated how fluid composition and binder affect abiotic dissolution of a representative stone wool MMVF. We compared six simulant fluids (all pH 4.5, reflecting the environment of alveolar macrophage lysosomes) that differed in organic acids, which have a critical role in their ability to modulate the formation of Si-rich gels on the fiber surfaces. Removing the binder accelerates the average dissolution rate by +104% (max. + 273%) across the fluids by suppression of gel formation. Apart from the high-citrate fluid that predicted a 10-fold faster dissolution than is observed in vivo, none of the five other fluids resulted in dissolution rates above 400 ng/cm2/h, the limit associated with the exoneration from classification for carcinogenicity in the literature. These findings were confirmed with and without binder. For corroboration, five more stone wool MMVFs were assessed with and without binder in one specific fluid. Again, the presence of the binder caused gel formation and reduced dissolution rates. To enhance the reliability and robustness of abiotic predictions of biodurability, we recommend replacing the critically influential citric acid in pH 4.5 fluids with other organic acids. Also, future studies should consider structural transformations of the fibers, including changes in fiber length, fiber composition, and reprecipitation of gel layers.

Which fraction of stone wool fibre surface remains uncoated by binder? A detailed analysis by time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy.

Biodurability of man-made vitreous fibres (MMVF) is often measured on naked fibres, i.e. fibres devoid of the phenol-urea-formaldehyde (PUF) binder that is sprayed and baked on the commercial product to reduce dustiness and to provide mechanical strength to fibre mats. This simplification of the hazard assessment relies on the assumption that the binder would not actually coat the entire fibre surface, but would occur only at the touching points where two fibres are glued together. We challenged this assumption by using surface analysis by X-ray photoelectron spectroscopy (XPS) and Time-of-Flight Secondary Ion mass spectrometry (ToF-SIMS). We analysed commercial stone wool MMVF sourced from Denmark, United Kingdom and Germany. XPS as well as ToF-SIMS-mapping combined with gas-cluster-ion-sputtering revealed that all mineral fibres investigated show a complete layer of organics over the surface of the fibres with only a few defects: before sputtering, organic components (PUF binder and oils) uniformly cover the spatial structures; only after sputtering, the inorganic components of the stone wool emerge on the visible surfaces. A preferential localisation of PUF binder on fibre-to-fibre touching points or as droplets was not observable. We finally explored the correlation to dissolution rates, but found that total PUF binder content and the experimentally determined thickness of the PUF binder layer are not sufficient to predict dissolution rates, which instead must consider chemical composition and other properties. In summary, none of the investigated stone wool fibre surfaces were uncoated by the PUF binder.

Computational modeling of fiber transport in human respiratory airways—A review

Investigations on the respiratory transport and deposition of airborne asbestos, man-made vitreous fibers (MMVFs), and carbon nanofiber/carbon nanotubes have been actively conducted in the past few decades. The elongated particles’ distinctive needle-like geometry has been identified as the main cause of extreme carcinogenicity when compared to inhaled spherical particles. Consequently, uncovering the intrinsic relationship between the particle’s unique elongated shape and its transport characteristics in human respiratory systems is crucial for understanding fiber inhalation toxicity. Currently, such information can only be provided by computational modeling. This review summarized the current state of the art of computational modeling of fiber transport in the human respiratory tract. The needed future researches were also discussed.

MINERAL WOOL WASTE IN AUSTRIA, ASSOCIATED HEALTH ASPECTS AND RECYCLING OPTIONS

Mineral wool products are man-made vitreous fibres that are used as thermal and acoustic insulation materials and as substrates for horticulture. Mineral wool waste is generated from demolition activities by the building and construction industry. Unfavourable mechanical properties, such as low compressibility, elastic behaviour, high volume and low bulk density, cause problems in landfills when mineral wool waste is disposed of. Mineral wool waste with a certain content of carcinogenic fibres is classified as hazardous waste type 31437 g “Asbestos Waste, Asbestos Dust” in Austria, since some characteristics of such fibres are similar to those of asbestos fibres. An exception is those mineral wool materials that have been tested to be noncarcinogenic due to their characteristics of biological solubility or geometrical dimension. Such noncarcinogenic mineral wool waste is classified as non-hazardous waste type 31416 “Mineral fibres”. Generally, it can be assumed that most of the industrial producers of mineral wool in the EU have not been producing carcinogenic material since 1998; however, carcinogenic mineral wool material has not yet been banned in Austria. Therefore, a segregation between so-called “old” and “new” mineral wool material is not necessarily possible. The medical aspects of mineral wool products are still controversial. The International Agency for Research on Cancer (IARC) evaluated mineral wool (glass wool and rock wool) as “possibly carcinogenic” in 1988 but revised this evaluation to “inadequate evidence in humans for the carcinogenicity” in 2002. Fibrous dusts that reach the alveolar region of the lungs undergo a congruent or incongruent chemical dissolution process. Alveolar macrophages ingest the intruded fibres and fulfil anti-infection and clearance functions. Biosolubility is a key property of this process. The recycling of mineral wool waste has not yet been performed in Austria due to economic inefficiency, technical problems and suspected health issues. However, some recycling and processing options already exist; other options are investigated in the project RecyMin, which compares different concepts with respect to environmental and economic criteria.

Fireproof Material Derived from Recycling Incinerator Ash Using Electric-Arc Technique

In this study, municipal solid waste incinerator (MSWI) ashes were melted by electric-arc technique to produce man-made vitreous fiber (MMVF) using a fiber blowing method. The capacity of 50 kg/h at the pilot level was constructed to treat MSWI ashes and produce MMVF simultaneously. The fibrous derivatives were blended with cement to manufacture fireproof product. The MMVF produced in this work belong to short fiber which the characteristics are presented as follow: (1) fiber diameter range from 5.1 ± 1.2 μm; (2) shot content 6.3±0.8 wt.%; (3) fibrous length ranged from 0.3–3.5 cm. When the amount of MMVF added is at 43 wt.% in fireproof product, the density, porosity, fracture loading and flexural strength are 0.8 g/cm3, 66%, 42 kgf and 98.4 kgf/cm2, respectively. After a series of fireproof test, the fire resistant product had good performance on flammability and incombustibility characteristics. The fireproof product is stable and has satisfactory physical, mechanical and thermal properties.

Filter Cassette Method for Analyzing Man-Made Vitreous Fibers Settled on Surfaces.

A new method was developed to analyze the surface count of fibers in a variety of environments. The method entails sampling surfaces with the help of suction to a filter cassette holder containing a cellulose filter. The filters were collapsed using microwave digestion in dilute acid, and the fibers filtered to polycarbonate filters, gilded, and analyzed by scanning electron microscopy (SEM). The method was compared to traditional gel tape sampling as described in International Standards Organization (ISO) standard 16000-27, following analysis with phase contrast microscopy. The methods were compared in industrial environments and in office-type environments, with the concentration range studied spanning from 0.1 to 100,000 fibers/cm2. The methods yielded similar results (p < 0.05) in concentrations from 100 to 10,000 cfu/cm2, while the filter cassette method gave systematically higher results in high concentrations (>10,000 cfu/cm2) as well as in all office-type environments studied, where the fiber count ranged from 0.1 to 20 fibers/cm2. Consequently, we recommend using the new method in working environments where the surface count is more than 100 fibers/cm2, as well as in office-type environments where the fiber count is below 10 fibers/cm2. It should be noted, however, that a similar limit of quantitation as with the gel tape method (0.1 fibers/cm2) requires sampling a minimum area of 100 × 100 cm2 with the fiber cassette method. Using the filter cassette method will require new guide values to be formed for office-type environments, since the results are higher than with the gel tape method. Alternatively, if present guide values or limit values are to be used with the filter cassette method, conventions as to which fiber sizes to count should be set, since SEM analysis in any case will allow for including a larger size range than phase contrast microscopy (PM). We, however, recommend against such an approach, since fibers less than 1 µm in width may not be less harmful by inhalation than larger fibers.

Reutilization of Leftovers from Agro-Industries for Textile Applications: A Mini Report

In the present scenario, environmental anxieties and human heath are the two major factors concentrated in many engineering sectors. Man-made vitreous fibers and its usage in many diverse applications are exhibiting better properties on one face, whereas on the other turn it sparks a lot of harmful situations to the atmosphere and people involved. Moreover, nowadays due to enactment of governmental laws, extraction of green raw materials and development of green products for many applications without disturbing the nature are under progress. Plant based fibers used in the textile engineering are being extracted by the harvesting of flora, which in turn increases the deforestation and also diminishes the safety factor of the earth in near future. Meanwhile, the animal based fibers being used in the textile engineering are extracted after the slaughter of faunas, which again leads to destruction of living beings in huge amount. In addition the existing fibers used in textile engineering are of very high cost and not economically viable. However, huge amount of agro wastes with potential fiber contents are being discarded from many industries are to be explored to meet the increasing demand for natural raw materials as well as it can solve the above critical issues in the collection of raw material for textile processing industries.

Characterization of industrial discarded fruit wastes ( Tamarindus Indica L.) as potential alternate for man-made vitreous fiber in polymer composites

Abstract Environmental degradation and its effects on human health due to unprecedented use of synthetic fibers, have been heavily felt by the fabricating workers and by the common people in general. The search to develop high-performance materials using environmental friendly natural fibers, is to be encouraged and needs comprehensive characterization. In this paper, discarded and polluting agro waste from food processing industry, known as Tamarind Fruit Fiber (TFF) is tested for its potentiality as a reinforcement in polymer composite. The extracted fibers are subjected to anatomical, physical, mechanical, morphological, thermal and chemical examination. The low density (1.27 g/cm3) provides high strength (1137–1360 MPa), better thermal stability (238 °C) and superior bonding characteristics revealed by standard investigations promotes TFF as a promising natural fiber reinforcement for many composite applications. Low cost and competent performance can be achieved with this natural fiber when reinforced in polymer matrix.

Comprehensive characterization of industrially discarded fruit fiber, Tamarindus indica L. as a potential eco-friendly bio-reinforcement for polymer composite

Utilizing industrially discarded bio-waste as a bio-reinforcement for polymer composite is one way to find alternate solution for harmful, conventional man-made vitreous fibers. In this work, one such agro waste, tamarind fruit fiber is tested comprehensively for its potentiality as a reinforcement in unsaturated polyester matrix to optimize the mechanical properties. 40 wt% fiber content provides optimum properties, while further addition of fiber reduces the strength due to ineffective bonding between the fiber and the matrix. This is revealed in the microscopic images of the fractured tensile specimens. The experimental results are verified and correlated with the Hirsch's and Series models and found that Hirsch's model agrees well with the experimental results. Thermal stability and aquatic properties are ascertained by the degradation temperature and the water absorption characteristics in fresh and sea water. The diffusion coefficient is found to follow pseudo-fickian behavior. Comprehensive analysis of this material confirms its applicability for light weight automotive and marine applications.

Causes and Pathophysiology of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) results from the neoplastic transformation of pleural mesothelial cells. Asbestos exposure is a major risk factor for MPM, but epidemiologic studies demonstrated the occurrence of MPM in populations exposed to other fibers, and an excess of MPM in populations occupationally exposed to man-made vitreous fibers and previously to asbestos. The development of nanotechnologies also raises some concern about the potential health effects of new particles of high aspect ration, such as carbon nanotubes. Toxicological studies investigated the mechanism of asbestos-induced transformation of mesothelial cells, and molecular analyses defined the genomic and physiopathological changes in MPM. These findings allowed identifying some key events accounting for the neoplastic process. This article summarizes the known and suspected causes of MPM, the cellular events and responses of mesothelial cells to asbestos fibers and the alterations of key genes and regulatory pathways involved in the pathological mechanism.

Cytotoxicity, oxidative stress and genotoxicity induced by glass fibers on human alveolar epithelial cell line A549

Man-made vitreous fibers have been widely used as insulation material as asbestos substitutes; however their morphology and composition raises concerns. In 1988 the International Agency for Research on Cancer classified fiberglass, rock wool, slag wool, and ceramic fibers as Group 2B, i.e. possibly carcinogenic to humans. In 2002 it reassigned fiberglass, rock and slag wool, and continuous glass filaments to Group 3, not classifiable as carcinogenic to humans. The aim of this study was to verify the cytotoxic and genotoxic effects and oxidative stress production induced by in vitro exposure of human alveolar epithelial cells A549 to glass fibers with a predominant diameter <3μm (97%) and length >5μm (93%). A549 cells were incubated with 5, 50, or 100μg/ml (2.1, 21, and 42μg/cm2, respectively) of glass fibers for 72h. Cytotoxicity and DNA damage were tested by the MTT and the Comet assay, respectively. Oxidative stress was determined by measuring inducible nitric oxide synthase (iNOS) expression by Western blotting, production of nitric oxide (NO) with Griess reagent, and concentration of reactive oxygen species by fluorescent quantitative analysis with 2′,7′-dichlorofluorescein-diacetate (DCFH-DA). The results showed that glass fiber exposure significantly reduced cell viability and increased DNA damage and oxidative stress production in a concentration-dependent manner, demonstrating that glass fibers exert cytotoxic and genotoxic effects related to increased oxidative stress on the human alveolar cell line A549.

Do insulation products of man-made vitreous fibres still cause skin discomfort?

BackgroundMan-made vitreous fibres (MMVFs) are used in products for insulation and as reinforcement in materials. Contamination of the skin may arise through direct or indirect contact, and from the deposition of airborne fibres. The scientific basis regarding the effects on skin of MMVFs dates from 1970–1980.ObjectivesTo investigate whether currently used insulation MMVF products still cause skin discomfort.MethodsFocus group interviews and structured interviews were performed among workers engaged in insulation tasks and among do-it-yourself consumers with a recent experience of MMVF products.ResultsA majority of interviewees experienced skin discomfort when handling MMVF products. Complaints caused by traditional (yellow) glass fibre products were more severe than those caused by products of rock or slag wool fibres. The wrists, forearms, neck and face were the locations where the skin was most affected. The situations causing problems varied between occupational tasks, but working with the hands over the head or in narrow spaces were described as the worst situations. Building construction apprentices performed insulation tasks more often than senior workers.ConclusionsMMVF insulation products do still cause skin discomfort. Updated knowledge about people’s experiences of work with such products should influence legislation.

Crystalline silica in heated man-made vitreous fibres: A review

Refractory ceramic fibres (RCF) and alkaline earth silicate (AES) wools are types of man-made vitreous fibre (MMVF) that are used in demanding high-temperature industrial applications, generally above 900°C and up to 1400°C. When exposed to prolonged high temperatures, MMVF can devitrify with the formation of cristobalite and other crystalline silica species, which is of potential concern because crystalline silica (CS) is classified as carcinogenic. This article reviews the chemico-physical processes and morphological consequences of fibre devitrification, the forms and micro-location of CS produced, and the toxicity of devitrified fibres and the CS species formed in this way. It also examines scenarios for worker exposure to the products of fibre devitrification in industries using RCF and/or AES wools. We identify gaps in knowledge and make recommendations for future research.

Characterization of a French series of female cases of mesothelioma

More than 80% of mesothelioma cases in men are attributable to occupational asbestos exposure compared to only 40% in women. The objective of the study was to characterize a series of female pleural mesotheliomas according to known and suspected risk factors. From the exhaustive recording of 318 female mesothelioma cases in the French National Mesothelioma Surveillance Program between 1998 and 2009, multiple correspondence analysis and hybrid clustering were performed to characterize these cases according to expert assessed occupational and non-occupational exposure to asbestos and man-made vitreous fibers, X-ray exposure, and history of cancer and non-malignant respiratory diseases. Four clusters were identified: (1) occupational exposure to asbestos and man-made vitreous fibers (7.9% of subjects); (2) radiation exposure during radiotherapy (12.9%); (3) increased asbestos exposure (19.8%); and (4) "non-exposure" characteristics (59.4%). These results will allow hypotheses to be generated about associations between mesothelioma and non-occupational asbestos exposure, X-ray exposure and history of respiratory disease.

Fiber glass exposure and human respiratory system cancer risk: Lack of evidence persists since 2001 IARC re-evaluation

Objective To determine whether IARC’s 2001 decision to downgrade the classification of insulation glass wool from Group 2B to Group 3 remains valid in light of epidemiological evidence reported after 2001. Methods We performed a systematic review of epidemiological evidence regarding respiratory cancer risks in relation to man-made vitreous fiber (MMVF) exposure before and after the 2001 IARC re-evaluation with focus on glass wool exposure and respiratory system cancer. Results Since 2001, three new community-based, case-control studies, two detailed analyses of existing cohort studies and two reviews/meta-analyses were published. These studies revealed no consistent evidence of an increased respiratory system cancer risk in relation to glass wool exposure. Conclusions From our evaluation of the epidemiological evidence published since 2001, we conclude that IARC’s 2001 decision to downgrade insulation glass wool from Group 2B to Group 3 remains valid.