Mortality from brain cancer and leukaemia among electrical workers

The relation of brain cancer and mortality from leukaemia to electrical occupations was investigated in a case-control study based on all deaths in 1985 and 1986 in the 16 states in the United States that report occupational data from death certificates to the national vital statistics registry. The case series comprised all 2173 men who died of primary brain cancer (International Classification of Diseases-9 ((ICD-9) code 191) and all 3400 who died of leukaemia (ICD-9 codes 204-208). Each was matched with 10 controls who died of other causes in the same year. Men employed in any electrical occupation had age race adjusted odds ratios (ORs) of 1.4 (95% confidence interval (CI) 1.1-1.7) for brain cancer and 1.0 (95% CI 0.8-1.2) for leukaemia, compared with men in all other occupations. Brain cancer odds ratios were larger for electrical engineers and technicians (OR 2.7, 95% CI 2.1-3.4), telephone workers (OR 1.6, 95% CI 1.1-2.4), electric power workers (OR 1.7, 95% CI 1.1-2.7), and electrical workers in manufacturing industries (OR 2.1, 95% CI 1.3-3.4). There was some evidence of excess leukaemia among the same groups (ORs of 1.1-1.5) despite absence of an association for all electrical workers. The excess of deaths from brain cancer was concentrated among men aged 65 or older, whereas leukaemia was associated with electrical work only among younger decedents and those with acute lymphocytic leukaemia. These results from a large and geographically diverse population corroborate reports of increased mortality from brain cancer among electrical workers, but gives only limited support to suggestions of excess deaths from leukaemia.     

Occupation and leukemia mortality among men in 16 states: 1985-1987

The relationship between leukemia and occupation was investigated in a case-control study using death certificates of 5,147 men who died of leukemia (ICD-9 codes 204-208) and 51,470 who died of other causes in 16 U.S. states from 1985 to 1987. Of six occupational activities identified previously as potentially increasing the risk of leukemia, only petroleum refining and rubber manufacturing had excess deaths for all leukemias combined (odds ratios (ORs) = 1.3, 95% confidence intervals (CI) = 0.6-2.8 and 0.9-1.8, respectively). Meat workers and wood workers had elevated mortality from acute lymphocytic leukemia (OR = 2.2, 95% CI = 0.7-7.0 and OR = 1.3, 95% CI = 0.8-2.2, respectively). There was no leukemia excess among farmers or auto mechanics. A survey of 43 other occupational groups indicated a widespread excess of leukemia among white collar occupations, primarily managers and professionals, but none among blue collar workers. This pattern was most pronounced for men under 65 years of age, and existed for all leukemia subtypes and among both blacks and whites. Despite the lack of specific exposure information and other limitations of death certificate data, these results encourage further examination of occupational causes of leukemia.     

Occupation and the risk of laryngeal cancer in Turkey

OBJECTIVES: A hospital-based case-referent study was conducted in Turkey to provide further information on occupational risk factors and laryngeal cancer. METHODS: Among 7631 cancer cases seen at an oncology treatment center between 1979 and 1984, 958 laryngeal cancer cases were identified among men. Occupational history, tobacco and alcohol use, and demographic data were obtained from patients with a standardized questionnaire. Special 7-digit standard occupational and industrial codes were created to classify the job and industrial titles of the subjects. After exclusions, 940 laryngeal cancer cases and 1519 referents were available for study. Age-, smoking- and alcohol-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated. RESULTS: Excess laryngeal cancer occurred among guards (OR 1.5, 95% CI 1.1-2.1), production supervisors (OR 1.8, 95% CI 1.1-3.1), textile workers (OR 1.9, 95% CI 1.2-3.3), drivers (OR 1.7, 95% CI 1.1-2.4), construction workers (OR 1.7, 95% Cl 1.2-2.6), and workers in grain mills (OR 3.1, 95% CI: 1.3-7.6), trade unions (OR 3.6, 95% CI: 1.1-11.7) and local government services (OR 4.7, 95% CI 1.7-12.5). Supraglottic cancer was excessive among the textile workers, construction workers, and local government laborers, all with potential dust exposure. The risks of the general managers, electricians, and workers from industries such as pharmaceutical production, industrial machinery production, electric utilities, and retail services were lower than expected. CONCLUSIONS: The risk of laryngeal cancer was associated with several occupations, and supraglottic larynx cancer appears to be more common among workers in dusty occupations and industries.     

Incidence of leukaemia and brain tumours in some "electrical occupations"

A 19 year follow up study was conducted to explore the association between occupations expected to be exposed to electromagnetic fields and the occurrence of leukaemia and brain tumours. Incidence of cancer between 1961-79 was calculated and the standardised morbidity ratio (SMR) with a 95% confidence interval (95% CI) was related to that of all Swedish working men. For all the selected "electrical occupations" the SMRs for total leukaemia and brain tumours were near unity. Increased risks were noted for all leukaemia among electrical/electronic engineers and technicians, (SMR 1.3; 95% CI 1.0-1.7) as well as in the sub-groups of telegraph/telephone (2.1; 1.1-3.6) and machine (2.6; 1.0-5.8) industries. Risk for chronic lymphoid leukaemia was increased in the same occupational category (1.7; 1.1-2.5) and in the sub-group of machine industry (4.8; 1.0-14.0), as well as for all linesmen (2.0; 1.0-3.5) and power linesmen (2.8; 1.1-5.7). Risk for acute myeloid leukaemia was increased among all miners (2.2; 1.0-4.1) and miners working in iron/ore mines (5.7; 2.1-12.4). Increased risk for all brain tumours (2.9; 1.2-5.9) and glioblastomas (3.4; 1.1-8.0) appeared among assemblers and repairmen in radio and TV industry. Raised risk for all brain tumours was seen for all welders (1.3; 1.0-1.7) and welders in iron/steel works (3.2; 1.0-7.4) and risk for glioblastomas was also increased for all welders (1.5; 1.1-2.1). No major changes in relative risk estimates were noted after the exclusion of persons who were over 65 at the time of diagnosis. Although a homogeneous pattern of increased risks of leukaemia or brain tumour was not noted, the hypothesis that magnetic fields might play a part in the origin of cancer cannot be rejected.     

Incidence of leukaemia and brain tumours in some "electrical occupations".

A 19 year follow up study was conducted to explore the association between occupations expected to be exposed to electromagnetic fields and the occurrence of leukaemia and brain tumours. Incidence of cancer between 1961-79 was calculated and the standardised morbidity ratio (SMR) with a 95% confidence interval (95% CI) was related to that of all Swedish working men. For all the selected "electrical occupations" the SMRs for total leukaemia and brain tumours were near unity. Increased risks were noted for all leukaemia among electrical/electronic engineers and technicians, (SMR 1.3; 95% CI 1.0-1.7) as well as in the sub-groups of telegraph/telephone (2.1; 1.1-3.6) and machine (2.6; 1.0-5.8) industries. Risk for chronic lymphoid leukaemia was increased in the same occupational category (1.7; 1.1-2.5) and in the sub-group of machine industry (4.8; 1.0-14.0), as well as for all linesmen (2.0; 1.0-3.5) and power linesmen (2.8; 1.1-5.7). Risk for acute myeloid leukaemia was increased among all miners (2.2; 1.0-4.1) and miners working in iron/ore mines (5.7; 2.1-12.4). Increased risk for all brain tumours (2.9; 1.2-5.9) and glioblastomas (3.4; 1.1-8.0) appeared among assemblers and repairmen in radio and TV industry. Raised risk for all brain tumours was seen for all welders (1.3; 1.0-1.7) and welders in iron/steel works (3.2; 1.0-7.4) and risk for glioblastomas was also increased for all welders (1.5; 1.1-2.1). No major changes in relative risk estimates were noted after the exclusion of persons who were over 65 at the time of diagnosis. Although a homogeneous pattern of increased risks of leukaemia or brain tumour was not noted, the hypothesis that magnetic fields might play a part in the origin of cancer cannot be rejected.     

Occupation and breast cancer risk among Shanghai women in a population-based cohort study

INTRODUCTION: A total of 74,942 female subjects were recruited in a population-based cohort study in Shanghai, China between 1997 and 2000. We examined the relationship between occupation and breast cancer risk. METHODS: Cases were 586 women previously diagnosed with breast cancer at baseline and 438 women newly diagnosed with breast cancer during follow-up through December 2004. Eight controls were randomly selected for each case from cancer-free cohort members and frequency-matched to the cases by year of birth and age at diagnosis. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer risk associated with occupations, adjusting for established breast cancer risk factors. RESULTS: In the prevalent breast cancer data analysis, increased risks of breast cancer were associated with technicians in engineering/agriculture/forestry (OR = 1.6, CI: 1.0-2.4), teaching personnel (OR = 1.5, CI:1.1-2.0), tailoring/sewing workers (OR = 1.6, CI:1.0-2.7), and examiners/measurers/testers (OR = 1.5, CI:1.1-2.1) among those who started the jobs at least 20 years ago. Among incident breast cancer cases, significantly increased risks were associated with medical/health care workers (OR = 1.4, CI:1.0-2.0), administrative clerical workers (OR = 1.5, CI:1.0-2.4), postal/telecommunication workers (OR = 2.2, CI:1.0-5.5), and odd-job workers (OR = 1.7, CI:1.1-2.8) among those who started the jobs at least 20 years ago. The excess risks were found in both prevalent and incident cases for postal/telecommunication workers and purchasing/marketing personnel, although ORs reached only marginal significance. CONCLUSIONS: This study suggests that white-collar professionals and several production occupations may be associated with an increased risk of breast cancer.     

Occupational risks for lung cancer among nonsmokers

We conducted a case-control study in 12 European study centers to evaluate the role of occupational risk factors among nonsmokers. We obtained detailed occupational histories from 650 nonsmoking cases (509 females/141 males) and 1,542 nonsmoking controls (1,011 females/531 males). On the basis of an a priori definition of occupations and industries that are known (list A) or suspected (list B) to be associated with lung carcinogenesis, we calculated odds ratios (ORs) for these occupations, using unconditional logistic regression models and adjusting for sex, age, and center effects. Among nonsmoking men, an excess relative risk was observed among those who had worked in list-A occupations [OR = 1.52; 95% confidence interval (C) = 0.78-2.97] but not in list-B occupations (OR = 1.05; 95%), CI = 0.60-1.83). Among nonsmoking women, there was an elevation of risk for list-A occupations (OR = 1.50; 95% CI = 0.49-4.53), although this estimate was imprecise, given that less than 1% of cases and controls were exposed. Exposure to list-B occupations was associated with an increase in relative risk (OR = 1.69; 95% CI = 1.09-2.63) in females, but not in males. Women who had been laundry workers or dry cleaners had an OR of 1.83 (95% CI = 0.98-3.40). Our findings confirm that certain occupational exposures are associated with an increased risk for lung cancer among both female and male nonsmokers; however, knowledge on occupational lung carcinogens is biased toward agents to which mainly men are exposed.     

Mortality at an automotive engine foundry and machining complex

Mortality was analyzed for an automotive engine foundry and machining complex, with process exposures derived from department assignments. Logistic regression models of mortality odds ratios (ORs) were calculated for 2546 deaths, and numbers of work-related deaths were estimated. Lung cancer mortality in the foundry was increased where cleaning and finishing of castings was performed (OR, 1.7; 95% CI, 1.15 to 2.4 [at mean exposure duration of exposed cases]) and in care-making after 1967 (OR, 1.5; 95% CI, 1.11 to 2.0). Black workers had excess lung cancer mortality in machining heat-treat operations (OR, 2.5, 95% CI, 1.4 to 4.3) and excess nonmalignant respiratory disease mortality in molding (OR, 2.5; 95% CI, 1.16 to 5.5) and core-making (OR, 2.7; 95% CI, 1.25 to 5.8). Stomach cancer mortality was elevated among workers with metalworking fluid exposures in precision grinding (OR, 2.4; 95% CI, 1.14 to 5.1). Heart disease mortality was increased among all workers in molding (OR, 1.6; 95% CI, 1.09 to 2.3), as was stroke mortality among workers exposed to metalworking fluids (OR, 1.8; 95% CI, 1.22 to 2.7). Malignant and nonmalignant liver disease mortality was elevated in assembly/testing and precision grinding. In this modern foundry, 11% of deaths were estimated to be work-related despite it's being largely in regulatory compliance over its 40-year existence. Machining plant exposures accounted for 3% or more of deaths there.     

Occupational risk of colon cancer. An analysis by anatomic subsite

A case-control study was conducted to investigate occupational risks for colon cancer. The Missouri Cancer Registry was used to identify a total of 1,993 white male cases and 9,965 age-matched cancer controls diagnosed between 1984 and 1987. Effect estimates were calculated for specific occupations and industries and for three levels of occupational physical activity. Odds ratios (ORs) and 95% confidence intervals (Cls) were also calculated according to anatomic subsite of colon cancer. Elevated risks were identified for workers in several occupations and industries including printing machine operators (OR = 1.9, 95% Cl 1.0-3.3), workers in food manufacturing (OR = 1.6, 95% Cl 1.2-2.2), communications workers (OR = 1.8, 95% Cl 1.0-3.3), and workers employed in the petroleum product trade (OR = 2.7, 95% Cl 1.0-7.2). Previous findings of excess risk among selected occupations of higher socioeconomic status were confirmed. Analyses by anatomic subsite showed that excess risk for an occupational group was usually confined to a single subsite, which suggests some specificity of effect. For example, elevated risk among males employed in manufacturing-related industries was shown primarily for cancer of the cecum. The findings by level of occupational physical activity corroborated recent reports of increased colon cancer risk associated with employment in sedentary occupations. Excess risk (OR = 1.4, 95% Cl 1.0-1.9) was shown among males employed in sedentary jobs and an inverse linear trend in risk was shown according to level of occupational physical activity. Risk associated with sedentary occupations was highest for cancer of the cecum (OR = 2.1, 95% Cl 1.1-4.0). Despite the limitations of the cancer registry-collected data, some associations were observed that deserve further study.     

Mortality among firefighters from three northwestern United States cities.

To explore whether exposure among firefighters to fire smoke could lead to an increased risk of cancer, lung disease, and heart disease, the mortality of 4546 firefighters who were employed by the cities of Seattle and Tacoma, WA and Portland, OR for at least one year between 1944 and 1979 were compared with United States national mortalities and with mortality of police officers from the same cities. Between 1945 and 1989, 1169 deaths occurred in the study population and 1162 death certificates (99%) were collected. Mortality due to all causes, ischaemic heart disease, and most other non-malignant diseases was less than expected based upon United States rates for white men. There was no excess risk of overall mortality from cancer but excesses of brain tumours (standardised mortality ratio (SMR) = 2.09, 95% confidence interval (95% CI) 1.3-3.2) and lymphatic and haematopoietic cancers (SMR = 1.31, 95% CI = 0.9-1.8) were found. Younger firefighters (< 40 years of age) appeared to have an excess risk of cancer (SMR = 1.45, 95% CI 0.8-2.39), primarily due to brain cancer (SMR = 3.75, 95% CI 1.2-8.7). The risk of lymphatic and haematopoietic cancers was greatest for men with at least 30 years of exposed employment (SMR = 2.05, 95% CI 1.1-3.6), especially for leukaemia (SMR = 2.60, 95% CI 1.0-5.4).     

Laryngeal and hypopharyngeal cancer and occupation: results of a case control-study.

OBJECTIONS: To ascertain whether certain occupations are associated with laryngeal or hypopharyngeal cancer. METHODS: A hospital based case-control study was carried out in 15 hospitals in France. It included 528 male cases diagnosed between January 1989 and April 1991, and 305 male controls with various other types of cancer. Interviews were carried out to obtain lifetime job histories and information on potential confounders. Logistic regression was used to compute the odds ratios (OR) for each of about 80 occupations and industries. RESULTS: There was an excess risk of laryngeal and hypopharyngeal cancer among service workers (OR 2.2, 95% confidence interval (95% CI) 1.3 to 3.9), agricultural and animal husbandry workers (OR 1.6, 95% CI 0.9 to 2.8), miners and quarrymen (OR 2.0, 95% CI 0.9 to 4.3), plumbers and pipe fitters (OR 2.6, 95% CI 0.8 to 8.1), glass formers and potters (OR 4.3, 95% CI 1.0 to 18) transport equipment operators (OR 1.5, 95% CI 1.0 to 2.5), and unskilled workers (OR 1.7, 95% CI 1.0 to 2.9). Analysis by industrial branch showed an excess risk for coal mining (OR 2.1, 95% CI 1.1 to 4.1), manufacture of metal products (OR 1.9, 95% CI 1.0 to 3.3), and administration and sanitary services (OR 1.7, 95% CI 1.1 to 2.5). CONCLUSION: These results suggest that occupational exposure might have a role in generating laryngeal and hypopharyngeal cancer, and indicate the need for further evaluation of these findings, an for the identification of the carcinogens which might account for the excess risks found for certain occupations.     

Mortality among firefighters from three northwestern United States cities.

To explore whether exposure among firefighters to fire smoke could lead to an increased risk of cancer, lung disease, and heart disease, the mortality of 4546 firefighters who were employed by the cities of Seattle and Tacoma, WA and Portland, OR for at least one year between 1944 and 1979 were compared with United States national mortalities and with mortality of police officers from the same cities. Between 1945 and 1989, 1169 deaths occurred in the study population and 1162 death certificates (99%) were collected. Mortality due to all causes, ischaemic heart disease, and most other non-malignant diseases was less than expected based upon United States rates for white men. There was no excess risk of overall mortality from cancer but excesses of brain tumours (standardised mortality ratio (SMR) = 2.09, 95% confidence interval (95% CI) 1.3-3.2) and lymphatic and haematopoietic cancers (SMR = 1.31, 95% CI = 0.9-1.8) were found. Younger firefighters (< 40 years of age) appeared to have an excess risk of cancer (SMR = 1.45, 95% CI 0.8-2.39), primarily due to brain cancer (SMR = 3.75, 95% CI 1.2-8.7). The risk of lymphatic and haematopoietic cancers was greatest for men with at least 30 years of exposed employment (SMR = 2.05, 95% CI 1.1-3.6), especially for leukaemia (SMR = 2.60, 95% CI 1.0-5.4).     

An analysis of occupational risks for brain cancer

We evaluated the risks of brain cancer in relation to employment history in a case-control study of 312 cases and 1,248 cancer controls. Subjects were identified through the Missouri Cancer Registry for the period 1984 through 1988. Job classification was based on data routinely abstracted from hospital records. Elevated risks were identified for certain white collar occupations: for men employed in engineering, the odds ratio (OR) = 2.1; 95% confidence interval (CI) = 0.4, 10.3; for social science professionals, the OR = 6.1; 95% CI = 1.5, 26.1. Among occupations with potential exposure to occupational carcinogens, increased risks were observed for men employed in agricultural crop production (OR = 1.5; 95% CI = 1.0, 2.4), printing and publishing (OR = 2.8; 95% CI = 1.0, 8.3), and brickmasons and tilesetters (OR = 2.5; 95% CI = 0.5, 11.5). Most of elevated brain cancer risks were due to astrocytic cancers, but the excess among agricultural workers occurred in other cell types. No increase in risk was noted for current cigarette smokers (OR = 0.9; 95% CI = 0.7, 1.5) or ex-smokers (OR = 1.0; 95% CI = 0.7, 1.5). This exploratory study indicates a need for further studies of occupational risks of brain cancer.     

Primary liver cancer death and occupation in Texas

A death certificate case-control study of primary liver cancer and occupation was conducted to determine if the high risk of liver cancer in Mexican-Americans can be explained by farmworker exposures to pesticides. The association of liver cancer with the petroleum and chemical industry and with other potentially high-risk occupations was also examined. For the years 1969 to 1980, 1,742 deaths from primary liver cancer were identified for Texas males. Controls were randomly selected from other causes of deaths among males excluding all neoplasms, liver and gallbladder diseases, infectious hepatitis, and alcoholism, and were frequency matched to cases by age, race, ethnicity, and year of death. Risk for farmworkers based on age, race, and ethnicity-adjusted odds ratios (ORs) was not excessive (OR = 1.4, 95% confidence limits [C.L.] 0.8-2.2) but was larger than the risk for farmers (OR = 1.0, 95% C.L. 0.8-1.2). Excess risk in the petroleum and chemical manufacturing industries was confined to oil refinery workers (OR = 2.0, 95% C.L. 1.1-3.5). Other occupations with twofold risk or greater were plumbers and pipefitters (OR = 2.0, 95% C.L. 1.0-3.8), butchers and meat cutters (OR = 2.6, 95% C.L. 1.1-6.6), textile workers (OR = 3.1, 95% C.L. 1.2-7.8), cooks (OR = 2.2, 95% C.L. 1.1-4.5), and longshoremen (OR = 2.2, 95% C.L. 0.6-7.4).     

Lung cancer in motor exhaust-related occupations

The association between employment in motor exhaust-related occupations and the risk for lung cancer was examined in 2,291 male cases of lung cancer and 2,570 controls in data pooled from three U.S. case control studies carried out by the National Cancer Institute between 1976 and 1983. Most analyses were limited to subjects providing direct, in-person interviews, including 1,444 cases and 1,893 controls. For those providing direct interviews and employed 10 years or more in motor exhaust-related (MER) occupations, the age, smoking, and study area adjusted odds ratio (OR) for lung cancer was 1.5 (95% CI = 1.2-1.9). Risk was elevated for truck drivers (OR = 1.5; 95% CI = 1.1-1.9) and for other MER occupations (OR = 1.4; 95% CI = 1.1-2.0). The odds ratios associated with MER employment of 10+ years were 1.6 (95% CI = 1.2-2.1) for whites and 1.4 (95% CI = 0.9-2.1) for nonwhites; 1.2 (95% CI = 0.7-2.0) [corrected] for those with possible exposure to other recognized or reported lung carcinogens; and 1.6 (95% CI 1.2-2.1) for those without such exposure. The 50% excess risk for lung cancer associated with employment in motor exhaust-related occupations could not be explained by greater use of cigarettes or by other occupational exposures among these workers.     

Lung cancer and occupation: results of a multicentre case-control study.

The objective of the current study was to estimate the risk of lung cancer attributable to occupational factors and not due to tobacco. At 24 hospitals in nine metropolitan areas in the United States, 1793 male lung cancer cases were matched for race, age, hospital, year of interview, and cigarette smoking (never smoker, ex-smoker, smoker (1-19 and > or = 20 cigarettes per day)) to two types of controls (cancer and non-cancer hospital patients). Information on usual occupation, exposure to specific potential carcinogens, and cigarette smoking was obtained by interview. Risk of lung cancer was increased significantly for electricians; sheetmetal workers and tinsmiths; bookbinders and related printing trade workers; cranemen, derrickmen, and hoistmen; moulders, heat treaters, annealers and other heated metal workers; and construction labourers. All of these occupations are potentially exposed to known carcinogens. Odds ratios (ORs) were increased for exposure to coal dust (adjusted OR = 1.5; 95% confidence interval (95% CI) 1.1-2.1). After stratification, this association was statistically significant only after 10 or more years of exposure. Lung cancer was also related to exposure to asbestos (adjusted OR = 1.8; 95% CI 1.5-2.2). The ORs increased with increasing duration of exposure to asbestos for all smoking categories except for current smokers of 1-19 cigarettes per day. The statistical power to detect ORs among occupations that were previously reported to be at increased risk of lung cancer but that failed to show an OR of at least 1.5 in the current study was small. The cumulative population attributable risk (PAR) of lung cancer due to occupation was 9.2%. It is concluded that occupational factors play an important part in the development of lung cancer independently of cigarette smoking. Because occupations at high risk of lung cancer were under-represented, the cumulative PAR of the present study is likely to be an underestimate of the true contribution of occupation to risk of lung cancer.     

Cancer mortality among Brazilian Navy personnel

OBJECTIVE: To identify differences in cancer proportionate mortality among male servicemen of the Brazilian Navy when compared to a referent population and to detect potential occupational risk factors. METHODS: Cancer proportionate mortality was estimated using death certificates and occupational histories of Brazilian navy servicemen aged 19 or more in the period of 1991 to 1995. The population of Rio de Janeiro (Brazil) was chosen as referent group because this city concentrates 70% of all Navy servicemen. RESULTS: Servicemen are more likely to die from brain neoplasm (age-adjusted cancer proportionate mortality ratio - ACPMR=339.27), prostate cancer (ACPMR=135.04), and non-Hodgkin lymphoma (ACPMR=152.28) than the referent population. Health-related occupations show an excess of brain neoplasm (ACPMR=2.7, 95% confidence interval, CI: 1.1-6.5) and liver cancer (ACPMR=2.9; 95% CI: 1.1-7.8); colon-rectal cancer was higher among officials of the Army Corp and other administrative occupations (ACPMR=2.4, 95% CI: 1.3-4.5); larynx cancer (ACPMR=2.3, 95% CI; 1.1-5.0) is more common among men working in maintenance and repair occupations. CONCLUSIONS: In this study, servicemen of the Brazilian Navy Force have a distinct cancer mortality profile from the general reference population. Risk factors for cancer need to be further evaluated, by using more specific diagnosis and occupational-related exposure data.     

Occupations and breast cancer risk among Chinese women in urban Shanghai

BACKGROUND: Although, an elevated risk of breast cancer has been suggested for a number of occupations, many earlier studies were limited by selection biases, the incomplete assessment of job histories, and the inability to control for confounding. METHODS: We examined the relationship between occupational history and breast cancer risk using data from a population-based case-control study of 1,458 cases and 1,556 age-matched controls (90% response rate) conducted in Shanghai, China. Unconditional logistic regression models were used to derive odds ratios (ORs) and 95% confidence intervals (95% CIs) of breast cancer risk associated with occupations and duration of employment adjusting for non-occupational risk factors. RESULTS: The following occupations were found to be associated with an increased risk of breast cancer: laboratory technicians (OR 9.94, 95% CI 1.20-82.37), telephone and telegraph operators (OR 4.63, 95% CI 1.85-11.59), leather and fur processors (OR 3.25, 95% CI 1.11-9.53), and glass-manufacturing workers (OR 2.08, 95% CI 1.14-3.82). A dose-response pattern for years of employment was observed for leather and fur processors (P = 0.02) and glass-manufacturing workers (P = 0.01). Stratified analyses also revealed dose-response relationships between the risk of breast cancer and years of employment as inspector and product analysts among pre-menopausal women (P = 0.02), and as farmers among post-menopausal women (P = 0.04). CONCLUSIONS: This study found that several occupations are associated with an increased risk of breast cancer among women. Studies examining various occupational exposures in these high-risk occupations are warranted to identify carcinogens that may play a role in the increased breast cancer risk.     

Occupational exposures and brain cancer mortality: a preliminary study of east Texas residents

The relationship between various occupational exposures and brain cancer was investigated in a case-control study using mortality data from 202 males who died in East Texas from gliomas in 1969-1978 and 238 male controls randomly selected from all deaths in East Texas in 1969-1978. Using the occupational classification scheme of the U.S. Bureau of the Census, the risk for brain cancer was significantly increased for male workers employed in the transportation, communication, and utilities industries [odds ratio (OR) = 2.26, confidence intervals (CI) = 1.18-4.32]. Further examination of this finding showed that male workers employed in occupations associated with electricity or electromagnetic (EM) fields had an elevated risk for brain cancer (OR = 3.94, CI = 1.52-10.20). In addition, there was a linear relationship between the probability of exposure to EM fields and brain cancer. Significantly elevated risk for brain cancer was also found among male workers in the trucking industry.     

Incidence of cancer in persons with occupational exposure to electromagnetic fields in Denmark.

Several studies suggest that work in electrical occupations is associated with an increased risk of cancer, mainly leukaemia and brain tumours. These studies may, however, not be representative if there is a publication bias where mainly positive results are reported. To study an unselected population the incidence of cancer was followed up over a 17 year period (1970-87) in a cohort of 2.8 million Danes aged 20-64 years in 1970. Each person was classified by his or her industry and occupation in 1970. Before tabulation of the data on incidence of cancer, each industry-occupation group was coded for potential exposure to magnetic fields above the threshold 0.3 microT. Some 154,000 men were considered intermittently exposed and 18,000 continuously exposed. The numbers for women were 79,000 and 4000 respectively. Intermittent exposure was not associated with an increased risk of leukaemia, brain tumours, or melanoma. Men with continuous exposure, however, had an excess risk of leukaemia (observed (obs) 39, expected (exp) 23.80, obs/exp 1.64, 95% CI 1.20-2.24) with equal contributions from acute and other leukaemias. These men had no excess risk of brain tumours or melanoma. A risk for breast cancer was suggested in exposed men but not in women. The risk for leukaemia in continuously exposed men was mainly in electricians in installation works and iron foundry workers. Besides electromagnetic fields other exposures should be considered as possible aetiological agents.