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OBJECTIVES: To evaluate potential airborne asbestos exposures during brake maintenance and repair activities on a P&H overhead crane, and during subsequent handling of the mechanic's clothing. METHODS: Personal (n = 27) and area (n = 61) airborne fiber concentrations were measured during brake tests, removal, hand sanding, compressed air use, removal and reattachment of chrysotile-containing brake linings, and reinstallation of the brake linings. The mechanic's clothing was used to measure potential exposure during clothes handling. RESULTS: All brake linings contained between 19.9% to 52.4% chrysotile asbestos. No amphibole fibers were detected in any bulk or airborne samples. The average full-shift airborne chrysotile concentration was 0.035 f/cc (PCM-equivalent asbestos-specific fibers, or PCME). Average task-based personal air samples collected during brake maintenance, sanding, compressed air use, and brake lining removal tasks ranged from 0 to 0.48 f/cc (PCME). The calculated 30-minute time-weighted average (TWA) airborne chrysotile concentration associated with 5-15 minutes of clothes handling was 0-0.035 f/cc PCME. CONCLUSION: The results indicated that personal and area TWA fiber concentrations measured during all crane brake maintenance and clothes handling tasks were below the current OSHA 8-h TWA Permissible Exposure Limit for asbestos of 0.1 f/cc. Further, no airborne asbestos fibers were measured during routine brake maintenance tasks following the manufacturer's maintenance manual procedures. All short-term airborne chrysotile concentrations measured during non-routine tasks were below the current 30-minute OSHA excursion limit for asbestos of 1 f/cc. This study adds to the available data regarding chrysotile exposure potential during maintenance on overhead cranes.

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Chrysotile fibers pose a threat to public health due to their association relation to respiratory malignant lung disease such as cancer. For this reason, they must be stored and discarded appropriately, including after treatment, which raises costs. In the present study, insoluble chrysotile fibers were milled in solid state with highly soluble K2HPO4, destroying both structures, making the chrysotile nontoxic and generating a new material with potential use as sustainable slow-release fertilizer (SSRF) containing mainly K and P. Based on the mills, milling conditions and chrysotile/K2HPO4 molar ratios used, Mg originating from chrysotile fibers reacted with K and P from dibasic potassium phosphate and were transformed into MgKPO4·H2O, MgKPO4·6H2O and probably a mixture of amorphous SiO2/MgO. In this study, a zirconia planetary mill and high-energy ball mill were used, both of them produced SSRF. In conclusion, it was possible to synthesize high-value and extremely useful materials for agriculture using a harmful waste. The release rate can be tailored by controlling chrysotile/K2HPO4 molar ratios, grinding speed and time, which makes the process even more promising for farming applications.

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Amphiphilic magnetic composites were produced based on chrysotile mineral and carbon structures by chemical vapor deposition at different temperatures (600-900 °C) and cobalt as catalyst. The materials were characterized by elemental analysis, X-ray diffraction, vibrating sample magnetometry, adsorption and desorption of N2, Raman spectroscopy, scanning electronic microscopy, and thermal analysis showed an effective growth of carbon structures in all temperatures. It was observed that at 800 and 900 °C, a large amount of carbon structures are formed with fewer defects than at 600 and 700 °C, what contributes to their stability. In addition, the materials present magnetic phases that are important for their application as catalysts and adsorbents. The materials have shown to be very active to remove the oil dispersed in a real sample of emulsified wastewater from biodiesel production and to remove methylene blue by adsorption and oxidation via heterogeneous Fenton mechanism.

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Chrysotile, like other types of asbestos, has been associated with mesothelioma, lung cancer and asbestosis. However, the cellular abnormalities induced by these fibers involved in cancer development have not been elucidated yet. Previous works show that chrysotile fibers induce features of cancer cells, such as aneuploidy, multinucleation and multipolar mitosis. In the present study, normal and cancer derived human cell lines were treated with chrysotile and the cellular and molecular mechanisms related to generation of aneuploid cells was elucidated. The first alteration observed was cytokinesis regression, the main cause of multinucleated cells formation and centrosome amplification. The multinucleated cells formed after cytokinesis regression were able to progress through cell cycle and generated aneuploid cells after abnormal mitosis. To understand the process of cytokinesis regression, localization of cytokinetic proteins was investigated. It was observed mislocalization of Anillin, Aurora B, Septin 9 and Alix in the intercellular bridge, and no determination of secondary constriction and abscission sites. Fiber treatment also led to overexpression of genes related to cancer, cytokinesis and cell cycle. The results show that chrysotile fibers induce cellular and molecular alterations in normal and tumor cells that have been related to cancer initiation and progression, and that tetraploidization and aneuploid cell formation are striking events after fiber internalization, which could generate a favorable context to cancer development.

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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.

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Trabajo de revisión sobre los aspectos clínicos de la asbestosis y el mesotelioma pleural en el contexto de una posible epidemia de mesotelioma pleural en los próximos 50 años. Estas enfermedades tienen como agente etiológico común a las fibras de asbesto. Se describe la historia del asbesto desde que los cipriotas lo usaron para hacer vestidos hace 5,000 años hasta su participación industrial en la década de 1870 y su prohibición al descubrirlo como causante de la asbestosis, el cáncer pulmonar y el mesotelioma pleural. Se describen las diferencias de la estructura, la química y las propiedades biológicas de los asbestos. En México se utiliza el crisotilo en un 90% para fabricar productos de fibrocemento destinados a la construcción y componentes destinados a piezas de rozamiento, de calefacción y textiles. Se analizan los aspectos clínicos, radiológicos, histológicos y funcionales de la asbestosis y el mesotelioma pleural, así como su tratamiento y prevención. Se refieren los diagnósticos diferenciales de estas enfermedades con otros padecimientos respiratorios. El periodo de latencia tanto de la asbestosis como del mesotelioma pleural varía de 20 a 40 años, por lo cual nos enfrentamos en México a una epidemia de mesotelioma pleural en los próximos 50 años. La única prevención efectiva de la asbestosis y el mesotelioma pleural maligno es la prohibición de las industrias que utilizan el asbesto.

Review article considering clinical issues of asbestosis and pleural mesothelioma in the context of a potential pleural mesothelioma outbreak in Mexico in the next 50 years. The common etiologic agent of asbestosis and pleural mesothelioma are asbestos fibers. The history of asbestos dates from 5 000 years ago when Cypriots used it to make their garments, until its industrial usage in the 1870s and its prohibition in some countries after finding its direct relationship with asbestosis, lung cancer, and pleural mesothelioma. The main structural characteristics, chemical profile, and biological properties of asbestos are described here. In Mexico, chrysotile, or white asbestos, is used in 90% of the production of fibercements for the building industry, as well as in components of friction pieces, heating and textile industries. This article analyses the clinical, radiological, histological, and functional issues of asbestosis and pleural mesothelioma; as well as their treatment and prevention. The differential diagnoses for this disease in relation to other respiratory illnesses are described. Since the latent period for both asbestosis and pleural mesothelioma is between 20 and 40 years, an outbreak of pleural mesothelioma can be expected in Mexico in the next 50 years. The only effective way to prevent asbestosis and malignant pleural mesothelioma is banning asbestos-related industries.

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Objective: This study describes the frequency, occupational, clinical, and pathological features in a large cohort of cases of Malignant Mesothelioma (MM) from the National Institute of Respiratory Diseases (INER), in México. Methods: A retrospective and transversal study was carried out in medical records of patients diagnosed with MM between the years 1991 to 2007. Results: Of the 247 patients, 184 were male and 63 were female with an average age of 51-60 years. Dyspnea and chest pain were the presenting symptoms in most of the patients. Exposure to asbestos was referred only in 34 percent of cases but direct exposition only was documented in five of them. Clinical features of MM patients were similar in asbestos related and non-asbestos related malignant mesothelioma. Conclusion: Although a growing tendency is observed in, the number of cases with MM, in many of them was not possible to establish the source of asbestos exposure.

Objetivo: Este estudio describe la frecuencia, características patológicas, ocupación y exposición a asbesto en una cohorte grande de casos de mesotelioma maligno (MM) admitidos en el Instituto Nacional de Enfermedades Respiratorias (INER), en México. Método: Se llevó a cabo un estudio retrospectivo y transversal en los registros médicos de pacientes diagnosticados con MM entre los años 1991-2007. Resultados: De los 247pacientes, 184 fueron hombres y 63 fueron mujeres con un promedio de edad de 51 y 60 años. Disnea y dolor torácico fueron los principales síntomas observados. Exposición a fibras de asbesto fue referida sólo en 34 por ciento) de los casos, aunque una exposición directa sólo puedo ser documentada en cinco de ellos. Las características clínicas de los pacientes con MM fueron similares en aquellos con y sin exposición a asbesto reconocida. Conclusión: Aunque se observa una tendencia creciente en el número de casos con MM, en muchos de ellos no fue posible establecer una fuente de exposición a asbesto como la causa de contaminación para el desarrollo de la enfermedad.

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