We have previously evaluated asbestos exposure associated with various maintenance procedures on light aircraft. The purpose of this study was to evaluate asbestos exposure during engine maintenance on light aircraft....We have previously evaluated asbestos exposure associated with various maintenance procedures on light aircraft. The purpose of this study was to evaluate asbestos exposure during engine maintenance on light aircraft. This test was designed to evaluate the potential for asbestos exposure to mechanics and others who remove asbestos-containing engine gaskets from reciprocating style aircraft engines. Utilized in this test was an air cooled, horizontally opposed, aviation gasoline burning engine, assembled during 1986 and operated intermittently up into 2015, having accumulated 1680 hours run time. Nearly 75% of the asbestos-containing gaskets installed during 1986 were still in place at the time of testing. Chrysotile asbestos contents of such gaskets ranged from 55% to 60% by area, for those of sheet style and 5% by area, for the spiral wound metal/asbestos style. Despite the levels of effort required to effect gasket removals, the professional aircraft mechanic was not exposed to airborne asbestos fibers at the lower limits of sampling and analytical detection achieved;all of which were substantially less than the current Occupational Safety and Health Administration Permissible Exposure Limits for asbestos. The results of this testing indicate an absence of gasket related asbestos exposure risk to mechanics who work with light aircraft engines, including those having asbestos-containing gaskets. These results are consistent with the findings of Mlyarek and Van Orden who studied the asbestos exposure risk occasioned during overhaul of larger radial style reciprocating aircraft engines [1].展开更多
Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable...Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable products were insulated using chrysotile asbestos. This research was undertaken to determine the asbestos fiber exposure risks associated with power stripping machinery to remove asbestos-containing insulation materials from electrical wire or cable. A Rigby Machinery, Inc., Model 4H electric powered wire/cable insulation stripping machine was acquired along with approximately 42 m of asbestos insulated cable. During two separate, but nearly identical, test sessions, a laborer used the wire stripper to remove the asbestos-containing insulation from the subject cable. This work took place within a closed metal building with a total interior volume of 2500 m3. Industrial hygiene personal and area air samples were collected for airborne fibers throughout all wire stripping periods. Collected air samples were analyzed using phase contract microscopy (PCM) and transmission microscopy (TEM). The results of analysis using PCM for personal samples (n = 3) taken during periods of continuous cable stripping activity showed test period airborne fiber exposures ranging from 0.034 to 0.068 (mean 0.056 f/cc). Follow-up analysis of these personal samples using TEM indicated asbestos adjusted PCM exposures ranging from 0.017 to 0.045 (mean 0.033 f/cc). Area air samples taken at distances ranging from 2 to 9 meters from the wire stripper (n = 16) showed asbestos adjusted PCM concentrations ranging from less than 0.0001 to 0.041 f/cc (mean 0.007 f/cc). The process of power stripping asbestos-containing insulation from electrical wires and cables can cause exposure to airborne asbestos fibers. However, the levels of such exposure are not expected to exceed the current occupational exposure limits for asbestos of 0.1 f/cc as an 8-hr TWA or 1.0 f/cc averaged over a 30-minute exposure period.展开更多
Asbestos containing materials (ACM) have been used for decades in research laboratory products including gloves, tong sleeves, Transite board, and other materials. These materials typically contain chrysotile asbestos...Asbestos containing materials (ACM) have been used for decades in research laboratory products including gloves, tong sleeves, Transite board, and other materials. These materials typically contain chrysotile asbestos with concentrations ranging up to 80%. The objective of this research was to evaluate asbestos exposure from gloves, tong sleeves, and Transite board with simulated laboratory use. An environmental chamber was used to simulate laboratory application of the products. Bulk samples of various products were tested before and after use. Personal breathing zone air samples as well as one cumulative air sample were collected during testing and followed the National Institute for Occupational Safety and Health (NIOSH) 7400/7402 methodologies. Phase contrast microscopy (PCM) and transmission electron microscopy (TEM) were used for sample analyses. Analysis of air samples using PCM, showed airborne fiber concentrations as high as 0.058 f/cc during use of tongs fitted with asbestos sleeves. Further analysis using TEM showed that the highest airborne fiber concentration was 0.0036 f/cc. Manipulation of Transite board resulted in 8-hour time-weighted-average (TWA) asbestos levels as high as 0.02 f/cc. Testing of various asbestos containing materials used in research laboratories indicate low potential for asbestos fiber exposures.展开更多
In the last decades,it has been widely demonstrated the risk to human health related to asbestos fibres exposure.Many studies have mainly focused on the mineralogical and geochemical characterization of ophiolites(i.e...In the last decades,it has been widely demonstrated the risk to human health related to asbestos fibres exposure.Many studies have mainly focused on the mineralogical and geochemical characterization of ophiolites(i.e.,serpentinite and metabasite rocks)since they are the main lithotypes associated with Naturally Occurring Asbestos(NOA).Nevertheless,derivative soil from these rocks inherits the mineralogical and geochemical composition of bed rock and may contain hazardous fibres,thus making its examination necessary as well.This paper provides a summary of asbestos-containing soils investigation worldwide with the purpose of providing an overview of the data obtained so far.To this aim,the most relevant available literature,testifying the presence of fibrous minerals in soils have been considered.This allowed the global territory mapping in order to depict the distribution of natural asbestos in soils worldwide.展开更多
Objective To compare the asbestos-induced DNA damage and repair capacities of DNA damage between 104 asbestosexposed workers and 101 control workers in Qingdao City of China and to investigate the possible association...Objective To compare the asbestos-induced DNA damage and repair capacities of DNA damage between 104 asbestosexposed workers and 101 control workers in Qingdao City of China and to investigate the possible association between polymorphisms in codon 399 of XRCC1 and susceptibility to asbestosis. Methods DNA damage levels in peripheral blood lymphocytes were determined by comet assay, and XRCC1 genetic polymorphisms of DNA samples from 51 asbestosis cases and 53 non-asbestosis workers with a similar asbestos exposure history were analyzed by PCR/RFLP. Results The basal comet scores （3.95±2.95） were significantly higher in asbestos-exposed workers than in control workers （0.10±0.28）. After 1 h H2O2 stimulation, DNA damage of lymphocytes exhibited different increases. After a 4 h repair period, the comet scores were 50.98±19.53 in asbestos-exposed workers and 18.32±12.04 in controls. The residual DNA damage （RD） was significantly greater （P〈0.01） in asbestos-exposed workers （35.62%） than in controls （27.75%）. XRCC1 genetic polymorphism in 104 asbestos-exposed workers was not associated with increased risk of asbestosis. But compared with polymorphisms in the DNA repair gene XRCC1 （polymorphisms in codon 399） and the DNA damage induced by asbestos, the comet scores in asbestosis cases with Gin/Gin, Gln/Arg, and Arg/Arg were 40.26±18.94, 38.03±28.22, and 32.01±11.65, respectively, which were higher than those in non-asbestosis workers with the same genotypes （25.58±11.08, 37.08±14.74, and 29.38±10.15）. There were significant differences in the comet scores between asbestosis cases and non-asbestosis workers with Gin/Gin by Student＇s t-test （P〈0.05 or 0.01）. The comet scores were higher in asbestosis workers with Gin/Gin than in those with Arg/Arg and in non-asbestosis workers exposed to asbestos, but without statistically significant difference. Conclusions Exposure to asbestos may be related to DNA damage or the capacity of cells to repair H2O2-induced DNA damage. DNA repair gene XRCC 1 codon 399 may be responsible for the inter-individual susceptibility in DNA damage and repair capacities.展开更多
The toxicity of asbestos has been constantly an active research topic.Although asbestos has lots of advantages owing to its stable physicochemical properties and economic characteristics,nations enforce policies prohi...The toxicity of asbestos has been constantly an active research topic.Although asbestos has lots of advantages owing to its stable physicochemical properties and economic characteristics,nations enforce policies prohibiting or limiting its use because of its critical impact on human health.Especially in Korea 96% of imported asbestos are slate construction materials and with the influence of Saemaul movement,thatched roofs have been drastically replaced with slate roofs.Efforts to know the distribution characteristics of extensively used asbestos cement slates and to find out the removal method that suits the distribution characteristics are still in an insufficient state.The purpose of this work was to probe into the distribution of asbestos cement slate buildings in Korea and provide basic data of distribution characteristics for policy making in which consideration of the differences between rural and urban regions is necessary based on findings of the studies so far.It is considered helpful in many ways to solving asbestos cement slate related problems in countries where asbestos usage is increasing even after the 2000s including China.展开更多
Tremolite group minerals could be present in the aggregate used as filler in the mix asphalt floor in the road surfaces and are subject to wear for vehicular traffic and materials ageing.Dust produced by the degradati...Tremolite group minerals could be present in the aggregate used as filler in the mix asphalt floor in the road surfaces and are subject to wear for vehicular traffic and materials ageing.Dust produced by the degradation of asphalt surfaces can disperse tremolite group minerals present in road paving causing exposure by asbestos fiber to an increasing number of people and animals.In recent years,attention has been focused on naturally occurring asbestos(NOA)as the greatest frequency of lung cancer has been observed in environments characterized by rocks and soils rich in Tremolite that characterize asbestos minerals.Asphalt samples object of this study were collected in a motorway segment of the Lombardia Region(north of Italy)for an exposure assessment research on road paving workers.The evaluation was performed using a metrological approach based on petrographic and mineralogical analyses in order to reduce the epidemiologic risks and to define the best treatment strategies on waste management with sustainable costs in fulfilment of Council Directive 67/548/EEC(1967)and EC Regulation 1272/2008(2008)(Paglietti et al.,2016).The fibers are generally not broken down to other compounds in the environment,but asbestos hazard could be related to the occurrence of tremolite fiber in road paving arises when natural weathering processes(e.g.,erosion)or human activities(e.g.,continuous passage of motorized vehicles)separate and break down the fibers,which could be lost into the environment as airborne and easily penetrate into the human respiratory tract(Punturo et al.,2019).Despite this,this work is not an epidemiological risk analysis but obtained data could be useful to other specialists to define the exposure risks.展开更多
In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile,a fixed cohort of 1932 workers in chrysotile asbes-tos mine was establi...In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile,a fixed cohort of 1932 workers in chrysotile asbes-tos mine was established in 1981 and followed till June 1,2010.Information on vital status,cause of death and smoking habits was collected.The workers were divided into two groups according to their exposure status.The exposed group was composed of frontline workers who worked directly on mining or processing asbestos products.The control group consisted of those who were not directly exposed to asbestos in their work.Standardized mortality ratio (SMR) was calculated according to Chinese national death rates.Cox proportional hazards model was applied to estimate the adjusted relative risks of deaths from major causes in exposed and control groups.The results of this study showed that main causes of mortality were malignant neoplasm,cardiovascular disease,cerebrovascular disease and respiratory disease for chrysotile miners.The mortality rate was 939.20 per 100 000 person-years for workers.The SMR for all causes of death was 1.46 in the cohort.Statistically significant mortality excesses were found for lung cancer (SMR=1.51),pulmonary heart disease (SMR=2.70),respiratory disease (SMR=1.93),asbestosis (SMR=9.62),and accident (SMR=1.59).The mortalities from malignant neo-plasm,lung cancer,cerebrovascular disease and digestive disease in the exposed group were signifi-cantly higher than those in the control group.The findings indicate that chrysotile exposure is a risk factor for lung cancer,respiratory disease,cerebrovascular disease and digestive disease.展开更多
Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the...Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating （patina） with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART^TM testers. Heterotrophic aerobic bacteria （HAB） and slime forming bacteria （SLYM） dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.展开更多
Objective To determine whether there was excessive risk of cancer among workers exposed to chrysotile fiber alone by applying a meta-analysis technique. Methods All data meeting the criteria of cohort studies on c...Objective To determine whether there was excessive risk of cancer among workers exposed to chrysotile fiber alone by applying a meta-analysis technique. Methods All data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile were incorporated into meta-analysis. Pooled standardized mortality ratios (SMRs) and their corresponding 95% confidence intervals (CIs) for main cancer sites were calculated using two approaches of unweighted ratio and random effect model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test. The dose-response effect as reflected in the percentage of all deaths due to mesothelioma served as a proxy measure of chrysotile exposure. Results A cohort of twenty six workers exposed to chrysotile alone was summarized. The significantly elevated meta-SMRs for all deaths (1.27), all cancers (1.28), cancers of respiratory organs (2.51), cancers of lung (2.35) and cancers of stomach (1.24) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.55), asbestos product manufacturers (3.30), miners and millers (2.24), cement product workers (1.22), and for stomach cancer among asbestos product manufacturers (1.49). Meta-SMRs for cancers at other sites were not significant. Meta-SMR for lung cancer showed an increasing trend with an elevated percentage of all deaths from mesothelioma, but no such trend for stomach cancer. Conclusion There are excessive risks of lung cancer and mesothelioma among workers exposed to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.展开更多
The cementitiousness of dehydration asbestos tailings(serpentine, 3MgO.2SiO 2.2H 2O) in different conditions was studied. The result shown that dehydration asbestos tailings have better cementitiousness in certain con...The cementitiousness of dehydration asbestos tailings(serpentine, 3MgO.2SiO 2.2H 2O) in different conditions was studied. The result shown that dehydration asbestos tailings have better cementitiousness in certain condition and it can be used in building materials industry. It was also found that MgO powder, fly ash or quick lime can improve regularly the cementitiousness of asbestos tailings.展开更多
In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observcd that the incidcnce (16.0%) of lung carcinomas was lowel, and the survival time (376 days) of...In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observcd that the incidcnce (16.0%) of lung carcinomas was lowel, and the survival time (376 days) of the first case of carcinoma and the mean survival time (758 days) of the rats with carcinoma were higher in the group of rats drinking 2% green tea extract for life than in the positive group (without drinking green tea extract). The mortality ratio (0.5047) was smaller in the cxperimental group than in the positive control group, and the survival curve of the experimental group significantly raised up, in comparison with the positive group.展开更多
The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption...The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption peaks in the 4000 - 400 cm-1 region of the infrared spectrum. In the present work, we compare the accuracy and precision of two analytical procedures (the Linear Calibration Curve Method and the Method of Addition) for the quantitative determination of asbestos in a host matrix. We have found that, providing careful samples preparation, both techniques quantify the asbestos content at the level of few micrograms with good precision. Due to less expensive equipment requirements and shorter analysis time, FT-IR can be a competitive analytical technique in the characterization of asbestos containing material with the respect to diffractometry or electron microscopy.展开更多
The main components of the hydrochloric acid leachate of the asbestos tailings were MgCl<sub>2</sub>,FeCl<sub>3</sub>, FeCl<sub>2</sub>,AlCl<sub>3</sub> and surplus acid...The main components of the hydrochloric acid leachate of the asbestos tailings were MgCl<sub>2</sub>,FeCl<sub>3</sub>, FeCl<sub>2</sub>,AlCl<sub>3</sub> and surplus acid.An experimental study on optimization of purification process of acid leachate focusing on preparing magnesium hydroxide solution was carried on.The main approach used in the experiment was to oxidize Fe<sup>2+</sup>to Fe<sup>3+</sup>,and then purified it by the precipitation reaction with alkali.展开更多
To use many asbestos tailings collected in Ya-Lu highway,and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures,and properties of some asphalt mixtures were evaluated as wel...To use many asbestos tailings collected in Ya-Lu highway,and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures,and properties of some asphalt mixtures were evaluated as well.X-ray diffraction （XRD）,X-ray fluorescent （XRF）,and atomic absorption spectrophotometry （AAS） were employed to determine the solid waste content of copper,zinc,lead,and cadmium.Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material.Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications.No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23,which is help to the adhesion with asphalt in the asphalt concrete.When compared with basalt,high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates.In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number （BPN） coefficient of surface.展开更多
The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had be...The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had been used to research the influence of the reaction temperature on the phase, structure and morphology of the product during the preparation of the basic magnesium carbonate. The results indicates that the product was needle-like magnesium carbonate hydrate at the lower reaction temperature (from 35 ℃ to 65℃), with the increase of the reaction temperature (75 ℃ to 95 ℃ ), the needle-like magnesium carbonate hydrate (MgCO3·xH2O) transformed to flake-like basic magnesium carbonate [Mg5(CO3)4(OH)2·4H2O], the reaction temperature plays an important role in the preparation of flake-like basic magnesium carbonate, the preparation of flake-like basic magnesium carbonate was a nucleation-dissolution-recrystallization growth mechanism process.展开更多
In this paper the method of chemical vapor depostion is used to discuss the principle and method of foam asbestos, a new heat insulation material whose synthetical properties are improved remarkably after modifying. I...In this paper the method of chemical vapor depostion is used to discuss the principle and method of foam asbestos, a new heat insulation material whose synthetical properties are improved remarkably after modifying. It becomes one of the best heat insulation materials and, a kind of safety, no social effects of pullution material to a great extent.展开更多
The research involves the calcination of Sichuanshimian asbestos tailings with ammonium sulfate in order to extract magnesium. This paper studies the effect of different calcination conditions on the magnesium extract...The research involves the calcination of Sichuanshimian asbestos tailings with ammonium sulfate in order to extract magnesium. This paper studies the effect of different calcination conditions on the magnesium extraction rate, and it also studies the mechanism of calcination of asbestos tailings mixed with ammonium sulfate. The results were characterized by XRD, TGA and elemental analysis. The results showed that as the temperature rises the magnesium extraction rate first increases and then decreases. Optimal experimental conditions are calcination temperature of 600℃, calcination time of 1.5 h, the amount of sodium added of 20%, under which condition a magnesium extraction rate of 85.16% can be achieved.展开更多
The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequen...The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancerl adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein mpitive. Seven cases were found to have mutations by PCRSSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be opitive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8)were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%,4/5). ffequencing analysis on two specimens revealed two hotspot mutations. In codon 234,TAC for tyrooin was mutated to AAC fOr aspar8gine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. ln conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.展开更多
Introduction: Mesothelioma is a malignant conditioncaused by exposure to asbestos that has typically a long latency period. The disease is usually found in the later stages when the prognosis is poor despite treatment...Introduction: Mesothelioma is a malignant conditioncaused by exposure to asbestos that has typically a long latency period. The disease is usually found in the later stages when the prognosis is poor despite treatments. Objective: To report a mesothelioma found in a laboratory. Method: We reported here a case of a 60 year-old-man who was exposed to asbestos fibres-first when he studied in a laboratory at high school and then he had exposure over the following years until graduating with a master’s degree, but he did not have exposure after it. He was a smoker as a teenager and he gave up after 23 years. His first symptom was coughing at night which lasted for several months until the pleural fluid was discovered on the right side of thorax. This triggered investigations led to a diagnosis of mesothelioma. According to a systematic literature search, mesothelioma has not been reported previously in relation to asbestos exposure in laboratory work. An operation was carried out, but the patient refused to take chemotherapy due to the limited benefits that could be expected from it. Instead, he opted for a Budwig protocol. The case has had a good quality of life since the surgery, and did not have any medications. He has regular check-ups at the hospital. Conclusion: Our study has shown that mesothelioma is not only a risk to people directly exposed to asbestos, but also indirectly from, for example, laboratory work. People should avoid exposure to asbestos in daily life.展开更多
文摘We have previously evaluated asbestos exposure associated with various maintenance procedures on light aircraft. The purpose of this study was to evaluate asbestos exposure during engine maintenance on light aircraft. This test was designed to evaluate the potential for asbestos exposure to mechanics and others who remove asbestos-containing engine gaskets from reciprocating style aircraft engines. Utilized in this test was an air cooled, horizontally opposed, aviation gasoline burning engine, assembled during 1986 and operated intermittently up into 2015, having accumulated 1680 hours run time. Nearly 75% of the asbestos-containing gaskets installed during 1986 were still in place at the time of testing. Chrysotile asbestos contents of such gaskets ranged from 55% to 60% by area, for those of sheet style and 5% by area, for the spiral wound metal/asbestos style. Despite the levels of effort required to effect gasket removals, the professional aircraft mechanic was not exposed to airborne asbestos fibers at the lower limits of sampling and analytical detection achieved;all of which were substantially less than the current Occupational Safety and Health Administration Permissible Exposure Limits for asbestos. The results of this testing indicate an absence of gasket related asbestos exposure risk to mechanics who work with light aircraft engines, including those having asbestos-containing gaskets. These results are consistent with the findings of Mlyarek and Van Orden who studied the asbestos exposure risk occasioned during overhaul of larger radial style reciprocating aircraft engines [1].
文摘Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable products were insulated using chrysotile asbestos. This research was undertaken to determine the asbestos fiber exposure risks associated with power stripping machinery to remove asbestos-containing insulation materials from electrical wire or cable. A Rigby Machinery, Inc., Model 4H electric powered wire/cable insulation stripping machine was acquired along with approximately 42 m of asbestos insulated cable. During two separate, but nearly identical, test sessions, a laborer used the wire stripper to remove the asbestos-containing insulation from the subject cable. This work took place within a closed metal building with a total interior volume of 2500 m3. Industrial hygiene personal and area air samples were collected for airborne fibers throughout all wire stripping periods. Collected air samples were analyzed using phase contract microscopy (PCM) and transmission microscopy (TEM). The results of analysis using PCM for personal samples (n = 3) taken during periods of continuous cable stripping activity showed test period airborne fiber exposures ranging from 0.034 to 0.068 (mean 0.056 f/cc). Follow-up analysis of these personal samples using TEM indicated asbestos adjusted PCM exposures ranging from 0.017 to 0.045 (mean 0.033 f/cc). Area air samples taken at distances ranging from 2 to 9 meters from the wire stripper (n = 16) showed asbestos adjusted PCM concentrations ranging from less than 0.0001 to 0.041 f/cc (mean 0.007 f/cc). The process of power stripping asbestos-containing insulation from electrical wires and cables can cause exposure to airborne asbestos fibers. However, the levels of such exposure are not expected to exceed the current occupational exposure limits for asbestos of 0.1 f/cc as an 8-hr TWA or 1.0 f/cc averaged over a 30-minute exposure period.
文摘Asbestos containing materials (ACM) have been used for decades in research laboratory products including gloves, tong sleeves, Transite board, and other materials. These materials typically contain chrysotile asbestos with concentrations ranging up to 80%. The objective of this research was to evaluate asbestos exposure from gloves, tong sleeves, and Transite board with simulated laboratory use. An environmental chamber was used to simulate laboratory application of the products. Bulk samples of various products were tested before and after use. Personal breathing zone air samples as well as one cumulative air sample were collected during testing and followed the National Institute for Occupational Safety and Health (NIOSH) 7400/7402 methodologies. Phase contrast microscopy (PCM) and transmission electron microscopy (TEM) were used for sample analyses. Analysis of air samples using PCM, showed airborne fiber concentrations as high as 0.058 f/cc during use of tongs fitted with asbestos sleeves. Further analysis using TEM showed that the highest airborne fiber concentration was 0.0036 f/cc. Manipulation of Transite board resulted in 8-hour time-weighted-average (TWA) asbestos levels as high as 0.02 f/cc. Testing of various asbestos containing materials used in research laboratories indicate low potential for asbestos fiber exposures.
基金financial support from University of Calabria and from“Piano Triennale della Ricerca(2017-2020)”(Universitàdi Catania,Dipartimento di Scienze Biologiche,Geologiche e Ambientali),scientific responsible Rosalda Punturo.
文摘In the last decades,it has been widely demonstrated the risk to human health related to asbestos fibres exposure.Many studies have mainly focused on the mineralogical and geochemical characterization of ophiolites(i.e.,serpentinite and metabasite rocks)since they are the main lithotypes associated with Naturally Occurring Asbestos(NOA).Nevertheless,derivative soil from these rocks inherits the mineralogical and geochemical composition of bed rock and may contain hazardous fibres,thus making its examination necessary as well.This paper provides a summary of asbestos-containing soils investigation worldwide with the purpose of providing an overview of the data obtained so far.To this aim,the most relevant available literature,testifying the presence of fibrous minerals in soils have been considered.This allowed the global territory mapping in order to depict the distribution of natural asbestos in soils worldwide.
基金This study was supported by a grant from National Natural Science Foundation of China (No. 30100147).
文摘Objective To compare the asbestos-induced DNA damage and repair capacities of DNA damage between 104 asbestosexposed workers and 101 control workers in Qingdao City of China and to investigate the possible association between polymorphisms in codon 399 of XRCC1 and susceptibility to asbestosis. Methods DNA damage levels in peripheral blood lymphocytes were determined by comet assay, and XRCC1 genetic polymorphisms of DNA samples from 51 asbestosis cases and 53 non-asbestosis workers with a similar asbestos exposure history were analyzed by PCR/RFLP. Results The basal comet scores （3.95±2.95） were significantly higher in asbestos-exposed workers than in control workers （0.10±0.28）. After 1 h H2O2 stimulation, DNA damage of lymphocytes exhibited different increases. After a 4 h repair period, the comet scores were 50.98±19.53 in asbestos-exposed workers and 18.32±12.04 in controls. The residual DNA damage （RD） was significantly greater （P〈0.01） in asbestos-exposed workers （35.62%） than in controls （27.75%）. XRCC1 genetic polymorphism in 104 asbestos-exposed workers was not associated with increased risk of asbestosis. But compared with polymorphisms in the DNA repair gene XRCC1 （polymorphisms in codon 399） and the DNA damage induced by asbestos, the comet scores in asbestosis cases with Gin/Gin, Gln/Arg, and Arg/Arg were 40.26±18.94, 38.03±28.22, and 32.01±11.65, respectively, which were higher than those in non-asbestosis workers with the same genotypes （25.58±11.08, 37.08±14.74, and 29.38±10.15）. There were significant differences in the comet scores between asbestosis cases and non-asbestosis workers with Gin/Gin by Student＇s t-test （P〈0.05 or 0.01）. The comet scores were higher in asbestosis workers with Gin/Gin than in those with Arg/Arg and in non-asbestosis workers exposed to asbestos, but without statistically significant difference. Conclusions Exposure to asbestos may be related to DNA damage or the capacity of cells to repair H2O2-induced DNA damage. DNA repair gene XRCC 1 codon 399 may be responsible for the inter-individual susceptibility in DNA damage and repair capacities.
基金Funded by a grant(12High-tech C20)from High-tech Urban Development Program from by Ministry of Land,Transport and Maritime Affairs of Korea
文摘The toxicity of asbestos has been constantly an active research topic.Although asbestos has lots of advantages owing to its stable physicochemical properties and economic characteristics,nations enforce policies prohibiting or limiting its use because of its critical impact on human health.Especially in Korea 96% of imported asbestos are slate construction materials and with the influence of Saemaul movement,thatched roofs have been drastically replaced with slate roofs.Efforts to know the distribution characteristics of extensively used asbestos cement slates and to find out the removal method that suits the distribution characteristics are still in an insufficient state.The purpose of this work was to probe into the distribution of asbestos cement slate buildings in Korea and provide basic data of distribution characteristics for policy making in which consideration of the differences between rural and urban regions is necessary based on findings of the studies so far.It is considered helpful in many ways to solving asbestos cement slate related problems in countries where asbestos usage is increasing even after the 2000s including China.
文摘Tremolite group minerals could be present in the aggregate used as filler in the mix asphalt floor in the road surfaces and are subject to wear for vehicular traffic and materials ageing.Dust produced by the degradation of asphalt surfaces can disperse tremolite group minerals present in road paving causing exposure by asbestos fiber to an increasing number of people and animals.In recent years,attention has been focused on naturally occurring asbestos(NOA)as the greatest frequency of lung cancer has been observed in environments characterized by rocks and soils rich in Tremolite that characterize asbestos minerals.Asphalt samples object of this study were collected in a motorway segment of the Lombardia Region(north of Italy)for an exposure assessment research on road paving workers.The evaluation was performed using a metrological approach based on petrographic and mineralogical analyses in order to reduce the epidemiologic risks and to define the best treatment strategies on waste management with sustainable costs in fulfilment of Council Directive 67/548/EEC(1967)and EC Regulation 1272/2008(2008)(Paglietti et al.,2016).The fibers are generally not broken down to other compounds in the environment,but asbestos hazard could be related to the occurrence of tremolite fiber in road paving arises when natural weathering processes(e.g.,erosion)or human activities(e.g.,continuous passage of motorized vehicles)separate and break down the fibers,which could be lost into the environment as airborne and easily penetrate into the human respiratory tract(Punturo et al.,2019).Despite this,this work is not an epidemiological risk analysis but obtained data could be useful to other specialists to define the exposure risks.
基金supported by a grant from Pneumoconiosis Compensation Funding Board,Hong Kong,SAR,China
文摘In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile,a fixed cohort of 1932 workers in chrysotile asbes-tos mine was established in 1981 and followed till June 1,2010.Information on vital status,cause of death and smoking habits was collected.The workers were divided into two groups according to their exposure status.The exposed group was composed of frontline workers who worked directly on mining or processing asbestos products.The control group consisted of those who were not directly exposed to asbestos in their work.Standardized mortality ratio (SMR) was calculated according to Chinese national death rates.Cox proportional hazards model was applied to estimate the adjusted relative risks of deaths from major causes in exposed and control groups.The results of this study showed that main causes of mortality were malignant neoplasm,cardiovascular disease,cerebrovascular disease and respiratory disease for chrysotile miners.The mortality rate was 939.20 per 100 000 person-years for workers.The SMR for all causes of death was 1.46 in the cohort.Statistically significant mortality excesses were found for lung cancer (SMR=1.51),pulmonary heart disease (SMR=2.70),respiratory disease (SMR=1.93),asbestosis (SMR=9.62),and accident (SMR=1.59).The mortalities from malignant neo-plasm,lung cancer,cerebrovascular disease and digestive disease in the exposed group were signifi-cantly higher than those in the control group.The findings indicate that chrysotile exposure is a risk factor for lung cancer,respiratory disease,cerebrovascular disease and digestive disease.
文摘Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating （patina） with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART^TM testers. Heterotrophic aerobic bacteria （HAB） and slime forming bacteria （SLYM） dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.
基金This study was partially supported by a grant from the Research Foundation in the year of 1997 of the Japan-China Medical Association (No. 001).
文摘Objective To determine whether there was excessive risk of cancer among workers exposed to chrysotile fiber alone by applying a meta-analysis technique. Methods All data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile were incorporated into meta-analysis. Pooled standardized mortality ratios (SMRs) and their corresponding 95% confidence intervals (CIs) for main cancer sites were calculated using two approaches of unweighted ratio and random effect model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test. The dose-response effect as reflected in the percentage of all deaths due to mesothelioma served as a proxy measure of chrysotile exposure. Results A cohort of twenty six workers exposed to chrysotile alone was summarized. The significantly elevated meta-SMRs for all deaths (1.27), all cancers (1.28), cancers of respiratory organs (2.51), cancers of lung (2.35) and cancers of stomach (1.24) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.55), asbestos product manufacturers (3.30), miners and millers (2.24), cement product workers (1.22), and for stomach cancer among asbestos product manufacturers (1.49). Meta-SMRs for cancers at other sites were not significant. Meta-SMR for lung cancer showed an increasing trend with an elevated percentage of all deaths from mesothelioma, but no such trend for stomach cancer. Conclusion There are excessive risks of lung cancer and mesothelioma among workers exposed to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.
文摘The cementitiousness of dehydration asbestos tailings(serpentine, 3MgO.2SiO 2.2H 2O) in different conditions was studied. The result shown that dehydration asbestos tailings have better cementitiousness in certain condition and it can be used in building materials industry. It was also found that MgO powder, fly ash or quick lime can improve regularly the cementitiousness of asbestos tailings.
文摘In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observcd that the incidcnce (16.0%) of lung carcinomas was lowel, and the survival time (376 days) of the first case of carcinoma and the mean survival time (758 days) of the rats with carcinoma were higher in the group of rats drinking 2% green tea extract for life than in the positive group (without drinking green tea extract). The mortality ratio (0.5047) was smaller in the cxperimental group than in the positive control group, and the survival curve of the experimental group significantly raised up, in comparison with the positive group.
文摘The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption peaks in the 4000 - 400 cm-1 region of the infrared spectrum. In the present work, we compare the accuracy and precision of two analytical procedures (the Linear Calibration Curve Method and the Method of Addition) for the quantitative determination of asbestos in a host matrix. We have found that, providing careful samples preparation, both techniques quantify the asbestos content at the level of few micrograms with good precision. Due to less expensive equipment requirements and shorter analysis time, FT-IR can be a competitive analytical technique in the characterization of asbestos containing material with the respect to diffractometry or electron microscopy.
文摘The main components of the hydrochloric acid leachate of the asbestos tailings were MgCl<sub>2</sub>,FeCl<sub>3</sub>, FeCl<sub>2</sub>,AlCl<sub>3</sub> and surplus acid.An experimental study on optimization of purification process of acid leachate focusing on preparing magnesium hydroxide solution was carried on.The main approach used in the experiment was to oxidize Fe<sup>2+</sup>to Fe<sup>3+</sup>,and then purified it by the precipitation reaction with alkali.
基金Funded by the Western Region Transport Development Science and Technology Program (200731800003)
文摘To use many asbestos tailings collected in Ya-Lu highway,and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures,and properties of some asphalt mixtures were evaluated as well.X-ray diffraction （XRD）,X-ray fluorescent （XRF）,and atomic absorption spectrophotometry （AAS） were employed to determine the solid waste content of copper,zinc,lead,and cadmium.Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material.Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications.No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23,which is help to the adhesion with asphalt in the asphalt concrete.When compared with basalt,high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates.In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number （BPN） coefficient of surface.
文摘The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had been used to research the influence of the reaction temperature on the phase, structure and morphology of the product during the preparation of the basic magnesium carbonate. The results indicates that the product was needle-like magnesium carbonate hydrate at the lower reaction temperature (from 35 ℃ to 65℃), with the increase of the reaction temperature (75 ℃ to 95 ℃ ), the needle-like magnesium carbonate hydrate (MgCO3·xH2O) transformed to flake-like basic magnesium carbonate [Mg5(CO3)4(OH)2·4H2O], the reaction temperature plays an important role in the preparation of flake-like basic magnesium carbonate, the preparation of flake-like basic magnesium carbonate was a nucleation-dissolution-recrystallization growth mechanism process.
文摘In this paper the method of chemical vapor depostion is used to discuss the principle and method of foam asbestos, a new heat insulation material whose synthetical properties are improved remarkably after modifying. It becomes one of the best heat insulation materials and, a kind of safety, no social effects of pullution material to a great extent.
文摘The research involves the calcination of Sichuanshimian asbestos tailings with ammonium sulfate in order to extract magnesium. This paper studies the effect of different calcination conditions on the magnesium extraction rate, and it also studies the mechanism of calcination of asbestos tailings mixed with ammonium sulfate. The results were characterized by XRD, TGA and elemental analysis. The results showed that as the temperature rises the magnesium extraction rate first increases and then decreases. Optimal experimental conditions are calcination temperature of 600℃, calcination time of 1.5 h, the amount of sodium added of 20%, under which condition a magnesium extraction rate of 85.16% can be achieved.
文摘The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancerl adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein mpitive. Seven cases were found to have mutations by PCRSSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be opitive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8)were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%,4/5). ffequencing analysis on two specimens revealed two hotspot mutations. In codon 234,TAC for tyrooin was mutated to AAC fOr aspar8gine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. ln conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.
文摘Introduction: Mesothelioma is a malignant conditioncaused by exposure to asbestos that has typically a long latency period. The disease is usually found in the later stages when the prognosis is poor despite treatments. Objective: To report a mesothelioma found in a laboratory. Method: We reported here a case of a 60 year-old-man who was exposed to asbestos fibres-first when he studied in a laboratory at high school and then he had exposure over the following years until graduating with a master’s degree, but he did not have exposure after it. He was a smoker as a teenager and he gave up after 23 years. His first symptom was coughing at night which lasted for several months until the pleural fluid was discovered on the right side of thorax. This triggered investigations led to a diagnosis of mesothelioma. According to a systematic literature search, mesothelioma has not been reported previously in relation to asbestos exposure in laboratory work. An operation was carried out, but the patient refused to take chemotherapy due to the limited benefits that could be expected from it. Instead, he opted for a Budwig protocol. The case has had a good quality of life since the surgery, and did not have any medications. He has regular check-ups at the hospital. Conclusion: Our study has shown that mesothelioma is not only a risk to people directly exposed to asbestos, but also indirectly from, for example, laboratory work. People should avoid exposure to asbestos in daily life.
