Abstract  The term asbestos is a generic designation referring usually to six types of naturally occurring mineral fibers that are or have been commercially exploited. These fibers belong to two mineral groups: serpentines and amphiboles. The serpentine group is represented by a single asbestiform variety-chrysotile. There also are five commercial asbestiform varieties of amphiboles-anthophyllite asbestos, cummingtonite-grunerite asbestos (amosite), riebeckite asbestos (crocidolite), tremolite asbestos, and actinolite asbestos. Amosite and crocidolite are no longer mined. Nearly all of the asbestos mined after the mid-1990s was chrysotile. Only very small amounts of actinolite, anthophyllite, and tremolite asbestos may be mined in a few countries. Asbestos was mined in Argentina, Brazil, Canada, China, India, Kazakhstan, and Russia in 2010; world production was estimated to be 1.97 × 106 tons. Properties that made asbestos valuable for industrial applications were their thermal, electrical, and sound insulation properties; inflammability; matrix reinforcement (cement, plastic, and resins); adsorption capacity (filtration, liquid sterilization); wear and friction properties (friction materials such as brakes and clutches); and chemical inertia (except in acids). These properties led to the use of asbestos in about 3,000 products by the 1960s. Since about 1995, asbestos-cement products, including pipe and sheets, accounted for more than 95% of global asbestos consumption as other uses of asbestos have declined. Global consumption of asbestos was estimated to have been about 1.98 × 106 tons in 2009. The leading consuming countries in 2009 were Brazil, China, India, Russia, and Thailand, each with more than 100,000 tons of consumption.

Abstract  Background: Poisson regression is routinely used in occupational and environmental epidemiology. For typical Poisson regression analyses, person-time and events are tabulated by categorising predictor variables that were originally measured on a continuous scale. In order to estimate a dose-response trend, a researcher must decide how to categorise exposures and how to assign scores to exposure groups. Aims: To investigate the impact on regression results of decisions about exposure categorisation and score assignment. Methods: Cohort data were generated by Monte Carlo simulation methods. Exposure categories were defined by quintiles or deciles of the exposure distribution. Scores were assigned to exposure groups based on category midpoint and mean exposure levels. Estimated exposure-disease trends derived via Poisson regression were compared to the "true" association specified for the simulation. Results: Under the assumption that exposures conform to a lognormal or exponential distribution, trend estimates tend to be negatively biased when scores are assigned based on category midpoints and positively biased when scores are assigned based on cell specific mean values. The degree of bias was greater when exposure categories were defined by quintiles of the exposure distribution than when categories were defined by deciles of the exposure distribution. Conclusions: The routine practice of exposure categorisation and score assignment introduces exposure misclassification that may be differential with respect to disease status and, consequently, lead to biased exposure-disease trend estimates. When using the Poisson regression method to evaluate exposure-disease trends, such problems can be minimised (but not necessarily eliminated) by forming relatively refined exposure categories based on percentiles of the exposure distribution among cases, and by assigning scores to exposure categories that reflect person-time weighted mean exposure levels.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM POLLUTION DRINKING WATER QUALITY NEW YORK USA

Abstract  We have used proton-induced X-ray emission (PIXE) techniques to assess the asbestos pollution of the Bécancour river in Québec. The asbestos pollution levels at twelve different sites along the river have been determined from the measured magnesium concentrations. The results clearly show that in the mining areas the asbestos pollution is high and that is decreases after the lakes located downstream. Furthermore, it has been shown that the meteorological conditions play a large rôle in the spread and variation of the pollution levels in river water.

Abstract  HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT RAT ASBESTOS PULMONARY FIBROSIS

Abstract  HEEP COPYRIGHT: BIOL ABS. RRM RAT MOUSE EMPHYSEMA FIBROSIS COMPLEMENT ASBESTOS

Abstract  HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT GUINEA-PIG ASBESTOSIS LUNG CANCER MACROPHAGE

Abstract  HEEP COPYRIGHT: BIOL ABS. RRM MOUSE LYMPH NODE ASBESTOS INTESTINAL TOXICITY

Abstract  HEEP COPYRIGHT: BIOL ABS. The relationship between lung function and radiological abnormality was compared in 46 subjects with asbestosis and 38 subjects with cryptogenic fibrosing alveolitis. Radiographs were graded separately by 2 observers according to the 1980 International Labor Organization criteria for classification of the pneumoconioses. The correlation between the transfer factor of the lungs and the radiographic profusion of small parenchymal opacities was found to be greater in subjects with asbestosis than in subjects with cryptogenic fibrosing alveolitis. At any level of radiological profusion transfer factor was higher in cases with asbestosis than in cases with fibrosing alveolitis. As pleural thickening was seen commonly in asbestosis and may influence lung volumes and the ratio of transfer factor to effective alveolar volume, the results of these measurements were compared only in the cases showing absent or minimal pleural thickening. Both of these variables were higher in the subjects with asbestosis. Despite pathological, functional asnd radiographic similarities, lung function for a given degree of radiographic parenchymal abnormality is better in subjects with absectosis than in subjects with cryptogenic fibrosing alveolitis. Changes in the plain chest X-ray appearances in asbestosis correlate more closely with the results of lung function tests.

Abstract  HEEP COPYRIGHT: BIOL ABS. RRM ABSTRACT RAT CELL-MEDIATED IMMUNITY INFLAMMATORY LESIONS

Abstract  The clinical aspects of respiratory disease due to mining are reviewed. Inhaled dusts damage the lungs in two ways: by a nonspecific effect on the airways, common to all types of dust; and by a specific action, peculiar to each type of mineral, that is exerted mainly on the respiratory surface and interstitial tissues of the lung. Nonspecific effects of dust are discussed. Dust inhalation tends to cause bronchospasms, which can be alleviated or prevented by inhaling a sympathomimetic drug, and which are more pronounced in those who smoke, those who are subject to allergic asthma, or those who have chronic obstruction of the airways. Dust diseases in coal miners are discussed; these include simple pneumoconiosis, progressive massive fibrosis, and Caplan's syndrome. Management of pneumoconiosis and progressive massive fibrosis are considered. Silicosis is reviewed. Diseases associated with asbestos are discussed. There are six abnormalities associated with asbestosis exposure: pleural effusion, hyaline pleural thickening, pleural calcification, pleural and peritoneal mesothelioma, asbestosis, and bronchial carcinoma. Management of asbestosis is described. The author concludes that suppression of dust can both delay the onset of disease and reduce its incidence. Control of these diseases requires improved environmental hygiene, and complete eradication should eventually be possible.

Abstract  HEEP COPYRIGHT: BIOL ABS. HUMAN CARCINOGENESIS MESOTHELIOMA OCCUPATIONAL EXPOSURE LIGHT MICROSCOPY

Abstract  HEEP COPYRIGHT: BIOL ABS. RAT HAMSTER ASBESTOS DUST CARCINOGEN INTRA PLEURAL ADMINISTRATION INHALATION

Abstract  HEEP COPYRIGHT: BIOL ABS.

Abstract  HEEP COPYRIGHT: BIOL ABS.

Abstract  HEEP COPYRIGHT: BIOL ABS. Natural resource conservation is studied from the ecological point of view. The introductory chapter examines the extent of America's resource and environmental problems and reviews the history of conservation efforts. The concepts and principles of ecology are covered in another chapter. Each resource is then studied with details on its nature, abuse and depletion, conservation and management. Soil, water, wildlife, forests and marine organisms are among the resources dealt with. Individual chapters are devoted to water, noise and air pollution. The pesticide and solid waste problems are also considered. Chapters cover the energy crisis, radiation effects and population problems. Topics include: soil nutrient depletion, sewage treatment and disposal, factors depleting animal population, fisheries management, cycling of pesticides in ecosystem, biological and integrated pest control, effects of air pollution on plants and animals, harmful physiological effects of noise pollution, occurrence and poisonous effects of Hg, Pb and asbestos found in the environment, possible sources of future energy, food shortage problem and environmental impact of economic growth. Numerous photographs, maps and charts supplement the text. Bibliographies, an index and a glossary are provided.

Abstract  HEEP COPYRIGHT: BIOL ABS. Ambient air concentrations of asbestos fibers were measured during the period 20 June to 12 Aug., 1980 at 3 locations; Danville, Asbestos and Wottenville in the eastern townships of Quebec. Measurements were made with low-volume samplers and measurement periods ranged from 3 to 13 days. Fiber counts were made by means of EM. Overall fiber concentrations apparently are related to atmospheric stability and to the direction of the prevailing wind with respect to the source of emission. Fiber concentrations are then related to total dust content of the ambient air for the town of Asbestos. Spatial variations of mortality are in turn related to the variations in the concentration of ambient air dust particles.