Lung and bladder cancer among Danish urban bus drivers and tramway employees: a nested case-control study

BACKGROUND: The combustion of fossil fuels produces small amounts of mutagenic and carcinogenic compounds. We investigated the association between employment and lung and bladder cancer in Danish bus drivers and tramway employees. METHODS: We carried out a nested case-control study of 153 lung and 84 bladder cancer cases, and 606 controls sampled in a cohort of 18 174 bus drivers or tramway employees employed in Copenhagen during the period 1900-1994. The cases and controls or their next of kin were interviewed about smoking, along with occupational and residential history. An exposure index based on which bus routes the bus drivers had mainly been driving was established. Relative risks (RRs) were estimated by conditional logistic regression. RESULTS: The analysis showed decreasing risk for lung cancer with increasing years of employment as a bus driver (RR = 0.97 for each added year, 95% confidence interval = 0.96-0.99). The air pollution index based on main bus for the bus drivers showed no positive correlation with risk.     

Cancer incidence among urban bus drivers in Denmark

Summary During the period from 1978–1984 the incidence of cancer among 2465 male urban bus drivers in three major cities in Denmark was studied. The information with regard to cancer diagnosis was obtained from the Danish Cancer Registry. Danish men in 1981 were used as reference. Standardized Morbidity Ratio (SMR) for bladder- and skin cancer was significantly elevated among the bus drivers with values of 206 and 202, respectively. As to other cancers, no significant deviations from the expected were found. The same result was found when only drivers with more than ten years' seniority were included in the calculations. The incidence of skin cancer remained significantly elevated when corrected for degree of urbanization. Traffic density and whether the drivers worked in Copenhagen or in the province were not related to cancer incidence.     

Risk factors for unintentional occupational injury among urban transit bus drivers: a cohort longitudinal study

PurposeAlthough many studies have focused on bus operators' occupational diseases, work-related injury and associated risk factor data are limited. The purpose of this longitudinal study was to investigate unintentional injury and exposures that may affect injury risk among metropolitan bus operators.MethodsDemographic, work-related, and injury data obtained from a metropolitan transit company for a 5-year period, enabled estimates of rates per 100 full time equivalents (FTEs) and adjusted Hazard Ratios (HRs), with 95% confidence intervals (CIs), using Generalized Estimating Equations and Cox proportional hazards models, respectively.ResultsThe 2095 bus operators, included in this study, had an unintentional injury rate (95% CI) of 17.8 (16.1–19.7) per 100 FTEs. Multivariable analysis identified increased risks for operators who were female, compared to male (HR = 2.4; 2.0–2.8); worked less than 7 versus 7 to less than 12 hours per day (HR = 4.6; 3.8–5.5); and drove less than 7 versus 7 to less than 12 hours per day (HR = 3.2; 2.7–3.8). Suggestive increased risks were identified for operators working split versus straight shifts (HR = 1.2; 1.0–1.4) and for driving limited versus regular bus routes (HR = 1.36; 1.0–1.8).ConclusionsResults serve as a basis for further studies and inform the development of targeted intervention strategies to reduce bus operators' occupational injuries.     

Cancer incidence in an urban community: an historical cohort study

This historical cohort study tested the hypothesis that residents of an industrialized urban community were at higher risk of cancer than residents of a comparable, but non-industrialized, community. The exposed (C1) and the unexposed (C2) cohorts resided in their respective neighbourhoods between 1952 and 1956. All incident cancers were identified through linkage with the Ontario Cancer Registry for 1964-1982. Cancer incidence rates in the two cohorts were 7.0 and 7.3 per 1,000 person-years, respectively. Relative risk estimates for all cancers, lung cancer and cancers associated with environmental exposure, were not significantly different from 1.0. Only colorectal cancers were significantly more frequent in the C1 than the C2 cohort, and these only in one sub-analysis. Overall, we conclude that if there was increased risk of cancer related to environmental pollution in the industrially exposed community, it was less than a two-fold increase.     

Mortality in a historical cohort of bus drivers

In an attempt to address previously reported excesses of ischaemic heart disease (IHD), lung cancer and bladder cancer among professional drivers, the mortality (SMR) of 2134 Montreal city bus drivers employed for at least five years as of January 1962 and followed until 31 December 1985 was compared with that of the male population of greater Montreal. The vital status of 94% of the cohort was ascertained. The number of deaths observed was 804. The overall mortality was somewhat lower than expected (SMR = 97). A small, non-significant excess mortality was found for ischaemic heart disease (IHD) (O/E = 313/295, SMR = 106, 95% CI: 95-118) and circulatory system diseases (O/E = 441/405, SMR = 109, 95% CI: 99-119). However, no excesses were observed for lung cancer (O/E = 78/84.4, SMR = 92, 95% CI: 73-114) or bladder cancer (O/E = 4/7.4, SMR = 54, 95% CI: 15-138). These results are compatible with other studies which have found a small risk of IHD for bus drivers.     

Cancer incidence among Danish seafarers: a population based cohort study

Aims: Seafarers aboard oil and chemical tankers may be exposed to many chemicals, including substances like benzene that are known to be carcinogenic. Other seafarers are exposed to engine exhaust, different oil products, and chemicals used aboard and some years ago asbestos was also used extensively in ships. The aim of this study was to study cancer morbidity among Danish seafarers in relation to type of ship and job title. Methods: A cohort of all Danish seafarers during 1986–1999 (33 340 men; 11 291 women) registered by the Danish Maritime Authority with an employment history was linked with the nationwide Danish Cancer Registry and followed up for cancer until the end of 2002. The number of person years at risk was 517 518. Standardised incidence ratios (SIR) were estimated by use of the corresponding national rates. Results: The SIR of all cancers combined was higher than expected: 1.26 (95% CI 1.19 to 1.32) for men and 1.07 (95% CI 0.95 to 1.20) for women. This was mainly due to an excess of cancer of the larynx, lung, tongue, mouth, pharynx, oesophagus, pancreas, kidney, urinary bladder, colon, and bone as well as skin melanomas among men (the three latter borderline significantly increased), and an excess of cancer of the lung, rectum, and cervix uteri among women. The differences in risk pattern for lung cancer between the different job categories among men ranged in terms of SIR from 1.2 (95% CI 0.9 to 1.7) (engine officers) to 2.3 (1.6 to 3.3) (engine room crew), and 4.1 (2.1 to 7.4) among maintenance crew. Non-officers had a 1.5 times higher lung cancer risk than officers. No increased occurrence of all lymphatic and haematopoietic malignancies combined was found for employees on tankers, but the number of cases was limited to a total of 7. Conclusions: Danish seafarers, especially men, face an increased overall cancer risk, in particular a risk for lung cancer and other tobacco associated cancers.     

Mortality and incidence of cancer among sewage workers: a retrospective cohort study.

To study the incidence of and mortality from cancer among sewage workers a retrospective analysis was performed on a cohort of 656 men employed for at least one year at any one of 17 Swedish sewage plants during the years 1965-86. Assessment of exposure was done by classification of work tasks. Lower than expected total mortality (standardised mortality ratio (SMR) = 0.75, 95% confidence interval (95% CI) 0.58-0.97) and cardiovascular mortality (SMR = 0.61, 95% CI 0.39-0.91) was found. This was interpreted as a result of the healthy worker effect. For all cancers combined the mortality (SMR = 1.08, 95% CI 0.68-1.67) and morbidity (SMR = 1.02, 95% CI 0.72-1.38) were comparable with those of the general population. There were increased incidences for brain tumours (SMR = 2.19, 95% CI 0.45-6.39), gastric cancers (SMR = 2.73, 95% CI, 1.00-5.94), and renal cancers (SMR = 1.68, 95% CI = 0.35-4.90). For lung cancer the risk was reduced (SMR = 0.70, 95% CI 0.15-2.05). Allowance for a latency period of 10 years from the start of exposure did not change the pattern. Logistic modelling was used to search for exposure-response relations. In a logistic model with the confounder age forced in, renal cancer had a significant positive relation with a weighted sum of employment times, where the weights describe the classification of exposure. No exposure-response relations were found for brain tumors or gastric cancers. The increased risks are based on small numbers of cases. A future follow up will add more conclusive power to the study. Specific exposures need to be identified to allow for a better dose-response analysis.     

Peptic ulcer among urban bus drivers in Denmark

As part of a survey on the work environment of bus drivers, 2045 (83%) of 2465 male bus drivers in the three major cities in Denmark in 1978 answered a postal questionnaire on health and working conditions. In order to evaluate the relative occurrence of peptic ulcer among the bus drivers, a follow-up study was also conducted. All hospital discharges with a peptic ulcer diagnosis among the bus drivers were registered from the Danish National Patient Register. All Danish men were used as reference group. On the basis of the 1978-questionnaire association between occupational and psychosocial factors and subsequent hospital discharge with a peptic ulcer diagnosis was studied. The prevalence of abdominal pain alleviated by food intake was 12% among bus drivers and 6% in the reference group. The incidence of hospital discharge with duodenal ulcer among younger bus drivers was twice the incidence among Danish men in the same age group. The incidence of all manifestations of peptic ulcer disease among bus drivers did not differ from the incidence among Danish men. Of occupational and psycho-social factors, wage dissatisfaction and smoking showed statistically significant association with hospital discharge with PU in a 6 3/4-year period. Job dissatisfaction, stress symptoms and lack of some social network factors tended to increase the risk of hospital discharge with PU.     

Wood dust exposure and cancer incidence: a retrospective cohort study of furniture workers in Estonia

BACKGROUND: Occupational wood dust exposure is associated with increased risk of sinonasal cancer in men. However, little is known whether it is associated with sinonasal cancer in women or with malignancies of other sites. METHODS: In a retrospective cohort study of furniture workers, cancer incidence in 3723 men and 3063 women between 1968 and 1995 was compared to the incidence in the general population of Estonia. Cancer risks were analyzed by employment duration and occupation. RESULTS: The standardized incidence ratio (SIR) for all cancers did not differ significantly from one. Two men and one woman had sinonasal cancer (expected 1.07 and 0.53, respectively). Significantly increased risk of colon cancer was seen in the cohort (SIR 1.65, 95% confidence interval (CI) 1.22-2.17). Subjects employed for 10 years and over had significant excess of colon cancer (SIR 2.29, 95% CI 1.28-3.77) and rectal cancer (SIR 2.10, 95% CI 1.05-3.76) in the analysis by employment duration using exposure with a latency of 20 years. The nonsignificant excess of pharyngeal cancer in men (SIR 1.82) and lung cancer in women (SIR 1.43) was restricted to short-term workers. CONCLUSIONS: This study found an excess of colon and rectal cancer in furniture workers. There was no increase in total cancer risk.     

Coronary heart disease risk factors in urban bus drivers

The purpose of this study was to determine the risk factors for coronary heart disease (CHD) in 2297 bus drivers and skilled workers from the Taipei Municipal Bus Administrative Bureau. Data for this study were compiled from the medical records of annual physical examinations for bus drivers and skilled workers conducted at Taipei Municipal Chronic Disease Hospital during the period from July 1998 to June 1999. The results showed that, after adjustment for age, hypertension rates for bus drivers (56.0%, 986/1361) were significantly greater than for skilled workers (30.6%, 164/536). All age groups demonstrated a similar difference. Significant differences were also noted in body mass index, serum cholesterol, serum triglyceride and ischemic heart disease between bus drivers and skilled workers. Among bus drivers, the prevalence of obesity was 9.6%, hypercholesterolemia 34.0%, hypertriglyceridemia 69.4% and ischemic heart disease 1.7%. By contrast, among skilled workers, the prevalence of obesity was only 4.6%, hypercholesterolemia 29.9%, hypertriglyceridemia 30.6% and ischemic heart disease 0.9%. These findings suggest that exposure to the occupation of driving a bus may carry an increased risk of CHD and that drivers who develop signs of cardiovascular illness should be transferred to non-driving occupations within the company.     

Low back trouble among urban bus drivers in Denmark

The occurrence of low back trouble and possible connection with psychosocial conditions among urban bus drivers were studied using a questionnaire and subsequent registration of hospital discharges. 2,045 (83%) full-time male bus drivers in the three largest cities in Denmark answered a questionnaire in 1978 regarding psychosocial factors and health. The prevalence of frequent low back pain was 57%. In a control group of 195 motormen the prevalence was 40%. Standardized Morbidity Ratio for bus drivers discharged from hospital during the period 1978-1984 with the diagnosis lumbar disc herniation was 137 compared to all Danish men. These differences were statistically significant. Of psychosocial factors only "the feeling of being mentally unbalanced" was found to be statistically significantly related to subsequent hospital discharge with a LBT-diagnosis. Long seniority as bus driver of those discharged from hospital with LBT makes it probable that LBT has etiologic factors in the work environment. The sedentary position and whole-body vibrations may be contributory causes.     

Mortality and cancer incidence among Swedish dock workers--a retrospective cohort study

The study originates from the arousal of suspicions that, in connection with loading and unloading work involving the use of trucks, exposure to diesel exhaust fumes may be carcinogenic. This report describes a register study in which a broad mapping of the cause-of-death pattern and cancer morbidity has been carried out through the matching of locally compiled personal data with those from a central register, the Cause-of-Death Register, and the Cancer Register. The results obtained thus far show a low total mortality--irrespective of cause of death--but a tendency towards an excess risk for cancer morbidity, mainly due to lung cancer.     

Cancer incidence among employees at a petrochemical research facility

This investigation evaluated cancer incidence among workers at a petrochemical research facility in Illinois. A cluster of brain cancer and other intracranial tumors had occurred at the facility before the study began. The subjects were 5641 people who had worked at the facility from 1970 through 1996 and who had lived in Illinois at any time between 1986 and 1997. Data on cancer cases came primarily from the Illinois State Cancer Registry. Analyses compared the 1986-to-1997 cancer incidence rates of employees with Illinois general population rates. Subjects had 18% fewer than expected total cancers (125 observed/153 expected cases; standardized incidence ratio [SIR], 82; 95% confidence interval [CI], 68 to 98), which was primarily attributed to a large deficit of lung cancer (10/26; SIR, 39; CI, 19 to 72). Brain cancer was increased in the overall study group (6/2.7; SIR, 222; CI, 81 to 484). This excess was restricted to white men who were scientists or technicians for one of the three companies at the facility (6/0.8; SIR, 750; CI, 275 to 1633); all cases in this group had worked in the "500 building complex" (6/0.6; SIR, 968; CI, 355 to 2106). Subjects also had an increased incidence of thyroid cancer (7/2.6; SIR, 265; CI, 106 to 546) that was not concentrated in particular occupational or building groups. The brain cancer incidence patterns indicated that an unidentified occupational exposure might have been responsible for the excess. Chance, socioeconomic factors leading to better case detection in facility employees than in the general population, and confounding by potential nonoccupational risk factors are plausible explanations of the observed increase in thyroid cancer.     

Cancer incidence in a cohort of infertile women

To explore further the relation between infertility and breast and female reproductive cancers, cancer incidence among 2,632 Israeli women treated for infertility between 1964 and 1974 was evaluated. Cancer incidence through December 1981 was determined by matching the study cohort to the Israel Cancer Registry. The observed number of cancers was compared with sex-age-ethnic and calendar-year, site-specific national cancer rates. There were 42 cancers observed compared with 37.4 expected, yielding a standardized incidence ratio of 1.1 (95% confidence interval (CI) = 0.8-1.5). Analysis by infertility diagnosis demonstrated no significant excess of total cancer incidence; the standardized incidence ratio was 1.3 (95% CI = 0.8-1.8) for infertility due to hormonal deficiency, 0.7 (95% CI = 0.3-1.4) for mechanical infertility, 1.6 (95% CI = 0.6-3.6) for infertility of the male partner, and 1.1 (95% CI = 0.5-2.2) for unclassified diagnosis. Site-specific analyses revealed a significantly increased risk (8.0; 95% CI = 2.5-19.3; four cases observed, 0.50 expected) of endometrial cancer for the hormonal group and a nonsignificant excess of breast cancer and melanoma. Although numbers were small, women with disorders causing unopposed estrogen production had a risk of 1.4 (95% CI = 0.8-2.2) for all cancer sites, which reached 10.3 (95% CI = 2.6-28.2; three cases observed, 0.29 expected) for endometrial cancer and 1.8 (95% CI = 0.8-3.4; eight cases observed, 4.43 expected) for breast cancer. Among women with nonhormonal infertility, there was a suggestion of increased risks of carcinoma of the ovary (3.2; 95% CI = 0.3-32.9; two cases observed, 0.63 expected) and thyroid (3.0; 95% CI = 0.3-24.6; two cases observed; 0.67 expected). No evidence of an association between ovulation-inducing drugs and cancer was found. This study supports the hypothesis that infertility caused by hormone deficiency is a risk factor for uterine cancer, but is inconclusive regarding breast cancer.     

上海某冶炼厂铅接触工人肿瘤死亡的回顾性队列研究

目的 了解职业铅接触工人肿瘤死亡情况,探讨职业铅接触与肿瘤的关系。方法 1985年1月1日前在本厂工人1年以上,且1985年1月1日仍存活的男性工人共6971名组成全队列,其中3344名在铅接触车间工作的工人组成的亚队列为接触队列。随访从1985年1月1日至1997年12月31日。以上海市人口的肿瘤死亡率作为标准对照,计算标化死亡比（SMR）;以本厂非接触人群作内对照计算相对危险度（RR）;估计累计接触剂量进行剂量－反应关系分析。结果 全队列6971人共观察87576人年,接触队列3344人共观察41505人年。全队列中,肺癌的SMR（95％CI）为128．0（101．1－159．7）。1965年后入厂的工人肺癌的SMR为463．7（P＜0．01）。有铅接触工作史且工龄超过20年的工人鼻咽癌的SMR＝408．0（P＜0．01）,肺癌的SMR＝156．6（P＜0．01）。肿瘤总计、恶性肿瘤总计、食管癌、胃癌、肝和胆道癌、肺癌和膀胱癌的RR（95％CI）分别为3．25（2．43－3．89）、3．28（2．54－4．32）、3．57（1．08－10．47）、2．93（1．15－4．87）、4．58（2．03－9．97）、8．58（4．82－15．11）、6．66（2．83－13．01）。将累计接触剂量分为高、中、低3个组,中、高组工人恶性肿瘤RR分别为1．62（P＜0．05）和1．70（P＜0．05）,且有随累计接触剂量增加危险性升高的趋势。中、高组工人的肺癌RR分别为2．55（P＜0．05）,和2．31（P＜0．05）。结论 工人肿瘤死亡危险性升高可能与铅接触有关,但还需要在控制其他职业有害因素接触和非职业性有害因素接触的情况下作进一步的研究。