Measurement and removal of asbestos in residential dwellings to be demolished-urban transformation experience in Izmir, Turkey.

Asbestos has been used extensively in the construction industry for its superior insulation properties before its health hazards were discovered and its use eventually banned. It is likely that many residential buildings built before the 2000s in Turkey contain asbestos. Therefore, it is important to raise awareness of the potential danger of asbestos exposure during demolition work and to identify asbestos-containing materials and ensure their safe removal and disposal. This study is executed to determine the residential dwellings containing asbestos in Izmir, Turkey. The research included field studies to determine asbestos presence in the buildings that were damaged during the 2020 earthquake. Air measurements and bulk samples were taken from 50 buildings that would go through the demolition process. Eleven buildings were found to contain asbestos which corresponds to 22%. The detected asbestos type was 60% chrysotile (white asbestos). Results could be helpful for future demolition work, which are conducted in the same region that includes buildings with similar properties. Also, it is expected that the database created for this study could be useful in other studies in Turkey, where accurate statistical data related with asbestos measurements is essentially non-existent.

Quantitative Assessment of Asbestos Fibers in Abdominal Organs: A Scoping Review.

BACKGROUND: Quantification of asbestos fibers has been mainly performed in the lung but rarely in other organs. However, this may be relevant to understanding better translocation pathways and the oncogenic effects of asbestos on the human body. Electron microscopy is the best technology available to assess the type of fiber, dimensions, and distribution of asbestos fibers in different tissues and as a biomarker of cumulative dose. OBJECTIVES: This scoping review aims to summarize the findings of the studies in which asbestos fibers have been quantified by electron microscopy, occasionally associated with X-ray microanalysis, in normal and pathological tissue of ten abdominal organs. METHODS: A scoping review has been performed by searching articles that quantified asbestos fibers in abdominal organs by electron microscopy (Scanning- SEM or Transmission- TEM). RESULTS: The 12 selected studies included 204 cases, and 325 samples were analyzed. The colon and rectum, kidney, bladder, and abdominal lymph nodes were the organs with at least ten samples available with quantification of asbestos fibers. Asbestos fibers were detected in all the abdominal organs considered: the highest value (152,32 million fibers per gram of dry tissue) was found in the colon and was identified using STEM with EDS. CONCLUSION: The studies included were heterogeneous in terms of exposure and cases, type of samples, as well as analytical techniques, therefore we cannot confirm a specific pattern of distribution in any organ, based on the low homogeneity of the exposure status. The colon is the organ in which the number of fibers is the highest, probably because of exposure arising from both internal distribution of inhaled fibers and ingestion. Additional studies of the number of asbestos fibers in abdominal organs should be made to achieve better representativity.

An updated evaluation of reported no-observed adverse effect levels for chrysotile, amosite, and crocidolite asbestos for lung cancer and mesothelioma.

This analysis updates two previous analyses that evaluated the exposure-response relationships for lung cancer and mesothelioma in chrysotile-exposed cohorts. We reviewed recently published studies, as well as updated information from previous studies. Based on the 16 studies considered for chrysotile (<10% amphibole), we identified the "no-observed adverse effect level" (NOAEL) for lung cancer and/or mesothelioma; it should be noted that smoking or previous or concurrent occupational exposure to amphiboles (if it existed) was not controlled for. NOAEL values ranged from 2.3-<11.5 f/cc-years to 1600-3200 f/cc-years for lung cancer and from 100-<400 f/cc-years to 800-1599 f/cc-years for mesothelioma. The range of best-estimate NOAELs was estimated to be 97-175 f/cc-years for lung cancer and 250-379 f/cc-years for mesothelioma. None of the six cohorts of cement or friction product manufacturing workers exhibited an increased risk at any exposure level, while all but one of the six studies of textile workers reported an increased risk at one or more exposure levels. This is likely because friction and cement workers were exposed to much shorter chrysotile fibers. Only eight cases of peritoneal mesothelioma were reported in all studies on predominantly chrysotile-exposed cohorts combined. This analysis also proposed best-estimate amosite and crocidolite NOAELs for mesothelioma derived by the application of relative potency estimates to the best-estimate chrysotile NOAELs for mesothelioma and validated by epidemiology studies with exposure-response information. The best-estimate amosite and crocidolite NOAELs for mesothelioma were 2-5 f/cc-years and 0.6-1 f/cc-years, respectively. The rate of peritoneal mesothelioma in amosite- and crocidolite-exposed cohorts was between approximately 70- to 100-fold and several-hundred-fold higher than in chrysotile-exposed cohorts, respectively. These findings will help characterize potential worker and consumer health risks associated with historical and current chrysotile, amosite, and crocidolite exposures.

Assessment of worst-case potential airborne asbestos exposure associated with the use of cosmetic talc: application of an exponential decay model.

Talc is used in cosmetic products to confer desirable properties, such as moisture absorption and smooth texture, to the finished products. Concerns have been raised about the potential presence of asbestos in products containing cosmetic talc. Reconstruction of potential asbestos exposure from the use of cosmetic talc products (assuming a trace level of asbestos) requires consideration of consumer use patterns. Although application generally only lasts seconds, exposure theoretically may continue if the consumer remains in the immediate vicinity. Most published exposure measurements have not adequately characterized the potential for continued exposure. In this analysis, estimates and measurements of airborne asbestos fiber concentrations associated with cosmetic talc use from 10 published studies were used as inputs to an exponential decay model to estimate "worst-case" exposure during and following application. The resulting geometric mean 30-min time-weighted average (TWA) concentrations were 0.006 f/cc for both puff and shaker application, for diapering, 0.0001 f/cc (adult applying baby powder) and 0.0002 f/cc (infant), and for makeup application, 0.0005 f/cc. Application of an exponential decay model to measured or estimated asbestos concentrations associated with the use of cosmetic talc products yields a conservative means to comprehensively reconstruct such exposures. Moreover, our results support that, if a cosmetic talc powder product contained a trace level of asbestos fibers, the "worst-case" airborne asbestos exposure associated with its application is low.

Lung asbestos fiber burden analysis: effects of the counting rules for legal medicine evaluations.

OBJECTIVES: The work shows the effect of counting rules, such as analysis magnification and asbestos fiber dimension to be count (with length ≥5 µm or also asbestos fibers with length <5 µm) in the lung asbestos fiber burden analysis for legal medicine evaluations. METHODS: On the same lung tissue samples, two different analyses were carried out to count any asbestos fibers with length ≥1 µm and with length ≥5 µm. Results of the amphibole burden of the two analyses were compared by linear regression analysis on log10-transformed values. RESULTS: The analysis should be carried out at an appropriate magnification and on samples prepared in such a way as they allow the counting of very fine fibers. If the analysis is limited to the asbestos fibers with length ≥5 µm, there is a high risk of not detecting possible residual chrysotile fiber burden and thinner crocidolite asbestos fibers. CONCLUSIONS: On average we estimated that 1 amphibole fiber with length ≥5 µm corresponds to ∼8 amphibole fibers with length ≥1 µm in the lung. The values of the Helsinki criteria should be updated taking this into account.

Expression of stathmin in asbestos-like fibers-induced mesothelioma: A preliminary report.

BACKGROUND: Mesothelioma is strongly associated with exposure to asbestos fibers, however, recent studies have also linked exposure to "naturally occurring asbestos" fibers with this disease. Fluoro-edenite, a silicate mineral found in the southeast of Biancavilla (Sicily, Italy), has been identified as a potential risk factor for mesothelioma. Unfortunately, this cancer often has a poor prognosis, and current diagnostic and prognostic biomarkers are inadequate. Histological subtype, gender, and age at diagnosis are the most significant parameters for mesothelioma. Stathmin, a cytosolic protein that regulates cell growth and migration and is overexpressed in many human malignancies, has not yet been linked to mesothelioma survival or clinical-pathological variables. AIM: The aim of this study was to investigate the immunohistochemical expression of stathmin in ten mesothelioma tissue samples with available clinical and follow-up data. MATERIAL AND METHODS: Paraffin-embedded tissue samples from ten mesothelioma patients were processed for immunohistochemical analyses to evaluate stathmin expression. RESULTS: Our findings suggest that stathmin overexpression is associated with shorter overall survival in patients with mesothelioma. Furthermore, stathmin expression was significantly correlated with the survival time of mesothelioma patients. CONCLUSION: Our results suggest that stathmin expression may serve as a potential prognostic biomarker for mesothelioma. This biomarker could be used to promptly identify patients with poor prognosis and to guide clinicians in the selection of treatment options.

Natural mineral fibers: conducting inhalation toxicology studies - part A: Libby Amphibole aerosol generation and characterization method development.

BACKGROUND: Asbestos has been classified as a human carcinogen, and exposure may increase the risk of diseases associated with impaired respiratory function. As the range of health effects and airborne concentrations that result in health effects across asbestos-related natural mineral fiber types are not fully understood, the National Institute of Environmental Health Sciences has established a series of research studies to characterize hazards of natural mineral fibers after inhalation exposure. This paper presents the method development work of this research project. RESULTS: A prototype nose-only exposure system was fabricated to explore the feasibility of generating natural mineral fiber aerosol for in vivo inhalation toxicity studies. The prototype system consisted of a slide bar aerosol generator, a distribution/delivery system and an exposure carousel. Characterization tests conducted using Libby Amphibole 2007 (LA 2007) demonstrated the prototype system delivered stable and controllable aerosol concentration to the exposure carousel. Transmission electron microscopy (TEM) analysis of aerosol samples collected at the exposure port showed the average fiber length and width were comparable to the bulk LA 2007. TEM coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis further confirmed fibers from the aerosol samples were consistent with the bulk LA 2007 chemically and physically. CONCLUSIONS: Characterization of the prototype system demonstrated feasibility of generating LA 2007 fiber aerosols appropriate for in vivo inhalation toxicity studies. The methods developed in this study are suitable to apply to a multiple-carousel exposure system for a rat inhalation toxicity testing using LA 2007.

An investigation of the internal morphology of asbestos ferruginous bodies: constraining their role in the onset of malignant mesothelioma.

BACKGROUND: Asbestos is a fibrous mineral that was widely used in the past. However, asbestos inhalation is associated with an aggressive type of cancer known as malignant mesothelioma (MM). After inhalation, an iron-rich coat forms around the asbestos fibres, together the coat and fibre are termed an "asbestos ferruginous body" (AFB). AFBs are the main features associated with asbestos-induced MM. Whilst several studies have investigated the external morphology of AFBs, none have characterised the internal morphology. Here, cross-sections of multiple AFBs from two smokers and two non-smokers are compared to investigate the effects of smoking on the onset and growth of AFBs. Morphological and chemical observations of AFBs were undertaken by transmission electron microscopy, energy dispersive x-ray spectroscopy and selected area diffraction. RESULTS: The AFBs of all patients were composed of concentric layers of 2-line or 6-line ferrihydrite, with small spherical features being observed on the outside of the AFBs and within the cross-sections. The spherical components are of a similar size to Fe-rich inclusions found within macrophages from mice injected with asbestos fibres in a previous study. As such, the spherical components composing the AFBs may result from the deposition of Fe-rich inclusions during frustrated phagocytosis. The AFBs were also variable in terms of their Fe, P and Ca abundances, with some layers recording higher Fe concentrations (dense layers), whilst others lower Fe concentrations (porous layers). Furthermore, smokers were found to have smaller and overall denser AFBs than non-smokers. CONCLUSIONS: The AFBs of smokers and non-smokers show differences in their morphology, indicating they grew in lung environments that experienced disparate conditions. Both the asbestos fibres of smokers and non-smokers were likely subjected to frustrated phagocytosis and accreted mucopolysaccharides, resulting in Fe accumulation and AFB formation. However, smokers' AFBs experienced a more uniform Fe-supply within the lung environment compared to non-smokers, likely due to Fe complexation from cigarette smoke, yielding denser, smaller and more Fe-rich AFBs. Moreover, the lack of any non-ferrihydrite Fe phases in the AFBs may indicate that the ferritin shell was intact, and that ROS may not be the main driver for the onset of MM.

Toxicological and epidemiological approaches to carcinogenic potency modeling for mixed mineral fiber exposure: the case of fibrous balangeroite and chrysotile.

CONTEXT: Excess mesothelioma risk was observed among chrysotile miners and millers in Balangero, Italy. The mineral balangeroite has been identified in an asbestiform habit from the Balangero chrysotile mine (Italy). Previous studies did not contain a detailed description of the fiber dimensions, thus limiting possible approaches to estimating their carcinogenic potential. OBJECTIVES: To reconstruct excess mesothelioma risk based on characteristics of mixed fiber exposure. METHODS: The lengths and widths of particles from a sample of balangeroite were measured by transmission electron microscopy (TEM). Statistical analysis and modeling were applied to assess the toxicological potential of balangeroite. RESULTS: Balangeroite fibers are characterized as asbestiform, with geometric mean length of 10 µm, width of 0.54 µm, aspect ratio of 19, and specific surface area of 13.8 (1/µm). Proximity analysis shows dimensional characteristics of balangeroite close to asbestiform anthophyllite. Modeling estimates the average potency of balangeroite as 0.04% (95% CI 0.0058, 0.16) based on dimensional characteristics and 0.05% (95% CI-0.04, 0.24) based on epidemiological data. The available estimate of the fraction of balangeroite in the Balangero mine is very approximate. There were no data for airborne balangeroite fibers from the Balangero mine and no lung burden data are available. All estimates were performed using weight fractions of balangeroite and chrysotile. However, based on reasonable assumptions, of the seven cases of mesothelioma in the cohort, about three cases (43%) can be attributed to fibrous balangeroite. CONCLUSION: The presence of different types of mineral fibers in aerosolized materials even in small proportions can explain observed cancer risks.

Closing the knowledge gap on the composition of the asbestos bodies.

Asbestos bodies (AB) form in the lungs as a result of a biomineralization process initiated by the alveolar macrophages in the attempt to remove asbestos. During this process, organic and inorganic material deposit on the foreign fibers forming a Fe-rich coating. The AB start to form in months, thus quickly becoming the actual interface between asbestos and the lung tissue. Therefore, revealing their composition, and, in particular, the chemical form of Fe, which is the major component of the AB, is essential to assess their possible role in the pathogenesis of asbestos-related diseases. In this work we report the result of the first x-ray diffraction measurements performed on single AB embedded in the lung tissue samples of former asbestos plant workers. The combination with x-ray absorption spectroscopy data allowed to unambiguously reveal that Fe is present in the AB in the form of two Fe-oxy(hydroxides): ferrihydrite and goethite. The presence of goethite, which can be explained in terms of the transformation of ferrihydrite (a metastable phase) due to the acidic conditions induced by the alveolar macrophages in their attempt to phagocytose the fibers, has toxicological implications that are discussed in the paper.

Manufactured doubt and the EPA 2020 chrysotile asbestos risk assessment.

While all forms of asbestos have been determined to be carcinogenic to humans by the International Agency for Research on Cancer (IARC) as well as other authoritative bodies, the relative carcinogenic potency of chrysotile continues to be argued, largely in the context of toxic tort litigation. Relatively few epidemiologic studies have investigated only a single form of asbestos; however, one study that included an asbestos textile plant located in Marshville, North Carolina that processed chrysotile asbestos was used by the United States Environmental Protection Agency (EPA) in 2020 to help inform the agency's chrysotile asbestos risk assessment. During the EPA proceedings toxic tort defense consultants submitted comments to the EPA docket and made public presentations asserting that the Marshville plant had processed amphibole asbestos types and should not be used for the chrysotile risk assessment. A detailed evaluation of defense consultant assertions and supporting information and a full assessment of the available information concerning asbestos types used at the Marshville plant was undertaken. The preponderance of evidence continues to support the conclusion that neither amosite nor crocidolite were likely to have been processed in the Marshville textile plant. Defense consultants' assertions about chrysotile use are not supported by the preponderance of evidence and constitute an example of manipulation of information to cast uncertainty and doubt rather than to seek truth and contribute to the body of scientific evidence.

Cancer risk assessment of exposure to asbestos during old building demolition.

BACKGROUND: Years ago, the use of asbestos in construction materials was common. Although asbestos has been recently banned in many countries, exposure to asbestos during old building demolition is not unexpected. OBJECTIVE: The aim of this study is to assess the concentration of exposure to asbestos and estimate its cancer risk among old building demolition workers. METHODS: In this study, personal air samples were collected during building demolition. The number of asbestos fibers in collected samples were determined according to the NIOSH-7400 standard method. Chemical compositions of fibers were assessed using scanning electron microscopy (SEM). The carcinogenic risk of exposure to asbestos was determined based on the recommended United State Environmental Protection Agency (USEPA) method and Monte-Carlo simulation used to estimate the probability of cancer. RESULTS: Chemical analysis confirmed the presence of asbestos in collected air samples, and 67% of counted fibers were asbestos. In a number of buildings, workers had exposed to asbestos that was higher than occupational exposure limit (0.10 f/ml). Results of cancer risk estimation showed that cancer risk were considerable among workers. CONCLUSION: Implementation of asbestos risk management program such as separation of asbestos containing material, personal protective equipment's and use of wet method in demolition could minimize asbestos exposure during old building demolition.

Characterizing Asbestos Hazard Emergency Response Act (AHERA) Compliance in New Jersey: 2008-2017.

CONTEXT: The Asbestos Hazard Emergency Response Act (AHERA) became a law in 1986, and the US Environmental Protection Agency (USEPA) was mandated to promulgate rules to regulate the inspection, management, and abatement of asbestos-containing building materials (ACBM) in schools. This study describes 10 years (2008-2017) of AHERA compliance site inspection data conducted by the New Jersey Department of Health (NJDOH). OBJECTIVES: To establish the level to which inspected NJ schools comply with AHERA regulations, to characterize compliance deficiencies including those that may lead to increased asbestos exposure risk to students and school employees, and to determine whether age, type, and geographic location of school impacted the likelihood of noncompliance. DESIGN: Information collected during 456 unique inspections between 2008 and 2017 was analyzed. SETTING AND PARTICIPANTS: Inspections were conducted at public and private schools in New Jersey. These included elementary, middle, and high schools, as well as charter and vocational/technical schools. MAIN OUTCOME MEASURES: Descriptive statistics and multiple logistic regression modeling of 3 factors, school type, geographical region, and school age. RESULTS: NJDOH inspectors found damage to friable ACBM in 50% (n = 229) of the schools and fiber release episodes in 27% of inspections (n = 121). The case of schools failing to attach warning labels on or immediately adjacent to ACBM was the most frequently noted compliance deficiency over the 10-year period. The modeling output showed that compliance was associated with the type of school and geographical region. CONCLUSIONS: Inspected schools during the 10-year period were in serious noncompliance with AHERA regulations. This included deficiencies that demonstrate a potential exposure to asbestos such as missing ACBM in management plans, damaged ACBM, lack of protection of short-term workers and custodial staff, and the identification of fiber release episodes. Modeling results of specific school characteristics can help direct limited resources to mitigate potential asbestos exposures.

Prevalence and Level of Occupational Exposure to Asbestos in Canada in 2016.

OBJECTIVE: Asbestos use has decreased over time but occupational exposure still exists today due to the presence of asbestos in older buildings. The objective of this study was to update CAREX Canada's prevalence of exposure estimate from 2006 to 2016, and to assess the level of occupational exposure by industry, occupation, province/territory, and sex. METHODS: Estimates by occupation, industry, province/territory, and sex were calculated using labor force data from the 2016 Census of Population and proportions of workers exposed by occupation and industry, which were previously developed for the 2006 estimates and updated here to reflect new knowledge and changes in exposures. Statistics Canada concordance tables were used to account for changes between the 2006 and 2016 job and industry coding systems. Expert assessment was used to qualitatively assign levels of exposure (low, moderate, or high) for each occupation and industry, with consideration of workers' proximity and access to asbestos-containing material, and the condition and content of asbestos. RESULTS: Approximately 235 000 workers are exposed to asbestos on the job in Canada. The majority of Canadian workers exposed to asbestos are male (89%). Only 5% of all exposed workers are in the high-exposure category, while most workers are in the low (49%) or moderate (46%) exposure categories. The construction sector and associated jobs (e.g. carpenters, trades helpers and laborers, electricians) accounted for the majority of exposed workers. CONCLUSIONS: Occupational exposure to asbestos continues to occur in Canada. Updating the prevalence of exposure estimate and adding exposure levels highlights the shift from high to lower-lever exposures associated with asbestos-containing materials remaining in the built environment.

Ecological and human health risk assessment of potentially toxic element contamination in waters of a former asbestos mine (Canari, Mediterranean Sea): implications for management.

Between 1948 and 1965, the Canari asbestos mine (Corsica, France) discharged 11 million tonnes of serpentinite rubble into the sea. This study, therefore, aims to assess the environmental and health risks associated with contamination of potentially toxic elements using bioindicators (seagrass and fish) in the areas bordering the former mine within the perimeter of the Cap Corse and Agriate Marine Natural Park. The results and multivariate statistical analyses of the potentially toxic elements, made it possible to identify a concentration gradient, a model of bioaccumulation, and the occurrence of different groups, thus reflecting a spatial variation of the contamination. These results indicate that the former asbestos mine can still be considered, 55 years after its closure, as a major source of Co, Cr, and Ni for marine ecosystems and still influences the quality of the coastal area today. Our study, therefore, indicates that the two most polluted sites (Albo and Negru) are the closest stations to the south of the old Canary asbestos mine. According to the Trace Elements Pollution Index (TEPI) values, 6 species were classified as having a high contamination level: Scorpaena notata (1.37), Scorpaena porcus (1.36), Sepia officinalis (1.27), Diplodus vulgaris (1.02), Spicara maena (0.95), and Mullus surmuletus (0.94). Regarding the potentially toxic elements measured in the edible tissues of fish, the concentrations were all below the regulatory thresholds and did not reveal any potential risk to human health (Cd, Cu, Fe, Pb, Se, Sn, Zn). This work provides new and useful information to improve the monitoring of the environmental quality of a region characterized by previous mining activity and to assess the potential risk to human health due to the consumption of fish. Beyond the purely scientific aspects, these results could serve as decision support at the regional level for the definition of long-term public policies.

Holton et al., Characterization of asbestos exposures associated with the use of facial makeups. Risk Analysis, 42, 2129-2139.

Holton and colleagues have performed a risk assessment after measuring asbestos released from several samples of facial makeup. Unfortunately, it is not possible to interpret or generalize their findings because the authors have not described the source(s) of the talc tested or the asbestos concentrations of the samples. The concentration of amphiboles varies widely between sources, and the authors are urged to divulge the locations of the ore bodies providing the talc for their samples, as well as the asbestos concentration of the samples, so that the results may be interpreted and possibly generalized.

Asbestos cement products and their impact on soil contamination in relation to various sources of anthropogenic and natural asbestos pollution.

The results of a quantitative analysis of asbestos content in the ground with varying degrees of concentration of this mineral as a result of natural phenomena such as rock weathering, contamination by the manufacture of asbestos and cement products, and the many years of use of "eternit roofs" are presented. Preliminary thermal treatment, soil grinding and sieving were used for the determinations, followed by electrostatic separation in order to obtain the concentration of asbestos in a smaller volume. It was used for microscopic preparations for the identification and planimetry of asbestos. A polarizing optical microscope was used in the qualitative and quantitative analysis. The levels of re-emission of asbestos dust into the air as a result of the exploitation of contaminated soil were estimated. Polluted land in industrially areas, at a distance of up to 1200 m, contains 0.0003 % to 0.02 % asbestos. The content of 0.01 % asbestos does not require remediation in the absence of soil use. It may cause <500 fibres/m3. Removing the facade of asbestos-cement panels from the building at a distance of up to 10 m resulted in concentration <0.007 % of free asbestos in the ground, and for used roofs <0.001 % from above the distance of 3 m. This means that land in the vicinity of buildings with facade or roofing made of a-c products can be safely exploited. The direct discharge of rainwater from the gutter into the ground, however, contaminates it well above this value and those places should be treated as hazardous waste due to the presence of asbestos fibres in unbound form, containing <9,8 %. Ultimately, the size of the threat depends on many factors and can be comparable with the pollution of industrial production.

Evaluation of Airborne Asbestos Concentrations Associated with the Operation and Maintenance of Brakes and Clutches on Nonautomated Heavy Equipment.

This study evaluated the potential for chrysotile asbestos exposure during maintenance and operation of older, nonautomated heavy equipment with chrysotile-containing brake and clutch linings. Recent reports indicate that such equipment may be in current use in the U.S. and other locations, including developing countries, due to its lower cost and ease of maintenance compared to newer equipment. Personal and area airborne fiber concentrations were measured for cranes with draglines during brake and clutch repair, equipment operation, shop cleanup, and clothes handling of the mechanic's coveralls over a period of three days. The range of airborne chrysotile concentrations during the complete friction band replacement process, including band removal from the equipment, friction lining replacement, and reinstallation, ranged from 0.0053 to 0.0273 f/cc (phase contrast microscopy-equivalent or PCME) over 3.3 to 6.2 hours. Additional bench work tasks, including electric wire brushing, hand sanding, riveting, and compressed air use were also performed. Full shift airborne chrysotile concentrations (6.1-8.5 hours) for all combined maintenance activities were 0.0093, 0.0414, and 0.0445 f/cc (PCME), on days 1, 2, and 3, respectively. Personal short-term samples (14-36 minutes) for lining removal, installation, wire brushing, hand sanding, and compressed air use ranged from nondetect (ND) to 0.238 f/cc (PCME), below the U.S. Occupational Safety and Health Administration's (OSHA's) 30-minute excursion limit of 1 f/cc. Short-term samples during crane operation, shop cleanup, and simulated laundry activities with the mechanic's coveralls ranged from ND to 0.01 f/cc (PCME; 15-36 minutes). The results indicated that full-shift measured airborne chrysotile concentrations during the brake and clutch maintenance activities evaluated remained below the U.S. 8-hour time-weighted average (TWA) permissible exposure limit (PEL) for asbestos of 0.1 f/cc. The results are likely to be relevant to farmers, construction workers, and vehicle maintenance workers historically, as well as today for those who choose to continue using and maintaining such equipment.

Asbestos fiber length and width comparison between manual and semi-automated measurements.

The objective of the present study is to find a fast and accurate procedure to measure the length and width of asbestos fibers using images acquired by a scanning electron microscope (SEM), a phase-contrast microscope (PCM), and a polarized light microscope (PLM). The accuracy of the procedure was evaluated by comparing fiber length and width measurements to manual measurements. Four different types of images were used in the evaluation: (1) backscattered electron SEM images of fibrous tremolite, (2) secondary electron SEM images of fibrous grunerite, (3) PCM images of fibrous grunerite, and (4) PLM images of fibrous grunerite. Fiber length and width were measured with ImageJ (manual measurement) and Image-Pro software and were compared on an individual fiber basis and over the number-length and number-width distribution of each sample. The results of the comparison showed that the individual length and width measurements with ImageJ and Image-Pro software had a nearly 1:1 relationship except for the width measurement in PLM images (8% of the variance in ImageJ width measurements was not explained by Image-Pro width measurements). Similarly, the number-length distributions were not significantly different (p > 0.05) between ImageJ and Image-Pro, but the number-width distributions were significantly different (p < 0.05) for PLM and secondary electron SEM images. Although the image analysis procedure for measuring fiber length and width with Image-Pro is not a fully automated procedure and still requires some manual intervention, it can be a more efficient and equally accurate alternative to time-consuming manual fiber length and width measurements for well dispersed fibers with high aspect ratios.