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Asbestos and non-asbestos containing brake products are currently used in low- and middle-income countries like Colombia. Because brake products are distributed detached from their supports, they require manipulation before installation, which release fibers and expose workers. Previous studies of our research group have documented exposures in excess of the widely accepted 0.1 f/cm³ exposure guideline. The aim of this study is to identify factors associated with non-compliance of the 8-h time weighted average (TWA) 0.1 f/cm³ asbestos occupational limit among brake mechanics (i.e. riveters). Eighteen brake repair shops (BRS) located in Bogotá (Colombia) were sampled during 3 to 6 consecutive days for the entire work-shift. Personal and short-term personal samples were collected following NIOSH methods 7400 and 7402. Longitudinal based logistic regression models were used to determine the association between the odds of exceeding the 8-h TWA 0.1 f/cm³ asbestos occupational limit and variables such as type of tasks performed by workers, workload (number of products manipulated daily), years of experience as riveters, and shop characteristics. These models can be used to estimate the odds of being currently or historically overexposed when sampling data do not exist. Since the information required to run the models can vary for both retrospective and current asbestos occupational exposure studies, three models were constructed with different information requirements. The first model evaluated the association between the odds of non-compliance with variables related to the workload, the second model evaluated the association between the odds of non-compliance with variables related to the manipulation tasks, and the third model evaluated the association between the odds of non-compliance with variables related with both the type of tasks performed by workers and the workload. Variables associated with the odds of non-compliance included conducting at least one manipulation activity with beveling and grinding of asbestos and non-asbestos containing brake products during the work shift, the location of the worker in the shop during non-manipulation activities, cleaning activities of the manipulation area, the years of experience working as riveters, and the number of asbestos and non-asbestos containing brake products manipulated daily. These models could be useful for current and retrospective occupational studies, in determining the odds of non-compliance of the asbestos occupational limit among brake mechanics. [ABSTRACT FROM AUTHOR]

Objective: The use of measurement data in occupational exposure assessment allows more quantitative analyses of possible exposure-response relations. We describe a quantitative exposure assessment approach for five lung carcinogens (i.e. asbestos, chromium-VI, nickel, polycyclic aromatic hydrocarbons (by its proxy benzo(a)pyrene (BaP)) and respirable crystalline silica). A quantitative job-exposure matrix (JEM) was developed based on statistical modeling of large quantities of personal measurements. Methods: Empirical linear models were developed using personal occupational exposure measurements (n = 102 306) from Europe and Canada, as well as auxiliary information like job (industry), year of sampling, region, an a priori exposure rating of each job (none, low, and high exposed), sampling and analytical methods, and sampling duration. The model outcomes were used to create a JEM with a quantitative estimate of the level of exposure by job, year, andregion. Results: Decreasing time trends were observed for all agents between the 1970s and 2009, ranging from -1.2% per year for personal BaP and nickel exposures to -10.7% for asbestos (in the time period before an asbestos ban was implemented). Regional differences in exposure concentrations (adjusted for measured jobs, years of measurement, and sampling method and duration) varied by agent, ranging from a factor 3.3 for chromium-VI up to a factor 10.5 for asbestos. Conclusion: We estimated time-, job-, and region-specific exposure levels for four (asbestos, chromium-VI, nickel, and RCS) out of five considered lung carcinogens. Through statistical modeling of large amounts of personal occupational exposure measurement data we were able to derive a quantitative JEM to be used in community-based studies. [ABSTRACT FROM AUTHOR]

Background: We published a meta-analysis of the association between work as a motor vehicle mechanic and mesothelioma in 2004. Since then, several relevant studies on this topic have been published. Thus, to update the state-of-the-science on this issue, we conducted a new systematic review and meta-analysis. Methods: A comprehensive PubMed literature search through May 2014 was conducted to identify studies that reported relative risk estimates for mesothelioma among motor vehicle mechanics (in general), and those who were engaged in brake repair (specifically). Studies were scored and classified based on study characteristics. Random-effects meta-analyses generated summary relative risk estimates (SRREs) and corresponding 95% confidence intervals (CI). Heterogeneity of results was examined by calculating Q-test P-values (P-H) and I² estimates. Sub-group and sensitivity analyses were conducted for relevant study characteristics and quality measures. Results: Ten case-control studies, one cohort study, and five proportionate mortality ratio (PMR)/standardized mortality odds ratio (SMOR) studies were identified and included in the quantitative assessment. Most meta-analysis models produced SRREs below 1.0, and no statistically significant increases in mesothelioma were observed. The SRRE for all studies was 0.80 (95% CI: 0.61-1.05) with significant heterogeneity (P-H <0.001, I² = 62.90). A similar SRRE was observed among the five Tier 1 studies with the highest quality ratings (SRRE = 0.76, 95% CI: 0.46-1.25), with no heterogeneity among studies (P-H = 0.912, I² = 0.00). Meta-analysis of the Tier 2 (n = 5) and Tier 3 (n = 6) studies resulted in SRREs of 1.09 (95% CI: 0.76-1.58) and 0.73 (95% CI: 0.49-1.08), respectively. Restricting the analysis to Tiers 1 and 2 combined resulted in an SRRE of 0.92 (95% CI: 0.72-1.29). The SRRE specific to brake work (n = 4) was 0.64 (95% CI: 0.38-1.09). Conclusions: This meta-analysis of the epidemiologic studies provides evidence that motor vehicle mechanics, including workers who were engaged in brake repair, are not at an increased risk of mesothelioma. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the concentrations of airborne asbestos that can be released into classrooms of schools that have amosite-containing asbestos insulation board (AIB) in the ceiling plenum or other spaces, particularly where there is forced recirculation of air as part of a warm air heating system. Air samples were collected in three or more classrooms at each of three schools, two of which were of CLASP (Consortium of Local Authorities Special Programme) system-built design, during periods when the schools were unoccupied. Two conditions were sampled: (i) the start-up and running of the heating systems with no disturbance (the background) and (ii) running of the heating systems during simulated disturbance. The simulated disturbance was designed to exceed the level of disturbance to the AIB that would routinely take place in an occupied classroom. A total of 60 or more direct impacts that vibrated and/or flexed the encapsulated or enclosed AIB materials were applied over the sampling period. The impacts were carried out at the start of the sampling and repeated at hourly intervals but did not break or damage the AIB. The target air volume for background samples was ~3000 l of air using a static sampler sited either below or ~1 m from the heater outlet. This would allow an analytical sensitivity (AS) of 0.0001 fibres per millilitre (f ml-1) to be achieved, which is 1000 times lower than the EU and UK workplace control limit of 0.1 f ml-1. Samples with lower volumes of air were also collected in case of overloading and for the shorter disturbance sampling times used at one site. The sampler filters were analysed by phase contrast microscopy (PCM) to give a rapid determination of the overall concentration of visible fibres (all types) released and/or by analytical transmission electron microscopy (TEM) to determine the concentration of asbestos fibres. Due to the low number of fibres, results were reported in terms of both the calculated concentration and the statistically relevant limits of quantification (LOQ), which are routinely applied. The PCM fibre concentrations were all below the LOQbut analytical TEM showed that few of the fibres counted in the background samples were asbestos. The background TEM asbestos concentrations for the individual samples analysed from all three schools were at or below the AS, with a pooled average below the L0Q(<0.00005 f ml-1). At the two CLASP schools, there was no significant increase in the airborne amosite concentration in the classrooms during simulated disturbance conditions. At the third school, four of the five classrooms sampled gave measurable concentrations of amosite by TEM during simulated disturbance conditions. The highest concentration of amosite fibres countable by PCM was 0.0043 f ml-1 with a pooled average of 0.0019 f ml-1. The air sampling strategy was effective and worked well and the results provide further important evidence to inform the sampling and management of asbestos in schools. [ABSTRACT FROM AUTHOR]

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

Introduction: Occupational exposure data on asbestos are limited and poorly integrated in Australia so that estimates of disease risk and attribution of disease causation are usually calculated from data that are not specific for local conditions. Objective: To develop a job-exposure matrix (AsbJEM) to estimate occupational asbestos exposure levels in Australia, making optimal use of the available exposure data. Methods: A dossier of all available exposure data in Australia and information on industry practices and controls was provided to an expert panel consisting of three local industrial hygienists with thorough knowledge of local and international work practices. The expert panel estimated asbestos exposures for combinations of occupation, industry, and time period. Intensity and frequency grades were estimated to enable the calculation of annual exposure levels for each occupation-industry combination for each time period. Two indicators of asbestos exposure intensity (mode and peak) were used to account for different patterns of exposure between occupations. Additionally, the probable type of asbestos fibre was determined for each situation. Results: Asbestos exposures were estimated for 537 combinations of 224 occupations and 60 industries for four time periods (1943-1966; 1967-1986; 1987-2003; ≥2004). Workers in the asbestos manufacturing, shipyard, and insulation industries were estimated to have had the highest average exposures. Up until 1986, 46 occupation-industry combinations were estimated to have had exposures exceeding the current Australian exposure standard of 0.1 f ml−1. Over 90% of exposed occupations were considered to have had exposure to a mixture of asbestos varieties including crocidolite. Conclusion: The AsbJEM provides empirically based quantified estimates of asbestos exposure levels for Australian jobs since 1943. This exposure assessment application will contribute to improved understanding and prediction of asbestos-related diseases and attribution of disease causation. [ABSTRACT FROM AUTHOR]

A Japanese round-robin study revealed that analysts who used a dark-medium (DM) objective lens reported higher fiber counts from American Industrial Hygiene Association (AIHA) Proficiency Analytical Testing (PAT) chrysotile samples than those using a standard objective lens, but the cause of this difference was not investigated at that time. The purpose of this study is to determine any major source of this difference by performing two sets of round-robin studies. For the first round-robin study, 15 AIHA PAT samples (five each of chrysotile and amosite generated by water-suspended method, and five chrysotile generated by aerosolization method) were prepared with relocatable cover slips and examined by nine laboratories. A second round-robin study was then performed with six chrysotile field sample slides by six out of nine laboratories who participated in the first round-robin study. In addition, two phase-shift test slides to check analysts' visibility and an eight-form diatom test plate to compare resolution between the two objectives were examined. For the AIHA PAT chrysotile reference slides, use of the DM objective resulted in consistently higher fiber counts (1.45 times for all data) than the standard objective (P-value < 0.05), regardless of the filter generation (water-suspension or aerosol) method. For the AIHA PAT amosite reference and chrysotile field sample slides, the fiber counts between the two objectives were not significantly different. No statistically significant differences were observed in the visibility of blocks of the test slides between the two objectives. Also, the DM and standard objectives showed no pattern of differences in viewing the fine lines and/or dots of each species images on the eight-form diatom test plate. Among various potential factors that might affect the analysts' performance of fiber counts, this study supports the greater contrast caused by the different phase plate absorptions as the main cause of high counts for the AIHA PAT chrysotile slides using the DM objective. The comparison of fiber count ratios (DM/standard) between the AIHA PAT chrysotile samples and chrysotile field samples indicates that there is a fraction of fibers in the PAT samples approaching the theoretical limit of visibility of the phase-contrast microscope with 3-degree phase-shift. These fibers become more clearly visible through the greater contrast from the phase plate absorption of the DM objective. However, as such fibers are not present in field samples, no difference in counts between the two objectives was observed in this study. The DM objective, therefore, could be allowed for routine fiber counting as it will maintain continuity with risk assessments based on earlier phase-contrast microscopy fiber counts from field samples. Published standard methods would need to be modified to allow a higher aperture specification for the objective. [ABSTRACT FROM AUTHOR]

Objectives: To analyse the asbestos exposure characteristics and mesothelioma trend in textile workers operating in the larger Tuscan textile industrial province of Prato between 1988 and 2012. Methods: All cases of textile workers recorded by the Tuscan mesothelioma register are considered. The demographic and clinical characteristics and asbestos exposure of cases working in the province of Prato are examined. Crude incidence rates between 1988 and 2012 and their 95% confidence intervals (CI) are calculated in rag sorters and other textile workers. The trends of standardized rates are also evaluated, as well as the sources of occupational asbestos exposure from occupational histories of cases affected by other asbestos-related diseases in rag sorters. Results: One hundred and seventy-two malignant mesotheliomas (MMs) have been diagnosed in textile workers in Tuscany. Among these, 46.5% were residents in the province of Prato at the time of diagnosis, half of whom working as rag sorters. All rag sorters with MM are classified as occupationally asbestos exposed, while 71.7% are other textile workers exposed to asbestos. The estimated crude incidence rate in rag sorters in Prato ranges from 74.1 × 100 000 (95% CI: 52.5-101.8) to 166.8 × 100 000 (95% CI: 118.1-229.0). The standardized rates in Prato rag sorters appeared higher throughout the 1990s while in other Prato textile workers the rates increased later on, at the very end of the 1990s. Another 40 cases of asbestos-related diseases in rag sorters were also collected. Conclusions: A very high incidence of MMs was observed in textile workers in Prato, especially among rag sorters. This result, together with the high number of other asbestos-related diseases in rag sorters, strongly supports the hypothesis of diffuse asbestos exposure in rag sorting, in the absence of any other relevant aetiological factor for malignant mesothelioma. [ABSTRACT FROM AUTHOR]

Objectives: Asbestos has been used in a broad variety of industrial products, including clutch discs of the transmission system of vehicles. Studies conducted in high-income countries that have analyzed personal asbestos exposures of transmission mechanics have concluded that these workers are exposed to asbestos concentrations in compliance with the US Occupational Safety and Health Administration (US OSHA) occupational standards. Clutch facings are the friction component of clutch discs. If clutch facings are sold separated from the support, they require manipulation before installation in the vehicle. The manipulation of asbestos containing clutch facings is performed by a group of mechanics known as riveters, and includes drilling, countersinking, riveting, sanding, and occasionally grinding, tasks that can potentially release asbestos fibers, exposing the mechanics. These manipulation activities are not reported in studies conducted in high-income countries. This study analyzes personal asbestos exposures of transmission mechanics that manipulate clutch facings. Methods: Air sampling campaigns in two transmission repair shops (TRS) were conducted in November 2012 and July 2013 in Bogotá, Colombia. Four workers employed in these TRS were sampled (i.e. three riveters and one supervisor). Personal samples (n = 39), short-term personal samples (n = 49), area samples (n = 52), blank samples (n = 8), and background samples (n = 2) were collected in both TRS during 3-5 consecutive days, following US National Institute for Occupational Safety and Health (US NIOSH) methods 7400 and 7402. Asbestos samples were analyzed by an American Industrial Hygiene Association accredited laboratory. Results: On at least one of the days sampled, all riveters were exposed to asbestos concentrations that exceeded the US OSHA permissible exposure limit or the Colombian permissible limit value. Additionally, from the forty-seven 30-min short-term personal samples collected, two (4.3%) exceeded the US OSHA excursion limit of 1 f cm"3. Conclusions: In this study, we identified that the working conditions and use of asbestos containing transmission products expose transmission mechanics to asbestos concentrations that exceed both the Colombian and OSHA standards. The potential consequences for the health of these workers are of great concern. [ABSTRACT FROM AUTHOR]

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

A pleural mesothelioma arose in an employee of a wine farm whose work history shows an unusual occupational exposure to asbestos. The information, gathered directly from the case and from a work colleague, clarifies some aspects of the use of asbestos in the process of winemaking which has not been previously reported in such details. The man had worked as a winemaker from 1960 to 1988 in a farm, which in those years produced around 2500 hectoliters of wine per year, mostly white. The wine was filtered to remove impurities; the filter was created by dispersing in the wine asbestos fibers followed by diatomite while the wine was circulating several times and clogging a prefilter made of a dense stainless steel net. Chrysotile asbestos was the sole asbestos mineralogical variety used in these filters and exposure could occur during the phase of mixing dry fibers in the wine and during the filter replacement. A daily and annual time weighted average level of exposure and cumulative dose have been estimated in the absence of airborne asbestos fiber monitoring performed in that workplace. Since 1993, the Italian National Mesothelioma Register, an epidemiological surveillance system, has recorded eight cases with at least one work period spent as winemaker. Four of them never used asbestos filters and presented exposures during other work periods, the other four used asbestos filters but had also other exposures in other industrial divisions. For the information hitherto available, this is the first mesothelioma case with exclusive exposure in the job of winemaking. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to elucidate changes in asbestos and non-asbestos fibre concentrations in the lung tissues of Japanese patients with mesothelioma over time. Methods: Lung tissues were obtained from 46 patients with mesothelioma who died or underwent surgery between 1971 and 2005. All of the patients had a history of occupational asbestos exposure. We classified patients into four groups according to the period during which their lung tissue was obtained. Asbestos and non-asbestos fibre concentrations were determined by transmission electron microscopy with energy-dispersive X-ray analysis using a low-temperature ashing procedure. Results: From the 1970s to the 2000s, we observed a decrease in the geometric mean of total asbestos concentration (67.4–1.05 million fibres per gram dry lung), chrysotile concentration (25.0–0.66 million fibres per gram dry lung), amphibole asbestos concentration (21.3–0.76 million fibres per gram dry lung), and non-asbestos fibre concentration (326–19.3 million fibres per gram dry lung). The mean duration of asbestos exposure decreased from 33.7 to 17.6 years, and the mean duration since the last exposure increased from 0.3 to 21.5 years. The percentage of longer fibres to total fibres tended to increase over time, whereas the mean fibre length did not differ significantly. Conclusions: The present study suggested that asbestos and non-asbestos fibre concentrations in the lung tissues of Japanese patients with mesothelioma who have occupational histories of asbestos exposure may have decreased from the 1970s to the 2000s. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to quantitatively estimate the long-term trends of occupational exposure to chemical agents in Finland for surveillance, prevention, and risk assessment purposes. Methods: We studied trends by utilizing the Finnish job-exposure matrix (FINJEM), which includes occupation-specific estimates of the prevalence P (percent of employed) and average level L (agent-specific units) of inhalation exposure to chemical agents at different time periods. We used FINJEM data to calculate national estimates of the numbers of exposed workers (Nexp), and the prevalence of and level of exposure to 41 chemical agents in 1950, 1970, 1990, and 2008. We also estimated the prevalence of employees exposed to levels exceeding 50% of the Finnish occupational exposure limit (OEL) (Phigh) and national occupational inhalation exposure (NOIE = Nexp × L). Future exposures in 2020 were estimated according to the predicted change of the occupational structure of the labor force and the observed agent-specific exposure trends in 1990–2008. We estimated dermal exposure indirectly from the statistics of occupational skin diseases in 1975–2009. Results: Inhalation exposure to most chemical agents had decreased. Using 1990 as the reference (100), the median values of P for 1950, 1970, 1990, 2008, and 2020 were 91, 149, 100, 58, and 41, respectively. The corresponding values were 218, 224, 100, 30, and 14 for Phigh, 151, 121, 100, 78, and 66 for L, and 119, 176, 100, 38, and 20 for NOIE. The trends varied considerably according to the agent. Exposure of, for example, asbestos, benzene, and benzo(a)pyrene substantially decreased. The annual incidence of occupational skin diseases due to chemical factors decreased from 6.9 per 10 000 employed in 1975–1979 to 4.6 per 10 000 in 2000–2009, suggesting a decrease in dermal exposure. Conclusions: Inhalation exposure to most chemical agents has decreased in Finland since 1970. High exposures and the average level of exposure started to decrease already in the 1950s. The declining incidence of occupational skin diseases suggests that dermal exposure has also diminished. However, high exposures still exist and cause a substantial amount of occupational diseases and symptoms. Chemical exposures and the related disease burden are expected to continue decreasing in the future. These results cannot be generalized to other countries, particularly if the development phase of technology and the occupational structure of the labor force differ significantly from those in Finland. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented in response to the article "Overreliance on a Single Study: There is no Real Evidence That Applying Quality Criteria to Exposure in Asbestos Epidemiology Affectsthe Estimated Risk," by D. Wayne Berman and Bruce W. Case in the 2012 issue of the "Annals of Occupational Hygiene."

Introduction: Brake linings and brake pads are among the asbestos-containing products that are readily available in Colombia. When sold separated from their support, brake linings require extensive manipulation involving several steps that include drilling, countersinking, riveting, bonding, cutting, beveling, and grinding. Without this manipulation, brake linings cannot be installed in a vehicle. The manipulation process may release asbestos fibers, which may expose brake mechanics to the fibers. Methods: Three brake repair shops located in Bogotá (Colombia) were sampled for 3 or 4 consecutive days using US National Institute for Occupational Safety and Health (NIOSH) methods 7400 and 7402. Standard procedures for quality control were followed during the sampling process, and asbestos samples were analyzed by an American Industrial Hygiene Association accredited laboratory. Personal samples were collected to assess full-shift and short-term exposures. Area samples were also collected close to the brake-lining manipulation equipment and within office facilities. Activities were documented during the sampling process. Results Using Phase Contrast Microscopy Equivalent counts to estimate air asbestos concentrations, all personal samples [i.e. 8-h time-weighted averages (TWAs) and 30-min personal samples] were in compliance with the US Occupational Safety and Health Administration standards. Personal asbestos concentrations based on transmission electron microscopy counts were extremely high, ranging from 0.006 to 3.493 f cm−3 for 8-h TWA and from 0.015 to 8.835 f cm−3 for 30-min samples. All asbestos fibers detected were chrysotile. Cleaning facilities and grinding linings resulted in the highest asbestos exposures based on transmission electron microscopy counts. There were also some samples that did not comply with the NIOSH’s recommended exposure limits. Conclusion: The results indicate that the brake mechanics sampled are exposed to extremely high asbestos concentrations (i.e. based on transmission electron microscopy counts), suggesting that this occupational group could be at excess risk of asbestos-related diseases. [ABSTRACT FROM PUBLISHER]

In 2011, we reported on the sensitivity of lung cancer potency estimates for asbestos to the quality of the exposure assessment component of underlying evidence. Both this meta-analysis and a separate reassessment of standards published by the Health Council of the Netherlands (Gezondheidsraad) have been commented on by Berman and Case. A criticism is that we used a truncated data set. We incrementally excluded poorer-quality studies to evaluate trends in meta-analyzed lung cancer potency estimates (meta-KL values). This was one of three analysis approaches we presented. The other two used the full set of studies: a meta-analysis stratified by covariates and dichotomized by poorer and better exposure assessment aspects; and a meta-regression modeling both asbestos fiber type and these covariates. They also state that our results are not robust to removal of one study. We disagree with this claim and present additional sensitivity analyses underpinning our earlier conclusion that inclusion of studies with higher-quality asbestos-exposure assessment yield higher meta-estimates of the lung cancer risk per unit of exposure. We reiterate that potency differences for predominantly chrysotile- versus amphibole-asbestos-exposed cohorts are difficult to ascertain when meta-analyses are restricted to studies with fewer exposure assessment limitations. We strongly argue that the existence of any uncertainty related to potency issues should not hamper the development of appropriate evidence-based guidelines and stringent policies in order to protect the public from hazardous environmental and occupational exposures. [ABSTRACT FROM AUTHOR]

A critical need exists for reliable risk management policies and practices that can effectively mitigate asbestos-related health threats, and such policies and practices need to be based on sound science that adequately distinguishes hazardous situations from those that are not. Toward that end, the disparate means by which study quality has been addressed in recent meta-analyses used to establish potency factors (KL and KM values) for asbestos cancer risks were compared by conducting additional sensitivity analyses. Results suggest that, other than placing undue emphasis on the influence of the KL and KM values reported from a single study, there appears to be little to no evidence of a systematic effect of study quality on KL or KM values; none of the findings warrant excluding studies from current or future meta-analyses. Thus, we argue that it is better to include as much of the available data as possible in these analyses while formally addressing uncertainty as part of the analysis itself, rather than sequentially excluding studies based on one type of limitation or another. Throwing out data without clearly proving some type of bias is never a good idea because it will limit both the power to test various hypotheses and the confidence that can be placed in any findings that are derived from the resulting, truncated data set. We also believe that it is better to identify the factors that contribute to variation between studies included in a meta-analysis and, by adjusting for such factors as part of a model, showing that the disparate values from individual studies can be reconciled. If such factors are biologically reasonable (based on other evidence) and, if such a model can be shown to fit the data from all studies in the meta-analysis, the model is likely to be predictive of the parameters being evaluated and can then be applied to new (unstudied) environments. [ABSTRACT FROM AUTHOR]

Objectives: The hypothesis that asbestos exposure may have more specific associations with particular histological types of lung cancer remains controversial. The aim of this study was to analyze the relationships between asbestos exposure and pulmonary carcinoid tumors. Methods: A retrospective case–control study was conducted in 28 cases undergoing surgery for pulmonary carcinoid tumors and aged >40 years and in 56 controls with lung cancer of a different histological type, matched for gender and age, from 1994 to 1999, recruited in two hospitals in the region of Paris. Asbestos exposure was assessed via expertise of a standardized occupational questionnaire and mineralogical analysis of lung tissue, with quantification of asbestos bodies (AB). Results: Definite asbestos exposure was identified in 25% of cases and 14% of controls (ns). Cumulative asbestos exposure was significantly higher in cases than in controls (P < 0.05), and results of the quantification of AB tended to be higher in cases than in controls (24 and 9% had >1000 AB per gram dry lung tissue, respectively, P = 0.09). Mean cumulative smoking was lower in cases than in controls (P < 0.05). Conclusions: This study argues in favor of a relationship between asbestos exposure and certain pulmonary carcinoid tumors. [ABSTRACT FROM PUBLISHER]

An ongoing research effort designed to reconstruct the character of historical exposures associated with use of chrysotile-containing joint compounds naturally raised questions concerning how the character (e.g. particle size distributions) of dusts generated from use of recreated materials compares to dusts from similar materials manufactured historically. This also provided an opportunity to further explore the relative degree that the characteristics of dusts generated from a bulk material are mediated by the properties of the bulk material versus the mechanical processes applied to the bulk material by which the dust is generated. In the current study, the characteristics of dusts generated from a recreated ready mix and recreated dry mix were compared to each other, to dusts from a historical dry mix, and to dusts from the commercial chrysotile fiber (JM 7RF3) used in the recreated materials. The effect of sanding on the character of dusts generated from these materials was also explored. Dusts from the dry materials studied were generated and captured for analysis in a dust generator-elutriator. The recreated and historical joint compounds were also prepared, applied to drywall, and sanded inside sealed bags so that the particles produced from sanding could be introduced into the elutriator and captured for analysis. Comparisons of fiber size distributions in dusts from these materials suggest that dust from commercial fiber is different from dusts generated from the joint compounds, which are mixtures, and the differences persist whether the materials are sanded or not. Differences were also observed between sanded recreated ready mix and either the recreated dry mix or a historical dry mix, again whether sanded or not. In all cases, however, such differences disappeared when variances obtained from surrogate data were used to better represent the ‘irreducible variation’ of these materials. Even using the smaller study-specific variances, no differences were observed between the recreated dry mix and the historical dry mix, indicating that chrysotile-containing joint compounds can be recreated using historical formulations such that the characteristics of the modern material reasonably mimic those of a corresponding historical material. Similarly, no significant differences were observed between dusts from sanded and unsanded versions of similar materials, suggesting (as in previous studies) that the characteristics of asbestos-containing dusts are mediated primarily by the properties of the bulk material from which they are derived. [ABSTRACT FROM PUBLISHER]

Asbestos may be naturally present in rocks and soils. In some cases, there is the possibility of releasing asbestos fibres into the atmosphere from the rock or soil, subsequently exposing workers and the general population, which can lead to an increased risk of developing asbestos-related diseases. In the present study, air contaminated with asbestos fibres released from serpentinites was investigated in occupational settings (quarries and processing factories) and in the environment close to working facilities and at urban sites. The only naturally occurrence of asbestos found in Valmalenco area was chrysotile; amphibole fibres were never detected. An experimental cut-off diameter of 0.25 μm was established for distinguishing between Valmalenco chrysotile and antigorite single fibres using selected area electron diffraction analyses. Air contamination from chrysotile fibres in the examined occupational settings was site-dependent as the degree of asbestos contamination of Valmalenco serpentinites is highly variable from place to place. Block cutting of massive serpentinites with multiple blades or discs and drilling at the quarry sites that had the highest levels of asbestos contamination generated the highest exposures to (i.e. over the occupational exposure limits) asbestos. Conversely, working activities on foliated serpentinites produced airborne chrysotile concentrations comparable with ambient levels. Environmental chrysotile concentrations were always below the Italian limit for life environments (0.002 f ml−1), except for one sample collected at a quarry property boundary. The present exposure assessment study should encourage the development of an effective and concordant policy for proper use of asbestos-bearing rocks and soils as well as for the protection of public health. [ABSTRACT FROM PUBLISHER]

Background Epidemics of malignant mesothelioma are occurring among inhabitants of Casale Monferrato and Bari never employed in the local asbestos-cement (AC) factories. The mesothelioma risk increased with proximity of residence to both plants. Objectives To provide information on the intensity of environmental asbestos exposure, in the general population living around these factories, through the evaluation of the lung fibre burden in mesothelioma patients. Methods We analysed by a scanning electron microscope equipped with X-ray microanalysis wet (formalin-fixed) lung tissue samples from eight mesothelioma patients who lived in Casale Monferrato or Bari and underwent surgery. Their occupational and residential history was obtained during face-to-face interviews. Semi-quantitative and quantitative indices of cumulative environmental exposure to asbestos were computed, based on residential distance from the AC plants and duration of stay. Results The lung fibre burden ranged from 110 000 to 4 300 000 fibres per gram of dry lung (f/g) and was >1 000 000 f/g in three subjects. In four cases, only amphibole fibres were detected. Environmental exposures had ceased at least 10 years before samples were taken. No patient had other definite or probable asbestos exposures. A linear relationship was observed between the lung fibre burden and all three indices of environmental cumulative exposure to asbestos. Conclusions Environmental exposure to a mixture of asbestos fibres may lead to a high lung fibre burden of amphiboles years after exposure cessation. The epidemiological evidence of an increased mesothelioma risk for the general population of Casale Monferrato and Bari, associated with asbestos contamination of the living environment, is corroborated. [ABSTRACT FROM AUTHOR]

The US Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration do not regulate cleavage fragments of amphibole and serpentine minerals as asbestos, even when particles meet the dimensional criteria for counting under standard phase-contrast microscopy methods. The OSHA ID-160 method cautions that discriminatory counting is difficult and should not be attempted unless necessary and no procedure is provided for differentiation. A standard published by the American Society for Testing and Materials (ASTM International D7200-06) includes an attempt to codify a procedure but recognizes that the procedure should be validated in an inter-laboratory study. The US National Institute for Occupational Safety and Health has carried out such a study with multiple laboratories using slides made from riebeckite and crocidolite, grunerite and amosite, tremolite and tremolite asbestos, and actinolite and actinolite asbestos using two different measurement aids (graticules). The asbestos fibers had dimensions consistent with those reported for air samples from actual amphibole asbestos operations, and the cleavage fragments were also dimensionally consistent with those found in non-asbestos mining and milling operations. The procedure for discriminating asbestos fibers from other mineral particles in the ASTM Standard calls for the recognition of characteristics supposedly common to asbestos. For the asbestos fibers created in this study, these characteristics were found not to be common and generally a function of length. More importantly, different laboratories did not recognize these features consistently. Laboratories were much more consistent in measuring dimensions, but excessive overlap in the lengths of asbestos fibers and cleavage fragments rendered length a poor criterion for discrimination. The ASTM discrimination procedure as written could not be supported on the basis of this study. Width was a much more consistent parameter for distinguishing the asbestos and non-asbestos fibers in this study and inclusion of aspect ratio, while considered important by some researchers, did not refine the discrimination further. The ability of the majority of microscopists in this study to discriminate fibers and cleavage fragments through measurement of particle widths was determined and found to be within limits of uncertainty typical for air sampling measurements. A width criterion might be a very simple and useful aid where discrimination between asbestos and non-asbestos fibers in fiber counting by phase-contrast microscopy is required for further investigation. Recognition of asbestos features can also be retained as excessive recognition by some laboratories will lead to a conservative decision for additional investigation. [ABSTRACT FROM AUTHOR]

Purpose: Automobile mechanics have been exposed to asbestos in the past, mainly due to the presence of chrysotile asbestos in brakes and clutches. Despite the large number of automobile mechanics, little is known about the non-malignant respiratory diseases observed in this population. The aim of this retrospective multicenter study was to analyse the frequency of pleural and parenchymal abnormalities on high-resolution computed tomography (HRCT) in a population of automobile mechanics. Methods: The study population consisted of 103 automobile mechanics with no other source of occupational exposure to asbestos, referred to three occupational health departments in the Paris area for systematic screening of asbestos-related diseases. All subjects were examined by HRCT and all images were reviewed separately by two independent readers; who in the case of disagreement discussed until they reached agreement. Multiple logistic regression models were constructed to investigate factors associated with pleural plaques. Results: Pleural plaques were observed in five cases (4.9%) and interstitial abnormalities consistent with asbestosis were observed in one case. After adjustment for age, smoking status, and a history of non-asbestos-related respiratory diseases, multiple logistic regression models showed a significant association between the duration of exposure to asbestos and pleural plaques. Conclusions: The asbestos exposure experienced by automobile mechanics may lead to pleural plaques. The low prevalence of non-malignant asbestos-related diseases, using a very sensitive diagnostic tool, is in favor of a low cumulative exposure to asbestos in this population of workers. [ABSTRACT FROM AUTHOR]

Asbestos-containing materials in place in buildings, especially sprayed-on asbestos, are still an important health threat. Clearance of these materials has to be operated by specifically trained workers wearing specific individual protection suits after containment of the contaminated area. Good work practices are, however, not always applied. We report the case of two workers hired for ∼1 week to remove sprayed-on amosite asbestos during the remodeling of a former industrial hall. Regulatory protective equipments were not used. A legal action was initiated after disclosure of the working conditions. Medical examinations were performed 18 and 22 months after exposure. Workers denied any other asbestos exposure. Lung function tests and chest computed tomography scans were normal. Very high levels of asbestos fibers and bodies were discovered on mineralogical analysis of bronchoalveolar lavage fluid (BALF) by phase contrast light microscopy and analytical electron microscopy. All fibers were amosite. An extrapolation considering duration of exposure, breathing pattern, and BALF fiber content suggests that the workers were exposed to airborne fiber concentrations in the range from several tens to about a hundred World Health Organization fibers per milliliter air. In conclusion, exposures to historical airborne fiber levels prevailing half a century ago may still occur today when the work regulations are not applied. In these conditions, even very short exposures may result in considerable lung fiber retention in case of amphibole exposure with the subsequent risk for developing asbestos-related diseases. Fiber analysis in BALF is useful to clarify such exposures. [ABSTRACT FROM AUTHOR]

Mounting evidence that long asbestos fibers (e.g. >20 or even 40 μm) pose the greatest cancer risk underscores the need for accurate measurement of concentrations of such fibers. These fiber lengths are of the same order of magnitude as the size of openings in the grids (typically ≈90 μm per side) used to analyze asbestos samples by transmission electron microscopy. This means that a substantial proportion of long fibers will cross the edge of a grid opening (GO) and therefore not be completely visible. Counting rules generally deal with such fibers by assigning a length equal to twice the visible length. Using both theoretical and simulation methods, we show that this doubling rule introduces bias into estimates of fiber concentrations and the amount of bias increases with fiber length. We investigate an alternative counting rule that counts only fibers that lie completely within a GO and weights those fibers by the reciprocal of the probability that a fiber of that length lies totally within a GO. This approach does not have the bias inherent in the doubling rule and is essentially unbiased if the stopping rule specifies a fixed number of GOs to be scanned. However, a stopping rule based on successively scanning GOs until a fixed number of fibers have been counted will introduce bias into any counting method, although this bias may typically not be large enough to be of practical concern. We recommend use of the weighted approach as a supplement to use of the doubling rule when estimating concentrations of long fibers, irrespective of the stopping rule employed. [ABSTRACT FROM AUTHOR]

Joint compound products containing chrysotile asbestos were commonly used for building construction from the late 1940s through the mid-1970s. Few relevant data exist to support reconstructing historical worker exposures to fibers generated by working with this material. Therefore, we re-created 1960s-era chrysotile-containing joint compound (JCC) and compared its characteristics to a current-day asbestos-free joint compound (JCN). Validation studies showed that a bench-scale chamber with controlled flow dynamics, designed to quantify particulate emissions from joint compound products, provided precise and reliable measurements of generated airborne dust mass, chrysotile fiber concentrations, and corresponding activity-specific emission rates. Subsequent chamber studies characterized fibers counted by phase contrast microscopy (PCM) per mass of respirable dusts and total suspended particulate dusts (total dusts), generated during JCC sanding or sweeping, as well as corresponding dust emission rates for JCC and JCN, and the ratio of total to respirable dust mass for JCN. From these data we estimated factors, FCH-rd and FCH-td (in units of f cm−3 per mg m−3), by which respirable JCN dust mass concentrations collected during construction use can be converted to corresponding airborne PCM fiber concentrations generated by sanding or sweeping JCC. For sanding, median values (95% confidence limits) of FCH-rd and FCH-td were estimated to be 0.044 (0.039–0.050) and 0.212 (0.115–0.390) f cm−3 per mg m−3, respectively. The FCH-td to FCH-rd ratio indicates that approximately five times as many airborne PCM fibers are anticipated per unit air volume sampled when JCC dust is collected on cassettes (as done historically), than when respirable JCC dust is collected on cyclones. As the sizes of individual fibers collected appear to be primarily respirable, this difference may be a sampling artifact and suggests caution in interpreting historical fiber concentration measures made using cassettes during work with JCC-like materials. FCH-rd can be used with published and newly generated field measurements of respirable dust mass concentrations associated with the use of JCN or equivalent JCN materials to better characterize historical worker exposures to PCM fibers from use of JCC or equivalent JCCs. The experimental process described also can be used to develop conversion factors for other combinations of modern-day asbestos-free and historical chrysotile-containing products. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate mounting methods for fiber examination of air sample filters by phase contrast microscopy (PCM) and to evaluate differences in fiber counts that might be due to fiber movement. Acetone/triacetin (AT) with various amounts of triacetin and acetone/Euparal (AE) where the mounting medium was placed between the cleared filter wedge and the coverslip were tested as a function of time. Field sample slides collected from a taconite iron-ore processing mill, a tremolitic talc-ore processing mill, and from around a crusher in a meta-basalt stone quarry were prepared with relocatable coverslips to revisit the same field areas on the slides. For each slide, three or four field areas were randomly selected and pictures were taken every 2 weeks to determine any sign of fiber movement over time. For 11 AT slides (named as AT-3.5) prepared with 3.5 μl of the mounting medium according to the NIOSH 7400 method, no fiber movements were detected over 59 weeks. On the other hand, AT slides prepared with larger quantities (10, 15, and 20 μl) of the mounting medium (named as AT-10) and AE slides prepared with ∼10 μl mounting medium showed fiber movement from the eighth day at the earliest. Fiber movement began earlier for the slides mounted with excess triacetin than for those mounted with Euparal. The sample slide storage method, either vertically or horizontally, did not seem to accelerate fiber movement. Additionally, two other modified methods, dimethylformamide solution/Euparal (mDE) and dimethylformamide solution/triacetin (mDT), were also prepared where the mounting medium was placed between the cleared filter wedge and the glass slide. The findings of fiber movements were similar; when 3.5 μl of triacetin was used for the mDT slides, fiber movements were not detected, while fibers on slides prepared with 10 μl triacetin (mDT-10) moved around. No fiber movements were observed for the mDE slides at any time during 59 weeks. Once fiber movement started, fibers moved over distances measured from 4 μm and up to >1000 μm within 22 weeks. However, since then, no further fiber movements have been observed in any field sample slides. Additional sample slides, two Amosite and two chrysotile, were prepared from Union for International Cancer Control (UICC) samples using the AT method with 5 μl triacetin mounting medium. Fiber movements were also observed in these samples; chrysotile fibers began to migrate in 3 weeks, while Amosite fiber movement started after 3 months. Although fiber movement was observed for the AT-10, AE, and mDT-10 sample slides, fiber counts were not significantly different from AT-3.5 and mDE samples that exhibited no fiber movement. Although fiber counts would not be significantly changed by fiber movement, the type and amount of mounting medium for sample slide preparation remains critical for issues such as quality assurance and training of analysts by revisiting the same fibers. [ABSTRACT FROM AUTHOR]

Mesothelioma deaths due to environmental exposure to asbestos in The Netherlands led to parliamentary concern that exposure guidelines were not strict enough. The Health Council of the Netherlands was asked for advice. Its report has recently been published. The question of quality of the exposure estimates was studied more systematically than in previous asbestos meta-analyses. Five criteria of quality of exposure information were applied, and cohort studies that failed to meet these were excluded. For lung cancer, this decreased the number of cohorts included from 19 to 3 and increased the risk estimate 3- to 6-fold, with the requirements for good historical data on exposure and job history having the largest effects. It also suggested that the apparent differences in lung cancer potency between amphiboles and chrysotile may be produced by lower quality studies. A similar pattern was seen for mesothelioma. As a result, the Health Council has proposed that the occupational exposure limit be reduced from 10 000 fibres m−3 (all types) to 250 f m–3 (amphiboles), 1300 f m–3 (mixed fibres), and 2000 f m–3 (chrysotile). The process illustrates the importance of evaluating quality of exposure in epidemiology since poor quality of exposure data will lead to underestimated risk. [ABSTRACT FROM AUTHOR]

Objectives: Asbestos is associated with South African diamond mines due to the nature of kimberlite and the location of the diamond mines in relation to asbestos deposits. Very little is known about the health risks in the diamond mining industry. The objective of this study was to explore the possibility of asbestos exposure during the process of diamond mining.Methods: Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis were used to identify asbestos fibres in the lungs of diamond mine workers who had an autopsy for compensation purposes and in the tailings and soils from three South African diamond mines located close to asbestos deposits. The asbestos lung fibre burdens were calculated. We also documented asbestos-related patholological findings in diamond mine workers at autopsy.Results: Tremolite–actinolite asbestos fibres were identified in the lungs of five men working on diamond mines. Tremolite–actinolite and/or chrysotile asbestos were present in the mine tailings of all three mines. Mesothelioma, asbestosis, and/or pleural plaques were diagnosed in six diamond mine workers at autopsy.Conclusions: These findings indicate that diamond mine workers are at risk of asbestos exposure and, thus, of developing asbestos-related diseases. South Africa is a mineral-rich country and, when mining one commodity, it is likely that other minerals, including asbestos, will be accidentally mined. Even at low concentrations, asbestos has the potential to cause disease, and mining companies should be aware of the health risk of accidentally mining it. Recording of comprehensive work histories should be mandatory to enable the risk to be quantified in future studies. [ABSTRACT FROM AUTHOR]

Mixed cellulose ester (MCE) filters, used routinely to collect dust samples from air for fiber analysis, are the only filter type that can be prepared for both phased contrast microscopy and transmission electron microscopy analyses. However, whenever fiber counts require collecting dust masses <100 μg on a single filter under variable relative humidity (RH) conditions, historically noted effects of humidity on MCE filter mass can hinder accurate estimates of dust mass, measured as loaded minus unloaded filter mass (M). In this study, a baseline set of hundreds of paired measures of change in RH versus M over different time intervals were obtained over a 5-day period for replicate series of 40 unloaded 37-mm MCE filters under varying RH conditions at a nearly constant temperature. Similar baseline data were obtained for 25-mm MCE filters. Linear regressions fit to these data allow improved estimates of dust mass loaded onto MCE filters from measures of M and RH made before and after loading occurs. Using established theory, these relationships were generalized to address temperature variation as well, and examples of numerical applications are provided. [ABSTRACT FROM PUBLISHER]

Objectives: Workers in the asbestos industry tend to have high smoking rates compared to the general population. Both asbestos exposure and cigarette smoking are recognized risk factors for lung cancer mortality, but the exact nature of the interaction between the two remains uncertain. The aim of this study was to examine the effect of smoking and smoking cessation among asbestos workers in Great Britain (GB) and investigate the interaction between asbestos exposure and smoking. Methods: The study population consisted of 98 912 asbestos workers recruited into the GB Asbestos Survey from 1971, followed-up to December 2005. Poisson regression was used to estimate relative risks of lung cancer mortality associated with smoking habits of the asbestos workers and to assess whether these effects differed within various categories of asbestos exposure. The interaction between asbestos exposure and smoking was examined using the Synergy (S) and Multiplicativity (V) indices, which test the hypotheses of additive and multiplicative interaction, respectively. The proportion of lung cancers among smokers attributable to the interaction of asbestos and smoking was also estimated. Results: During 1 780 233 person-years of follow-up, there were 1878 deaths from lung cancer (12% of all deaths). Risk of lung cancer mortality increased with packs smoked per day, smoking duration, and total smoke exposure (pack-years). Asbestos workers who stopped smoking remained at increased risk of lung cancer mortality up to 40 years after smoking cessation compared to asbestos workers who never smoked. The effects of smoking and stopping smoking did not differ by duration of asbestos exposure, main occupation, age at first asbestos exposure, year of first exposure, or latency period. The interaction between asbestos exposure and smoking for asbestos workers was greater than additive [S 1.4, 95% confidence interval (CI) 1.2–1.6], and the multiplicative hypothesis could not be rejected (V 0.9, 95% CI 0.3–2.4). For those asbestos workers who smoked, an estimated 26% (95% CI 14–38%) of lung cancer deaths were attributable to the interaction of asbestos and smoking. Conclusions: This study emphasizes the importance of smoking prevention and cessation among those who work in the asbestos industry. [ABSTRACT FROM AUTHOR]

In the 1960s and 1970s, well designed case-referent studies put beyond doubt that exposure to airborne asbestos fibres was a cause of malignant mesothelioma. Some 35 cohort mortality studies in a large variety of industries during the 20-year period, 1974–1994, showed a wide range of outcomes, but in general that the risk was higher in exposures which included amphiboles rather than chrysotile alone. Real progress began, however, with discoveries along several lines: the link between pleural changes and mineralogy, the concept and importance of biopersistence, the developments in counting and typing mineral fibres in lung tissue, and data on amphibole mining in South Africa and Australia for comparison with that on chrysotile in Canada and Italy. This led to the recognition of the potential contamination in North America of chrysotile with tremolite. A survey in Canada in 1980–1988 and other surveys demonstrated that crocidolite, amosite, and tremolite could explain almost all cases of mesothelioma. Effective confirmation of this was finally achieved with data on vermiculite miners in Libby, Montana, in the years 1983–1999, where exposure was to tremolite–actinolite and/or other amphibole fibres alone. [ABSTRACT FROM AUTHOR]

Historically, asbestos-containing roof cements and coatings were widely used for patching and repairing leaks. Although fiber releases from these materials when newly applied have been studied, there are virtually no useful data on airborne asbestos fiber concentrations associated with the repair or removal of weathered roof coatings and cements, as most studies involve complete tear-out of old roofs, rather than only limited removal of the roof coating or cement during a repair job. This study was undertaken to estimate potential chrysotile asbestos fiber exposures specific to these types of roofing products following artificially enhanced weathering. Roof panels coated with plastic roof cement and fibered roof coating were subjected to intense solar radiation and daily simulated precipitation events for 1 year and then scraped to remove the weathered materials to assess chrysotile fiber release and potential worker exposures. Analysis of measured fiber concentrations for hand scraping of the weathered products showed 8-h time-weighted average concentrations that were well below the current Occupational Safety and Health Administration permissible exposure limit for asbestos. There was, however, visibly more dust and a few more fibers collected during the hand scraping of weathered products compared to the cured products previously tested. There was a notable difference between fibers released from weathered and cured roofing products. In weathered samples, a large fraction of chrysotile fibers contained low concentrations of or essentially no magnesium and did not meet the spectral, mineralogical, or morphological definitions of chrysotile asbestos. The extent of magnesium leaching from chrysotile fibers is of interest because several researchers have reported that magnesium-depleted chrysotile fibers are less toxic and produce fewer mesothelial tumors in animal studies than normal chrysotile fibers. [ABSTRACT FROM AUTHOR]

There is ongoing argument about the potency of chrysotile asbestos to cause malignant mesothelioma. Risk assessment for chrysotile is influenced by the alleged absence of mesotheliomas among workers at the Raybestos Manhattan friction products plant in Connecticut, a plant that essentially used only chrysotile asbestos. Regrettably, the statement that there is an absence of mesothelioma deaths in the Connecticut plant is false. In this paper, we report on our review of the work histories and pathological reports of five individuals from the Connecticut plant who were diagnosed with mesothelioma. We discuss the Connecticut plant in relation to the most recent epidemiological information for chrysotile. Calculation suggests that mesothelioma rates at this plant were similar to those observed among Quebec miners and the South Carolina textile plant. We urge everyone concerned with the risk assessment of chrysotile asbestos to make use of all available data. [ABSTRACT FROM AUTHOR]

This article describes two atmosphere generation systems used for the production of replicas. The first, the Sputnic system, is based on the Sputnic air sampler developed by the National Institute of Occupational Health in Oslo (Norway). It is used to generate asbestos fibres or silica particles and allows the simultaneous production, by means of sampling on filters, of up to 114 replicas. The second is a multipurpose system that allows dust sampling on foams used with the CIP 10-R device. Twenty samples can be taken simultaneously. In total, 120 series of samples allowed characterization of the variability of the two generation systems used for the production of replicas loaded with asbestos fibres or silica dust. The coefficients of variation characterizing the dispersion of the filter loading in the Sputnic system are <10% for high densities asbestos fibre or silica dust samples. The coefficient of dispersion is on average higher when the asbestos fibre density is lower. The differences observed between the measurements taken on the different crowns of the Sputnic system are low and <2%. The results obtained with the multipurpose system show that replica dispersion is on average equal to 4%, which will allow proposal in the near future of a proficiency test dedicated to the quantitative analysis of crystalline silica on foams sampled with the CIP 10-R device. [ABSTRACT FROM AUTHOR]

The amphibole asbestos, anthophyllite, is associated with asbestos-related disease in humans, along with mesothelioma in animal models. In humans, however, there are only three cases of histologically proven malignant mesothelioma of the pleura associated with anthophyllite that have been documented in the English-language literature. A fourth case is presented in a man who lived in South Africa and had anthophyllite in his lung. Anthophyllite was never commercially mined in South Africa. Using scanning electron microscopy, his lung fibre burden was calculated to be 358 000 fibres and 31 000 asbestos bodies per gram of dry weight of lung tissue. The mean aspect ratio of the anthophyllite fibres in the lung was 41.2 (SD = 28.8). No other types of asbestos were detected in the lung. His exposure was almost certainly occupational. He worked in the plastic manufacturing industry and was exposed to talc and asbestos blankets that were used to insulate machinery. [ABSTRACT FROM PUBLISHER]

Transmission electron microscopy observations most frequently form a basis for estimating asbestos fibre concentration in the environment and in buildings with asbestos-containing materials. Sampled fibres can be transferred to microscope grids by applying either a direct [ISO (1995) Draft International ISO/DIS 10312. Ambient air. Determination of asbestos fibres. Direct transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] or an indirect [AFNOR (1996) Détermination de la concentration en fibres d'amiante par microscopie électronique à transmission—Méthode indirecte. Cedex, France: AFNOR, p. 42; ISO (1997) Draft International ISO/DIS 13794. Ambient air. Determination of asbestos fibres. Indirect-transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] method. In the latter case, ISO Standard 13794 recommends filtering calcination residues either on a polycarbonate (PC) filter (PC indirect method) or on a cellulose ester (CE) membrane (CE indirect method). The PC indirect method requires that fibres deposited on a PC filter be covered by a carbon layer, whereas in the CE indirect method, the CE membrane has to be directly processed using a method described in ISO Standard 10312. The purpose of this study was to compare results obtained using, on the one hand, direct preparation methods and, on the other hand, PC indirect or CE indirect methods, for counting asbestos fibres deposited on filters as a result of liquid filtration or air sampling. In direct method-based preparation, we observed that an etching time of 6–14 min does not affect the measured densities, except for fibres <1 μm deposited by liquid filtration. Moreover, in all cases, the direct method gives higher densities than the PC indirect method because of possible fibre disappearance when using the carbon evaporator implemented in the PC indirect method. The CE membrane used for sample preparation in the CE indirect method is collapsed prior to passing it through the carbon evaporator, so the fibres are less likely to disappear at this stage. We then note that the resulting fibre densities for chrysotile-loaded filters prepared using the direct method are close to those obtained with filters prepared using the CE indirect method. Our study therefore shows that, under the implemented experimental conditions, the PC and CE indirect preparation methods described in ISO Standard 13794 are not equivalent. [ABSTRACT FROM PUBLISHER]

The article presents the authors' response to Drs. Kottek and Kilpatrick's comments on their article and Kottek and Kilpatrick's concerns about low cumulative asbestos exposure estimates in some job titles that was attributed to underestimation of the frequency and duration of peak exposures. They express their disagreement with the suggestion that AsbJEM is inadequate as an instrument to assess asbestos exposure in Australian work situations.

The article discusses issues related to mesothelioma in people who worked as vehicle mechanics or in brake repair. It addresses 2 questions such as whether studies of motor vehicle repair activities and brake repair activities are appropriate settings to examine risks of mesothelioma from chrysotile exposure and whether it is appropriate to require evidence of elevated associations between an occupation and a disease to ascertain if one incurred the disease due to exposure in that occupation.

Asbestos-containing brake linings were used in heavy-duty construction equipment such as tractors, backhoes, and bulldozers prior to the 1980s. While several published studies have evaluated exposures to mechanics during brake repair work, most have focused on automobiles and light trucks, not on heavy agricultural or construction vehicles. The purpose of this study is to characterize the airborne concentration of asbestos to workers and bystanders from brake wear debris during brake removal from 12 loader/backhoes and tractors manufactured between 1960 and 1980. Asbestos content in brake lining (average 20% chrysotile by polarized light microscopy) and brake wear debris [average 0.49% chrysotile by transmission electron microscopy (TEM)] was also quantified. Breathing zone samples on the lapel of mechanics (n = 44) and area samples at bystander (n = 34), remote (n = 22), and ambient (n = 12) locations were collected during 12 brake changes and analyzed using phase contrast microscopy (PCM) [National Institute for Occupational Safety and Health (NIOSH) 7400] and TEM (NIOSH 7402). In addition, the fiber distribution by size and morphology was evaluated according to the International Organization for Standardization method for asbestos. Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results, the average airborne chrysotile concentrations (PCM equivalent) were 0.024 f/cc for the mechanic and 0.009 f/cc for persons standing 1.2–3.1 m from the activity during the period of exposure (∼0.5 to 1 h). Considering the time involved in the activity, and assuming three brake jobs per shift, these results would convert to an average 8-h time-weighted average of 0.009 f/cc for a mechanic and 0.006 f/cc for a bystander. The results indicate that (i) the airborne concentrations for worker and bystander samples were significantly less than the current occupational exposure limit of 0.1 f/cc; (ii) ∼2% of respirable fibers were >20 μm in length; and (iii) ∼95% of chrysotile in the brake linings degraded in the friction process. The industrial hygiene data presented here should be useful for conducting retrospective and current exposure assessments of individuals, as well as hazard assessments of work activities that involve repairing and replacing asbestos-containing brakes in heavy construction equipment. [ABSTRACT FROM PUBLISHER]

Objectives: The aim of this study was to assess the reliability of asbestos fibre concentration in bronchoalveolar lavage fluid (BALF) by carrying out the mineralogical analysis of BALF at different times in the same patient and comparing the results. [ABSTRACT FROM PUBLISHER]

This study sought to evaluate exposure from specific products to evaluate potential risk from roof repair activities. Five asbestos-containing fibered roof coatings and plastic cements, representing a broad range of these types of products, were tested in exposure simulations. These products were applied to representative roof substrates. Release of asbestos fibers during application and sanding of the product shortly thereafter (wet sanding) were tested initially. Other roof substrates were cured to simulate a product that had been on a rooftop for several months and then were tested to evaluate release of fibers during hand sanding and hand scraping activities. Additional tests were also conducted to evaluate asbestos release during product removal from tools and clothing. Two personal (n = 84) and background/clearance (n = 49) samples were collected during each 30-min test and analyzed for total fiber concentration [phase-contrast microscopy (PCM)] and for asbestos fiber count [transmission electron microscopy (TEM)]. PCM concentrations ranged from <0.005 to 0.032 fibers per cubic centimeter (f cc−1). Chrysotile fibers were detected in 28 of 84 personal samples collected. TEM concentrations ranged from <0.0021 to 0.056 f cc−1. Calculated 8-h time-weighted averages (TWAs) ranged from 0.0003 to 0.002 f cc−1 and were comparable to the background TWA concentration of 0.0002 f cc−1 measured in this study. Based on these results, it is unlikely that roofers were exposed to airborne asbestos concentrations above the current or historical occupational guidelines during scraping and sanding of these products during roof repair. [ABSTRACT FROM PUBLISHER]

A lung cancer case-control study was conducted in a Slovenian asbestos-cement factory for which unusually good records of asbestos exposures were available. The cohort consisted of all 6714 workers employed at the Salonit Anhovo factory after 31 December 1946 who worked there for at least one day between 1964 and 1994. Fifty-eight histologically confirmed cases of primary lung cancer and 290 controls were selected from the cohort. Working life exposure histories to amphibole and chrysotile forms of asbestos were estimated separately. Airborne asbestos concentrations were low. For example, the arithmetic mean exposure to all forms of asbestos in the highest exposure period (1947–1971) was 1.2 f/cm3. Chrysotile asbestos made up about 90% of this exposure (mean 1.1 f/cm3), whereas amphibole accounted for 10% (0.1 f/cm3). Comparing those above and below the 90 percentile of cumulative exposure, the odds ratios for all asbestos, chrysotile and amphibole were 1.5, 1.6 and 2.0, respectively, but confidence intervals were wide. There are only a few asbestos-lung cancer studies with high-quality exposure data and exposures in this low range. Though imprecise, the findings are important to the ongoing debate about asbestos risks. [ABSTRACT FROM PUBLISHER]

Throughout the European Union, millions tonnes of asbestos were used in the manufacture of products for building and for industrial installations. Today, in the UK, it is estimated that over half a million non-domestic premises alone have asbestos-containing materials in them and it is recognized that those working in building maintenance trades continue to be at significant risk. In part II, the awareness of UK plumbers to when they are working with asbestos was investigated and compared with the monitored levels reported in part I. The plumbers were issued by post with passive samplers, activity logs to monitor a working week and a questionnaire. The activity logs were used to assess whether maintenance workers were knowingly or unknowingly exposed to airborne asbestos fibres during a course of a working week. The questionnaire was designed to gather information on their: age, employment status, current and past perception of the frequency which they work with asbestos and knowledge of the precautions that should be taken to limit exposure and risk. Approximately 20% of workers reported on the sample log that they had worked with asbestos. There was a high correlation (93%) between the sampling log replies that they were knowingly working with asbestos and measured asbestos on the passive sampler. However, some 60% of the samples had >5 μm long asbestos structures found by transmission electron microscopy (TEM) analysis suggesting that the plumbers were aware of about only one-third of their contacts with asbestos materials throughout the week. This increased to just over one half of the plumbers being aware of their contact based on the results for phase contrast microscopy (PCM) countable asbestos fibres. The results from the questionnaire found that over half of the plumbers replying thought that they disturb asbestos only once a year and 90% of them thought they would work with asbestos for <10 h year−1. Their expectations and awareness of work with asbestos were therefore far lower than found during the period of monitoring. The response to an open question on the precautions to be taken, found that 61% of plumbers would avoid disturbance and 59% would use respiratory protection if they did disturb asbestos. However, their awareness of the methods and the need to reduce their risk by control of emissions at source was very low and suggests that further awareness raising and training is needed. The survey was carried out prior to the introduction of the duty to manage and gives a useful baseline to assess the impact of regulatory initiatives. [ABSTRACT FROM AUTHOR]

Epidemiological data suggest that there has been and may continue to be a significant risk to maintenance workers, who through their work may disturb asbestos-containing materials (ACM). The sampling and assessment of maintenance workers'' exposure is a particular problem because they may not know that they are working with ACM. A strategy to monitor their true exposure has been developed and applied to one group of workers. The asbestos exposure of industrial plumbers was measured using personal passive samplers developed at the Health and Safety Laboratory (HSL). The light-weight samplers, which collect particles by electrostatic attraction, are simple to use and do not require prior knowledge that asbestos is to be disturbed as does conventional sampling. The samplers were issued by post and analysed, after return, using transmission electron microscopy (TEM). The strategy was found to be a reasonably efficient and cost-effective way to obtain data on maintenance worker''s exposure to asbestos. The results of the TEM analysis of the passive samplers showed that the percentage of workers exposed to >5 μm long asbestos fibres was 62% in Round 1 and 58% in Round 2. For phase contrast microscopy equivalent (PCME) asbestos fibres, the values were 46 and 29%, respectively. The three samples with the highest numbers of fibres were followed up and were associated with plumbers working in areas which had supposedly been stripped of asbestos just prior to their starting work, suggesting that poor removal, clean-up and clearance practice presents a significant part of the risk to plumbers. Although flow rates will vary with conditions and time, an approximate average sampling rate from previous comparisons was used to calculate the concentration. This gave an average exposure to regulated PCME fibres of 0.009 f ml−1 for amphibole asbestos and 0.049 f ml−1 for chrysotile. The calculate risk based on the PCME fibre types collected and their estimated concentrations, showed that the risk from airborne amphibole fibres was ∼6 times greater than from chrysotile fibres. If representative, the estimated lifetime risk of death from an asbestos related cancer for an exposure from age 20 for 40 years would be 68 per 100 000, which equates to an annual risk of death of the order of 10 per million. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the relationship between estimated exposure to man-made vitreous fibres (MMVF) and to asbestos fibres and their concentration in the lung tissue of lung cancer cases amongst MMVF production workers.Methods: Retrospective retrieval of available lung tissue specimens was conducted following a case–control study that assessed estimated occupational exposures of MMVF workers. Fibre recovery and analysis by transmission electron microscopy (TEM) were conducted to determine fibre type, fibre dimension and numbers per gram of dry lung tissue. For cases with detailed exposure data, geometric mean (GM) concentrations were compared across the exposure categories, and regression models were used to investigate the relationship between the lung fibres and the variables of estimated exposure, with and without additional variables that may affect fibre retention.Results: A total of 24 samples from 17 cases of lung cancer were available for analysis: MMVF were detected in all cases. Asbestos fibres were detected in 16. No difference or trend in GM MMVF concentration was observed across the estimated exposure categories. Odds ratio (OR) for MMVF g−1 dry lung was 0.5 (95% confidence interval: 0.1–2.4) for the second, and 3.5 (0.6–18.9) for the third quartile of index of average exposure to MMVF in industry, compared with the first (lowest exposed) quartile (no cases in the highest quartile).Conclusions: No observable relationship existed between estimated exposure and directly-measured lung fibres among this sample of cases. Retrospective specimen collection, intra-individual variability in fibre concentration, effect of unknown factors on fibre retention and small sample size militated against this study providing evidence for or against a relationship between estimated exposure and lung fibre concentrations. [ABSTRACT FROM AUTHOR]

Introduction: Inhalation of asbestos fibres is known to cause two main kinds of cancer—mesothelioma and lung cancer. While the vast majority of mesothelioma cases are generally accepted as being caused by asbestos, the proportion of asbestos-related lung cancers is less clear and cannot be determined directly because cases are not clinically distinguishable from those due to other causes. The aim of this study was to estimate the number of asbestos-related lung cancers among males by modelling their relative lung cancer mortality among occupations within Great Britain in terms of smoking habits, mesothelioma mortality (as an index of asbestos exposure) and occupation type (as a proxy for socio-economic factors).Methods: Proportional mortality ratios for lung cancer and mesothelioma for the 20-year period from 1980 to 2000 (excluding 1981) were calculated for occupational groups. Smoking indicators were developed from three General Household Surveys carried out during the 1980s and 1990s. Poisson regression models were used to estimate the number of asbestos-related lung cancers by estimating the number of lung cancer deaths in each occupation assuming no asbestos exposure and subtracting this from the actual predicted number of lung cancer deaths.Results: The effect of asbestos exposure in predicting lung cancer mortality was weak in comparison to smoking habits and occupation type. The proportion of current smokers in occupational groups and average age at which they started smoking were particularly important factors. Our estimate of the number of asbestos-related lung cancers was between two-thirds and one death for every mesothelioma death: equivalent to between 11 500 and 16 500 deaths during the time period studied.Conclusions: Asbestos-related lung cancer is likely to have accounted for 2–3% of all lung cancer deaths among males in Great Britain over the last two decades of the 20th century. Asbestos-related lung cancers are likely to remain an important component of the total number of lung cancer deaths in the future as part of the legacy of past asbestos exposures in occupational settings. [ABSTRACT FROM AUTHOR]

We conducted a systematic review and analysis of the epidemiological literature that examines the risk of lung cancer and mesothelioma among motor vehicle mechanics who may have been engaged in brake repair and, thus, were potentially exposed to asbestos. All relevant studies were classified into three tiers according to their quality. Tier III (lowest quality) studies were cited for completeness, but were not included in the meta-analysis. Meta relative risks (meta-RRs) were calculated for mesothelioma and lung cancer using both fixed and random effects models for Tiers I and II, separately, followed by stratified analyses based on study design or exposure characterization (garage workers versus brake workers) and, for lung cancer studies, based on adequate adjustment for smoking. The meta-analysis for Tier I (higher quality) and Tier II (lower quality) studies of mesothelioma yielded RR estimates of 0.92 (95% CI 0.55–1.56) and 0.81 (95% CI 0.52–1.28), respectively. Further stratification according to exposure characterization did not affect the results. The meta-analysis for lung cancer produced RR estimates of 1.07 (95% CI 0.88–1.31) for Tier I and 1.17 (95% CI 1.01–1.36) for Tier II. When the lung cancer analysis was limited to studies that used adequate control for smoking, the resulting RR estimate was 1.09 (95% CI 0.92–1.28). Based on these findings, we conclude that employment as a motor vehicle mechanic does not increase the risk of developing mesothelioma. Although some studies showed a small increase in risk of lung cancer among motor vehicle mechanics, the data on balance do not support a conclusion that lung cancer risk in this occupational group is related to asbestos exposure. [ABSTRACT FROM AUTHOR]

Objective: To describe the occupational background of cases with an asbestos-related disease and to present overall mesothelioma risks across industries with historical exposure to asbestos. Methods: For the period 1990-2000, cases were collected from records held by two law firms. Information on jobs held, previous employers, activities performed and specific products used were obtained from patients themselves or next of kin. Branches of industry and occupations were coded and the likelihood of asbestos exposure was assessed. For each branch of industry, the overall risk of mesothelioma was calculated from the ratio of the observed number of mesothelioma cases and the cumulative population-at-risk in the period 1947-1960. In order to compare mesothelioma risks across different industries, risk ratios were calculated for the primary asbestos industry and asbestos user industries relative to all other branches of industry. Results: In total, 710 mesotheliomas and 86 asbestosis cases were available. The average latency period was ∼40 yr and the average duration of exposure was 22 yr. Ship building and maintenance contributed the largest number of cases (27%), followed by the construction industry (14%), the insulation industry (12%), and the navy and army, primarily related to ship building and maintenance (5%). In the insulation industry, the overall risk of mesothelioma was 5 out of 100 workers, and in the ship building industry, 1 out of 100 workers. The construction industry had an overall risk comparable with many other asbestos-using industries (7 per 10 000 workers), but due to its size claimed many mesothelioma cases. Conclusion: The majority of cases with asbestos-related diseases had experienced their first asbestos exposure prior to 1960. For cases with first asbestos exposure after 1960, a shift was observed from the primary asbestos industry towards asbestos-using industries, such as construction, petroleum refining, and train building and maintenance. Due to the long latency period, asbestos exposure from 1960 to 1980 will cause a considerable number of mesothelioma cases in the next two decades. [ABSTRACT FROM AUTHOR]

Objectives: A large number of workers in the USA are exposed to chrysotile asbestos through brake repair, yet only a few cases of malignant mesothelioma (MM) have been described in this population. Epidemiologic and industrial hygiene studies have failed to demonstrate an increased risk of MM in brake workers. We present our experience of MM in individuals whose only known asbestos exposure was to brake dust and correlate these findings with lung asbestos fiber burdens. Methods: Consultation files of one of the authors were reviewed for cases of MM in which brake dust was the only known asbestos exposure. Lung fiber analyses were performed using scanning electron microscopy (SEM) in all cases for which formalin-fixed or paraffin-embedded lung tissue was available. Results: Ten cases of MM in brake dust-exposed individuals were males aged 51-73 yr. Nine cases arose in the pleura and one in the peritoneum. Although the median lung asbestos body count (19 AB/g) is at our upper limit of normal (range 0-20 AB/g), half of the cases had levels within our normal range. In every case with elevated asbestos fiber levels by SEM, excess commercial amphibole fibers were also detected. Elevated levels of chrysotile and non-commercial amphibole fibers were detected only in cases that also had increased commercial amphibole fibers. Conclusions: Brake dust contains exceedingly low levels of respirable chrysotile, much of which consists of short fibers subject to rapid pulmonary clearance. Elevated lung levels of commercial amphiboles in some brake workers suggest that unrecognized exposure to these fibers plays a critical role in the development of MM. [ABSTRACT FROM AUTHOR]