Asbestos Exposure during Gasket Removal from Aircraft Engine

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].

Assessment of Asbestos Exposure Associated with a Brake Grinder

The wear patterns for drum-style automotive brakes tend to enlarge internal drum diameters. Such enlargement is most profound when used brake drums are machined to restore the metal friction surfaces. Specialized arc grinding machinery has been used to match replacement shoe-style brake friction materials to enlarged drums. The process of arc grinding removes friction material, thereby producing dust. When organic-style friction materials contained asbestos, use of arc grinding machinery posed an asbestos fiber exposure risk to operators and proximate personnel. The manufacturers of arc grinding machinery have incorporated local exhaust ventilation systems designed to capture and remove this dust at the point of grinding contact and propel this dust into collection bags or other systems. This research was designed to evaluate the dust capture and retention characteristics of a specific arc grinder product, when used to custom grind asbestos-containing brake friction materials. A Bear Model 1420 automotive brake shoe arc grinder was the subject of this study. During two separate but consecutive test sessions, newly relined sets of shoe-style automobile brake friction materials were precision ground. Both area and personal air samples were collected throughout each testing session. This work took place within a closed and unventilated metal building, with total interior volume of 2500 m3. Collected air samples were analyzed using phase contrast microscopy (PCM) and transmission electron microscopy (TEM). The results of analysis using PCM for personal samples (n = 6) ranged from <0.044 to 0.055 fibers per cc (f/cc) (mean 0.05). Follow-up analysis of these personal samples using TEM indicated asbestos-adjusted PCM exposures ranging from <0.0074 to 0.055 f/cc (mean ≤ 0.041). Area air samples, taken at distances ranging from 1.5 to 9 meters from the arc grinder (n = 12), showed asbestos-adjusted PCM concentrations ranging from <0.0075 to 0.041 f/cc (mean ≤ 0.017). The process of custom arc grinding shoe-style, asbestos-containing brake friction materials can cause exposure to airborne asbestos fibers. However, when done using properly equipped arc grinding machines, such exposures are not expected to exceed the current occupational exposure limits for asbestos of 0.1 f/cc 8-hour time-weighted average (TWA) or 1.0 f/cc 30-minute average.

Analysis of Mortality in Chrysotile Asbestos Miners in China

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.

Cohort Studies on Cancer Mortality Among Workers Exposed Only to Chrysotile Asbestos: a Meta-analysis

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.

Association Between Polymorphisms of DNA Repair Gene XRCC1 and DNA Damage in Asbestos-Exposed Workers

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.

Study on the cementitiousness of asbestos tailings

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.

Comparison between Two FT-IR Spectroscopy Analytical Procedures for Micrograms Determination of Asbestos Species in Bulk Materials

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.

Inhibitory Effect of Green Tea Extract on the Carcinogenesis Induced by Asbestos Plus Benzo(a)pyrene in Rat

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.

Process Optimization on Purification of Hydrochloric Acid Leachate of Asbestos Tailings

The main components of the hydrochloric acid leachate of the asbestos tailings were MgCl2,FeCl3, FeCl2,AlCl3 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 Fe2+to Fe3+,and then purified it by the precipitation reaction with alkali.

Comparison of distribution characteristics of asbestos cement slates in rural and urban regions of Korea

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.

Study on the Effect and Mechanism of Calcination of Asbestos Tailings Mixed with Ammonium Sulfate

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.

PRINCIPLE AND METHOD OF CVD MODIFIED TECHNIQUE OF FOAM ASBESTOS

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.

Asbestos Tailings as Aggregates for Asphalt Mixture

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.

Prepartion of Flake-Like Basic Magnesium Carbonate from the Ammonium Sulfte Leaching Liquid of Asbestos Tailing

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.

Power Stripping of Asbestos-Containing Insulation from Electrical 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.

Evaluation of Asbestos Exposure Associated with Research Laboratories

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.

Mesothelioma in relation to asbestos exposure in laboratory work

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.

The Method of Testing for Asbestos in Electronic and Electric Products through Polarizing Microscope and X-Ray Diffraction

Asbestos is widely applied in such sectors as manufacturing automobiles, tractors, chemical industrial equipment, and electric equipment. Asbestos fiber is harmful to human health. Therefore, the technology of testing for asbestos in products is especially important. At present, in our country’s national specifications, there is no determination method or specification that is applicable to the asbestos in electronic and electric products. In this article, the components of asbestos in electronic and electric products are identified using the method of combining polarizing microscope with X-ray diffractometer. This method is simple, fast, highly reliable, and suitable to be widely adopted.

Poly (ethylene terephthalate) synthesis with catalysts derived from chrysotile asbestos

The chrysotile asbestos was converted to the forsterite-type compounds by calcination at 740 and 800oC (F7-740 and F7-800), which were used as a catalyst for the polycondensation of bis(hydroxyethyl) terephthalate affording poly (ethylene terephthalate). The obtained forsterite-type compounds did not show any catalytic activity. However, the products obtained by simply treating them with acetic acid significantly promoted the polymerization that produced a THFinsoluble polymer. It was found that the polymer prepared with the acetic acid-treated F7-740 at 160oC for 2 h showed a 93% yield and the number average molecular weight of 6.4 × 103. The observed catalytic activity was higher than that for the acetic acid-treated magnesium oxide, as well as the typical polycondensation catalysts, such as magnesium acetate and antimony oxide.

Determination of Levels of Asbestos Fiber in Cosmetic and Non-Cosmetic Products Sold within Enugu Metropolis—Enugu State, Nigeria

Studies were carried out to determine asbestos fiber levels in cosmetic (talc powder) and non-cosmetic (gauze pad, plastic filler and ceiling tiles) products sold in market outlets within Enugu, metropolis, Enugu State, Nigeria, using standard established procedures. The samples were pretreated based on its physical make-up and the asbestos fiber levels determined using scanning electron microscopy (SEM) with energy dispersing spectroscopy techniques. The mean range of asbestos fiber was, 0.02 - 0.06;0.01 - 0.05;0.01 - 0.04 and 0.03 - 0.06 f/cc for talc powder, gauze pads, plastic filler and ceiling tile samples respectively. The mean levels of asbestos fibers in the studied samples were within the recommended permissible limits. The samples contain asbestos fiber in the following decreasing order: ceiling tiles > talc powders > gauze pads > plastic fillers. Asbestos fiber was found present in the investigated local and foreign items sold in market outlets within the metropolis. This study shows that despite the ban on the use of asbestos in the industry in the manufacture of items meant for human use, its enforcement appears weak and lethargic and this could portend health danger especially in the use of produced items with high asbestos fiber friability such as talc powder.