Fibrogenic effect of wollastonite compared with asbestos dust and dusts containing quartz.

The distribution of length and diameter and the aspect ratio of crocidolite asbestos, a mineral substitute for asbestos (wollastonite), a manmade mineral fibre (glass wool), and synthetic fibres (polypropylene and polyacrylonitrite) were determined by light microscopy with phase contrast and, for crocidolite, also with transmission electron microscopy. The synthetic organic fibres and manmade mineral fibre used were of a size exceeding that considered respirable. Respirable materials were given to rats by the intratracheal method and after exposure for a standard time interval the main indices of fibrogenic effects--the total hydroxyproline content, the wet weight of the lung, and the total lipid content in the lung--were estimated. For wollastonite there was a significant increase in these variables in comparison with the controls. The fibrogenicity was considerably less than that of crocidolite and quartz.     

Dissolution of silicic acid from amosite and quartz dusts under physiological conditions.

The dissolution of silica from amosite dust in human serum and in Ringer buffer at 37 degrees C was found to be significantly higher than that from quartz. The significance of this finding in relation to their fibrogenic effects has been discussed.     

粉尘中游离二氧化硅含量测定方法的改进

目的对国家标准(GB5748-1985)测定粉尘中游离二氧化硅(SiO_2)含量“焦磷酸质量法”的一些操作进行改进,提高方法的可操作性。方法从样品采集、样品预处理、焦磷酸溶解样品、过滤样品、样品恒质称量5个步骤进行改进,并使用改进前后的方法对已知样品含量测定和未知样品平行双样进行比较实验。结果对已知SiO_2含量为6．0%±2．0%的样品,用改进前方法测的结果为11%,超出了已知样品中SiO_2的含量范围；用改进后的方法测得相同样品结果为4．7%,在已知样品SiO_2含量范围内。结论提高了粉尘中游离SiO_2含量测定实验效率,使结果有较好的平行性,更接近已知值。     

Chemical composition and morphology of welding fume particles and grinding dusts.

Elemental composition and morphology of pure manual metal arc (MMA) welding fumes, pure grinding dust, and combined fume/dust air samples were collected and determined separately under semilaboratory conditions. The base material was stainless steel. The purpose of the present study was to create a "synthetic" work situation under semilaboratory conditions by combining one grinding period and two MMA welding periods and comparing these results with results during welding in a workshop. The duty cycles of pure welding and of pure grinding were also observed. A comparison was also made between metal inert gas (MIG) and MMA welding on stainless steel as well as a nickel-rich alloy under regular conditions. The amount of collected material was determined by weighing the membrane filters before and after exposure, and the element contents were determined by atomic spectroscopy. Other transmission electron microscopy (TEM) filters were used for TEM and computer-image analysis, in which the amount of collected material and its morphological characteristics were observed. The arcing time and the consumption of filler material were estimated for different kinds of electrodes. Chemical analysis showed that the contents of manganese and total chromium were lower in grinding dust than in welding fumes. The contents of hexavalent chromium, Cr(VI), in grinding dust were undetectable. Samples collected in welding shops where concomitant grinding was performed contained about 30% less Cr(VI) than those collected under laboratory conditions during welding only. The sizes and shapes of the particles depend on the welding process and distance of collection from the plume of the fume. To compare laboratory experiments with regular welding situations, the experiment must resemble industrial welding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alterations in the surface-related phenomena of alveolar macrophages following inhalation of crocidolite asbestos and quartz dusts: an overview.

The possibility that immunological factors could be involved in the pathogenesis of asbestosis and silicosis was investigated. This study formed the basis of a Ph.D. Thesis. A brief discussion of the results obtained with particular reference to the differing effect of quartz and asbestos inhalation is presented. Rats were used as experimental animals and were exposed to the relevant dusts by inhalation to provide a model of the in vivo participation of the constituent mononuclear phagocytes. Early changes included alteration of surface morphology of the macrophages and an increased number of IgG receptor sites. In vivo membrane deposition of complement components on asbestos macrophages from crocidolite-dusted rats was demonstrated. When macrophages from crocidolite-dusted rats were cultured in vitro with splenic lymphocytes a prolonged physical interaction occurred followed by lymphocyte proliferation. The surface-related alterations leading to these phenomena were characterized. It is postulated that dusted macrophages participate in both cell-mediated and humoral interactions, and that host factors contribute to the development of dust diseases.     

Smoking habits and lifetime occupational exposure to gases or dusts, including asbestos and quartz, in a Norwegian community

Past or present occupational airborne exposure was recorded with a self-administered questionnaire sent to a random sample (N = 4992) of the 15- to 70-year-old population of Hordaland County, Norway. Completed questionnaires were returned by 90% of the sample. The respondents comprised 39% smokers, 20% ex-smokers, and 41% nonsmokers. Altogether 46% of the men and 12% of the women had a history of occupational gas or dust exposure. Occupational asbestos exposure was reported by 10% of the men and 0.4% of the women, and quartz exposure had been experienced by 8% of the men and 0.4% of the women. Smokers with a history of asbestos exposure represented 5% of the male population. Thirty percent of the smokers reported having been advised to stop smoking by a physician. The asbestos-exposed smokers had not received such advice more often than the smokers not exposed to asbestos. The findings indicate that airborne occupational exposure is widespread in the Norwegian County of Hordaland.     

Factors affecting the accuracy of airborne quartz determination

Samples collected in a foundry were used to analyze sources of variation and factors influencing the overall accuracy of sampling results. Air samples were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) using NIOSH Method 7602 to study particle size effects, analytical precision, sampling equipment performance, and production factors. The FTIR technique provides accuracy when silica particle size is taken into consideration. In this case, the variability due to analytical factors is small compared with other sources of error. The typical coefficient of variation of the analytical procedure is 0.08; variation associated with sampling reaches 0.21; and interday coefficient of variation can be as high as 0.48. The IR method has advantages over XRD analysis, including cost effectiveness, sensitivity, and a lower detection limit.