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The 1891-1920 birth cohort of Quebec chrysotile miners and millers: development from 1904 and mortality to 1992.

https://arctichealth.org/en/permalink/ahliterature210233
Source
Ann Occup Hyg. 1997 Jan;41(1):13-36
Publication Type
Article
Date
Jan-1997
Author
F D Liddell
A D McDonald
J C McDonald
Author Affiliation
Department of Epidemiology and Biostatistics, McGill University Montreal, Canada.
Source
Ann Occup Hyg. 1997 Jan;41(1):13-36
Date
Jan-1997
Language
English
Publication Type
Article
Keywords
Aged
Air Pollutants, Occupational - adverse effects
Asbestos, Serpentine - adverse effects
Asbestosis - etiology - mortality
Cause of Death
Cohort Studies
Environmental monitoring
Epidemiological Monitoring
Humans
Male
Mesothelioma - etiology - mortality
Mining - statistics & numerical data
Neoplasms - etiology - mortality
Quebec - epidemiology
Abstract
This paper draws together the mortality experience for a cohort of some 11000 male Quebec Chrysotile miners and millers, reported at intervals since 1971 and now again updated. Of the 10918 men in the complete cohort, 1138 were lost to view, almost all never traced after employment of only a month or two before 1935; the other 9780 men were traced into 1992. Of these, 8009 (82%) are known to have died: 657 from lung cancer, 38 from mesotheliona, 1205 from other malignant disease, 108 from pneumoconiosis and 561 from other non-malignant respiratory diseases (excluding tuberculosis). After early fluctuations. SMRs (all causes) against Quebec rates have been reasonably steady since about 1945. For men first employed in Asbestos, mine or factory, they were very much what might have been expected for a blue collar population without any hazardous exposure. SMRs in the Thetford Mines area were almost 8% higher, but in line with anecdotal evidence concerning socio-economic status. At exposures below 300 (million particles per cubic foot) x years, (mpcf.y), equivalent to roughly 1000 (fibres/ml) x years-or, say, 10 years in the 1940s at 80 (fibres/ml)-findings were as follows. There were no discernible associations of degree of exposure and SMRs, whether for all causes of death or for all the specific cancer sites examined. The average SMRs were 1.07 (all causes), and 1.16, 0.93, 1.03 and 1.21, respectively, for gastric, other abdominal, laryngeal and lung cancer. Men whose exposures were less then 300 mpcf.y suffered almost one-half of the 146 deaths from pneumoconiosis or mesothelioma; the elimination of these two causes would have reduced these men's SMR (all causes) from 1.07 to approximately 1.06. Thus it is concluded from the viewpoint of mortality that exposure in this industry to less than 300 mpcf.y has been essentially innocuous, although there was a small risk or pneumoconiosis or mesothelioma. Higher exposures have, however, led to excesses, increasing with degree of exposure, of mortality from all causes, and from lung cancer and stomach cancer, but such exposures, of at least 300 mpcf.y, are several orders of magnitude more severe than any that have been seen for many years. The effects of cigarette smoking were much more deleterious than those of dust exposure, not only for lung cancer (the SMR for smokers of 20+ cigarettes a day being 4.6 times higher than that for non-smokers), but also for stomach cancer (2.0 times higher), laryngeal cancer (2.9 times higher), and-most importantly-for all causes (1.6 times higher).
Notes
Comment In: Ann Occup Hyg. 1997 Jan;41(1):3-129072948
Comment In: Ann Occup Hyg. 2001 Jun;45(4):329-35; author reply 336-811414250
PubMed ID
9072947 View in PubMed
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The 1891-1920 birth cohort of Quebec chrysotile miners and millers: mortality 1976-88.

https://arctichealth.org/en/permalink/ahliterature219707
Source
Br J Ind Med. 1993 Dec;50(12):1073-81
Publication Type
Article
Date
Dec-1993
Author
J C McDonald
F D Liddell
A. Dufresne
A D McDonald
Author Affiliation
School of Occupational Health, McGill University, Montreal, Canada.
Source
Br J Ind Med. 1993 Dec;50(12):1073-81
Date
Dec-1993
Language
English
Publication Type
Article
Keywords
Aged
Aged, 80 and over
Asbestos, Serpentine
Asbestosis - mortality
Cause of Death
Cohort Studies
Humans
Lung Neoplasms - mortality
Male
Mesothelioma - mortality
Middle Aged
Mining
Occupational Exposure
Quebec - epidemiology
Smoking - mortality
Time Factors
Abstract
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.
Notes
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
Cites: Br J Ind Med. 1991 Aug;48(8):543-71878311
PubMed ID
8280638 View in PubMed
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Chrysotile, tremolite and carcinogenicity.

https://arctichealth.org/en/permalink/ahliterature207077
Source
Ann Occup Hyg. 1997 Dec;41(6):699-705
Publication Type
Article
Date
Dec-1997
Author
J C McDonald
A D McDonald
Author Affiliation
Department of Occupational and Environmental Medicine, National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, London, U.K.
Source
Ann Occup Hyg. 1997 Dec;41(6):699-705
Date
Dec-1997
Language
English
Publication Type
Article
Keywords
Aged
Aged, 80 and over
Asbestos, Amphibole - adverse effects
Asbestos, Serpentine - adverse effects
Case-Control Studies
Coal Mining
Humans
Logistic Models
Male
Mesothelioma - chemically induced - mortality
Neoplasms - chemically induced - mortality
Occupational Diseases - chemically induced - mortality
Odds Ratio
Quebec - epidemiology
Abstract
It has been suspected for many years that amphibole fibres in the tremolite series, a low level contaminant of chrysotile asbestos, may contribute disproportionately to the incidence of mesothelioma and perhaps other exposure-related cancers. A cohort of some 11,000 Quebec chrysotile workers, 80% of whom have now died, provided the opportunity to examine this hypothesis further. An analysis was made of deaths from mesothelioma (21), cancers of the lung (262), larynx (15), stomach (99), and colon and rectum (76), in men employed by the largest company in Thetford Mines, with closely matched referents. Risks were estimated by logistic regression for these five cancers in two groups of mines--five mines located centrally and ten mines located peripherally; tremolite contamination had been demonstrated to be some four times higher in the former than in the latter. Odds ratios for work in the central mines were raised substantially and significantly for mesothelioma and lung cancer, but not for the gastric, intestinal or laryngeal cancer sites. In the peripheral mines, there was little or no evidence of increased risk for any of the five cancers. The hypothesis that, because of the difference in distribution of fibrous tremolite, cancer risks in the central area would be greater than in the periphery was thus substantiated. That the explanation may lie in the greater biopersistence of amphibole fibres than chrysotile is important in framing policies for the use and control of asbestos and is directly relevant to the selection of man-made mineral fibre substitutes.
PubMed ID
9375528 View in PubMed
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Chrysotile, tremolite, and mesothelioma.

https://arctichealth.org/en/permalink/ahliterature215812
Source
Science. 1995 Feb 10;267(5199):776-7
Publication Type
Article
Date
Feb-10-1995

Dust exposure and lung cancer in Quebec chrysotile miners and millers.

https://arctichealth.org/en/permalink/ahliterature205820
Source
Ann Occup Hyg. 1998 Jan;42(1):7-20
Publication Type
Article
Date
Jan-1998
Author
F D Liddell
A D McDonald
J C McDonald
Author Affiliation
Department of Epidemiology and Biostatistics, McGill University, Montreal, Canada.
Source
Ann Occup Hyg. 1998 Jan;42(1):7-20
Date
Jan-1998
Language
English
Publication Type
Article
Keywords
Aged
Aged, 80 and over
Asbestos, Serpentine - adverse effects
Dust - adverse effects
Humans
Likelihood Functions
Lung Neoplasms - mortality
Male
Mining
Occupational Diseases - mortality
Occupations
Odds Ratio
Quebec - epidemiology
Abstract
A large cohort of men born between 1891 and 1920 and employed for at least a month in the chrysotile producing industry of Quebec has been under study since 1966. These men were followed from first employment (the earliest in 1904) to 1992, by which time over 8000 had died, 657 from lung cancer. The current study is of 488 cases of lung cancer formerly employed at three places, viz. a major complex, here called Company 3, in the region of Thetford Mines (243 cases), the mine and mill in the town of Asbestos (206) and a small asbestos-products factory in the same town (39). For each case, four referents were sought by random selection from among survivors to a greater age, after matching on place of employment, age of starting work, smoking habit and date of birth. This process was highly successful, although six cases had less than four referents. For each man (the 488 cases with 1941 referents) and for each calendar year of employment, we obtained the fraction of the year worked at various levels of intensity, assessed in 13 'dust categories' of mpcf (million particles per cubic foot). We then calculated how many years each man spent at these various levels; these years, adjusted for the length of the working week (66 h until 1937; 48 h 1938-1949; and 40 h 1950-1985), were accumulated up to ten years before the death of the case. The men were classified according as they were non- or ex-smokers, or smokers, of cigarettes. For each man at Company 3 and one referent for each, his years of work in a central area of five mines and in a peripheral area of ten mines were differentiated; contamination of the chrysotile by fibrous tremolite was known to be much greater in the central than in the peripheral area. Case-referent comparisons, within place of employment, were made by conditional logistic regression. As anticipated from earlier subject-years analyses, lung cancer risks were found to be negligible for years worked in dust categories 1 and 2 (averaging 0.5 and 2 mpcf), regardless of place; as the upper limit of category 1 is considerably higher than permitted nowadays, the lung cancer risk from exposure to chrysotile at permitted levels can be taken as extremely small. Patterns of exposure-response for higher categories were irregular. At Company 3, some risks appeared elevated for years spent in the higher dust categories: 3-4, 5-7, 8-10 and 11-13, with averages around 9, 20, 36 and 92 mpcf, respectively. For categories 3-4 and 8-10, the odds ratios were high for some or all work in the central area, but minimal for years spent in the peripheral area only. Odds ratios were fairly low for cigarette smokers who worked in categories 5-7 and also for years spent in the highest categories (11-13). At the mine and mill in Asbestos, all risks were low except for years worked by non- and ex-smokers in categories 7-13 (ca. 40 mpcf). There were no increased risks at the factory. It was known from the subject-years analyses that most of the excess had occurred at Company 3, but it is now clear that for all practical purposes it was confined to the central area there, probably due largely to fibrous tremolite and in dust conditions of at least dust category 3. The average of this category was 7 mpcf or very roughly 24 fibres/ml, about two orders of magnitude higher than today's hygiene standards.
Notes
Comment In: Ann Occup Hyg. 2001 Jun;45(4):327-9; author reply 336-811414249
Comment In: Ann Occup Hyg. 2001 Jun;45(4):329-35; author reply 336-811414250
PubMed ID
9566111 View in PubMed
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Dust exposure and mortality in chrysotile mining, 1910-75.

https://arctichealth.org/en/permalink/ahliterature246109
Source
Br J Ind Med. 1980 Feb;37(1):11-24
Publication Type
Article
Date
Feb-1980
Author
J C McDonald
F D Liddell
G W Gibbs
G E Eyssen
A D McDonald
Source
Br J Ind Med. 1980 Feb;37(1):11-24
Date
Feb-1980
Language
English
Publication Type
Article
Keywords
Accidents
Aged
Asbestos - adverse effects
Asbestosis - mortality
Cerebrovascular Disorders - mortality
Dust
Employment
Environmental Exposure
Female
Follow-Up Studies
Heart Diseases - mortality
Humans
Lung Neoplasms - mortality
Male
Middle Aged
Mining
Neoplasms - mortality
Occupational Diseases - mortality
Quebec
Respiration Disorders - mortality
Smoking - complications
Time Factors
Abstract
We report a further follow-up of a birth cohort of 11 379 workers exposed to chrysotile. The cohort consisted of 10 939 men and 440 women, born 1891-1920, who had worked for at least a month in the mines and mills of Asbestos and Thetford Mines in Quebec. For all subjects, length of service and estimates of accumulated dust exposure were obtained, with a smoking history for the vast majority. Three methods of analysis, two based on the "man-years" methods, the other a "case-and-multiple-controls" approach, gave results consistent with one another and with previous analyses. By the end of 1975, 4463 men and 84 women had died. Among men, the overall excess mortality, 1926-75 was 2% at Asbestos and 10% at Thetford Mines, much the dustier region. The women, mostly employed at Asbestos, had a standardised mortality ratio (SMR) all causes, 1936-75) of 0.90. Analysis of deaths 20 years or more after first employment showed that in men with short service (less than five years) there was no discernible correlation with dust exposure. Among men employed at least 20 years, there were clear excesses in those exposed to the heaviest dust concentrations. Reanalysis in terms of exposure to age 45 showed definite and consistent trends for SMRs for total mortality, for lung cancer, and for pneumoconiosis to be higher the heavier the exposure. The response to increasing dose was effectively linear for lung cancer and for pneumoconiosis. Lung cancer deaths occurred in non-smokers, and showed a greater increase of incidence with increasing exposure than did lung cancer in smokers, but there was insufficient evidence to distinguish between multiplicative and additive risk models. There were no excess deaths from laryngeal cancer, but a clear association with smoking. Ten men and one woman died from pleural mesothelioma. If the only subjects studied had been the 1904 men with at least 20 years' employment in the lower dust concentrations, averaging 6.6 million particles per cubic foot (or about 20 fibres/cc), excess mortality would not have been considered statistically significant, except for pneumoconiosis. The inability of such a large epidemiological survey to detect increased risk at what, today, are considered unacceptable dust concentrations, and the consequent importance of exposure-response models are therefore emphasised.
Notes
Cites: Biometrics. 1969 Jun;25(2):339-555794104
Cites: Arch Environ Health. 1971 Jun;22(6):677-865574010
Cites: Arch Environ Health. 1972 Mar;24(3):189-975059627
Cites: Arch Environ Health. 1974 Feb;28(2):61-84809914
Cites: Arch Environ Health. 1974 Feb;28(2):69-714809915
Cites: Arch Environ Health. 1975 May;30(5):266-71130842
Cites: Br J Prev Soc Med. 1976 Dec;30(4):225-301009272
Cites: Int J Cancer. 1977 Sep 15;20(3):323-31903186
Cites: Prev Med. 1977 Sep;6(3):426-42333420
Cites: J Occup Med. 1977 Nov;19(11):737-40915568
Cites: Lancet. 1978 Mar 4;1(8062):484-976030
Cites: Br J Ind Med. 1964 Oct;21:304-714253230
PubMed ID
7370189 View in PubMed
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Dust exposure and mortality in chrysotile mining, 1910-75. 1980.

https://arctichealth.org/en/permalink/ahliterature219708
Source
Br J Ind Med. 1993 Dec;50(12):1058-72
Publication Type
Article
Date
Dec-1993
Author
J C McDonald
F D Liddell
G W Gibbs
G E Eyssen
A D McDonald
Source
Br J Ind Med. 1993 Dec;50(12):1058-72
Date
Dec-1993
Language
English
Publication Type
Article
Keywords
Asbestos, Serpentine
Asbestosis - history - mortality
Dust
History, 20th Century
Humans
Mining - history
Occupational Exposure - history
Quebec
Notes
Cites: Int J Cancer. 1977 Sep 15;20(3):323-31903186
Cites: Br J Prev Soc Med. 1976 Dec;30(4):225-301009272
Cites: Prev Med. 1977 Sep;6(3):426-42333420
Cites: J Occup Med. 1977 Nov;19(11):737-40915568
Cites: Lancet. 1978 Mar 4;1(8062):484-976030
Cites: Environ Res. 1978 Dec;17(3):340-6233818
Cites: Br J Ind Med. 1964 Oct;21:304-714253230
Cites: Biometrics. 1969 Jun;25(2):339-555794104
Cites: Arch Environ Health. 1971 Jun;22(6):677-865574010
Cites: Arch Environ Health. 1972 Mar;24(3):189-975059627
Cites: Arch Environ Health. 1974 Feb;28(2):61-84809914
Cites: Arch Environ Health. 1974 Feb;28(2):69-714809915
Cites: Arch Environ Health. 1975 May;30(5):266-71130842
Cites: N Engl J Med. 1976 Mar 25;294(13):687-9055969
Comment In: Occup Environ Med. 1994 Jun;51(6):4318044238
PubMed ID
8280637 View in PubMed
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Fibre exposure and mortality from pneumoconiosis, respiratory and abdominal malignancies in chrysotile production in Quebec, 1926-75.

https://arctichealth.org/en/permalink/ahliterature240667
Source
Ann Acad Med Singapore. 1984 Apr;13(2 Suppl):340-4
Publication Type
Article
Date
Apr-1984
Author
F D Liddell
D C Thomas
G W Gibbs
J C McDonald
Source
Ann Acad Med Singapore. 1984 Apr;13(2 Suppl):340-4
Date
Apr-1984
Language
English
Publication Type
Article
Keywords
Abdominal Neoplasms - etiology - mortality
Aged
Asbestos - adverse effects
Asbestosis - mortality
Dust - adverse effects
Female
Humans
Lung Neoplasms - etiology - mortality
Male
Mining
Occupational Diseases - etiology - mortality
Quebec
Smoking
Abstract
To define the relationships between chrysotile exposure in fibre terms and death from specific cancers, and pneumoconiosis, all 11,379 persons born 1891-1920 who had worked in the asbestos mines and mills of Quebec for a month or more before 1967 were followed to the end of 1975. Among the 10,939 men, there had been 4,463 deaths, 634 from these causes. For each death, referents were randomly selected from among men in the cohort born in the same year as the case and known to have survived to a greater age. For each case and his referents, exposures accumulated up to nine years before the death of the case had been obtained as (million particles per cubic foot) x years. Fibre counts were estimated for each work-place so that all exposures could be expressed in (fibres/ml) x years. The ratio of the means for all 2,586 accumulated exposures was 3.46 (f/ml)/mpcf. Relative Risks (RR) were related to exposure by matched analysis. For pneumoconiosis and lung cancer, RR = 1 + b.(f/ml).y fitted well, with b estimated as 0.00647 and 0.00038, respectively. For cancers of upper and of lower G.I. tract, severe exposure was associated with elevated RRs, but rather unclearly. For other abdominal cancers, and laryngeal cancer, risks and exposure were not positively associated. The asbestos-smoking interaction in lung cancer was closer to multiplicative than to additive.
PubMed ID
6497336 View in PubMed
Less detail

Follow-up respiratory measurements in Quebec chrysotile asbestos miners and millers.

https://arctichealth.org/en/permalink/ahliterature243680
Source
Scand J Work Environ Health. 1982;8 Suppl 1:105-10
Publication Type
Article
Date
1982
Author
M R Becklake
D. Thomas
F. Liddell
J C McDonald
Source
Scand J Work Environ Health. 1982;8 Suppl 1:105-10
Date
1982
Language
English
Publication Type
Article
Keywords
Adult
Asbestos - adverse effects
Follow-Up Studies
Humans
Lung Diseases - epidemiology - radiography
Lung Volume Measurements
Male
Middle Aged
Mining
Occupational Diseases - epidemiology - radiography
Quebec
Abstract
In 1974 changes in dyspnea, lung function, and pneumoconiotic radiographic abnormalities were recorded among the 1,015 Quebec chrysotile miners and millers surveyed in 1967-1968. The aim was to relate these changes to dust exposure--age, smoking, and earlier health status being taken into account. Dyspnea and lung function were assessed in 722 men, and for 277 recent radiographs were read separately by three experts for changes in the parenchyma and pleura. Each measure was analyzed independently for men without any abnormality when first seen (eligible for "attack") and for others (eligible for progression/regression). Age significantly influenced the rate of attack of pleural abnormality and the rates of attack and progression of dyspnea and lung function decline. Smoking had comparatively minor effects. The only associations with exposure were for progression of parenchymal change (one reader), and for progression of dyspnea. These essentially negative findings are similar to those obtained in a previous longitudinal survey of radiographs from the same workforce.
PubMed ID
7100836 View in PubMed
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20 records – page 1 of 2.