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Background: Few studies have investigated occupational lung cancer risk in relation to specific histopathological subtypes., Methods: A case-control study was conducted to evaluate the relationship between lung cancer and occupation/industry of employment by histopathological subtype. A total of 2,998 male cases and 10,223 cancer controls, diagnosed between 1983 and 1990, were identified through the British Columbia Cancer Registry. Matched on age and year of diagnosis, conditional logistic regression analyses were performed for two different estimates of exposure with adjustment for potentially important confounding variables, including tobacco smoking, alcohol consumption, marital status, educational attainment, and questionnaire respondent., Results: For all lung cancers, an excess risk was observed for workers in the primary metal (OR = 1.31, 95% CI, 1.01-1.71), mining (OR = 1.53, 95% CI, 1.20-1.96), machining (OR = 1.33, 95% CI, 1.09-1.63), transport (OR = 1.50, 95% CI, 1.08-2.07), utility (OR = 1.60, 95% CI, 1.22-2.09), and protective services (OR = 1.27, 95% CI, 1.05-1.55) industries. Associations with histopathological subtypes included an increased risk of squamous cell carcinoma in construction trades (OR = 1.25, 95% CI, 1.06-1.48), adenocarcinoma for professional workers in medicine and health (OR = 1.73, 95% CI, 1.18-2.53), small cell carcinoma in railway (OR = 1.62, 95% CI, 1.06-2.49), and truck transport industries (OR = 1.51, 95% CI, 1.00-2.28), and large cell carcinoma for employment in the primary metal industry (OR = 2.35, 95% CI, 1.11-4.96)., Conclusions: Our results point to excess lung cancer risk for occupations involving exposure to metals, polyaromatic hydrocarbons and asbestos, as well as several new histopathologic-specific associations that merit further investigation.

Objectives: The purpose of our study was to assess the risk of cardiovascular disease (CVD) mortality in a Canadian cohort of 337 397 individuals (169 256 men and 168 141 women) occupationally exposed to ionizing radiation and included in the National Dose Registry (NDR) of Canada., Material and Methods: Exposure to high doses of ionizing radiation, such as those received during radiotherapy, leads to increased risk of cardiovascular diseases. The emerging evidence of excess risk of CVDs after exposure to doses well below those previously considered as safe warrants epidemiological studies of populations exposed to low levels of ionizing radiation. In the present study, the cohort consisted of employees at nuclear power stations (nuclear workers) as well as medical, dental and industrial workers. The mean whole body radiation dose was 8.6 mSv for men and 1.2 mSv for women., Results: During the study period (1951-1995), as many as 3 533 deaths from cardiovascular diseases have been identified (3 018 among men and 515 among women). In the cohort, CVD mortality was significantly lower than in the general population of Canada. The cohort showed a significant dose response both among men and women. Risk estimates of CVD mortality in the NDR cohort, when expressed as excess relative risk per unit dose, were higher than those in most other occupational cohorts and higher than in the studies of Japanese atomic bomb survivors., Conclusions: The study has demonstrated a strong positive association between radiation dose and the risk of CVD mortality. Caution needs to be exercised when interpreting these results, due to the potential bias introduced by dosimetry uncertainties, the possible record linkage errors, and especially by the lack of adjustment for non-radiation risk factors.

Objective: We collected information on lifetime occupational histories, smoking, and alcohol consumption from 15,463 incident cancer cases. Occupational risk factors for bladder cancer are presented in this report., Method: A matched case-control design was used. All cases were diagnosed with bladder cancers, with controls being internal controls consisting of all other cancer sites, excluding lung and unknown primary. Data were analyzed using conditional logistic regression for matched sets data and the likelihood ratio test., Results: Excess bladder cancer risks was observed in a number of occupation and industries, particularly those involving exposure to metals, including aluminum, paint and solvents, polycyclic aromatic hydrocarbons, diesel engine emissions, and textiles., Conclusions: The results of our study are in line with those from the literature and further suggest that exposure to silica and to electromagnetic fields may carry an increased risk of bladder cancer.

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories as well as information on lifetime cigarette smoking and alcohol consumption from 15,643 incident cancer cases, of whom 782 had a diagnosis of non-Hodgkin's lymphoma (NHL). Occupational risks for this cancer site are examined using a matched case-control study design, and the results are presented in this report for all cases and for histopathology subtypes. The results of our study indicate excess NHL risk, particularly for a number of occupations that involve exposures to electromagnetic fields, treated and fresh wood, metals, and solvents.

Objectives: A study was conducted to investigate cancer risks in a cohort of pulp and paper workers., Methods: All male workers with > or =1 years of employment in 14 pulp and paper mills in 1950-1992 were studied. Standardized incidence ratios (SIR) were used to compare the cancer incidence of the cohort with that of the Canadian male population. Record linkage with the National Cancer Registry was performed using the generalized iterative record linkage method., Results: Altogether 1756 cancer cases were observed in the entire cohort. For > or =15 years of work, the entire cohort had significantly increased SIR values for pleural and prostate cancer and skin melanoma; there was also a significantly increased risk for skin melanoma among workers in the kraft process only, rectal cancer among workers in the sulfite process only, and stomach and prostate cancer and all leukemias combined among workers in both the kraft and sulfite processes. A separate analysis comparing workers in pulping and papermaking with those in the pulping process only did not reveal any difference in cancer risk and hence did not modify the results. The SIR values for skin melanoma were not significantly increased in a comparison using the British Columbia male population. Nine of 10 pleural cancers were mesotheliomas, which likely reflect past asbestos exposure., Conclusions: The results suggest that long-term work in the pulp and paper industry is associated with excess risks of prostate and stomach cancers and all leukemias for work in both kraft and sulfite processes and of rectal cancer for work in the sulfite process only.

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories from 15,643 incident cancer cases, of whom 1519 had a diagnosis of prostate cancer. Occupational risks for this cancer site are examined using this large data set, and the results are presented in this report.

To identify occupational cancer risk factors, lifetime occupational, smoking, and alcohol-consumption histories were collected by means of a self-administered questionnaire from 15,463 male cancer patients aged 20 years and over as ascertained from the British Columbia population-based cancer registry; all cases were histologically confirmed. The study methodology, descriptive results, and cancer risks from cigarette smoking are reported. Assessment of questionnaire validation and reliability showed very high correlations between all variables analysed. Non-response bias, assessed among 221 non-responders and 432 matched controls, revealed no statistically significant differences for smoking status, education, or for 11 usual (longest-held job) occupational groups, except for managerial occupations and for four pooled groups that represented 6.7% of all occupations. Except for pancreatic cancer, a significant relationship was found for all cancer sites known to be strongly associated with cigarette smoking.

The authors studied a cohort of 30,157 male pulp and paper workers in British Columbia, Canada. Of these, 20,373 worked in kraft mills only, 5,249 in sulfite mills only, and 4,535 in both kraft and sulfite mills. All workers with at least 1 year of employment on January 1, 1950, or thereafter until December 31, 1992, were studied. Standardized mortality ratios (SMRs) were used to compare the mortality rates of the cohort with those of the Canadian male population. Ninety percent confidence intervals (CIs) for the SMRs were obtained. Cancer risks significantly associated with work duration and time from first employment of 15 years or more were observed: 1) total cohort: pleura (SMR = 3.61, 90% CI 1.42-7.58); kidney (SMR = 1.69, 90% CI 1.13-2.43); brain (SMR = 1.51, 90% CI 1.03-2.16); 2) workers in kraft mills only: kidney (SMR = 1.92, 90% CI 1.04-3.26); 3) workers in sulfite mills only: Hodgkin's disease (SMR = 4.79, 90% CI 1.29-12.37); 4) workers ever employed in both kraft and sulfite mills: esophagus (SMR = 1.91, 90% CI 1.00-3.33). These malignancies have been associated with the following known or suspected carcinogens to which pulp and paper workers may have been exposed: asbestos (pleura), biocides (kidney), formaldehyde (kidney, brain, Hodgkin's disease), hypochlorite (esophagus). A nested case-control study with detailed exposure assessment is under way to help determine whether excess risks for specific cancers reflect exposure among subsets of workers.

Despite the special working environment and exposures of airline pilots, data on risk of death and cancer incidence in this occupational group are limited. The authors investigated a cohort of 2,740 Air Canada pilots who contributed 62,449 person-years of observation. All male pilots employed for at least 1 year on and since January 1, 1950, were studied. The cutoff date for outcome information was December 31, 1992. Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) were used to compare mortality rates and cancer incidence rates of the cohort with the respective Canadian population rates. Ninety percent confidence intervals of the SMR and SIR were calculated. Statistically significant decreased mortality was observed for all causes (SMR = 0.63, 90% confidence interval (CI) 0.56-0.70), for all cancers (SMR = 0.61, 90% CI 0.48-0.76), and for all noncancer diseases (SMR = 0.53, 90% CI 0.45-0.62). Mortality from aircraft accidents was significantly raised (SMR = 26.57, 90% CI 19.3-35.9). Significantly decreased cancer incidence was observed for all cancers (SIR = 0.71, 90% CI 0.61-0.82), rectal cancer (SIR = 0.42, 90% CI 0.14-0.96), lung cancer (SIR = 0.28, 90% CI 0.16-0.46), and bladder cancer (SIR = 0.36, 90% CI 0.12-0.82). Prostate cancer (SIR = 1.87, 90% CI 1.38-2.49) and acute myeloid leukemia (SIR = 4.72, 90% CI 2.05-9.31) were significantly increased. The preferred relative risk model for radiation-induced nonchronic lymphoid leukemia (Beir V report) was applied to the cohort by using published estimates of in-flight radiation exposures. The estimated relative risk ranged from 1.001 to 1.06 and did not differ significantly from the observed SIR (SIR = 1.88, 90% CI 0.80-3.53). However, the incidence rate of acute myeloid leukemia was significantly increased. Monitoring of in-flight radiation exposure and long-term follow-up of civil aviation crew members is needed to further assess cancer incidence and leukemia risk in this special occupational group.

The mortality profile of female nurses and teachers in British Columbia (BC) was examined using age-standardized proportional mortality ratios (PMRs) calculated for the period 1950-1984. Lowered overall mortality among nurses was seen for degenerative heart disease and for cerebrovascular accidents. Significantly elevated PMR values were observed for cancer of the breast and ovary in nurses of age 20-65 years. PMRs were significantly elevated for cancer of the pancreas and leukemia among those age 20 years and older. Elevated values were also observed for motor vehicle accidents and suicide among nurses in both age groups. Lower than expected mortality from degenerative heart disease and cerebrovascular accidents was seen in working age teachers (age 20-65 years). However, elevated PMRs were detected for carcinoma of the colon, breast, endometrium, brain, and melanoma. Among those 20 years and over, significantly elevated PMRs were also observed for cancers of the ovary and other digestive organs. Elevated PMRs were found for motor vehicle and aircraft accidents. Mortality from cirrhosis of the liver was lower than anticipated in both teachers and nurses. A number of significant PMRs declined when deaths of "homemakers" were withdrawn from the comparison group used to generate PMR values, suggesting that risk of death from various causes among women working outside the home differ from those seen in women who are predominantly in the home.

An historical cohort study was conducted among 4,213 men who worked for 5 or more years at a Soderberg aluminum reduction plant in British Columbia (BC), Canada. Standardized mortality and incidence ratios were used to compare the mortality and cancer incidence of the cohort with that of the BC population and to examine risk by cumulative exposure to coal-tar pitch volatiles (CTPV) and electromagnetic fields. Significantly elevated rates were observed for bladder cancer incidence (standardized incidence ratio [SIR] = 1.69) and brain cancer mortality (standardized mortality ratio = 2.17). The risk of bladder cancer was strongly related to cumulative exposure to CTPV (P less than .01). The risk for non-Hodgkin's lymphoma also increased with increasing exposure (P less than .05), although the overall rate was similar to that of the general population (SIR = 1.06). The lung cancer rate was as expected (SIR = 0.97), but showed a weak association with CTPV exposure that was not statistically significant. No individual cause of death or incident cancer site was related to exposure to electromagnetic fields. Analysis of the joint effect of smoking and CTPV exposure on lung and bladder cancer showed the exposure response relationships to be independent of smoking.

We studied the mortality experience of all pilots who died in the province of British Columbia between 1950 and 1984, using proportional mortality ratios (PMR) and proportional cancer mortality ratios (PCMR). There were 341 deaths during that time in males whose usual occupation was listed as pilot. The PMR for aircraft accidents was significantly elevated (PMR = 3196, 95% C.I. 2810, 3634), and the PMR for atherosclerotic heart disease was significantly depressed (PMR = 47, 95% C.I. 30, 70). Although based on small numbers of deaths, and not statistically significant, elevated PCMRs were seen for cancers of the colon, brain, and nervous system, as well as for Hodgkin's disease. These findings suggest the need for further epidemiologic studies of commercial airline pilots.

A 10-digit hierarchical method for coding occupationally encountered chemicals offering significant advantages over existing chemical coding systems has been developed and tested. With this unique system, substances are categorized and coded according to their composition and physical natures. Consequently, compounds of similar structure may be distinguished, and classes of similar compounds (for example, all halogenated organic compounds, all inorganic sulfates) can be readily retrieved. This novel coding system was developed to assist primarily in the identification of potential carcinogens in occupational studies using job exposure matrices. However, the system has wider applications as it can be employed by industry to facilitate data management and monitoring programs in the workplace.

In a study of 6,389 male cancer patients diagnosed and treated at the Cancer Control Agency of British Columbia from 1950-1975, several associations were detected between occupation and specific cancers. Elevated risks for lung cancer were seen in miners, metal processors and machinists, while a reduced risk was seen in farmers. Lip cancer excesses were detected in individuals involved in several outdoor occupations, and melanoma excesses were seen for three groups of predominantly indoor workers. These results confirm previous findings in the literature, whereas the following associations have not been previously reported. Fishermen were found to have an excess of Hodgkin's Disease (RR = 3.0, 95% C.I. = 1.4,6.5), engineers are at an elevated risk of cancer of the pancreas (RR = 4.2, C.I. = 1.8,9.9), and forestry workers have an elevated risk of bladder cancer (RR = 1.7, C.I. = 1.1,2.6). Further studies will be needed to replicate the new associations detected here.

The study of Xuan Wei fuel use and lung cancer mortality and also the interim case-control study suggested an association between domestic smoky coal use and Xuan Wei lung cancer. The collaborative studies of physical characterization, chemical analysis, and toxicology further substantiated this linkage. The Xuan Wei residents who used smoky coal inhaled extremely high concentrations of mostly submicron-sized particles, which can be inhaled and deposited effectively deep in the lung. These fine particles were composed mostly of organic compounds (72%), including mutagenic and carcinogenic organic compounds, especially in the aromatic and polar fractions. These residents were exposed to polycyclic aromatic compounds, such as benzo[a]pyrene, at comparable or higher levels than those measured in coke oven plants and other occupational environments (International Agency for Research on Cancer 1984). In comparison with wood and smokeless coal combustion emissions, the organic extracts of smoky coal emission particles showed much higher activity of genotoxicity and carcinogenicity. These results all point to a strong etiological link between the complex organic mixtures from smoky coal emissions and Xuan Wei lung cancer. This study and studies reported by other investigators (de Koning et al. 1984) suggested little association between indoor open-fire wood smoke and lung cancer. The less efficient lung deposition of the larger particles from wood combustion, as well as the lower concentrations of biologically active organic compounds, may contribute to the low rate of lung cancer in the wood-burning communes. As to the smokeless coal emissions, the lower particulate concentration and the lower organic content of the particles emitted may also contribute to the low lung cancer rate in the commune using this fuel. In conclusion, the complex organic mixtures from combustion emissions are genotoxic and carcinogenic in animal and in vitro assays. The magnitude of the cancer risks from the complex organic mixtures in man depends on the degree of the exposure, the types of the compounds contained in the mixtures, and the concentrations of these biologically active compounds present in the combustion emissions.

To evaluate occupational cancer mortality in British Columbia, we calculated the age-standardized proportional mortality ratios (PMR) and proportional cancer mortality ratios (PCMR) for 4,091 woodworkers, 5,457 loggers, 2,020 fishermen, 4,066 farmers, and 1,912 miners. Woodworkers 20-65 years old had significantly elevated risks of death from stomach cancer (PCMR = 128, P less than .01) and non-Hodgkin's lymphoma (PCMR = 140, P less than .05). Loggers appear to have an elevated risk of death from nasal sinus tumors (PCMR = 364, P less than .05). Fishermen had an elevated risk of stomach cancer (PCMR = 168, P less than .01). Farmers in British Columbia appeared to have excess risks of stomach (PCMR = 136, P less than .01) and liver cancer (PCMR = 173, P less than .05), but decreased risk from lung cancer (PCMR = 76, P less than .01). Miners had an elevated risk of death from lung cancer (PCMR = 127, P less than .05) and primary eye tumors (PCMR = 569, P less than .05).

Marked atypia (MA) is considered to represent a late stage in the sequence of cellular changes leading to carcinoma. In 1974 we undertook a sputum cytology (SC) survey of uranium workers (UW) and controls (Cancer 1980; 45:1273). Sixteen cases of MA (four with cells suspicious of malignancy) were diagnosed among the initial cohort of 292 male smokers; 11/172 (6.4%) underground UW; 4/78 (5%) surface UW; and 1/42 (2.4%) male controls. Follow up consisted of at least three yearly SC; in addition, selective segmental fiberoptic bronchoscopy was performed yearly for the first 3 years of observation. Three of the four-cases with marked atypia and suspicious malignant cells developed lung cancer. The remaining cases were followed for an average duration of 54 months; all 13 reverted to mild atypia or to normal cytologies. The high frequency of reversibility of MA will cause difficulties in interpreting results of chemoprevention trials if MA is used as the sole marker of effect. Chemoprevention trials should focus on differences in cancer incidence rates between treated and control groups at high risk of developing lung cancer and not on the reversibility of MA as the sole marker of effect.

In a study of occupational mortality among all females dying at age 20 years or over in British Columbia during the period 1950 through 1978, significantly elevated proportional mortality ratios (PMRs) were seen for breast and/or ovarian cancer among teachers, nurses, office clerks, and sales clerks. Approximately 91% of the female deaths were recorded as occurring among "homemakers." When the PMRs were recalculated for "working women" only (ie., excluding homemakers), most of the excesses in risks for breast and ovarian cancer observed among the four occupational groups disappeared. The authors suggest that the differences in PMR values between all women and working women are due to protective higher parity and lower maternal age at first birth among homemakers as opposed to working women in general. In occupational studies of hormone-related tumors among women, every effort should be made to control for parity level and maternal age at first birth.

In order to evaluate occupational mortality, age standardized proportional mortality ratios (PMR) were calculated for 160 female cosmetologists and hairdressers and 1,001 male barbers and hairdressers utilizing cause of death and occupation statements from British Columbia death registrations collected from 1950 to 1978. Female cosmetologists had elevated risks of death from multiple myeloma (PMR = 619, p = .03) and ovarian cancer (PMR = 204, p = .09). Male barbers and hairdressers had no corresponding elevated risk of myeloma but had a significantly high risk of death from leukemia (PMR = 188, p = .05). Further detailed studies of these occupations would be worthwhile to confirm and extend these findings.

Occupational mortality from cutaneous malignant melanoma was evaluated for deaths occurring in British Columbia from 1950-1978 by using age standardised proportional mortality ratios (PMR). For males, significantly elevated PMRs for melanoma were seen in managers and owners, accountants, architects, chemical engineers, and gardeners and nursery workers. Female school teachers were also at elevated risk of death from cutaneous melanoma.