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1.
Toxicol Appl Pharmacol ; 361: 3-13, 2018 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-30240695

RESUMO

This paper presents a geologic and mineralogical investigation of asbestiform amphibole from blueschist in the Diablo Range, northern California. The analysis of fibers in air samples shows that the dominant blueschist amphibole composition ranges from glaucophane to subordinate winchite. In outcrop, blueschist amphibole exhibits a velvety luster, and its occurrence ranges from crosscutting veins to highly deformed foliated and lineated tectonites. TEM and SEM photographs reveal a highly fibrous habit typically associated with asbestiform amphiboles. Dimensional analysis reveals a mean fiber width of 0.27 µm, and lengths and aspect ratios are shorter than reported for commercially exploitable asbestos, with a mean length of 2.8 µm and mean aspect ratio of 11.5. The data are consistent with other research showing that the width population of fibers, and not length or aspect ratio, is the key indicator of the asbestiform habit. The blueschist data are compared to non-asbestiform hornblende amphibole in granitic rocks. The fiber concentration of the hornblende (458 MFG) is low compared to the blueschist amphibole (107,880 MFG) and chrysotile in serpentinite (196,066 MFG), indicating that under similar conditions, the exposure potential from cleaved particles could be several orders of magnitude lower than from asbestiform particles. The asbestiform habit of glaucophane is present at two other locations in the Franciscan Complex, suggesting that asbestiform blueschist amphibole may be characteristic within blueschist terranes, and rock formations containing asbestiform amphibole may be more common and widespread than previously assumed.


Assuntos
Poluentes Ocupacionais do Ar/análise , Amiantos Anfibólicos/análise , Minerais/análise , Asbestos Serpentinas/análise , California , Monitoramento Ambiental , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Tamanho da Partícula
2.
Toxicol Appl Pharmacol ; 361: 36-46, 2018 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-30134140

RESUMO

The length distributions of single fibrils of Coalinga, UICC-B and wet dispersed chrysotile were measured by transmission electron microscopy (TEM). It was found that the distributions significantly diverged above approximately 10 µm (µm) in length, corresponding to differences in published results of animal experiments. This result is in contrast to published data in which counting of an insufficient number of fibers resulted in an erroneous conclusion that the length distribution of Coalinga chrysotile fibrils was indistinguishable from those of other sources of chrysotile. The size distributions of the respirable particle size fractions from acknowledged tremolite asbestos samples were found to be dominated by elongate particles longer than 5 µm that are within the dimensional range of non-asbestiform amphiboles. Prior studies have shown that these elongate particles obscure a correlation between a specific size range of particles and results of animal implantation studies that used tremolite of various morphologies. In the prior studies, a reference protocol was developed from four crushed non-asbestiform amphiboles to differentiate the size range of amphibole particles that correlates with the mesothelioma frequencies observed in the animal studies. In the work reported here, this correlation was tested with TEM analyses of amphiboles from Libby, MT, Sparta, NJ and Homestake mine, Lead, SD, which represent known environmental/occupational situations. Further TEM analyses of the tremolite samples used in the original animal implantation studies have also shown that the numbers of elongate tremolite particles with lengths ≤5 µm implanted into the animals are not correlated with the observed mesothelioma frequencies.


Assuntos
Fibras Minerais/análise , Minerais/análise , Material Particulado/análise , Animais , Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Asbestos Serpentinas/toxicidade , Humanos , Neoplasias Pulmonares/induzido quimicamente , Neoplasias Pulmonares/epidemiologia , Mesotelioma/induzido quimicamente , Mesotelioma/epidemiologia , Microscopia Eletrônica de Transmissão , Fibras Minerais/toxicidade , Minerais/toxicidade , Exposição Ocupacional , Tamanho da Partícula , Material Particulado/toxicidade
3.
J Occup Environ Med ; 60(7): 661-671, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29608538

RESUMO

OBJECTIVES: The aim of the study was to reanalyze an updated database of lung asbestos fiber levels for 21 brake repair workers who died of mesothelioma using robust maximum likelihood-based regression methods to address nondetectable measurements. METHODS: We applied bivariate normal regression to address the doubly left-censored situation where both the lung fiber concentration of noncommercial (TAA) and commercial amphiboles (AC) were subject to detection limits. For the single left-censored situation, we applied censored normal regression to study the relationship between duration of employment (DOE) and TAA. RESULTS: We found a statistically significant positive relationship between TAA and AC (ß = 0.49, 95% confidence interval [CI], 0.11 to 0.86) and a not statistically significant relationship between DOE and TAA (ß = 0.02, 95% CI, -0.03 to 0.06). CONCLUSIONS: Our results provide additional support for the conclusion that exposure to commercial amphibole asbestos, and not chrysotile, is related to the occurrence of mesothelioma among some brake workers.


Assuntos
Amiantos Anfibólicos/análise , Automóveis , Pulmão/química , Mesotelioma/etiologia , Doenças Profissionais/etiologia , Exposição Ocupacional/estatística & dados numéricos , Neoplasias Peritoneais/etiologia , Neoplasias Pleurais/etiologia , Adulto , Idoso , Amiantos Anfibólicos/toxicidade , Humanos , Limite de Detecção , Manutenção , Pessoa de Meia-Idade , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/análise , Análise de Regressão
4.
Int J Epidemiol ; 47(6): 1745-1756, 2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29534192

RESUMO

Background: Occupational and environmental airborne asbestos concentrations are too low and variable for lifetime exposures to be estimated reliably, and building workers and occupants may suffer higher exposure when asbestos in older buildings is disturbed or removed. Mesothelioma risks from current asbestos exposures are therefore not known. Methods: We interviewed and measured asbestos levels in lung samples from 257 patients treated for pneumothorax and 262 with resected lung cancer, recruited in England and Wales. Average lung burdens in British birth cohorts from 1940 to 1992 were estimated for asbestos-exposed workers and the general population. Results: Regression analysis of British mesothelioma death rates and average lung burdens in birth cohorts born before 1965 suggests a lifetime mesothelioma risk of approximately 0.01% per fibre/mg of amphiboles in the lung. In those born since 1965, the average lung burden is ∼1 fibre/mg among those with no occupational exposure. Conclusions: The average lifetime mesothelioma risk caused by recent environmental asbestos exposure in Britain will be about 1 in 10 000. The risk is an order of magnitude higher in a subgroup of exposed workers and probably in occupants in the most contaminated buildings. Further data are needed to discover whether asbestos still present in buildings, particularly schools, is a persistent or decreasing hazard to workers who disturb it and to the general population, and whether environmental exposure occurs predominantly in childhood or after beginning work. Similar studies are needed in other countries to estimate continuing environmental and occupational mesothelioma hazards worldwide, including the contribution from chrysotile.


Assuntos
Asbestos/efeitos adversos , Carcinógenos Ambientais/efeitos adversos , Exposição Ambiental/normas , Neoplasias Pulmonares/mortalidade , Mesotelioma/mortalidade , Idoso , Idoso de 80 Anos ou mais , Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Feminino , Humanos , Neoplasias Pulmonares/etiologia , Masculino , Mesotelioma/etiologia , Pessoa de Meia-Idade , Análise de Regressão , Medição de Risco , Fatores de Risco , Reino Unido/epidemiologia
5.
Int J Environ Health Res ; 28(2): 134-146, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29564927

RESUMO

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.


Assuntos
Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Itália , Microscopia Eletrônica , Fibras Minerais/análise , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
6.
Inhal Toxicol ; 29(10): 443-456, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-29124998

RESUMO

Talc has been used for over a century in a variety of cosmetic products. While pure cosmetic talc (free of asbestos) is not considered a risk factor for mesothelioma, it has been recently suggested that inhalation of cosmetic talc containing trace levels of asbestos is a risk factor for mesothelioma. Bulk analyses of cosmetic talcum products were performed in the 1960s and 1970s, however, the analytical methods used at that time were incapable of determining whether asbestos minerals were present in the asbestiform versus non-asbestiform habit. The distinction between these two mineral habits is critical, as non-asbestiform amphibole minerals do not present an asbestos-related cancer risk via inhalation. As such, we evaluated six historical talcum powders using modern-era analytical methods to determine if asbestos is present, and if so, to identify the mineral habit (asbestiform versus non-asbestiform) of the asbestos. Based on their labels, the products were produced by four manufacturers and sold between 1940 and 1977. The products were analyzed in duplicate by two laboratories using standard protocols. Laboratory A analyzed samples using X-ray diffraction (XRD) and polarized light microscopy (PLM), and Laboratory B analyzed samples using PLM and transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX) and selected area electron diffraction (SAED). No asbestiform minerals were found in any of the products. Nonetheless, even if some historical cosmetic talcum products contained trace amounts (≤0.1%) of asbestiform minerals, any resulting asbestos exposure would be expected to be exceedingly low, and comparable to exposures from breathing ambient air.


Assuntos
Amiantos Anfibólicos/análise , Cosméticos/química , Talco/química , Humanos , Microscopia Eletrônica de Transmissão , Espectrometria por Raios X , Difração de Raios X
7.
Inhal Toxicol ; 29(9): 404-413, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-29039215

RESUMO

During its days of operation (1920s-1990), the world's largest source of vermiculite was extracted from a mine located near Libby, Montana. The material mined at this site was shipped for various commercial applications to numerous sites in the United States. There was a "fibrous" component with toxic potential within the vermiculite deposit that has resulted in "asbestos-like" diseases/deaths being reported in numerous studies involving miners as well as residents of the town of Libby. The present case involves the clinical assessments of an individual who worked at the mine from 1969 to 1990. He had no other known occupational exposures to fibrous materials. He developed a clinical picture that included "asbestos-like" pathological features and eventually an adenocarcinoma. The clinical assessment including radiographic features will be presented. The evaluation will also include the analytical evaluation of the fibrous/ferruginous body composition of the lung tissue. This is to our knowledge the first time such an extensive evaluation has been conducted in a vermiculite miner from Libby, Montana.


Assuntos
Silicatos de Alumínio , Amiantos Anfibólicos/análise , Pulmão/química , Exposição Ocupacional , Idoso , Asbestose/patologia , Humanos , Pulmão/patologia , Masculino , Mineração , Montana , Fibrose Pulmonar
8.
Environ Sci Pollut Res Int ; 23(24): 25180-25190, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27680005

RESUMO

Serpentine and amphibole asbestos occur naturally in certain geologic settings worldwide, most commonly in association with ultramafic rocks, along associated faults. Ultramafic rocks have been used in Piên County, Southern Brazil for decades for the purpose of road paving in rural and urban areas, but without the awareness of their adverse environmental and health impact. The aim of this study was the chemical characterization of aerosols re-suspended in two rural roads of Piên, paved with ultramafic rocks and to estimate the pulmonary deposition of asbestos aerosols. Bulk aerosol samples were analyzed by means of X-ray fluorescence spectrometry and X-ray diffraction analysis, in order to characterize elemental composition and crystallinity. Single-particle compositions of aerosols were analyzed by computer-controlled electron-probe microanalysis, indicating the presence of a few percentages of serpentine and amphibole. Given the chemical composition and size distribution of aerosol particles, the deposition efficiency of chrysotile, a sub-group of serpentine, in two principal segments of the human respiratory system was estimated using a lung deposition model. As an important finding, almost half of the inhaled particles were calculated to be deposited in the respiratory system. Asbestos depositions were significant (∼25 %) in the lower airways, even though the selected breathing conditions (rest situation, nose breathing) implied the lowest rate of respiratory deposition. Considering the fraction of inhalable suspended chrysotile near local roads, and the long-term exposure of humans to these aerosols, chrysotile may represent a hazard, regarding more frequent development of lung cancer in the population of the exposed region.


Assuntos
Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Aerossóis , Amiantos Anfibólicos/farmacocinética , Amiantos Anfibólicos/toxicidade , Asbestos Serpentinas/farmacocinética , Asbestos Serpentinas/toxicidade , Brasil , Humanos , Exposição por Inalação , Neoplasias Pulmonares , Modelos Biológicos , Sistema Respiratório/metabolismo , Medição de Risco
9.
J Air Waste Manag Assoc ; 66(9): 922-9, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27145298

RESUMO

UNLABELLED: The purpose of this study was to detect asbestos-containing products and released asbestos fibers from home appliances. The authors investigated a total of 414 appliances manufactured between 1986 and 2007. Appliances were divided into three categories: large-sized electric appliances, small-sized electric appliances, and household items. Analysis for asbestos-containing material (ACM) was performed using polarized light microscopy (PLM) and stereoscopic microscopy. Air sampling was performed to measure airborne concentration of asbestos using a phase-contrast microscope (PCM). The results of the analysis for ACM in appliances show that large-sized electric appliances (refrigerators, washing machines, kimchi-refrigerators) and household items (bicycles, motorcycles, gas boilers) contain asbestos material and small-sized electric appliances do not contain asbestos material. All appliances with detected asbestos material showed typical characteristics of chrysotile (7-50%) and tremolite (7-10%). No released fibers of ACM were detected from the tested appliances when the appliances were operating. This study gives the basic information on asbestos risk to people who use home appliances. IMPLICATIONS: All appliances with detected asbestos material showed typical characteristics of chrysotile (7-50%) and tremolite (7-10%). No released fibers of ACM were detected from the tested appliances when the appliances were operating.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Monitoramento Ambiental/métodos , Utensílios Domésticos , Fibras Minerais/análise
10.
Inhal Toxicol ; 28(8): 357-63, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27151190

RESUMO

The purpose of this work is to define a sample preparation protocol that allows inorganic fibers and particulate matter extracted from different biological samples to be characterized morphologically, crystallographically and chemically by transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS). The method does not damage or create artifacts through chemical attacks of the target material. A fairly rapid specimen preparation is applied with the aim of performing as few steps as possible to transfer the withdrawn inorganic matter onto the TEM grid. The biological sample is previously digested chemically by NaClO. The salt is then removed through a series of centrifugation and rinse cycles in deionized water, thus drastically reducing the digestive power of the NaClO and concentrating the fibers for TEM analysis. The concept of equivalent hydrodynamic diameter is introduced to calculate the settling velocity during the centrifugation cycles. This technique is applicable to lung tissues and can be extended to a wide range of organic materials. The procedure does not appear to cause morphological damage to the fibers or modify their chemistry or degree of crystallinity. The extrapolated data can be used in interdisciplinary studies to understand the pathological effects caused by inorganic materials.


Assuntos
Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Manejo de Espécimes/métodos , Amiantos Anfibólicos/química , Asbestos Serpentinas/química , Humanos , Pulmão , Microscopia Eletrônica de Transmissão , Hipoclorito de Sódio/química
11.
Environ Res ; 147: 97-101, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26855127

RESUMO

A significantly increased incidence of pleural mesothelioma in Biancavilla (Sicily, Italy) has been attributed to exposure to fluoro-edenite (FE), a fibrous amphibole extracted from a local stone quarry. The lymph-nodes draining the pulmonary lobes of sheep grazing around the town were examined, to gain insights into fibre diffusion. The pasture areas of six sheep flocks lying about 3km from Biancavilla were located using the global positioning system. The cranial tracheobronchial and one middle mediastinal lymph-node as well as four lung tissue samples were collected from 10 animals from each flock and from 10 control sheep for light and scanning electron microscopy (SEM) examination. The lymph-nodes from exposed sheep were enlarged and exhibited signs of anthracosis. Histologically, especially at the paracortical level, they showed lymph-follicle hyperplasia with large reactive cores and several macrophages (coniophages) containing grey-brownish particulate interspersed with elements with a fibril structure, forming aggregates of varying dimensions (coniophage nodules). Similar findings were detected in some peribronchiolar areas of the lung parenchyma. SEM examination showed that FE fibres measured 8-41µm in length and 0.4-1.39µm in diameter in both lymph-nodes and lung tissue. Monitoring of FE fibres in sheep lymph-nodes using appropriate techniques can help set up environmental pollution surveillance.


Assuntos
Amiantos Anfibólicos/toxicidade , Exposição Ambiental , Poluentes Ambientais/toxicidade , Linfonodos/química , Doenças Linfáticas/veterinária , Doenças dos Ovinos/patologia , Ovinos , Animais , Amiantos Anfibólicos/análise , Monitoramento Ambiental , Pulmão/química , Pulmão/patologia , Pulmão/ultraestrutura , Linfonodos/patologia , Linfonodos/ultraestrutura , Doenças Linfáticas/induzido quimicamente , Doenças Linfáticas/patologia , Microscopia Eletrônica de Varredura/veterinária , Doenças dos Ovinos/induzido quimicamente , Sicília
12.
J Expo Sci Environ Epidemiol ; 26(1): 63-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26242170

RESUMO

This study describes fibre size and type-specific airborne asbestos exposures in an asbestos product factory. Forty-four membrane filter samples were analysed by scanning electron microscopy to determine the size distribution of asbestos fibres, by workshop. Fibre frequencies of bivariate (length by width) categories were calculated and differences between workshops were tested by analysis of variance. Data were recorded for 13,435 chrysotile and 1075 tremolite fibres. The proportions between size metrics traditionally measured and potentially biologically important size metrics were found to vary in this study from proportions reported in other cohort studies. One, common size distribution was generated for each asbestos type over the entire factory because statistically significant differences in frequency between workshops were not detected. This study provides new information on asbestos fibre size and type distributions in an asbestos factory. The extent to which biologically relevant fibre size indices were captured or overlooked between studies can potentially reconcile currently unexplained differences in asbestos-related disease (ARD) risk between cohorts. The fibre distributions presented here, when combined with similar data from other sites, will contribute to the development of quantitative models for predicting risk and our understanding of the effects of fibre characteristics in the development of ARD.


Assuntos
Poluentes Ocupacionais do Ar/análise , Amiantos Anfibólicos/efeitos adversos , Amiantos Anfibólicos/análise , Asbestos Serpentinas/efeitos adversos , Asbestos Serpentinas/análise , Fibras Minerais/efeitos adversos , Fibras Minerais/análise , Exposição Ocupacional/análise , China , Estudos de Coortes , Tamanho da Partícula
13.
Occup Environ Med ; 73(5): 290-9, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26715106

RESUMO

BACKGROUND: We have conducted a population-based study of pleural mesothelioma patients with occupational histories and measured asbestos lung burdens in occupationally exposed workers and in the general population. The relationship between lung burden and risk, particularly at environmental exposure levels, will enable future mesothelioma rates in people born after 1965 who never installed asbestos to be predicted from their asbestos lung burdens. METHODS: Following personal interview asbestos fibres longer than 5 µm were counted by transmission electron microscopy in lung samples obtained from 133 patients with mesothelioma and 262 patients with lung cancer. ORs for mesothelioma were converted to lifetime risks. RESULTS: Lifetime mesothelioma risk is approximately 0.02% per 1000 amphibole fibres per gram of dry lung tissue over a more than 100-fold range, from 1 to 4 in the most heavily exposed building workers to less than 1 in 500 in most of the population. The asbestos fibres counted were amosite (75%), crocidolite (18%), other amphiboles (5%) and chrysotile (2%). CONCLUSIONS: The approximate linearity of the dose-response together with lung burden measurements in younger people will provide reasonably reliable predictions of future mesothelioma rates in those born since 1965 whose risks cannot yet be seen in national rates. Burdens in those born more recently will indicate the continuing occupational and environmental hazards under current asbestos control regulations. Our results confirm the major contribution of amosite to UK mesothelioma incidence and the substantial contribution of non-occupational exposure, particularly in women.


Assuntos
Amiantos Anfibólicos/efeitos adversos , Neoplasias Pulmonares/induzido quimicamente , Pulmão , Mesotelioma/induzido quimicamente , Doenças Profissionais/induzido quimicamente , Exposição Ocupacional/efeitos adversos , Neoplasias Pleurais/induzido quimicamente , Adulto , Idoso , Amianto Amosita/efeitos adversos , Amianto Amosita/análise , Amiantos Anfibólicos/análise , Asbesto Crocidolita/efeitos adversos , Asbesto Crocidolita/análise , Asbestos Serpentinas/efeitos adversos , Asbestos Serpentinas/análise , Asbestose/complicações , Emprego , Feminino , Humanos , Pulmão/química , Pulmão/patologia , Neoplasias Pulmonares/patologia , Masculino , Mesotelioma/patologia , Pessoa de Meia-Idade , Fibras Minerais/efeitos adversos , Fibras Minerais/análise , Doenças Profissionais/patologia , Neoplasias Pleurais/patologia , Medição de Risco
14.
Artigo em Inglês | MEDLINE | ID: mdl-25825806

RESUMO

Anthropogenic and nonanthropogenic (erosion) processes contribute to the continuing presence of asbestos and nonasbestos elongated mineral particles (EMP) of amphibole and serpentine in air and water of urban, rural, and remote environments. The anthropogenic processes include disturbance and deterioration of asbestos-containing materials, mining of amphibole- and serpentine-bearing rock, and disturbance of soils containing amphibole and serpentine. Atmospheric dispersal processes can transport EMP on a global scale. There are many methods of establishing the abundance of EMP in air and water. EMP include cleavage fragments, fibers, asbestos, and other asbestiform minerals, and the methods employed do not critically distinguish among them. The results of most of the protocols are expressed in the common unit of fibers per square centimeter; however, seven different definitions for the term "fiber" are employed and the results are not comparable. The phase-contrast optical method used for occupational monitoring cannot identify particles being measured, and none of the methods distinguish amphibole asbestos from other EMP of amphibole. Measured ambient concentrations of airborne EMP are low, and variance may be high, even for similar environments, yielding data of questionable value for risk assessment. Calculations based on the abundance of amphibole-bearing rock and estimates of asbestos in the conterminous United States suggest that amphibole may be found in 6-10% of the land area; nonanthropogenic erosional processes might produce on the order of 400,000 tons or more of amphibole per year, and approximately 50 g asbestos/km(2)/yr; and the order of magnitude of the likelihood of encountering rock bearing any type of asbestos is approximately 0.0001.


Assuntos
Poluentes Atmosféricos/análise , Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Asbestos/análise , Poluentes Químicos da Água/análise , Animais , Humanos
15.
Ann Occup Hyg ; 59(7): 909-21, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25878166

RESUMO

The present study analysed the asbestos lung burden in necroscopic samples from 55 subjects free from asbestos-related diseases, collected between 2009 and 2011 in Milan, Italy. Multiple lung samples were analysed by light microscopy (asbestos bodies, AB) and EDXA-scanning electron microscopy (asbestos fibres and other inorganic fibres). Asbestos fibres were detected in 35 (63.6%) subjects, with a higher frequency for amphiboles than for chrysotile. Commercial (CA) and non-commercial amphiboles (NCA) were found in roughly similar frequencies. The estimated median value was 0.11 million fibres per gram of dry lung tissue (mf g(-1)) for all asbestos, 0.09 mf g(-1) for amphiboles. In 44 (80.0%) subjects no chrysotile fibres were detected. A negative relationship between asbestos mass-weighted fibre count and year of birth (and a corresponding positive increase with age) was observed for amphiboles [-4.15%, 95% confidence interval (CI) = -5.89 to -2.37], talc (-2.12%, 95% CI = -3.94 to -0.28), and Ti-rich fibres (-3.10%, 95% CI = -5.54 to -0.60), but not for chrysotile (-2.84%, 95% CI = -7.69 to 2.27). Residential district, birthplace, and smoking habit did not affect the lung burden of asbestos or inorganic fibres. Females showed higher burden only for amphiboles (0.12 versus 0.03 mf g(-1) in males, P = 0.07) and talc fibres (0.14 versus 0 mf g(-1) in males, P = 0.03). Chrysotile fibres were shorter and thinner than amphibole fibres and NCA fibres were thicker than CA ones. The AB prevalence was 16.4% (nine subjects) with concentrations ranging from 10 to 110 AB g(-1) dry, well below the 1000 AB g(-1) threshold for establishing occupational exposure. No AB were found in subjects younger than 30 years. Our study demonstrated detectable levels of asbestos fibres in a sample taken from the general population. The significant increase with age confirmed that amphibole fibres are the most representative of cumulative exposure.


Assuntos
Asbestos/análise , Pulmão/química , Exposição Ocupacional/análise , Adulto , Asbestos/efeitos adversos , Amiantos Anfibólicos/análise , Asbestos Serpentinas/análise , Autopsia , Feminino , Humanos , Itália , Masculino , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Fibras Minerais/análise , Doenças Profissionais/etiologia
17.
J Occup Environ Hyg ; 12(5): D47-53, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25715191

RESUMO

The National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of exposures to asbestiform amphibole, known as Libby Amphibole (LA), to personnel from the US Department of Agriculture-Forest Service (USFS) working in the Kootenai National Forest near a former vermiculite mine close to Libby, Montana. LA is associated with vermiculite that was obtained from this mine; mining and processing over many years have resulted in the spread of LA into the surrounding Kootenai Forest where it has been found in tree bark, soil, and forest floor litter. As a result of this and other contamination, Libby and surrounding areas have been designated a "Superfund" site by the US Environmental Protection Agency (EPA). This article describes the application of EPA methods for assessing cancer risks to NIOSH sampling results. Phase-contrast microscopy for airborne asbestos fiber evaluation was found to be less useful than transmission electron microscopy in the presence of interfering organic (plant) fibers. NIOSH Method 7402 was extended by examination of larger areas of the filter, but fiber counts remained low. There are differences between counting rules in NIOSH 7402 and the ISO method used by EPA but these are minor in the context of the uncertainty in concentration estimates from the low counts. Estimates for cancer risk are generally compatible with those previously estimated by the EPA. However, there are limitations to extrapolating these findings of low risk throughout the entire area and to tasks that were not evaluated.


Assuntos
Amiantos Anfibólicos/análise , Exposição Ocupacional/análise , Material Particulado/análise , Silicatos de Alumínio/análise , Amiantos Anfibólicos/toxicidade , Monitoramento Ambiental/métodos , Agricultura Florestal , Humanos , Neoplasias Pulmonares/induzido quimicamente , Montana , National Institute for Occupational Safety and Health, U.S. , Exposição Ocupacional/efeitos adversos , Casca de Planta/química , Medição de Risco , Árvores/química , Estados Unidos
18.
J Expo Sci Environ Epidemiol ; 25(1): 12-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24496219

RESUMO

Recent meta-analyses of occupational epidemiology studies identified two important exposure data quality factors in predicting summary effect measures for asbestos-associated lung cancer mortality risk: sufficiency of job history data and percent coverage of work history by measured exposures. The objective was to evaluate different exposure parameterizations suggested in the asbestos literature using the Libby, MT asbestos worker cohort and to evaluate influences of exposure measurement error caused by historically estimated exposure data on lung cancer risks. Focusing on workers hired after 1959, when job histories were well-known and occupational exposures were predominantly based on measured exposures (85% coverage), we found that cumulative exposure alone, and with allowance of exponential decay, fit lung cancer mortality data similarly. Residence-time-weighted metrics did not fit well. Compared with previous analyses based on the whole cohort of Libby workers hired after 1935, when job histories were less well-known and exposures less frequently measured (47% coverage), our analyses based on higher quality exposure data yielded an effect size as much as 3.6 times higher. Future occupational cohort studies should continue to refine retrospective exposure assessment methods, consider multiple exposure metrics, and explore new methods of maintaining statistical power while minimizing exposure measurement error.


Assuntos
Amiantos Anfibólicos/efeitos adversos , Mineração/estatística & dados numéricos , Exposição Ocupacional/análise , Adulto , Amiantos Anfibólicos/análise , Estudos de Coortes , Feminino , Humanos , Neoplasias Pulmonares/induzido quimicamente , Neoplasias Pulmonares/epidemiologia , Neoplasias Pulmonares/mortalidade , Masculino , Montana/epidemiologia , Exposição Ocupacional/estatística & dados numéricos , Fumar/efeitos adversos , Fumar/epidemiologia
19.
J Expo Sci Environ Epidemiol ; 25(1): 4-11, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23695492

RESUMO

Residents of Libby, MT were exposed to amphibole asbestos through multiple environmental pathways. Previous exposure characterization has primarily relied on qualitative report of these exposure activities. The objectives of this study were to describe available data from the US EPA preremediation actions for Libby amphibole (LA) exposure in Libby, MT and develop an approach to characterize outdoor residential exposure to LA among children. Homes in Libby, MT included in the US EPA preremediation Contaminant Screening Survey (CSS) were categorized by the presence of interior and/or exterior visible vermiculite and concentrations of LA were measured in samples of dust and soil. Airborne exposure to LA while digging/gardening, raking, and mowing were estimated using US EPA activity-based sampling (ABS) results. Residential histories and frequency/duration of childhood activities were combined with ABS to demonstrate the approach for estimating potential exposure. A total of 3154 residential properties participated in the CSS and 44% of these had visible exterior vermiculite. Airborne concentrations of LA where there was visible vermiculite outdoors were 3-15 times higher during digging/gardening, raking, and mowing activities compared with homes without visible outdoor vermiculite. Digging and gardening activities represented the greatest contribution to estimated exposures and 73% of the participants reported this activity before the age of 6 years. This methodology demonstrated the use of historical preremediation data to estimate residential exposures of children for specific activities. Children younger than age 6 years may have been exposed to LA while digging/gardening, especially at homes where there is visible outdoor vermiculite. This approach may be extended to other activities and applied to the entire cohort to examine health outcomes.


Assuntos
Amiantos Anfibólicos/análise , Exposição Ambiental/análise , Adolescente , Silicatos de Alumínio/análise , Amiantos Anfibólicos/efeitos adversos , Criança , Pré-Escolar , Exposição Ambiental/estatística & dados numéricos , Humanos , Lactente , Recém-Nascido , Exposição por Inalação/análise , Exposição por Inalação/estatística & dados numéricos , Mineração , Montana/epidemiologia , Solo/química , Inquéritos e Questionários
20.
Ann Occup Hyg ; 59(1): 91-103, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25268000

RESUMO

Well-characterized amphibole asbestos mineral samples are required for use as analytical standards and in future research projects. Currently, the National Institute for Standards and Technology Standard Reference Material samples of asbestos are listed as 'Discontinued'. The National Institute for Occupational Safety and Health (NIOSH) has a goal under the Asbestos Roadmap of locating and characterizing research materials for future use. Where an initial characterization analysis determines that a collected material is appropriate for use as a research material in terms of composition and asbestiform habit, sufficient amounts of the material will be collected to make it publicly available. An abandoned mine near Lone Pine, California, contains a vein of tremolite asbestos, which was the probable source of a reference material that has been available for the past 17 years from the Health and Safety Laboratory (HSL) in the UK. Newly collected fibrous vein material from this mine was analyzed at Research Triangle Institute (RTI International) with some additional analysis by the US Geological Survey's Denver Microbeam Laboratory. The analysis at RTI International included: (i) polarized light microscopy (PLM) with a determination of principal optical properties; (ii) X-ray diffraction; (iii) transmission electron microscopy, including energy dispersive X-ray spectroscopy and selected-area electron diffraction; and (iv) spindle stage analysis using PLM to determine whether individual fibers and bundles of the samples were polycrystalline or single-crystal cleavage fragments. The overall findings of the study indicated that the material is tremolite asbestos with characteristics substantially similar to the earlier distributed HSL reference material. A larger quantity of material was prepared by sorting, acid-washing and mixing for sub-division into vials of ~10g each. These vials have been transferred from NIOSH to RTI International, from where they can be obtained on request.


Assuntos
Amiantos Anfibólicos/análise , Amiantos Anfibólicos/química , California , Humanos , Microscopia Eletrônica de Transmissão , Minerais/química , Minerais/normas , Padrões de Referência , Espectrometria por Raios X , Difração de Raios X
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