Abstract  This paper examines the microstructures and nanostructures for natural (mined) chrysotile asbestos nanotubes (Mg3 Si2O5 (OH)4) in comparison with commercial multiwall carbon nanotubes (MWCNTs), utilizing scanning and transmission electron microscopy (SEM and TEM). Black carbon (BC) and a variety of specific soot particulate (aggregate) microstructures and nanostructures are also examined comparatively by SEM and TEM. A range of MWCNTs collected in the environment (both indoor and outdoor) are also examined and shown to be similar to some commercial MWCNTs but to exhibit a diversity of microstructures and nanostructures, including aggregation with other multiconcentric fullerenic nanoparticles. MWCNTs formed in the environment nucleate from special hemispherical graphene "caps" and there is evidence for preferential or energetically favorable chiralities, tube growth, and closing. The multiconcentric graphene tubes ( approximately 5 to 50 nm diameter) differentiate themselves from multiconcentric fullerenic nanoparticles and especially turbostratic BC and carbonaceous soot nanospherules ( approximately 8 to 80 nm diameter) because the latter are composed of curved graphene fragments intermixed or intercalated with polycyclic aromatic hydrocarbon (PAH) isomers of varying molecular weights and mass concentrations; depending upon combustion conditions and sources. The functionalizing of these nanostructures and photoxidation and related photothermal phenomena, as these may influence the cytotoxicities of these nanoparticulate aggregates, will also be discussed in the context of nanostructures and nanostructure phenomena, and implications for respiratory health.

Abstract  An increased standardised rate of mortality from pleural mesothelioma among the population of Biancavilla (Sicily, Italy) has been attributed to exposure to fluoro-edenite fibres. Our aim was to establish whether and how these fibres may induce pathological effects using an in vivo model. Lung tissue collected from 60 healthy sheep selected from six flocks habitually grazing near Biancavilla and from 10 control sheep was fixed formalin and paraffin-embedded; sections were stained with haematoxylin-eosin, Masson trichrome and Gomori argentic impregnation. Histochemical studies and immunohistochemical analysis for the localisation of TRAIL, DR5 and MMP13 were also performed. The lungs of exposed sheep exhibited fibrosis and loss of alveolar architecture with honeycombing of alveolar cavities. Fluoro-edenite fibres were detected close to the alveolar epithelium and interstitia. The parenchyma showed hyaline degeneration and strong PAS-positivity in the interstitium, proteoglycan alterations, reflecting a damaged basal membrane and an involvement of the interstitial matrix. MMP-13 was overexpressed, mainly in fibroblasts and epithelial cells, while positivity for TRAIL and DR5 was detected on alveolar surfaces and in the vascular stroma. The initial pathological event seems to involve first the alveoli and subsequently the interstitium, giving rise to classic honeycombing. The triggering event at the level of type I pneumocytes would damage the cytoplasmic membrane resulting in loss of cell elements and exposure of underlying capillaries, and eventually in a series of reactions including macrophage activation, possible release of growth factors and metaplasic reconstruction of lung alveoli. Immunopositivity for TRAIL and MMP-13 receptor suggests that apoptotic processes may also be activated by fluoro-edenite.

Abstract  BACKGROUND: Crystalline silica and asbestos are common minerals that occur throughout South Africa, exposure to either causes respiratory disease. Most studies on silicosis in South Africa have been cross-sectional and long-term trends have not been reported. Although much research has been conducted on the health effects of silica dust and asbestos fibre in the gold-mining and asbestos-mining sectors, little is known about their health effects in other mining sectors.

OBJECTIVE: The aims of this thesis were to describe silicosis trends in gold miners over three decades, and to explore the potential for diamond mine workers to develop asbestos-related diseases and platinum mine workers to develop silicosis.

METHODS: Mine workers for the three sub-studies were identified from a mine worker autopsy database at the National Institute for Occupational Health.

RESULTS: From 1975 to 2007, the proportions of white and black gold mine workers with silicosis increased from 18 to 22% and from 3 to 32% respectively. Cases of diamond and platinum mine workers with asbestos-related diseases and silicosis, respectively, were also identified.

CONCLUSION: The trends in silicosis in gold miners at autopsy clearly demonstrate the failure of the gold mines to adequately control dust and prevent occupational respiratory disease. The two case series of diamond and platinum mine workers contribute to the evidence for the risk of asbestos-related diseases in diamond mine workers and silicosis in platinum mine workers, respectively. The absence of reliable environmental dust measurements and incomplete work history records impedes occupational health research in South Africa because it is difficult to identify and/or validate sources of dust exposure that may be associated with occupational respiratory disease.

Abstract  Inflammatory responses of THP-1 cells (macrophage cell line) exposed to chrysotile asbestos (Chry) and Libby six-mix (LIB) and the subsequent impact on bronchial epithelial cells were determined. Direct treatment of THP-1 cells with Chry caused cell death, activation of caspase-1 and release of IL-1β, while the addition of caspase-1 inhibitor, Z-YVAD-FMK, reduced IL-1β, suggesting that Chry activated the caspase-1 mediated Nod-like receptor protein 3 (NLRP3) inflammasome; by comparison, LIB had less effects on all of these parameters. Expression of antioxidant enzymes, protein oxidation and nitration, and lipid peroxides in THP-1 cells treated with the two particles suggest that LIB generated more reactive oxygen species (ROS) than the same dose of Chry. Differences in fiber length and surface area suggest a possible role for particulate size in the differential activation of the inflammasome. BEAS-2B cells, representing the bronchial epithelium, treated with supernatants of medium from Chry- or LIB-treated THP-1 cells (conditioned medium) activated the MAPK cascade, increased phosphorylation of ERK and Cot (MAP3K8), increased AP-1 binding activity and induced IL-6 release. To verify that IL-1β from THP-1 cells was responsible for activation of BEAS-2B, conditioned medium with added IL-1Ra, an IL-1β antagonist, was applied to BEAS-2B. Results show that IL-1Ra attenuated effects of conditioned medium, supporting a role of IL-1β, as a secondary mediator, in the transduction of inflammatory signaling from the macrophage to epithelial cells. The effects of LIB-conditioned medium appeared to be less dependent on IL-1β. In conclusion, Chry and LIB induce differential inflammatory responses in THP-1 cells that subsequently lead to differential effects in epithelial cells.

Abstract  Environmental samples for airborne silica containing dusts are collected at seven different job areas involved in making abrasive chips, 18 samples for total dust and 16 samples for respirable dust. The substances evaluated include aluminum-oxide (1344281), silicon carbide, iron-oxide (1332372), quartz (14808607), and tremolite (14567738), and the standard concentration is given for each substance. The physical agent evaluated, noise, has a standard level of 90 decibels. The silica (7631869) dust levels are found to exceed the Federal silica standard in the aluminum oxide separation area, inspection and boxing area, material handling area, special refracting area, and batch-mixing area. The tremolite concentrations exceed the standard in the batch mix area. No radiographic or other evidence is found for any serious respiratory problem from the dusts, although much dust is found accumulated in workers' nose at the end of the day. Recommendations include replacement of tremolite by a non-fibrous material; installation of a local exhaust system on the vibrating screens and hoppers, improved housekeeping, provision of respirators and ear protectors, periodic medical examination, and introduction of a hearing correction program.

Abstract  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  During intraperitoneal administration of dispersiveness-comparable chrysotile or asbestos cement fibers to rats (20 mg thrice), mesotheliomas were found in 45.1 and 7.7% of cases respectively. Asbestos cement dust induced tumors in 2.5% of cases, which is of biological importance. Cement or freeze asbestos destruction cement dust failed to cause tumors. The latter were not detected in a control group receiving physiological saline. Asbestos cement fibers and fascicles are covered by a cement matrix. Fiber amorphization gradually occurs. In lung tissue, there may be destruction of the cement coat of fascicles and release of native chrysotile fibers that are carcinogenic.

Abstract  Inhaled asbestos causes progressive interstitial lung disease. The authors have performed a series of studies to elucidate early pathogenetic events at sites of fiber deposition in asbestos-exposed rats. This study reports that a single 5-hour exposure to chrysotile asbestos induces significant increases in incorporation of tritiated thymidine (3HTdR) into nuclei of epithelial and interstitial cells of bronchiolar-alveolar regions. No cell populations in air-exposed or carbonyl iron-exposed control animals exhibited more than 1% labeling at any point in time. Immediately after the 5-hour asbestos exposure, incorporation was normal. By 19 hours after exposure there was a significant increase in incorporation of 3HTdR, particularly by Type II epithelial cells of the first alveolar duct bifurcations. The greatest increase in degree of incorporation (up to 18-fold) was observed 24 hours after exposure, and increased percentages of 3HTdR-labeled cells were maintained through the 48 hours postexposure period. Normal labeling was present by 8 days after exposure, and this level remained through the 1-month period studied. This apparent mitogenic response correlates with increased numbers of bronchiolar-alveolar epithelial and interstitial cells demonstrated by ultrastructural morphometry in correlative studies. The authors speculate that the incorporation of 3HTdR could be induced by the direct effects of inhaled fibers or by mitogenic factors released from macrophages attracted to the inhaled asbestos.

Abstract  Papers are presented for the British Occupational Hygiene Society Spring Conference on environmental hygiene, particularly control of industrial air pollution. Topics include: threshold limit values for environmental monitoring; atmospheric pollution from fossil fuels; assessment of occupational noise exposure; sampling of particulates from stationary sources; infrared spectrophotometric determination methods for quartz in respirable dusts; airborne asbestos (1332214) dust evaluation, including use of a scanning electron microscope; use of radioactive tracers in investigating effects of cigarette smoking; hazards associated with vapor degreasing with trichloroethylene (7631869) and 1,1,1-trichloroethane (71556); and a hygienic standard for silica (79016).

Abstract  Case histories which illustrated the adverse health consequences associated with exposure to environmental pollutants were presented. Exposure of male factory workers to dibromochloropropane (35691657) or kepone (143500) resulted in sterility. Epidemics of poisoning from heavy metals were discovered among children who lived in the vicinity of smelters. Consumption of fish from a river in Japan contaminated with factory waste containing methylmercury resulted in an epidemic of neurologic disorders and the births of 40 children with cerebral palsy. In South Africa, a cluster of cases of mesothelioma were found to be associated with living near open pit asbestos (1332214) mines as children. Accidental contamination of cooking oil with polychlorinated-biphenyl (1336363) resulted in an epidemic of chloracne in Kyushu, Japan. Cattle feed contaminated with polybrominated biphenyls caused devastating debilitation and death among livestock in Michigan. Inappropriate disposal of chemical byproducts of hexachlorophene (70304) onto floors of horse arenas caused deaths of 63 horses and illnesses among children who played on the floor. Nearly all known teratogens and carcinogens were first recognized through clinical observations by patients or their physicians and were subsequently tested epidemiologically and experimentally. Proposed steps for the epidemiologic study of areawide contamination were outlined. A list of available resources which may aid in the study of environmental contamination was provided. The special susceptibilities of the child and fetus, and of the reproductive system to chemical pollutants were emphasized. The author concludes that priorities need to be set and plans formulated for the evaluation of health hazards of environmental contamination.

Abstract  In response to a request from OSHA, possible hazardous working conditions at the McGraw-Edison (SIC-3612) facility located in Canonsburg, Pennsylvania were investigated. The company produced large power transformers plus various sizes of power circuit breakers. Exposures to welding fumes, high voltage electricity, paint solvent vapors, noise, and transformer oils were possible. Past exposures to oils containing polychlorinated-biphenyls (1336363), and asbestos (1332214) were possible. A group of 58 employees was examined in an attempt to verify possible clustering of cancer cases. Of the original 58, no records were found for three, and 18 individuals had died but had never had cancer. The remaining 37 were all confirmed cancer cases covering 13 different types. An apparent clustering of cancer in recent years was demonstrated. All but one case occurred in white males between the ages of 43 and 69 years. Lung cancer was the most common type, 16 of the 37 cases. The authors conclude that, compared with the general population, lung cancer was occurring probably at no greater rate among these employees than in the general population. No evidence was found to associate causally the number of cancer cases among the workers and any occupational exposures they may have been experiencing at this facility. The authors recommend that a thorough industrial hygiene survey be made at this facility.

Abstract  Chemistry enables more than 95% of products in the marketplace. Over the past 20 years, various entities began to generate inventories of chemicals ("chemical watch lists") potentially associated with human or environmental health risks. Some lists included thousands of chemicals, while others listed only a few chemistries with limited properties or toxicological endpoints (e.g., neurotoxicants). Enacted on October 1, 2013, the California Safer Consumer Products Regulation (SCP) utilized data from chemical inventory lists to create one master list. This paper aims to discuss the background and requirements of this regulation. Additionally, we wanted to understand the universe of Candidate Chemicals identified by the Regulation. Data from all 23 chemical lists identified in the SCP Regulation were entered into a database. The most prevalent chemicals among the ∼2900 chemicals are identified, including the most prevalent chemical, lead, appearing on 65% of lists, followed by DEHP (52%), perchloroethylene (48%), and benzene (48%). Our results indicated that the most prevalent Candidate Chemicals were either persistent, bioaccumulative, carcinogenic, or reprotoxic. This regulation will have wide-ranging impact in California and throughout the global supply chain, which is highlighted through selected examples and case studies.

Abstract  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 ( approximately 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) approximately 2% of respirable fibers were >20 microm in length; and (iii) approximately 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  OBJECTIVE: To investigate whether asbestosis is a risk factor for mortality of lung cancer.

METHODS: A fixed cohort study was established in an asbestos plant in Chongqing, China, and followed up for 30 years from the beginning of 1972. Basic personal information on life state, cause of death, and diagnosis of asbestosis was collected. Multiple logistic regressions were applied to analyze risk factors.

RESULTS: During the 30-year follow-up, 584 male workers constituting a total of 14,664 person-years were monitored and data were analyzed. Among them, 203 (34.8%) died and the mortality rate was 13.8 per 1000 person-years, cancer accounting for 37.4%. Excess risks were observed for lung cancer (OR = 3.72) and nonmalignant respiratory diseases (OR = 2.73) among workers with asbestosis. High-exposure level was another risk factor for lung cancer (OR = 3.20). Workers with category II of asbestosis demonstrated a higher OR of both lung cancer and nonmalignant respiratory diseases than those with category I of asbestosis.

CONCLUSION: High asbestos exposure level and asbestosis were the risk factors for death of lung cancer and nonmalignant respiratory diseases. Asbestosis is an independent risk factor for lung cancer among Chinese workers exposed to chrysotile, the risk increases with the increasing profusion of opacities of lung.

Abstract  The research project entitled "Comprehensive approach on asbestos-related diseases" supported by the "Special Coordination Funds for Promoting Science and Technology (H18-1-3-3-1)" began in 2006 and was completed at the end of the Japanese fiscal year of 2010. This project included four parts; (1) malignant mesothelioma (MM) cases and specimen registration, (2) development of procedures for the early diagnosis of MM, (3) commencement of clinical investigations including multimodal approaches, and (4) basic research comprising three components; (i) cellular and molecular characterization of mesothelioma cells, (ii) immunological effects of asbestos, and (iii) elucidation of asbestos-induced carcinogenesis using animal models. In this special issue of the Japanese Journal of Hygiene, we briefly introduce the achievements of our project. The second and third parts and the third component of the fourth part are described in other manuscripts written by Professors Fukuoka, Hasegawa, and Toyokuni. In this manuscript, we introduce a brief summary of the first part "MM cases and specimen registration", the first component of the fourth part "Cellular and molecular characterization of mesothelioma cells" and the second component of the fourth part "Immunological effects of asbestos". In addition, a previous special issue presented by the Study Group of Fibrous and Particulate Substances (SGFPS) (chaired by Professor Otsuki, Kawasaki Medical School, Japan) for the Japanese Society of Hygiene and published in Environmental Health and Preventive Medicine Volume 13, 2008, included reviews of the aforementioned first component of the fourth part of the project. Taken together, our project led medical investigations regarding asbestos and MM progress and contributed towards the care and examination of patients with asbestos-related diseases during these five years. Further investigations are required to facilitate the development of preventive measures and the cure of asbestos-related diseases, particularly in Japan, where asbestos-related diseases are predicted to increase in the next 10 to 20 years.

Abstract  There are considerable problems in the radiological and pulmonary physiological assessment of the potential consequences of low-level exposure to chrysotile. Pleural plaques, though physiologically and prognostically benign, provide the best early evidence of such exposure.

Abstract  The authors evaluated possible increase in metabolic disorders risk in workers exposed to natural asbestos and to mixed asbestos stock dust, on the background of improper nutrition. Findings are excessive intake of food with high content of free sugar, saturated fatty acids and common salt (2.3-11.0 times) with lack of chicken meat, cereals, fish, vegetables, fruits and cultured milk foods in diet. Excessive body weight was seen in 81.0% of the workers, every third worker was obese. Chances ratio proved that the workers with excessive body weight are more probable in developing high serum levels of glucose, cholesterol, triglycerids, low density lipoproteins, higher atherogenicity index (2.4-3.1 times), and probability of arterial hypertension is higher by 78%.

Abstract  To reveal major principles in system of occupational lung diseases prevention among workers engaged into extraction and usage of chrysotile asbestos, the authors specified main criteria for diagnosis of asbestos-related pulmonary diseases and signs of exposure to chrysotile dust, with identification of risk groups for occupational diseases development. The authors formulated main principles of prevention and rehabilitation for workers with asbestos-related pulmonary diseases. Special attention was paid to harmonization of all medical and technical measures aimed at prevention and liquidation of occupational asbestos-related diseases.

Abstract  The rationale behind and operation of the Workplace Analysis Scheme for Proficiency (WASP) were described. WASP was designed as an external quality assurance check for laboratories conducting chemical analysis of air samples collected in the workplace. The types of samples offered in the initial rounds of WASP included samples of lead (7439921), cadmium (7440439), chromium (7440473), benzene (71432), toluene (108883), m-xylene (1330207), 1,1,1-trichloroethane (71556), trichloroethene (79016), and tetrachloroethane (79345) loaded onto glass fiber, membrane filter, charcoal, or Tenax mediums. The analyte loading ranges of each sample reflected levels that would normally be collected by sampling work atmospheres between 0.2 and 2.0 times the relevant occupational exposure limit. The participating laboratories received four samples of each type selected and were allowed one month to return the results. Conclusions from the WASP surveys conducted to date indicated that there are significant differences in performance between laboratories, and many analyses are not of an acceptable standard.

Abstract  The occurrence of multiple and combined exposures to hazardous chemicals was determined from survey data. Information from the US National Occupational Hazard Survey conducted between 1972 and 1974 was used to derive indices relating to the prevalence of multiple and combined exposures. Data from a Finnish survey of small industry conducted in 1976 was treated in a similar fashion. According to the US data the average number of potentially hazardous chemical exposures per worker was 13.7. Exclusion of non toxic substances and dusts such as silica (7631869) and asbestos (1332214) reduced this number to 7.6. On the same basis, the average number of solvent exposures was 3.4 per worker. The most common individual solvents were alcohols, trichloroethylene (79016), toluene (108883), xylene (1330207), butanone-2 (78933), glycol ethers, and aliphatic hydrocarbons. The Finnish survey showed that multiple and combined exposures were common in small industry. Overall, 14 percent of the workers were exposed to at least three chemicals. Multiple and combined exposures were most common in industries such as the manufacture of plastics and other chemical products. The authors conclude that multiple and combined exposures to chemical agents are very common in industry and that the effects of combined exposure are largely unknown.

Abstract  Objectives: Pulmonary parenchymal changes appear many years after the start of exposure to asbestos and their progression has been observed to continue many years after cessation of the exposure. The aim of the present analysis is to assess the risk of progression of radiological changes in the respiratory system, based on long-term follow-up of groups of workers occupationally exposed to asbestos dust. Materials and methods: The analysis included 3144 individuals voluntarily applying for a medical examination in 2000-2010, who had performed at least two radiographs of the chest. Probability of progression in subsequent studies was based on the evaluation of radiographs for the presence of small, irregular type s, t, u opacities in the parenchymal lung tissue with profusion categories as specified in the classification of ILO, 1980. Multistate hidden Markov model was used in the statistical analysis. Results: In the group of patients, small irregular opacities with a profusion of 1/1 or higher occurred in 640 (20%) patients in the first examination, and in 918 (29%) patients in the last examination. No parenchymal changes were observed in 1360 (43%) patients in the first examination (opacity profusion category 0/0), and in 645 (20%) patients in the last examination. The risk of progression of radiographic changes in former workers of asbestos processing plants is higher in smokers, from profusion category 0 to 1 - by 30% (HR = 1.30, 95% CI: 1.15-1.47), from profusion category 1 to 2 - by 50% (HR = 1.50, 95% CI: 0.92-2.45). The risk of progression of parenchymal changes decreases in the workers employed in subsequent calendar years: for category changes from 1 to 2, the decrease is nearly 40% for every 10 years of subsequent employment (HR = 0.60, 95% CI: 0.45-0.80). The probability of the progression increases with longer latency period: for change of category from 1 to 2, the increase is about 20% (HR = 1.19, 95% CI: 1.00-1.42) per 10 years of employment for blue collar workers. The risk of the 1 to 2 category progression is significant, nearly 2.5-fold higher in the workers employed in the asbestos-processing textile industry. Conclusions: Our results show that the risk of progression of pulmonary parenchymal fibrotic processes was higher in the smokers, workers employed during the earlier calendar years of the discussed period, those with longer latency period, blue collar workers involved directly in the production processes, and employees of the asbestos cement and/or textile industries.

Abstract  A comparison was made of progressive bronchoalveolar cellular response to two chrysotile (12001295) asbestos samples with different fibrogenic potential. Male Wistar-rats were given single intratracheal injections of saline, UICC chrysotile-B asbestos, or very short 4T30 chrysotile fibers. At various intervals after instillation, bronchoalveolar lavage (BAL) was performed. Significant increases were noted in inflammatory cells in response to the asbestos treatment. This effect persisted for a longer period of time in animals treated with chrysotile-B. The finding of mitotic figures in BAL fluid suggests that macrophage replication may contribute in part to this response. After injection of long chrysotile fibers, causing fibrotic lesions in 7 days, polymorphonuclear leukocytes (PMN) appeared as quickly as day one and persisted through day seven. Multinucleated cells (MGC) were present in lavage fluid from day seven to day 21. Most of these cells were binucleated and none had more than three nuclei. Exposure to very short chrysotile fibers caused only a transient influx of PMN on day one. A significant increase in MGC was noted by day seven and persisted through day 21. No fibrosis was apparent by day 21. Many cells had three nuclei or more. Giant cells were predominantly of the foreign body type. MGC of the Langhans type were also present. The author concludes that bronchoalveolar cell alterations correlated with differences in lung injury, and suggests a possible role for PMN and MGC in modulating macrophage function and lung response to injury.

Abstract  ABSTRACTS BACKGROUND: Multi-walled carbon nanotubes (MWCNT)s are suspected to induce pulmonary and pleural cancers due to their asbestos-like configurations. Therefore, accurate measurement of inhaled nanotubes in target organs is crucial for assessing cancer risk. Conventionally, nanotubes are measured after combustion at high temperature for conversion into CO2; however, the sensitivity is poor and the method lacks versatility. We have therefore developed a novel approach using hybrid markers for nanotube analysis, featuring high sensitivity and the capacity to conduct repeated analyses. The method involves adsorption of markers to nanotubes, followed by their desorption and assessment by means of high performance liquid chromatography (HPLC).

METHODS: Recovery of MWCNT from rat lungs was conducted, and pulmonary MWCNT amounts were determined using rats intratracheally-exposed to MWCNT aerosol at 5 mg/m3 for 6 hours/day.

RESULTS: The correlation coefficient for the calibration curve of MWCNT weight and the HPLC area was 0.9991. Consequently, the lower quantitation limit yielded was 0.2 μg. The recovery was 92-98% at approximately 0.4-2.0 μg demonstrating that MWCNTs in the lung could be measured accurately and precisely.

CONCLUSIONS: We have developed a novel method using a hybrid marker approach for nanotube analysis, featuring very high sensitivity and the capacity to conduct repeated analyses. We further confirmed correlations between the amounts of nanotubes and markers and pulmonary nanotube measurement demonstrated that trace amounts could be detected with values closely relating to the administered dose, verifying that the method is sensitive and precise.

Abstract  Mesothelioma is considered a signal tumor for exposure to asbestos (fibrous materials) and can occur decades after first exposure. The present case study reports on tissue burden of fibrous dust in a person who used a vermiculite material (Zonolite) as an attic insulator some 50 years prior to her death. The exposure occurred in two construction/renovation projects in her private residencies. She potentially had exposures to wall board/joint compounds during renovations. She additionally was reported to occasionally be involved in occupational activity, including drilling holes in presumed asbestos-containing electrical boxes. The tissue burden analysis revealed the presence of noncommercial amphibole asbestos fibers and consistent presence in the lung and lymph samples of Libby amphibole fibers. The findings of Libby amphibole fibers in human tissue can be attributed to exposure to Libby vermiculite. This study illustrates that analytical transmission electron microscopy can distinguish these structures from "asbestos" fibers. Further, the findings indicate that a population of these structures is biodurable and retained in the tissue years after first/last exposure.