We have examined data from 12 epidemiologic studies for quantitative evidence of biologic synergy between asbestos and smoking on lung cancer risks. Estimates of the effect associated with joint exposure to the two agents exceeded the sum of their separate effects in each study. We explored the variations in the strength of the synergistic effect across the studies using three indices: the ratio of the combined effects to the sum of the separate effects of smoking and asbestos (S), the relative excess risk due to interaction (RERI), and the attributable proportion of risk due to interaction (AP). The weighted average of S across all studies was 1.64 (95% confidence interval = 1.33-2.03). The attributable proportion associated with this average S was estimated as 33%, that suggests that one-third of cancer cases among smokers who were exposed to asbestos can be attributed to the synergistic behavior of the two carcinogens, as distinct from their separate effects and those attributable to other ("background") factors.
A unique data set of 3,380 British coal miners has been reanalyzed with major focus on nonpneumoconiotic respiratory conditions. The aim was to assess the independent contribution of smoking and exposure to respirable dust to clinically significant measures of respiratory dysfunction. Exposure to coal-mine dust was monitored over a 10-yr period. Medical surveys provided estimates of prior dust exposure and recorded respiratory symptoms. Each man's FEV1 was compared with the level predicted for his age and height by an internally derived prediction equation for FEV1. Four respiratory indices were considered at the end of the 10-yr period: FEV1 less than 80%, chronic bronchitis, chronic bronchitis with FEV1 less than 80%, and FEV1 less than 65%. Results were uniformly incorporated into logistic regression equations for each condition. The equations include coefficients for age, dust, and when indicated, an interaction term for age and dust. Dust-related increases in prevalence of each of the 4 conditions were statistically significant and were similar for smokers and nonsmokers at the mean age (47 yr). There was no evidence that smoking potentiates the effect of exposure to dust. Estimates of prevalences at the mean age of all 4 measures of respiratory dysfunction were greater in smokers. At intermediate and high dust exposure the prevalence of the 4 conditions in nonsmokers approached the prevalence in smokers at hypothetically zero dust exposure. Both smoking and dust exposure can cause clinically important respiratory dysfunction and their separate contributions to obstructive airway disease in coal miners appear to be additive.(ABSTRACT TRUNCATED AT 250 WORDS)
Few studies have investigated the association between body mass index and fecundability, that is, the ability to conceive in a menstrual cycle, among fertile women with normal menstrual cycle pattern. We examined the independent and combined effects of duration and regularity of the menstrual cycle, body mass index, and fecundability from records on pregnant women attending antenatal care at Odense University Hospital, Denmark, between 1972 and 1987. We included only the first birth of each woman who had planned pregnancies and no pre-pregnancy disease (N = 10,903). We estimated the fecundability odds ratio (FR) as the odds of conception in a menstrual cycle. After adjusting for confounders, the fecundability for women with a body mass index >25 kg/m2 was lower than for women with a body mass index of 20-25 kg/m2 [FR = 0.77; 95% confidence interval (CI) = 0.70-0.84]. FR was lower for women with long (>35 days) (FR = 0.74; 95% CI = 0.63-0.87) or irregular cycles (FR = 0.78; 95% CI = 0.70-0.87), even when their body mass index was within the normal range (20-25 kg/m2) and/or their cycles were regular.
General mortality in approximately 25 000 British coalminers over 22 year periods ending in 1980 was 13% lower on average than in English and Welsh men in the same regions of Britain. There were significant within region variations between collieries, and standardised mortality ratios increased during the later years of the follow up, approaching or slightly exceeding 100 in most of the 20 coalmines studied. Age specific comparisons of 22 year survival rates were made in subgroups. Relative risks of death from all non-violent causes for men with the earliest stage of progressive massive fibrosis (PMF category A), compared with risks in miners with no pneumoconiosis (category 0), ranged from 1 2 in those aged 55-64 initially to 3-5 for those aged 25-34. Mortality in miners with higher categories of PMF (B or C) was even more severe. Survival rates in men with category 1 simple pneumoconiosis were about 2% to 3% lower than in miners with radiographs classified as category 0, but there was no consistent evidence of an increase in mortality with increasing category of simple pneumoconiosis. Mortality from all non-violent causes increased systematically with increases in estimates of exposure to dust before the start of the follow up. That gradient was attributable primarily to deaths certified as due to pneumoconiosis and those recorded as due to bronchitis and emphysema (p < 0 001). There was some evidence of a dust related increase in deaths from cancers of the digestive system (p ; 0 05), but none of an association between exposure to coalmine dust and lung cancer. Lung cancer mortality, assessed over 17 year periods, was about 5-5 times higher in smokers than in life long non-smokers. Smokers with no pneumoconiosis had slightly higher lung cancer death rates than smokers with pneumoconiosis. We conclude that miners exposed to excessive amounts of respirable coalmine dust are at increased risk of premature death, either from progressive massive fibrosis or from chronic bronchitis or emphysema.
Five physicians' radiological assessments of coalworkers' simple pneumoconiosis (CWP) in 2600 coalminers at 10 British collieries have been studied in relation to the individuals' estimated lifetime (mean 33 years) exposure to respirable coalmine dust. Estimates of exposure were based on 20 years of observations at each colliery. Radiographic classifications were clearly associated with the measures of dust exposure. Important unexplained differences between some of the collieries were disclosed. Among men with similar cumulative dust exposures those with longer exposure time had higher prevalence of CWP. In general there was no evidence that the quartz concentrations experienced (average 5 % of mixed dust) affected the probability of developing coalworkers' simple pneumoconiosis. Some men reacted unfavourably (two or more steps of change on the 12-point radiological scale) over a 10-year period to coalmine dust with a relatively high quartz content.Earlier reports from the National Coal Board's Pneumoconiosis Field Research have described an association between exposure to respirable coalmine dust and incidence of coalworkers' simple pneumoconiosis (CWP).1-5 The effect of quartz has also been studied.6 These were interim investigations, based on a 10-year period of observations of coalface workers at 20 British collieries. Results from a longer-term study at 10 collieries are presented in this paper, which has two main objectives. The first is to report new dust-related estimates of long-term incidence risks of pneumoconiosis among working miners. The second is to present further information on how the chances of developing CWP are influenced by the quartz content of the coalmine dust to which men are exposed. SubjectsSince 1953 medical surveys of the Pneumoconiosis Field Research have been carried out at roughly five-year intervals at selected collieries from all the major British coalfields. Ten collieries were surveyed at least five times. They cover a wide range of environmental and geological conditions. All currently employed miners were asked to take part on each occasion. This report considers primarily the 2600 men who attended the first, third, and fifth surveys at the 10 collieries, and for whom complete and reliable data were available. Men no longer in the industry were not studied: 8394 men, examined at these collieries at the first surveys, were alive and under 65 years old 20 years later. The 2600 long-term working miners studied form 31 % of that group. Some results are reported for a further 1730 men who attended the third and fifth surveys, but not the first, at these same collieries. Methods RADIOLOGICAL DATAEach of five physicians experienced in the radiology of pneumoconiosis classified the fifth survey fullsized (posteroanterior) chest radiographs of the men separately, independently, and in random order according to the ILO U/C International Classification of Radiographs of the Pneumoconioses,7 using 1968 standard films. Additionally, the readers classified all 4330 pairs of the third a...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.