A cohort of some 11,000 men born 1891-1920 and employed for at least one month in the chrysotile mines and mills of Quebec, was established in 1966 and has been followed ever since. Of the 5351 men surviving into 1976, only 16 could not be traced; 2508 were still alive in 1989, and 2827 had died; by the end of 1992 a further 698 were known to have died, giving an overall mortality of almost 80%. This paper presents the results of analysis of mortality for the period 1976 to 1988 inclusive, obtained by the subject-years method, with Quebec mortality for reference. In many respects the standardised mortality ratios (SMRs) 20 years or more after first employment were similar to those for the period 1951-75--namely, all causes 1.07 (1951-75, 1.09); heart disease 1.02 (1.04); cerebrovascular disease 1.06 (1.07); external causes 1.17 (1.17). The SMR for lung cancer, however, rose from 1.25 to 1.39 and deaths from mesothelioma increased from eight (10 before review) to 25; deaths from respiratory tuberculosis fell from 57 to five. Among men whose exposure by age 55 was at least 300 million particles per cubic foot x years (mpcf.y), the SMR (all causes) was elevated in the two main mining regions, Asbestos and Thetford Mines, and for the small factory in Asbestos; so were the SMRs for lung cancer, ischaemic heart disease, cerebrovascular disease, and respiratory disease other than pneumoconiosis. Except for lung cancer, however, there was little convincing evidence of gradients over four classes of exposure, divided at 30, 100, and 300 mpcf.y. Over seven narrower categories of exposure up to 300 mpcf.y the SMR for lung cancer fluctuated around 1.27 with no indication of trend, but increased steeply above that level. Mortality form pneumoconiosis was strongly related to exposure, and the trend for mesothelioma was not dissimilar. Mortality generally was related systematically to cigarette smoking habit, recorded in life from 99% of survivors into 1976; smokers of 20 or more cigarettes a day had the highest SMRs not only for lung cancer but also for all causes, cancer of the stomach, pancreas, and larynx, and ischaemic heart disease. For lung cancer SMRs increased fivefold with smoking, but the increase with dust exposure was comparatively slight for non-smokers, lower again for ex-smokers, and negligible for smokers of at least 20 cigarettes a day; thus the asbestos-smoking interaction was less than multiplicative. Of the 33 deaths from mesothelioma in the cohort to date, 28 were in miners and millers and five were in employees of a small asbestos products factory where commercial amphiboles had also been used. Preliminary analysis also suggest that the risk of mesothelioma was higher in the mines and mills at Thetford Mines than in those at Asbestos. More detailed studies of these differences and of exposure-response relations for lung cancer are under way.
Cites: Br J Ind Med. 1980 Feb;37(1):11-247370189
Cites: Br J Cancer. 1982 Jan;45(1):124-357059455
Cites: Biometrics. 1983 Mar;39(1):173-846871346
Cites: Br J Ind Med. 1987 Jun;44(6):396-4013606968
Cites: Ann N Y Acad Sci. 1979;330:91-116294225
Cites: Br J Ind Med. 1992 Aug;49(8):566-751325180
Cites: Arch Environ Health. 1971 Jun;22(6):677-865574010
Cites: Arch Environ Health. 1972 Mar;24(3):189-975059627
BACKGROUND: The association between occupational quartz exposure and ventilatory function was investigated in men in a general population after adjusting for other potential determinants of outcome. METHODS: All eligible men aged 30-46 years living in western Norway (n = 45,380) were invited to a cross sectional community survey. This included a self administered questionnaire (with respiratory symptoms, smoking habits and occupational exposures), spirometric recordings (using dry wedge below spirometers), and a chest radiograph (65% attendance). Measurements of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were obtained in 91% (n = 26,803) of those who participated, 26,106 of whom performed successful spirometric tests and had normal chest radiographs and remained for further analysis. Age, body mass index, and technician standardised residuals ((observed minus predicted value)/residual standard error) of maximum FEV1/height2 and FVC/height2 were used as outcome variables for adjusted lung function levels, respectively. RESULTS: Occupational quartz exposure was reported by 13% (n = 3445) of those who participated in the survey, with a mean duration of seven years. Among those exposed to quartz, significant inverse linear relationships were observed between years of exposure and FEV1 level and the ratio of FEV1/FVC, independent of host characteristics. Multiple linear regression analyses showed that the difference in FEV1 associated with each year of quartz exposure was -4.3 ml (95% CI -1.1 to -7.5 ml; p = 0.01) compared with -6.9 ml (95% CI -4.7 to -9.1 ml; p
One of objective methods of early and differential diagnosis of occupational pulmonary diseases in miners (pneumoconiosis, silicotuberculosis, dust bronchitis) is bronchoscopy with a cytologic examination of bronchoalveolar lavage fluid (BAF). BAF-examination was carried out in a total of 88 patients with incipient and advanced forms of dust bronchitis, pneumoconiosis and silicotuberculosis. A direct relationship has been revealed between a decline in local cell-bound immunity caused by a dust-inducted affection mononuclear phagocytes and advancing of stages of dust-related diseases.
New material was presented from pending publications arising from the follow-up to 1988 of the Quebec cohort of over 10,000 chrysotile miners and millers born 1891-1920. In reviewing these and previous findings, the following conclusions were drawn; they are supported, insofar as this is possible, by the only other relevant information, that from Balangero, in Northern Italy. There is strong evidence that the risk of lung cancer as a result of exposure to chrysotile at concentrations of less than 15 million particles per cubic foot is vanishingly small. At higher concentrations, the relative risk of lung cancer is elevated, but less so in smokers of 20 or more cigarettes a day than in others. The magnitude of this risk cannot be evaluated with any certainty, but this is unimportant as these higher concentrations (above about 50 f ml-1) are well outside the range of experience nowadays. There is no evidence that the risk of laryngeal cancer or of stomach cancer are adversely affected by exposure to chrysotile. Nor is there evidence of increased risks of other abdominal malignancies or of kidney cancer among chrysotile miners and millers. The risk of mesothelioma in chrysotile miners and millers is very low compared with the risks in populations exposed to amphiboles or to mixtures of fibres including even small proportions of amphiboles.
Relation between the risk of lung cancer and combined home and work indoor radon exposure was studied on the example of the population of Lermontov town (Stavropol Region, Russia). The town is situated in the former uranium mining area. Case (121 lung cancer cases) and control (196 individuals free of lung cancer diagnosis) groups of the study included both ex-miners and individuals that were not involved in the uranium industry. Home and work radon exposures were estimated using archive data as well as contemporary indoor measurements. The results of our study support the conclusion about the effect of radon exposure on the lung cancer morbidity.
The paper comparatively assesses the level and qualitative spectrum of chromosomal aberrations (CA) in 192 workers engaged in 3 industries (cake and by-product, aluminum, and mining concentration processes). The maximum and minimum rates (6.43(+)-0.32% and 3.81(+)-0.46%) of CA have been observed in those engaged in cake and by-product and mining concentration processes, respectively. The combined influence of chemical and radiation factors are a cause of the higher rate of CA. Gender- and age-specific features do not effect on the level of structural CA. Smoking is a factor of their slight modification as there are no significant differences in the frequencies of aberrations between smokers and non-smokers in any professional group. There is an indirect relationship between the frequency of CA and the length of service, which may be different under the conditions of various industries.
Complete clinical and physiologic examination of 415 tunnelers exposed to intensive vibration in cooling microclimate proved that extreme functioning of thermoregulation results in shorter development, quicker progression of vibration disease and abortive types of the disease. The data obtained were helpful to base treatments and prophylaxis including special clothes, appropriate therapy.
The fatty acid spectrum of an expired air condensate was studied in the workers of the Kharanor coal stripping and in the dwellers of Chita (a control group). Regularities in the changes of the expired air fatty acid profile were assessed by the degree of exposure to coal dust and by the length of service. The findings indicated the relationship of profile changes with the degree of exposure to occupational noxious agents: the proportion of saturated fatty acids decreases much more significantly in workers who were directly exposed to the dust than in those were indirectly done. It is concluded that the fatty acid composition of an expired air condensate adequately reflects the changes occurring in the respiratory system upon exposure to dust.