Potential airborne asbestos exposures in dentistry: a comprehensive review and risk assessment.

Chrysotile was formerly used in the manufacture of casting ring liner (CRL) and periodontal dressing powder (PDP). The purpose of this study was to describe the potential for airborne asbestos exposure among dental professionals who may have used these products and to assess their risk of asbestos-related disease (ARD). Task-specific exposure data associated with CRL and PDP were identified and compared to regulatory standards for asbestos and health-based benchmarks. Personal airborne fiber concentrations ranged from 0.008-3.5 f/cc by PCM (duration: 3-420 minutes) for CRL (tearing, placement), and from <0.0044-<0.297 f/cc by PCM (duration: 5-28 minutes) for PDP (mixing). Eight-hour time-weighted average (TWA) exposures were calculated using the reported task-based airborne fiber concentrations and associated sampling durations. For CRL tasks, the upper-bound calculated 8-hour TWA of 0.022 f/cc (tearing, placement) did not exceed regulatory standards for asbestos (≥0.1 f/cc). All samples collected during the mixing of PDP resulted in non-measurable fiber concentrations. The greatest estimated cumulative asbestos exposure for dental professionals using CRL (tearing, placement) of 0.33 f/cc-years is well below "best estimate", published chrysotile no-observed-adverse-effect-levels (NOAEL) for ARD (lung cancer = 89-168 f/cc-years; pleural mesothelioma = 208-415 f/cc-years). As such, the use of asbestos-containing CRL and/or PDP is not expected to pose an increased risk of ARD among dental professionals. This conclusion is consistent with the lack of an increased risk of ARD reported in epidemiological studies of these occupations.

Cohort study of workers employed in an Italian tire manufacturing plant, 1962-2004.

PURPOSE: To investigate mortality and bladder cancer incidence among workers of a tire manufacturing plant where antioxidants severely contaminated by beta-naphthylamine were never used. METHODS: Mortality follow-up was performed of 9,501 workers first hired between 1962 when the plant started operations and 2000. Person-years of observation from 1962 to 2004, expected deaths, and standardized mortality ratios (SMR) were calculated. Follow-up for bladder cancer incidence from 1988 to 2003 was carried out, and standardized incidence ratios (SIR) were calculated. Multivariable (Poisson) analyses of bladder cancer incidence and mortality by duration of employment (DOE) and time since first employment (TSFE) were performed. RESULTS: Among men, SMRs were significantly reduced for all causes, all cancers, lung cancer, cardiovascular, and ischemic heart diseases. Bladder cancer mortality and leukemia mortality were close to expectation but increased with TSFE. Seventy-two incident cases of bladder cancer were observed (SIR = 1.15; 95 % confidence interval 0.90-1.44), and multivariable analysis suggested a possible increase in rate ratios with DOE. Among women, mortality was close to expectation, but the limited number of observed deaths prevented detailed analyses. CONCLUSIONS: No significant cancer excess was observed. A suggestion of increased risks of bladder cancer and leukemias after extended TSFE was present in men, deserving consideration as exposure to carcinogens possibly occurred early in plant operation. Furthermore, this cohort of workers is still relatively young and less than 10 % have died. There was, thus, limited power to detect small increases in risk at rare cancer sites. Further epidemiological surveillance of this cohort is planned.

[Health evaluation of the population of the city of Trino Vercellese: epidemiological study on cancer incidence and mortality]. / Analisi dello stato di salute della popolazione del comune di Trino V.se: studio epidemiologico sull'incidenza e mortalità delle patologie neoplastiche.

The study includes an analysis of the state of health of the inhabitants of the City of Trino, County of Vercelli, 15 km south-west of the capital town. With industries making a significant environmental impact and an old nuclear centre under dismantlement, in recent years, the City has often been mentioned in local newspapers and pressurised by residents and local associations. Hence the drawing up of this study to describe the state of health of residents and cancer pathologies (incidence and mortality rate) and, consequently, to evaluate the need for further epidemiological analysis. The rates (SIR and SMR) were obtained by calculating the expected results compared with those of the Local Health Authority of Vercelli and the Airtum registries of Northern Italy: the results (divided by sex) highlight significant excesses in neoplasias of the mouth, nervous system, peritoneum in addition to eukaemias and mesoteliomas. Furthermore, the analysis by age shows epidemiological anomalies both at paediatric (0-14 years) and young people (0-44 years) levels: these results certainly require further epidemiological research through aetiological studies, including an ad hoc questionnaire.

Natural organic fibers--health effects.

OBJECTIVES: Natural organic fibers are used in large quantities in the production of paper products and textiles. They are also constituents of food and added to food to promote health. The objective of this review is to evaluate the health effects of natural organic fibers. The health effects of dietary fibers are excluded from the review. METHODS: This is a literature review. RESULTS: Exposure to these fibers in industry is usually not characterized as fibers but as dust. Rather dusty conditions have been reported in both paper and textile industries with concentrations up to and above 30 mg/m3. Both in the paper and textile industry inorganic fibers may occur making it hard to evaluate health effects of natural organic fibers from studies of workers in the paper and textile industry. There seems to be no increased risk of mesothelioma, lung cancer or lung fibrosis in workers exposed to natural organic fibers in contrast to workers exposed to inorganic crystalline fibers as asbestos. However, workers with a heavy exposure to paper dust or textile dust seem to have an increased risk of obstructive lung disease and bronchitis. These effects have not been causally linked to the fibrous shape of the particles but rather to the dust, chemicals absorbed on the dust or microorganisms occurring together with the dust. There is some indication that work in the textile industry may increase the risk of sinonasal cancer, but the etiological agents are unknown. CONCLUSION: Natural organic fibers are not causally linked with the well-known effects of some inorganic fibers, i.e. mesothelioma, lung cancer, lung fibrosis or some pleural diseases. The health effects of natural organic fibers, e.g. irritative effects, seem not to be linked to their fibrous shape.

A survey of cancer and occupation in young and middle aged men. I. Cancers of the respiratory tract.

In a search for clues to previously industrial carcinogens the occupational and smoking histories of young and middle aged men with different types of cancer were compared. The study population comprised men aged 18-54 and resident in the counties of Cleveland, Humberside, and Cheshire (including the Wirral). From hospital and cancer registration records 2942 members of the study population in whom cancers were diagnosed during the period 1975-80 were identified retrospectively. The occupational and smoking histories of these patients were sought by a postal questionnaire addressed either to the patients themselves or, if they had died, to their next of kin. The overall response rate to the questionnaire was 52.1%. Additionally, limited occupational information was obtained for 89% of cases from their hospital notes. Analysis of these data suggests that no serious bias arose as a consequence of the incomplete response to the questionnaire. This paper concentrates on the results for cancers of the respiratory tract and mesothelioma. Mesothelioma was found to cluster in laggers, electricians, and shipyard workers, and nasal carcinoma in woodworkers. Carcinomas of the larynx and of the bronchus were examined by formal statistical techniques, each being compared with a control group made up of all other cancers combined. Several interesting occupational and industrial associations were shown, in particular, an excess of bronchial carcinoma in the leather industry (RR = 2.6, CI 1.2-6.0), in building labourers (RR = 1.7, CI 1.0-2.9) and other construction workers (RR = 1.8, CI 1.0-3.0), in bakers and pastry cooks (RR = 3.6, CI 1.3-10.4). and in cooks (RR = 2.5, CI 1.2-5.1). In addition, a small cluster of lung tumours was observed in men who had worked as dental mechanics.