A case-referent study of lung cancer, occupational exposures and smoking. III. Etiologic fraction of occupational exposures

The proportion of lung cancer related to occupational exposure to respiratory carcinogens and other workplace contaminants has been studied in a hospital-based case-referent study of 176 incident cases and 176 referents, recruited from the medical ward of two county hospitals in southern Norway. On the basis of job title and exposure information, three different approaches for the estimation of etiologic fraction were used, all based upon a trichotomous categorization of the exposure variable. Among the definitely exposed subjects, the etiologic fraction for lung cancer related to occupational exposure factors was from 22 to 35%, increasing to 37-47% when the "possibly exposed" categories were included. When asbestos was the only factor to be eliminated, the etiologic fraction estimate suggested a 23% reduction in the lung cancer incidence in the study population. More than 90% of the lung cancer cases would theoretically have been prevented if smoking had been completely removed. The relative merits of preventing one or several of the study factors simultaneously is discussed.     

A case-referent study of lung cancer, occupational exposures and smoking. II. Role of asbestos exposure

In a hospital-based case-referent study of 176 incident lung cancer cases, ascertained during a five-year period from two county hospitals, the role of asbestos exposure and smoking has been studied. Information on asbestos exposure was obtained from personal interviews, and allocated to four exposure categories, according to the intensity and duration of the exposure. Twenty-five percent of the cases and 10% of the referents had been moderately to heavily exposed to asbestos during their working career. A statistically significant trend in risk ratio related to the degree of exposure was observed, with a more than fourfold risk among the heavily exposed. The strongest association was found between asbestos exposure and small cell carcinoma, and the weakest association between asbestos exposure and adenocarcinoma. Very high risk ratios were observed among asbestos-exposed subjects who were heavy smokers, and the interaction observed between asbestos and smoking conformed more closely to a multiplicative model than to an additive one. The results suggest that the observed association between lung cancer and occupational exposures in this study was, to a large extent, due to asbestos exposure. Information on such exposure was missing in 90% of the medical records of these patients.     

Risk of astrocytic brain tumors associated with occupational chemical exposures. A case-referent study

A case-referent study was conducted on the risk of brain tumors among workers exposed to organic chemicals in petroleum refining and chemical manufacturing. Brain tumor cases in northern New Jersey, Philadelphia, and the Gulf Coast of Louisiana were identified from death certificates of a recent three-year period. The cases (N = 300) were white men aged greater than or equal to 30 years with a confirmed diagnosis of glioblastoma multiforme, astrocytoma, or a mixed glioma with astrocytic cells. The referents (N = 386) were white men who died from causes other than brain tumor, epilepsy, cerebrovascular disease, suicide, or homicide and were frequency-matched with the cases on age at death, year of death, and study area. Next-of-kin were interviewed for complete occupational histories. No statistically significantly elevated odds ratios (OR) were associated with employment in the chemical industry. The risk of astrocytic tumors was elevated among the subjects with production or maintenance jobs in petroleum refining (OR 1.7, 95% confidence interval 0.7-4.2); however, it decreased with duration employed. There were nonsignificant excess risks of astrocytic tumors among the men exposed to cutting fluids (OR 1.6) or organic solvents (OR 1.3), and also among the subjects exposed to lubricating oils (OR 1.4), organic solvents (OR 1.5), or cutting fluids (OR 1.8) for greater than or equal to 20 years.     

A case-referent study of lung cancer and incense smoke, smoking, and residential radon in Chinese men

Background: Burning incense generates large amounts of air pollutants, many of which are confirmed or suspected human lung carcinogens.Objectives: We conducted a population-based case-referent study to examine the effect of incense smoke exposure on lung cancer risk among Chinese males and explored the joint effect of cigarette smoking and exposure to residential radon.Methods: We recruited 1,208 male lung cancer incident cases and 1,069 community referents from 2004 to 2006 and estimated their lifetime exposures to incense smoke and other residential indoor air pollutants based on self-reported information collected during interviews. We performed unconditional multivariable logistic regression analysis to estimate the odds ratio (OR) for lung cancer associated with exposure to incense smoke after adjusting for possible confounders. We conducted stratified analyses by smoking status and exposures to incense burning and residential radon and explored the potential additive-scale interactions.Results: We observed an association between incense exposure and lung cancer that was limited primarily to smokers. Cigarette smoking and high cumulative incense exposure at home appeared to have a synergistic effect on lung cancer (compared with never-smokers who never used incense, the OR for lung cancer for smokers who used incense ≥ 60 day-years = 5.00; 95% confidence interval: 3.34, 7.51). Power was limited, but we also found preliminary evidence suggesting that radon exposure may increase risk among smokers using incense.Conclusion: Our study suggests that exposure to incense smoke in the home may increase the risk of lung cancer among smokers and that exposure to radon may further increase risk.     

Quantifying the mediating effects of smoking and occupational exposures in the relation between education and lung cancer: the ICARE study

Smoking only partly explains the higher lung cancer incidence observed among socially deprived people. Occupational exposures may account for part of these inequalities, but this issue has been little investigated. We investigated the extent to which smoking and occupational exposures to asbestos, silica and diesel motor exhaust mediated the association between education and lung cancer incidence in men. We analyzed data from a large French population-based case–control study (1976 lung cancers, 2648 controls). Detailed information on lifelong tobacco consumption and occupational exposures to various carcinogens was collected. We conducted inverse probability-weighted marginal structural models. A strong association was observed between education and lung cancer. The indirect effect through smoking varied by educational level, with the strongest indirect effect observed for those with the lowest education (OR = 1.34 (1.14–1.57)). The indirect effect through occupational exposures was substantial among men with primary (OR = 1.22 (1.15–1.30) for asbestos and silica) or vocational secondary education (OR = 1.18 (1.12–1.25)). The contribution of smoking to educational differences in lung cancer incidence ranged from 22 % (10–34) for men with primary education to 31 % (?3 to 84) for men with a high school degree. The contribution of occupational exposures to asbestos and silica ranged from 15 % (10–20) for men with a high school degree to 20 % (13–28) for men with vocational secondary education. Our results highlight the urgent need for public health policies that aim at decreasing exposure to carcinogens at work, in addition to tobacco control policies, if we want to reduce socioeconomic inequalities in the cancer field.     

Effects of occupational exposures and smoking on lung function in tile factory workers

Purpose  

The aims of this study were to investigate the relations of occupational exposures in tile industry to lung function and to evaluate potential interaction between smoking and tile dust exposure containing silica.     

A case-control study of cancer of the nose and paranasal sinuses and occupational exposures.

The association between nasal cancer and various occupations was investigated in a case-control study in the provinces of Verona and Vicenza (northeastern Italy) and Siena (central Italy). Cases of malignant epithelial neoplasm of the nasal cavities and paranasal sinuses diagnosed in the years 1982-1987 in the hospitals of Verona, Legnago, Bussolengo, Vicenza, and Siena comprised the study. Controls were patients admitted to the same hospitals as the cases, with any diagnosis except chronic rhino-sinusal disease and nasal bleeding. Age, gender, residency, and date of admission were taken into account by matching. Cases and controls, or their next of kin, were interviewed or required to fill in a mailed questionnaire; the overall response rate was 70%. Altogether, 78 cases and 254 controls provided information on occupational history. Significantly increased risks were associated (in males) with work in the wood industry (odds ratio [O.R.]: 5.8; 90% confidence interval [C.I.]: (2.2-16) and in the leather industry (6.8; 1.9-25). Textile workers, furnacemen, construction workers, and workers with possible exposure to organic dusts showed increased risks even if statistical significance was not reached.     

Case-control study of occupational exposures and male breast cancer

OBJECTIVE: To investigate whether risk of male breast cancer is associated with workplace exposures. METHODS: A case-control study of 178 cases of male breast cancer and 1041 controls was carried out with data from the United States national mortality follow-back survey, which collected questionnaire information from proxy respondents of a 1% sample of all 1986 United States deaths among subjects aged 25-74 years. Occupational exposure to electromagnetic fields, high temperatures, polycyclic aromatic hydrocarbons (PAHs), herbicides, other pesticides, and organic solvents was assessed by applying job- exposure matrices, based on the 1980 United States census occupation and industry codes, to the longest job held by study subjects as reported by the informants. A socioeconomic status index was created by combining information on annual family income, education, assets, and occupation to assess the association of socioeconomic status with male breast cancer. Relative risks were derived from logistic regression modelling, which included age, socioeconomic status, marital status, and body mass index, as well as occupational exposures. RESULTS: Risk for male breast cancer increased significantly with increasing socioeconomic status index (test for trend: p < 0.01), but the risks associated with individual socioeconomic status variables were smaller and the trends were not significant. A significant increase in risk of male breast cancer was associated with employment in blast furnaces, steel works, and rolling mills (odds ratio (OR) 3.4; 95% confidence interval (95% CI) 1.1 to 10.1, based on six cases), and motor vehicle manufacturing (OR 3.1; 95% CI 1.2 to 8.2, based on seven cases). However, exposures to electromagnetic fields, high temperature, PAHs, herbicides, other pesticides, and organic solvents were not associated with risk of male breast cancer. CONCLUSIONS: The role of workplace exposures in increasing risk of breast cancer among men employed in motor vehicle manufacturing and in blast furnaces, steel works, and rolling mills deserves further investigation. The finding on socioeconomic status suggests that, as well as reproductive factors, other lifestyle factors such as diet that may be related to high socioeconomic status in men should be investigated further.

 

     

吸烟、被动吸烟与肺癌发病风险的病例对照研究

目的 探讨吸烟、被动吸烟与肺癌的关联.方法 采用病例对照研究设计,面访肺癌新发病例1 303例和按性别、年龄(±2岁)频数匹配的健康对照1 303例.结果 吸烟是男性肺癌的重要危险因素(调整OR=4.974,95％ CI:3.933 ～6.291),随着开始吸烟年龄提前、吸烟年限延长、日吸烟量、吸烟包年以及吸烟深度的增加,患肺癌危险性增高,呈剂量反应关系(Ptrend＜0.001),戒烟≥10年患肺癌的危险性降低45.4％.男性吸烟患肺鳞癌的危险性比患肺腺癌大.被动吸烟是非吸烟者肺癌的危险因素(调整OR=1.912,95％CI:1.486～2.460),工作环境被动吸烟的男性非吸烟者患肺癌的调整OR为2.221(95％CI:1.361 ～3.625),家庭环境被动吸烟的女性非吸烟者患肺癌的调整OR为1.804(95％ CI:1.270～2.562).68.04％男性肺癌的发生可归因于吸烟,26.51％非吸烟者肺癌的发生可归因于被动吸烟.结论 吸烟是肺癌的重要危险因素,工作环境被动吸烟是男性非吸烟者肺癌的主要危险因素,家庭环境被动吸烟是女性肺癌的主要危险因素.戒烟具有重大的公共卫生学意义.     

Ovarian cancer and occupational exposures in Finland.

BACKGROUND: No single occupational or environmental agent has been established as causing ovarian cancer, existing studies often being based on ecologic or proportional mortality data in which potential confounders related to reproductive history have not been taken into account. METHODS: This study linked 324 job titles of occupationally active Finnish women (n = 892,591) at 1970 census with incidence of ovarian cancer (Finnish Cancer Registry, 5,072 cases) during 1971-1995 (over 15 million person-years). The job titles were converted into indicators of exposure to 33 agents, using a national job-exposure matrix based on measurements and surveys (FINJEM). Poisson regression analyses were performed with stratification by birth cohort, follow-up period, and socioeconomic status, and adjusted for mean number of children, mean age at first delivery, and turnover rate for each job title. RESULTS: We found indications of elevated risks for aromatic hydrocarbon solvents (standardized incidence ratio 1.3 (95% CI 1.0-1.7), leather dust (1.4; 0.7-2.7), man-made vitreous fibers (1.3; 0.9-1.8), and high levels of asbestos (1.3; 0.9-1.8), and diesel (1.7; 0.7-4.1), and gasoline (1.5; 1.0-2.0) engine exhausts). Previously reported findings for hairdressers and women in the printing industry were supported in our data, but not for women in dry cleaning jobs. CONCLUSIONS: Given the various drawbacks in linkage studies and job-exposure matrices, the excesses found in this study need confirmation in individual-level studies.     

A case-referent study investigating the relationship between exposure to silica dust and lung cancer

Summary A case-referent study was carried out to investigate the relationship between lung cancer and exposure to silica dust in an area where a relatively high proportion of the workforce was exposed to silica dust in the past. The cases were 309 lung cancer patients admitted at the Chest Department of the Central Belluno Hospital during the period 1973–1980, while the 309 controls were patients admitted at the same department for diseases other than lung cancer and bronchitis during the same period. Information on exposure to silica and smoking habits were collected from hospital records. The results show an elevated risk, supported by a clear dose-response, due to smoking. Exposure to silica also appears to increase the risk of lung cancer, but only in presence of silicosis. The risk estimates tend to increase both with amount of smoking and duration of exposure to silica, with the magnitude of the risk being, however, much smaller for the latter effect. No clear interaction appears to exist between the two factors. The limitations of the study and the problems in interpreting the results are discussed.     

Isocyanate exposure and occupational asthma: a case-referent study

OBJECTIVE—To examine the quantitative relation between exposure to isocyanates and occupational asthma, and to explore the role of atopy and smoking in occurrence of the disease.
METHOD—A case-referent study was undertaken of cases from two manufacturing companies (A and B) from which referents without disease could be selected and reliable exposure measurements were available. In company A, 27 cases mainly attributed to toluene diisocyanate (TDI) were matched to 51 referents on work area, start and duration of employment, sex, and age. Exposures were estimated from existing measurements by job category. In company B there were seven cases attributed to 4,4'-diphenylmethane diisocyanate (MDI) in two areas of the plant; 12 non-cases from the same areas were used as referents. Personal exposure measurements were available for all cases and 11 referents.
RESULTS—No difference in peak exposures between cases and referents was found in either plant; but in both, time weighted average (TWA) exposures at the time of onset of asthma were higher for cases. In A, the mean TWA exposure for cases was 1.5 (95% confidence interval (95% CI) 1.2 to 1.8) ppb compared with 1.2 (1.0 to 1.4) ppb for referents. From a matched analysis, the odds ratio (OR) associated with 8 hour TWA exposure to isocyanates greater than 1.125 ppb (the median concentration for the referent group) was 3.2 (95% CI 0.96 to 10.6; p=0.06). Occupational asthma was associated with a pre-employment history of atopic illness (OR 3.5, p=0.04) and, less strongly, with smoking (OR 2.1, p=0.14). In B, small numbers limited analysis, but three of seven cases had at least one TWA exposure measurement greater than 5 ppb compared with one of 11 referents (OR 7.5, p=0.09).
CONCLUSION—Asthma can occur at low concentrations of isocyanates, but even at low concentrations, the higher the exposure the greater the risk. By contrast with other studies, smoking and atopy seemed to increase the odds of occupational asthma due to isocyanates, but did not affect the estimate of risk associated with exposure.


Keywords: occupational asthma; isocyanates     

Low-dose exposure to asbestos and lung cancer: dose-response relations and interaction with smoking in a population-based case-referent study in Stockholm,Sweden

This population-based case-referent study investigated the lung cancer risk associated with occupational exposure to asbestos, focusing on dose-response relations and the interaction with tobacco smoking. Incident cases of lung cancer among males aged 40-75 years in Stockholm County, Sweden, were identified from 1985 to 1990. Referents were selected randomly within strata (age, inclusion year) of the study base. Questionnaires administered to subjects or their next of kin gave information on occupations, tobacco smoking habits, and residences. Response rates of 87% and 85% resulted in 1,038 cases and 2,359 referents, respectively. Occupational exposures were assessed by an industrial hygienist. Lung cancer risk increased almost linearly with cumulative dose of asbestos. The risk at a cumulative dose of 4 fiber-years was 1.90 (95% confidence interval (CI): 1.32, 2.74), higher than that predicted by downward linear extrapolation from highly exposed occupational cohorts. The relative risk (exp(beta)) for a transformed dose variable ln(fiber-years + 1) was 1.494 (95% CI: 1.193, 1.871) per unit of exposure. The joint effect of asbestos and smoking was estimated to be 1.15 (95% CI: 0.77, 1.72) times that predicted from the sum of their individual effects and 0.31 (95% CI: 0.11, 0.86) times that predicted from their product, indicating a joint effect between additivity and multiplicativity.     

Paternal occupational exposures and childhood cancer

The objective of the study described here was to test the hypothesis that paternal occupational exposure near conception increases the risk of cancer in the offspring. We conducted a cohort study based on a population of 235,635 children born shortly after two different censuses in Sweden. The children were followed from birth to 14 years, and cases of cancer were identified in the Swedish Cancer Registry. Occupational hygienists assessed the probability of exposure to different agents in each combination of the father's industry and occupation as reported in the censuses. We also analyzed individual job titles. We compared the cancer incidence among children of exposed fathers to that among children of unexposed fathers using Cox proportional hazards modeling. The main findings were an increased risk of nervous system tumors related to paternal occupational exposure to pesticides [relative risk (RR) = 2.36; 95% confidence interval (CI), 1.27-4.39] and work as a painter (RR = 3.65; 95% CI, 1.71-7.80), and an increased risk of leukemia related to wood work by fathers (RR = 2.18; 95% CI, 1.26-3.78). We found no associations between childhood leukemia and paternal exposure to pesticides or paint. Our results support previous findings of an increased risk of childhood brain tumors and leukemia associated with certain paternal occupational exposures. Some findings in previous studies were not confirmed in this study.