Hemolytic activity of five different calcium silicates.

Mineral characteristics and the in vitro hemolytic activity of three synthetic and two natural calcium silicates (CaSi) are compared. Hemolysis is higher for the synthetic compounds than for the natural ones. The difference is accentuated by weak ultrasonication of the minerals. No variation was observed within the two groups, including both acicular and fibrous forms. Calcium was released from the minerals during storage in Tris-buffered saline. At the same time, hemolysis decreased, and crystallographic alterations occurred in the leached minerals. Treatment of the CaSi with calcium chelators (EGTA and EDTA) did not change hemolytic activity. An increase was observed when 30 mM calcium was added. Hemolysis is related to specific surface areas and the crystalline structure of the minerals. Calcium may also be a contributing factor.

Topographic and size distribution of asbestos bodies in exposed human lungs.

The concentration and the length distribution of asbestos bodies in exposed human lungs have been determined in autopsy material by scanning electron microscopy after two different methods for preparing the tissue samples. The results demonstrate that the number of bodies vary between the right and left lung, as well as between the different lobes of a lung. The length distribution between the different lungs was, on the average, more or less the same; however small differences occurred between the different lobes. It was further shown that drying the tissue pieces before the analyses affected both the number and the length of the bodies. Examples of different types of asbestos bodies are presented, and their possible biological activity is discussed.

Evaluation of chromium exposure based on a simplified method for urinary chromium determination.

The urine chromium levels for unexposed and chromium exposed persons were determined by a simplified method which is well suited for routine, large-scale use. A group of welders working on chromium alloyed steel were investigated. For these welders a high degree of correlation was found between the concentration of inhaled chromium and the chromium concentration in the urine immediately after work. At an exposure level of 0.05 mg/m3, measured as chromium, a urinary chromium concentration of approximately 40 microng/l was measured after work. This urinary chromium level is suggested as a guideline indicating the need for a thorough investigation of chromium exposure.

Occurrence of fibrous sodium aluminumtetrafluoride particles in potrooms of the primary aluminum industry.

Inorganic fibrous particles have been found in the work environment of the primary aluminum industry. Based on scanning electron microscopic analysis, the concentrations ranged from 9 to 720 fibers/cc. The fibers were generally thinner than 0.1 micron in diameter and shorter than 5 microns. By electron microscopy, energy dispersive X-ray microanalysis, and selected area electron diffraction the fibers were identified as sodium aluminumtetrafluoride.

Occupational asbestos exposure, lung-fiber concentration and latency time in malignant mesothelioma.

Mineral fiber concentration in lung tissue was analyzed by scanning electron microscopy in 73 males with malignant mesothelioma and in 36 referents who died of cardio- or cerebrovascular diseases. The investigation showed apparent differences in the median lung-fiber concentration between occupational groups with different levels of asbestos exposure, as judged from their occupational history. Thus the mineral fiber content in human lung tissue provides a useful indicator of cumulative asbestos exposure. There was also a statistically significant difference between the median lung-fiber concentration among mesothelioma cases with unlikely or unknown occupational asbestos exposure and the reference group. The latency times in 42 of the cases with definite or probable occupational asbestos exposure showed a log-normal distribution with a median of 37 years and a range of 19-68 years. No statistically significant correlation was found between the logarithm of the latency time and the logarithm of the lung-fiber concentration.

Determination of inorganic fiber density in human lung tissue by scanning electron microscopy after low temperature ashing.

The concentration of asbestos fibers in lung tissue may give information about previous occupational asbestos exposure. A procedure for the preparation, quantification and identification of asbestos fibers in human tissue is presented in this report. The procedure is based on low-temperature plasma ashing of dry tissue, examination of the ash by scanning electron microscopy, and energy dispersive X-ray microanalysis. The advantages and disadvantages of this method are also discussed briefly.

Analysis of inorganic fiber concentrations in biological samples by scanning electron microscopy.

Analyzing fibers with electron microscopic techniques involves several preparation steps, especially during the analysis of fibers in human tissue. The influence of these steps on the analytical result was studied in detail. Fiber number was unaffected by the mild sonication of fiber suspensions analyzed with scanning electron microscopy. Significant fiber losses appeared during the filtration of fiber suspensions through 0.8-micrometer pore-size Nuclepore membranes. Shrinkage of the tissue during dry ashing broke lung fibers and consequently increased the fiber concentration and affected the fiber length distribution. Dry ashing, however, removed more of the organic debris than wet ashing; thus specimens prepared with dry ashing were more suitable for scanning electron microscopic analysis. A fairy good correlation was demonstrated for the analysis of fibers with scanning and transmission electron microscopy.

Inorganic fibers in lung tissue from patients with pleural plaques or malignant mesothelioma.

The concentration of inorganic fibers in the lungs of patients with malignant mesothelioma and pleural plaques has been compared to that of patients without cancer or chronic respiratory diseases. The fiber concentrations have been determined by scanning electron microscopy and given as number of fibers per gram of dried tissue. A statistically significant difference in inorganic fiber content was found between the different groups.

Vanadium in the blood and urine of workers in a ferroalloy plant.

The concentration of vanadium in the blood and urine of both nonexposed and occupationally exposed workers have been determined by neutron activation analysis. A comparison of the exposure data and the corresponding blood and urine values shows that the urine vanadium concentration adjusted for creatinine concentration is the most reliable exposure indicator. The normal levels of vanadium in blood are less than 20 nmol/l. The corresponding urine values are less than 3.5 nmol/mmol of creatinine.

Mica pneumoconiosis--a literature review.

Sixty-six cases of mica pneumoconiosis have been reported in the literature. Twenty-six of the cases suggest that pneumoconiosis may be caused by pure mica alone. In only six cases the diagnosis was based on clinical examination, radiography, and lung biopsy or autopsy results. In one of these six, doubt was raised by the authors about the purity of the mica exposure. Seven epidemiologic studies have been performed among mica-processing workers, and these studies are all cross-sectional. In addition 30 experimental investigations have been carried out. However, there are no controlled inhalation studies among them. The results from the intratracheal instillation studies do not give a unanimous conclusion as to whether pure mica is fibrogenic or not. Present knowledge suggests that pure mica is moderately toxic and may induce pneumoconiosis. Exposure to mica is usually associated with exposure to other minerals such as quartz and feldspar.

An exchange of membrane filter samples of airborne asbestos between one United Kingdom and three Scandinavian laboratories.

An asbestos fiber counting trial based on the postal exchange of mounted and unmounted membrane filter samples was conducted between laboratories in Denmark, Norway, Sweden and the United Kingdom. The exchange was organized on the same basis as a previous international exchange involving nine countries (5); the United Kingdom laboratory had also participated in the previous exchange. Differences in counting techniques were distinguished from those due to the method used to make the filter transparent. Counting techniques gave rise to the biggest differences, giving a ratio of highest to lowest count of 2.75 for amphibole and 3.2 for chrysotile asbestos slides. A comparison was also made with the results of the previous international trial; it was made possible by the recounting of some of the slides from this exchange. Serious deterioration over two years was found in all slides except those mounted with the acetone/triacetin method.

Analysis of titanium pigments in human lung tissue.

Methods are described for the unequivocal identification of mineral deposits in lung tissues obtained during the autopsy of a titanium dioxide-exposed worker who died of an undifferentiated malignant tumor. The methods included scanning and transmission electron microscopy, electron and X-ray diffractometry, and atomic absorption spectroscopy. The presence of considerable amounts of rutile was revealed. Despite this heavy loading, no lung tissue reaction was evident. Within the limits imposed by the period since the first exposure (6 years), this finding lends support to the supposition that the rutile crystal modification of titanium dioxide is biologically inert.

Analysis of asbestos fibers and asbestos bodies in tissue samples from human lung. An international interlaboratory trial.

In order to compare methods of counting asbestos fibers in lung tissue, seven laboratories participated in an interlaboratory trial in which tissue samples from five human lungs were analyzed. In some laboratories, fiber concentrations were assessed with the light microscope and, in others, with either scanning or transmission electron microscopes. Within each laboratory the ranking of the results was similar, but there were marked differences in the absolute values obtained by the different laboratories. It is concluded that the laboratories participating in this trial appear to produce internally consistent results, but there is difficulty in directly comparing results from one laboratory to the next.

Relation between pathological grading and lung fibre concentration in a patient with asbestosis.

The fibre concentration and extent and severity of fibrosis have been analysed in 48 specimens from the left lung of a patient with asbestosis. Two different methods of fibre analysis were used. The results obtained by transmission electron microscopy were 2-2.5 times higher than those obtained by scanning electron microscopy. Low temperature ashed samples showed on average twice the number of fibres obtained after wet digestion of the samples. The transmission electron microscope detected considerably shorter fibres than the scanning electron microscope. Low temperature ashing produced also shorter fibres compared with the wet digestion procedure. A statistically significant correlation between fibre concentration and the grade of fibrosis was found only for low temperature ashed samples analysed in the transmission electron microscope. When dividing the lung into nine anatomical compartments and pooling the grade of fibrosis and the fibre concentration data within each compartment, an even better correlation was obtained.

Occupational exposure and regional variation of malignant mesothelioma in Norway, 1970-79.

This investigation is based on a study of 117 men and 24 women with malignant mesothelioma registered by the Cancer Registry of Norway, 1970-79. The age-adjusted incidence rate in men for each county varied from 1.7 to 13.3 per million per year. Eighty-two percent of the men revealed possible occupational asbestos exposure. They were evenly distributed between counties with high and low mesothelioma incidence. Only 17% of the women had possible occupational asbestos exposure. Total lung fiber concentration was analyzed with scanning electron microscopy in 65 men and 13 women. The median lung fiber concentration in men was 2.4 million per gram of dried tissue (range less than 0.4-490), in women 1.0 million per gram (range less than 0.4-41), and in male controls less than 0.4 million per gram (range less than 0.4-4.8). The median year of first exposure was 1937 (range 1909-60) for men from counties with a high incidence rate and 1945 (range 1938-59) for men from counties with a low incidence rate. The counties with a high compared to a low incidence rate of malignant mesothelioma, 1970-79, showed an apparent difference in the percentage of population employed in industry in 1946. The regional variation in the incidence of malignant mesothelioma in men is mainly attributable to the proportion of population exposed to asbestos in industry per county prior the 1950s and the time since exposure started.(ABSTRACT TRUNCATED AT 250 WORDS)

Medico-legal aspects of malignant mesothelioma.

The object of this investigation was to discuss medico-legal aspects of malignant mesothelioma in relation to social insurance legislation for occupational injuries and diseases in Norway. During the period 1960-79 the Cancer Registry of Norway recorded a total of 155 men and 35 women with malignant mesothelioma. However, only 21 men and no women were notified to the National Insurance Institution as occupational disease cases before 31 December 1979, in spite of the well established causal association between occupational asbestos exposure and the disease. The investigation is based on these 21 patients. The long latency period from first asbestos exposure until appearance of the disease and the short survival were evident in this study. Furthermore, the legislation and provisions for occupational injuries and diseases in Norway are obviously intended for occupational accidents, and consequently the legal assessment of patients with malignant mesothelioma was complicated. For those notified, the delay in notification was considerable, and only 50% were notified before death. Delay in the claim procedure was also substantial, and few patients survived the claim procedure period. The decisions were not consistent, particularly decisions regarding "the year of injury" and appeared to have been more restrictive during recent years. One of the 21 cases was not accepted as occupational disease, because domestic exposure was considered more probable than occupational exposure.

Silicotic lesions of the bone marrow: histopathology and microanalysis.

Silica deposition and characteristic nodular silicotic lesions of the bone marrow, virtually unknown features of silicosis, are described in a case of severe lung silicosis with silicotic granulomas of the liver and spleen. Scanning electron microscopy and X-ray microanalysis confirmed the presence of quartz and feld-spars. The bone marrow lesions included inconspicuous accumulations of silica-containing macrophages, free silica, slight lymphocyte and plasma cell infiltration, and reticulin fibre formation; and development of slightly larger partly fibrous silicotic nodules, comparable to those of the lung, liver, and spleen. Silicosis must therefore be considered in the differential diagnosis of bone marrow granulomas.

Amphibole fibers in a taconite mine and in the lungs of the miners.

Fibers of the amphibole mineral series have been demonstrated in the dust from an open taconite ore mine. Though the total dust levels in some places are high, exposures to fibers are below one fiber/cc. The energy dispersive X-ray spectra of the amphibole fibers correspond to those of cummingtonite-grunerite, hornblende, or actinolite. The same type and size distribution of fibers were found during post mortem analyses of lung tissue from two previously exposed miners. The pathological examination revealed an undifferentiated small cell carcinoma of left lung as well as pulmonary fibrosis in one of the cases. In the second case a poorly differentiated squamous cell carcinoma of left lung was found along with silicosis.

Talc dust pneumoconiosis.

Various types of mineral dust can induce interstitial pulmonary fibrosis, but there is no definite correlation between lung X-ray findings, tissue lesions and the type of dust. In this paper, we report on the post mortem verification of talcosis by lung tissue analysis, using light microscopy, scanning electron microscopy, energy dispersive x-ray microanalysis and x-ray diffractometry.

Fibre type and concentration in the lungs of workers in an asbestos cement factory.

The predominant asbestos fibre type used in the production of asbestos cement is chrysotile. The use of asbestos in relation to fibre type in a Norwegian asbestos cement plant during 1942-80 was 91.7% chrysotile, 3.1% amosite, 4.1% crocidolite, and 1.1% anthophyllite respectively. Electron microscopy and x ray microanalysis of lung tissue samples of asbestos cement workers who had died of malignant pleural mesothelioma or bronchogenic carcinoma showed a completely inverse ratio with regard to fibre type. The percentage of chrysotile asbestos in lung tissue varied between 0% and 9% whereas the corresponding numbers for the amphiboles were 76% and 99%. These differences are discussed with respect to the behaviour of different fibre types in the human body and to the occurrence of malignant mesothelioma in this asbestos cement factory.