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Biomedical subjects

A Tossavainen

Publications and source records attributed to A Tossavainen.

At least 37 records · Page 2Linked to original sources
PubMed1995

Radiographic small lung opacities and pleural abnormalities as a consequence of asbestos exposure in an adult population.

OBJECTIVES: The purpose of this study was to estimate the role of past asbestos exposure as a cause of radiographic small lung opacities and pleural abnormalities in the Finnish adult population. METHODS: The study was conducted in 1978-1981 and was based on a population sample (N = 8000) representative of the Finnish population aged 30 years or over. Full-size chest radiographs and a complete job title history were available for 3811 women and 3274 men. The radiographs were classified according to the 1980 classification of radiographs of pneumoconioses published by the International Labour Office and the work histories according to the probability of occupational asbestos exposure. Age- and smoking-adjusted relative risks of radiographic parenchymal and pleural abnormalities were calculated with the analysis of covariance according to the probability of asbestos exposure. RESULTS: About 13% of the men and 0.8% of the women were classified as probably exposed to asbestos. There was more than 90% agreement in the repeated work history evaluations. The risk of small lung opacities was significantly increased among the probably exposed men [risk ratio (RR) 1.7 for ILO profusion category 1/1 or more and RR 1.6 for profusion category 1/0]. The risk of pleural plaques was increased both among the men (RR 3.0) and the women (RR 4.8) with probable exposure. The risk of thickened horizontal interlobar fissure was also increased among the probably exposed men (RR 1.7). Among the men, the etiologic fraction attributable to occupational asbestos exposure was about 30% for small lung opacities, about 40% for pleural plaques, and about 20% for thickened horizontal fissure. Among the women the etiologic fractions for asbestos were similar for pleural abnormalities, but much lower for parenchymal ones. CONCLUSIONS: Occupational asbestos exposure has been common among Finnish men, and it plays a significant role in the etiology of both pleural and parenchymal abnormalities also at the level of the general population.

Adult↗
PubMed1995

Silica, silicosis and cancer in Finland.

Approximately 100 000 Finnish workers are currently employed in jobs and tasks that may involve exposure to airborne silica dust. The major industries involved are mining and quarrying; production of glass, ceramics, bricks and other building materials; metal industry, particularly iron and steel founding; and construction. Over 1500 cases of silicosis have occurred in Finland since 1935. Tuberculosis has been a frequent complication of silicosis. Results of studies from several countries strongly suggest that silica dust also causes lung cancer. The results of the relevant Finnish epidemiologic and industrial hygiene studies addressing cancer risk and exposure to quartz dust are summarized.

Confidence Intervals↗
PubMed1994

Pleural plaques and exposure to mineral fibres in a male urban necropsy population.

OBJECTIVES: The study aimed to evaluate the risk of pleural plaques according to the degree of past exposure to asbestos, type of amphibole asbestos, and smoking, as well as to estimate the aetiologic fraction of asbestos as a cause of plaques among urban men. METHODS: The occurrence and extent of pleural plaques were recorded at necropsies of 288 urban men aged 33 to 69 years. The pulmonary concentration of asbestos and other mineral fibres was analysed with scanning electron microscopy. The probability of past exposure was estimated from the last occupation. RESULTS: Pleural plaques were detected in 58% of the cases and their frequency increased with age, probability of past occupational exposure to asbestos, pulmonary concentration of asbestos fibres, and smoking. The risk of both moderate and widespread plaques was raised among asbestos exposed cases, and the risk estimates were higher for widespread plaques than for moderate plaques. The age adjusted risk was higher for high concentrations of crocidolite/amosite fibres than for anthophyllite fibres. The aetiologic fraction of pulmonary concentration of asbestos fibres exceeding 0.1 million fibres/g was 43% for widespread plaques and 24% for all plaques. The median pulmonary concentrations of asbestos fibres were about threefold greater among cases with widespread plaques than among those without plaques. No increased risk of pleural plaques was associated with raised total concentrations of non-asbestos fibres. CONCLUSION: The occurrence of pleural plaques correlated closely with past exposure to asbestos. The risk was dependent on the intensity of exposure. Due to methodological difficulties in detecting past exposures to chrysotile and such low exposures that may still pose a risk of plaques, the aetiologic fractions calculated in the study probably underestimate the role of asbestos.

Adult↗
PubMed1994

Retention of asbestos fibers in the human body.

The number, type, and size of retained asbestos fibers were measured by scanning electron microscopy (SEM) in lung tissues of 10 workers who had died from lung cancer or mesothelioma. The levels were 190-3000 x 10(6) fibers/g of dry tissue in three crocidolite sprayers, 6-39 x 10(6) fibers/g of dry tissue in two asbestos product workers and 13-280 x 10(6) fibers/g of dry tissue in five insulators exposed to anthophyllite. The duration of past exposure corresponding to the limit of 1 million fibers/g of dry tissue was 1 to 2 days in spraying, 3 to 10 days at the production plant and 1 to 4 months in insulation work. No long-term clearance of amphibole fibers, > 5 microns in length, could be demonstrated. In one of the sprayers the fiber concentrations of lung parenchyma, visceral and parietal pleura, hilar lymph nodes, and kidney cortex were orders of magnitude higher than in a series of unselected autopsies. The size and aspect ratio of crocidolite fibers in various tissues were similar, indicating that the translocation processes are rather unselective in respect to fiber dimensions.

Adult↗
PubMed1994

Is there an association between pleural plaques and lung cancer without asbestosis?

OBJECTIVES: A recent review or meta-analysis of epidemiologic studies concluded that persons with asbestos-related pleural plaques do not have an increased risk of lung cancer in the absence of parenchymal asbestosis. The reviewer inferred that this conclusion provided indirect supportive evidence for the proposition that asbestosis is a necessary precursor of asbestos-related lung cancer. The objective of the present communication is to contest these claims. METHODS: Finnish epidemiologic data and population statistics were used to estimate the apparent risk ratio of lung cancer associated with radiographic signs of pleural plaques. Power calculations were applied to compute the needed population sizes to demonstrate that the association is statistically significant. RESULTS: Unrealistically large population studies would be needed to observe the statistical relation between pleural plaques and lung cancer, quantitated as a risk ratio of 1.1, resulting from relatively low levels of environmental asbestos exposure. In realistic and valid epidemiologic studies on heavily exposed subpopulations, a two- or threefold risk can be identified. CONCLUSIONS: Uninformative studies should not be interpreted as providing suppressive evidence that pleural plaques are a noncausal risk indicator of lung cancer. Even for the null hypothesis, the inference that asbestosis is a necessary causal link between asbestos and lung cancer is illogical.

Adult↗
PubMed1994

Asbestos exposure and pulmonary fiber concentrations of 300 Finnish urban men.

OBJECTIVES: The aim of the study was to determine the pulmonary concentrations of mineral fibers in the Finnish male urban population and to evaluate the analysis of pulmonary fiber burden by scanning electron microscopy (SEM) as an indicator of past fiber exposure. METHODS: The pulmonary concentration of mineral fibers was determined by SEM and compared with occupational history for a series of 300 autopsies of urban men aged 33 to 69 years. RESULTS: The concentration of fibers (f) longer than 1 micron ranged from < 0.3 to 163.10(6) per gram of dry tissue (f.g-1). Asbestos fiber concentrations exceeding 1.10(6) f.g-1 were observed in 33% of the cases with probable occupational exposure to asbestos and 1% of the cases with unlikely occupational exposure. Even asbestos fiber concentrations of 0.3 to 1.10(6) f.g-1, especially of crocidolite-amosite fibers, were rare among the men with unlikely occupational exposure. Fiber concentrations exceeding or equaling 1.10(6) f.g-1 were 10 times more frequent among the men more than 60 years of age as compared with those less than 40 years of age. Inorganic fibers other than asbestos had a weaker correlation with occupational history and age. Smoking habits had no significant effect on the pulmonary fiber counts. CONCLUSIONS: Asbestos fiber concentrations exceeding 1.10(6) f.g-1 are highly indicative of past occupational exposure to asbestos. The distribution of fiber concentrations in the different age groups of this study indicated decreasing asbestos exposure in Finland since the 1970s.

Adult↗
PubMed1993

Asbestos exposure according to different exposure indices among Finnish lung cancer patients.

During a 6-month period all lung cancer patients in a university hospital chest clinic were investigated for asbestos exposure by means of personal interview, bronchoalveolar lavage (BAL), roentgenograms, lung function testing, histology and measurement of fibre concentrations in lung tissue samples using scanning electron microscopy (SEM). About one-third of the patients (33%) were classified as having been exposed to asbestos on the basis of the interview. BAL was performed and AB counts were done in 51 patients. Fourteen (27%) BAL specimens had AB counts of 1 or more AB/ml, which is the conventional limit for non-trivial asbestos exposure. For a subgroup of 25 operated lung cancer patients fibre analysis was also available. In six cases (30%) the asbestos-containing samples had asbestos fibre concentrations equal to or more than 1 million fibres/g dry lung. In eight (32%) of the operated lung cancer patients histopathologically confirmed fibrosis was seen; five of these patients were in the two highest exposure classes. Pleural plaques on X-ray films were seen in six (24%) of the operated cases. With each indicator of exposure about 30% of lung cancer patients were found to have been exposed, confirming the "one-third rule"; however, when all the information was collated there were three cases (12%) in which exposure was most obvious according to the different parameters used in this study. In these three cases the cancer could well be attributed to asbestos. Anthophyllite was present in all asbestos-containing samples and anthophyllite was the main fibre type in 61% of these samples.

Adult↗
PubMed1992

Urinary and blood manganese in occupationally nonexposed populations and in manual metal arc welders of mild steel.

To obtain reference values for blood and serum manganese levels, blood specimens were collected from 29 men and 36 women. Mn in blood showed a normal distribution; its upper 97.5% limit in blood was 0.38 mumol/l. Mn in serum showed a skewed distribution, which did not differ from the normal one after logarithmic transformation. The respective reference limit was 19 nmol/l. In both specimens, the levels of Mn were significantly lower in men than in women. To obtain reference values for Mn in urine, midday urine specimens were collected from 58 men and 96 women. Mn in urine also showed a skewed distribution, and the upper 97.5% limit was 38 nmol/l. The levels of Mn in blood and urine were statistically significantly higher in manual metal arc (MMA) welders of mild steel (MS) than in the reference populations. Five MMA/MS welders were subjected to a further study in which the ambient intramask Mn levels and urinary Mn excretion were monitored throughout a full working week. For two welders the correlation of Mn in urine specimens voided in the afternoon was good with the before noon Mn concentrations in the hygienic measurements; for the rest the correlation was minimal. Mn in diurnal urine specimens collected in six portions showed fluctuation if specific gravity or creatinine in urine was used to standardize for the urinary flow, but it was less evident for urinary Mn excretion rate. Our results seem to indicate that the measurement of Mn in urine or blood may be used for monitoring Mn exposure in MMA/MS welders only at the group level.

Adolescent↗
PubMed1991

Relative risk of mesothelioma associated with different levels of exposure to asbestos.

The relative risk of mesothelioma associated with different levels of exposure to asbestos was evaluated. The exposure was assessed from work histories of 51 mesothelioma cases and 51 sarcoidosis referents. The lung fiber concentration of the mesothelioma patients was compared with that of two reference groups (13 random autopsy cases and 43 male lung cancer patients). When the categories definite and probable were used as an estimated probability of occupational exposure, an odds ratio of 17.7 [90% confidence interval (90% CI) 3.4-253] and 3.0 (90% CI 0.9-10.6), respectively, was obtained. A lung fiber concentration of greater than 1 million fibers/g of dry tissue as an indicator of accumulated exposure gave an odds ratio of 14.4 (90% CI 2.5-178) for the men in comparison with the autopsy cases and 3.1 (90% CI, 1.3-7.5) in comparison with the lung cancer patients. Elevated risk of mesothelioma was shown to be associated with a lung fiber concentration of greater than 1 million fibers/g of dry tissue.

Adult↗
PubMed1989

Mineral fiber concentration in lung tissue of mesothelioma patients in Finland.

The mineral fibers in lung tissue samples of 19 mesothelioma patients and 15 randomly selected autopsy cases were analyzed using low-temperature ashing, scanning electron microscopy (SEM) and x-ray microanalysis. The fiber concentration ranged from 0.5 to 370 million fibers per gram of dry tissue in the mesothelioma group and from less than 0.01 to 3.2 million fibers per gram of dry tissue in the autopsy group. In 80% of the mesothelioma patients and in 20% of the autopsy cases, the fiber concentration exceeded 1 million fibers per gram of dry tissue. Amphibole asbestos fibers predominated in both groups, and only a few chrysotile fibers were found. In the lungs of six mesothelioma patients, anthophyllite was the main fiber type. The overall analytical precision of sample preparation and fiber counting with SEM was 22%.

Adolescent↗
PubMed1989

Fungi carried from farmers' work into farm homes.

Airborne fungal spore concentrations and main fungal genera were compared in rural and urban living environments in Finland during the winter. In addition to conventional viable fungal spore counts (based on the six-stage impactor sampling and cultivation), total spore concentrations were obtained by scanning electron microscope (SEM) investigation of filter samples. The viable spore counts were only 0.2%-25% of the number of total spore aggregates. A high correlation between these two methods was noted, however, at the recommended measuring ranges of the methods. In the farm houses, viable and total spore levels were 10(3) to 10(4) colony forming units/m3 (cfu/m3) and 10(4) to 10(5), spores/m3, respectively. These counts were 10-10(3)-fold higher than the concentrations in an urban apartment. The spore levels of farmers' homes, however, were somewhat lower than those observed in their cow barns. Aspergillus, Cladosporium, and Penicillium spores were present in both urban and rural environments. Actinomycetes and some fungal genera--such as Acremonium, Alternaria, Botrytis, and Chrysosporium--which were detected in cow barns and in farm houses, were not present in urban environment. The results indicated that airborne fungal spores may be carried from cow barns to farmers' homes.

Agriculture↗
PubMed1986

Cytotoxic effects of four types of welding fumes on macrophages in vitro: a comparative study.

The effects of fume particles given off by the manual metal arc (MMA) and metal inert gas (MIG) welding of stainless steel (SS) and mild steel (MS) were studied on rat alveolar macrophage cultures in vitro. The fumes were generated by welding, and particulate material obtained was collected on membrane filters. The macrophage cultures were exposed to the total dust and to its water-insoluble fractions. Cell variability and the release of both lactate dehydrogenase and one lysosomal enzyme from the cells to the medium were measured after an exposure period of 24 h. The cytotoxic control dust was DQ 12 quartz, and the inert control dust was pure titanium dioxide. According to the parameters studied, SS/MMA and MS/MMA welding fumes were cytotoxic to rat alveolar macrophages. The cytotoxic effect of SS/MMA welding fumes decreased after the samples had been washed with phosphate-buffered salt solution. The MIG welding fumes of SS and MS had markedly smaller effects on the cells. Diluted solutions of potassium chromate were also tested in order to investigate its role in the cytotoxicity of SS/MMA welding fumes. The results suggest that hexavalent chromium may be responsible for the cytotoxicity of SS/MMA.

Air Pollutants, Occupational↗
PubMed1986

Comparative studies of fibrogenic properties of wollastonite, chrysotile and crocidolite.

Fibrogenous effects of wollastonite, chrysotile and crocidolite have been investigated in experiments on animals. (Wollastonite is a calcium silicate of fibrous structure, occasionally applied as asbestos substitute). The experimental animals were intratracheally administered single doses of 50 mg of the test material suspended in 0.6 ml of physiological NaCl solution. The animals were decapitated 3, 6 and 9 months after the experiment. Fibrogenic properties were evaluated basing on the weight of wet lungs, content of lipids and hydroxyproline in lungs, as well as histopathological tests of lungs, mediastinal lymph nodes and spleen. Histopathological preparations were evaluated using an optical, microscope or transmission electron microscope. The findings of biochemical, pathomorphological, and ultrastructural studies demonstrated slight fibrogenic effects of wollastonite, as compared to chrysotile and crocidolite.

Animals↗
PubMed1985

Cardiorespiratory strain in jobs that require respiratory protection.

Twenty-one workers in the construction, foundry, shipyard, and metal industries, and nine firemen were studied in jobs that require the regular use of various industrial respirators. The subjects' heart rates (HR) were continuously recorded during 1 to 2 workshifts or during special tasks. Their oxygen consumption (VO2) and ventilation rates were measured during main work phases. The subjects' VO2max were determined by a submaximal bicycle-ergometer test. In construction and industrial jobs, when a filtering device or an air-line apparatus was worn, the subjects' mean HR-values ranged from 66 to 132 beats min-1, which is equivalent to a relative aerobic strain of 12 to 57% VO2max. In smog-diving and repair and rescue tasks with self-contained breathing apparatus and protective clothing, the corresponding mean values were 142 to 160 beats min-1 and 54-74% VO2, respectively. The field results were compared with those measured in the laboratory with the same type of respirator. The suitability of different respirators in practical work situations was then evaluated, as were the physical qualifications required of the wearer.

Adult↗