Parental occupational exposures and Ewing's sarcoma

A case-control study of Ewing's sarcoma (ES) was conducted to search for occupational exposures associated with ES. The study consisted of 196 cases and 196 random-digit controls matched on geographical region, gender, ethnic origin and birth date. A questionnaire was administered to mothers of participants to obtain information on medical conditions, medications, and parental occupations during and after the index pregnancy. An occupational exposure expert coded jobs and industries for possible and probable exposure to selected occupational hazards. Risk of ES was increased with probable parental exposure to wood dusts during their usual occupation post pregnancy (odds ration [OR] = 3.2; 95% confidence interval [CI] = 1.1-9.2). Other exposures, including a priori suspected risk factors such as exposure to pesticides and farm animals, were not significantly associated with ES. A history of household pesticide extermination was associated with ES among boys aged 15 or younger (OR = 3.0; 95% CI = 1.1-8.1), but not among girls or older boys. Our results suggest that earlier reports of associations of ES with parental farm employment may have been describing risks associated with organic dusts encountered when working on a farm, rather than agricultural exposures or other farming related exposures.     

Occupation and larynx and hypopharynx cancer: a job-exposure matrix approach in an international case-control study in France,Italy, Spain and Switzerland

Objective: To investigate the effect of exposure to occupational agents on the risk of hypopharyngeal/laryngeal cancer. Methods: Case-control study conducted during 1979–1982 in six centres in South Europe. An occupational history and information on exposure to non-occupational factors were collected for 1010 male cases of hypopharyngeal/laryngeal cancer as well as for 2176 population controls. The exposure to 10 occupational agents was assessed through a job-exposure matrix. As occupational histories had been collected since 1945 major analyses were restricted to subjects aged less than 55 years (315 cases and 819 controls). Results: Significant elevated risks adjusted for non-occupational variables (smoking, alcohol consumption and diet) and other occupational exposures were consistently found for organic solvents (odds ratio (OR) for ever-exposure: 1.7, 95% confidence interval: 1.1–2.5) and asbestos (OR: 1.6, 1.0–2.5). A significant positive trend for both probability of exposure and duration was found for exposure to solvents. A positive association between exposure to formaldehyde and laryngeal cancer was also suggested. No association was found for exposure to arsenic and compounds, chromium and compounds, and polycyclic aromatic hydrocarbons. Analyses restricted to subjects aged 55 or more did not show elevated risks, with the exception of wood dust (OR: 1.8, 1.3-2.7). Conclusions: In our study occupational exposure to solvents was associated with an increased risk of hypopharyngeal/laryngeal cancer. Results also provide additional evidence of an excess of risk for exposure to asbestos.     

Cancer incidence among Finnish seafarers, 1967–92

A cohort of 30,940 male and 11,529 female seafarers registered in the files of Seafarers' Pension Fund in Finland was followed up through the Finnish Cancer Registry for cancer in 1967–92. Among male seafarers, there were 1,199 cases of cancer, which corresponds to the average cancer incidence in Finnish men. There was a statistically significant excess of non-melanoma skin cancer (standardized incidence ratio [SIR]=1.8, 95 percent confidence interval [CI]=1.2–2.5) and mesothelioma (SIR=2.9, CI=1.2–5.6) in the follow-up category of 20 or more years since the first employment. Alcohol-related cancers were increased among seafarers (SIR for cancer of the mouth and pharynx = 1.; esophagus = 1.4; and liver = 1.5; combined CI=1.1–1.9). Deck crews had a significantly high risk of cancer of the pancreas (SIR=2.0) and also prostate after 10 years since first employment (SIR=1.6). Occupational asbestos exposure among seafarers is likely strong enough to cause excess cases of mesothelioma but not of lung cancer. Occupational exposures also may be associated with increased risk of cancers of the kidney, pancreas, prostate and old-age brain cancer in some of the main occupational categories. Cumulative ultraviolet radiation likely doubles the risk of nonmelanoma skin cancer among older men and repeated sunburns that of skin melanoma in ages below 30 (SIR among deck and engine crew = 4.6, CI=3.1–6.5). Female ship personnel had a significantly elevated total cancer risk (observed number of cases = 732) which increased over follow-up time (SIR in the category 20 years since the first employment was 1.3, CI=1.1–1.5). This excess was attributable primarily to lung cancer (SIR=2.6, CI=2.0–3.3). Also cancers of the cervix uteri, vulva, and vagina showed significant excess after 10 to 20 years since first employment aboard.Address correspondence to Dr Pukkala, Finnish Cancer Registry, Litsankatu 21 B, FIN-00170 Helsinki, Finland. The Finnish Work Environment Fund financially supported this project.Dr Pukkala is with the Finnish Cancer Registry, Helsinki, Finland. Dr Saarni is with the Regional Institute of Occupational Health, Turku, Finland.     

Case-control study of bladder cancer in New Jersey. I. Occupational exposures in white males

The occupational bladder cancer risk for New Jersey white males was estimated with the use of both industry-job title-based and exposure-based analyses of data from 658 incident cases and 1,258 general population controls. The overall bladder cancer risk attributable to occupational exposures was estimated as 20-22%. A wide variety of employment categories and exposures contributed to this risk. Odds ratios were significantly high for employment as garage and gas station workers and food counter workers and/or cooks and for exposure to leather, rubber, paint, printing ink, and other organic compounds. Odds ratios for textile mill workers, chemical workers, and metal workers for the a priori high-risk employment category and odds ratios for those exposed to dyes, chlorinated compounds, and rubber showed significant differences between younger and older subjects. Bladder cancer risk associated with occupational exposures was not limited to persons with initial exposures before 25 years of age. However, there was significantly decreasing risk for bladder cancer with increasing age at first exposure for chemical workers and metal workers and for the a priori high-risk materials and metals. Drivers and/or deliverymen and miscellaneous laborers had significantly increasing bladder cancer risk with increasing duration of employment.     

Acute leukemia in electrical workers: a New Zealand case-control study

Objectives: To assess the risks for adult-onset acute leukemia associated with electrical employment in New Zealand. Methods: The occupational and environmental exposures histories of 110 incident leukemia cases and 199 general population controls were compared. The cases were recruited through referrals to treatment centers in New Zealand between 1989 and 1991. For subjects classified as having worked in one or more of the electrical occupations, the degree of exposures to extremely low frequency electromagnetic fields (ELF-EMFs) was assessed in detail using a job-exposure matrix. Results: An odds ratio of 1.9 (95% Cl 1.0–3.8) was found for subjects who had ever worked in an electrical occupation. Significantly increased risks for leukemia are seen amongst welders/flame cutters (OR = 2.8 (95% Cl 1.2–6.8)) and telephone line workers (OR = 5.81 (95% Cl 1.2–27.8)). The excess leukemia risk appeared to be confined to acute non-lymphocytic leukemia (OR = 2.31 (95% Cl 1.2–4.6)), in comparison to acute lymphoblastic leukemia (OR = 0.9 (95% Cl 0.3–2.9)) but for the latter category the numbers were very small. A dose–response effect was also found, with acute leukemia risk rising with increasing occupational magnetic field exposure, based on both current and historical occupational field exposure estimates. Conclusions: The findings of the current study indicate a significantly elevated risk of acute leukemia for electrical workers overall, and for the specific occupational categories of welders/flame cutters and telephone line workers. A dose–response effect was also found, indicating that acute leukemia risk was related to historical and current magnetic field exposures in an occupational context.     

Occupational exposure to ultraviolet radiation and risk of non-Hodgkin lymphoma.

Individuals diagnosed with skin cancer have elevated risk of non-Hodgkin lymphoma, and those with non-Hodgkin lymphoma have excess rates of various types of skin cancers. Sunshine and other sources of ultraviolet radiation are major risk factors for skin cancer, and hence a potential common link between skin cancer and non-Hodgkin lymphoma. We analyzed the relationship between occupational exposure to ultraviolet radiation and the risk for non-Hodgkin lymphoma using data from a case-control study conducted in Northern Italy between 1985 and 1997. Cases were 446 patients with histologically confirmed incident non-Hodgkin lymphoma, and controls were 1295 patients admitted to hospital for acute non-neoplastic, non-immunological conditions. The multivariate odds ratios were computed after allowance for age, sex, area of residence, education and smoking. The odds ratio for patients reporting ever ultraviolet exposure at work was 1.01 (95% confidence interval 0.72-1.43) and 1.03 (95% confidence interval 0.72-1.49) for exposure longer than 10 years. The odds ratio was 1.09 for manual workers and 0.79 for farmers exposed to ultraviolet radiation, compared with those with other occupations not exposed to ultraviolet radiation. Our study found no association between occupational exposure to ultraviolet radiation and the risk of non-Hodgkin lymphoma.     

Occupational exposure to dusts and risk of renal cell carcinoma

Background:

Occupational exposures to dusts have generally been examined in relation to cancers of the respiratory system and have rarely been examined in relation to other cancers, such as renal cell carcinoma (RCC). Although previous epidemiological studies, though few, have shown certain dusts, such as asbestos, to increase renal cancer risk, the potential for other occupational dust exposures to cause kidney damage and/or cancer may exist. We investigated whether asbestos, as well as 20 other occupational dust exposures, were associated with RCC risk in a large European, multi-center, hospital-based renal case–control study.

Methods:

General occupational histories and job-specific questionnaires were reviewed by occupational hygienists for subject-specific information. Odds ratios (ORs) and 95% confidence intervals (95% CIs) between RCC risk and exposures were calculated using unconditional logistic regression.

Results:

Among participants ever exposed to dusts, significant associations were observed for glass fibres (OR: 2.1; 95% CI: 1.1–3.9), mineral wool fibres (OR: 2.5; 95% CI: 1.2–5.1), and brick dust (OR: 1.5; 95% CI: 1.0–2.4). Significant trends were also observed with exposure duration and cumulative exposure. No association between RCC risk and asbestos exposure was observed.

Conclusion:

Results suggest that increased RCC risk may be associated with occupational exposure to specific types of dusts. Additional studies are needed to replicate and extend findings.     

Adult-onset acute leukemia and employment in the meat industry: a New Zealand case-control study

Objectives: To assess the risks for adult-onset acute leukemia associated with employment in the New Zealand meat industry. Methods: A total of 110 incident leukemia cases identified from referrals to one of six treatment centers between 1989 and 1991 were compared with 199 general population controls. Detailed occupational exposure histories were obtained by interview. Results: There was an elevated risk associated with ever having worked in an abattoir (OR = 2.3, 95% CI 1.0–5.2), which appeared confined to those with over 2 years exposure (OR = 4.9, 95% CI 1.5–15.6). The excess risk was confined to abattoir workers having direct contact with animals or animal products (OR = 5.2, 95% CI 1.2–22.2). Ever having worked as a butcher was associated with elevated risk (OR = 2.9, 95% CI 1.1–7.2), confined to those individuals who worked as a butcher in an abattoir (OR = 4.8) or who butchered livestock on farms (OR = 8.2). No increased risk was found for work as a retail/wholesale butcher or meatpacker (OR = 1.2). Conclusions: This study found increased leukemia risks associated with employment in the meat industry. These were confined to abattoir workers with over 2 years employment in the industry, and to persons whose jobs involved contact with animals or animal tissue, implying that biological exposures may be responsible.     

Use of job-exposure matrix in an occupational analysis of lung and bladder cancers on the basis of death certificates

A job-exposure matrix has been applied in a case-control study of lung and bladder cancer on the basis of occupational information abstracted from British death certificates. The expected association between lung cancer and jobs entailing exposure to asbestos was clearly demonstrated (relative risk, 1.5; 95% confidence interval, 1.2-1.9). The effects of three other known industrial carcinogens were not apparent, and reasons for this were discussed. Also included in the matrix were five substances whose carcinogenicity in humans has not been established. Formaldehyde, diesel fumes, and cutting oils were all associated with carcinoma of the bronchus, but the absence of a risk in "high-exposure" occupations was against a causal relationship. Bladder cancer was more common in jobs involving high exposure to printing inks (relative risk, 5.0; 95% confidence interval, 1.0-25.8) and cutting oils (relative risk, 1.5; 95% confidence interval, 0.8-2.8). Use of the job-exposure matrix added considerably to the conventional analysis of cancer risk in individual occupational categories.     

Occupational extremely low-frequency magnetic field exposure and selected cancer outcomes in a prospective Dutch cohort

Purpose

To investigate the association between exposure to occupational extremely low-frequency magnetic fields (ELF-MF) and the risk of a priori selected cancer outcomes within the prospective Netherlands Cohort Study.

Methods

120,852 men and women aged 55–69 years at time of enrollment in 1986 were followed up (17.3 years) for incident lung, breast and brain cancer, and hemato-lymphoproliferative malignancies. Information on occupational history and potential confounders such as sex, age, smoking, alcohol use, and attained educational level were collected at baseline through a self-administered questionnaire. Occupational ELF-MF exposure was assigned with a job-exposure matrix. Using a case-cohort approach, associations with cancer incidence were analyzed with Cox regression stratified by sex, using three exposure metrics: (1) ever had a job with low or high exposure to ELF-MF versus background, (2) duration of exposure, and (3) cumulative exposure.

Results

None of the exposure metrics showed an effect on incidence for lung, breast, and brain cancer, nor any of the assessed subtypes in men and women. Of the hemato-lymphoproliferative malignancies in men, ever high exposed to ELF-MF showed a significant association with acute myeloid leukemia (AML) [hazard ratio (HR) 2.15; 95 % confidence interval (CI) 1.06–4.35] and follicular lymphoma (FL) (HR 2.78; 95 % CI 1.00–5.77). Cumulative exposure to ELF-MF showed a significant, positive association with FL but not AML among men.

Conclusions

In this large prospective cohort study, we found some indications of an increased risk of AML and FL among men with occupational ELF-MF exposure. These findings warrant further investigation.     

Occupation and lung cancer risk among New Jersey white males

The association of occupation with lung cancer risk was examined in a case-control study conducted in six areas of New Jersey. The study included 763 white males with incident histologically confirmed primary cancer of the trachea, bronchus, and lung and 900 general population white male controls selected from driver's license and death certificate files. Altogether, 27 employment categories had a smoking-adjusted odds ratio (OR) of 1.3 or greater; five of these with significantly high OR contributed to an occupational population attributable risk of 13%. Masons and tilesetters; janitors and cleaners; printing workers; and trucking service, warehousing, and storage workers had significantly high risks overall and for longer durations of employment. Shipbuilding workers had significantly high risk overall and for short duration of employment. Although the excess risk for all shipbuilding workers was primarily among those with reported exposure to asbestos, the risk was also high among welders, burners, sheet metal workers, and boilermakers with no reported asbestos exposure.     

Are the known bladder cancer risk-factors associated with more advanced bladder cancer?

Risk factors for superficial and invasive bladder cancer were examined in a case-control study of 470 cases Identified in 1967–68 in the Brockton and Boston Standard Metropolitan Areas (MA, United States) and of 500 population-based controls. Histologic specimens were reviewed and classified as superficial or invasive, following a standardized protocol. The tobacco-associated risk for superficial bladder cancer was odds ratio (OR)=2.6 (95 percent confidence interval [CI]=1.7–4.1) and the risk for invasive bladder cancer was OR=1.7 (CI=1.1–2.5). For subjects less than 60 years of age, the risks were greater for invasive tumors (OR=4.3, CI=1.2–15) than for superficial tumors (OR=0, CI=0.9–4.2), but this pattern for tobacco use was not found in older subjects. A strong trend of increased risk with increased amount of cigarettes smoked was shown only for invasive bladder tumors. No clear pattern of excess risk for invasive bladder tumors was seen for age at first use and years since last use of tobacco. The risk associated with occupational exposure to aromatic amine bladder carcinogens was OR=1.7 (CI=0.8–3.3) for superficial and OR=1.5 (CI=0.8–3.0) for invasive bladder cancer. For subjects less than 60 years of age, the risks were greater for invasive (OR=12.0, CI=2.1–65) than for superficial tumors (OR=4.3, CI=0.8–24), but this pattern for occupational exposure was not found in older subjects. Risk by age at first exposure to occupational aromaticamine, bladder carcinogens was similar for superficial and invasive tumors. Overall, there was no association between known bladder-cancer risk-factors and more advanced bladder cancer. The relative risk associated with cigarette smoking and occupational exposure to aromatic amines was higher for invasive than superficial cancer only for men less than 60 years of age.Drs Hayes and Zahm are with the Environmental Epidemiology Branch, National Cancer Institute, Bethesda, MD, USA. Authors are affiliated also with the Lucille P. Markey Cancer Center, Lexington, KN, USA (Dr Friedell) and the Department of Epidemiology, University of Alabama, Birmingham, AL, USA (Dr Cole). Address correspondence to Dr Hayes, Environmental Epidemiology Branch, National Cancer Institute, EPN 418, Bethesda, MD 20892, USA.     

Definition of exposure in epidemiological studies on foundry workers

Epidemiological analytical studies investigating lung cancer risk among foundry workers are reviewed in relation to the available information on exposure. Nine studies (eight historical cohorts and one case-control) have been included. Overall, the information on exposure was poor. In none of the studies were there industrial hygiene measurements for investigating dose-response relationships, while duration of employment was the most common proxy of exposure utilized. None of the studies made an attempt to construct job-exposure matrices. The interpretation of the evidence in causal terms appears mainly based on the consistency across studies of the increased lung cancer mortality rather than on the relationship between the exposure in the working environment and the excess mortality reported.     

Primary liver cancer and occupation in men: a case-control study in a high-incidence area in Northern Italy.

The objective of our study was to evaluate the association between occupation and risk of liver cancer. A hospital-based case-control study was carried out during 1997-1999 in the Province of Brescia, a highly industrialized area in Northern Italy with a high incidence of this neoplasm. The cases were 144 male patients with incident liver cancer (96% hepatocellular carcinoma). Controls were 283 male patients, matched to cases on age (+/-5 years), period and hospital of admission. Information on lifetime occupational history and alcohol consumption was obtained via interview. Specific occupational exposures to pesticides, solvents and other suspected hepatocarcinogens were evaluated. A blood sample was collected to detect hepatitis B and C infections. Odds ratios (OR) of occupational exposure and 95% confidence intervals (CI), adjusted for age, residence, education, heavy alcohol intake, hepatitis B surface antigen and hepatitis C virus antibodies positivity were computed. A statistically significant increased OR was observed for employment in repair of motor vehicles (OR 3.7; 95% CI 1.1-12.3; 9 exposed cases, 10 exposed controls). Increased ORs, although not statistically significant, were found for field-crop farm workers, food and beverage processors, blacksmiths and machine-tool operators, electrical fitters, clerical workers, manufacture of industrial machinery and personal and household services. A slightly increased OR was noted in workers exposed to toluene and xylene (OR 1.4; 95% CI 0.7-3.0, 23 cases, 36 controls); the OR was 2.8 (95% CI 1.0-7.6, 11 cases, 12 controls) for 20 or more years of exposure and 2.0 (95% CI 0.9-4.1, 21 cases, 28 controls) for 30 or more years of time since first exposure. The increase in OR seemed to be independent from that of alcohol or viral infections. Our study showed that the role of occupational exposures in liver carcinogenesis is limited. However, prolonged exposure to organic solvents such as toluene and xylene may represent a risk factor for liver cancer.     

Thyroid cancer and employment as a radiologic technologist

The association between chronic occupational ionizing radiation exposure in the medical field and thyroid cancer is not well characterized. Thyroid cancer incidence was ascertained for 2 periods in a cohort of radiologic technologists certified for a minimum 2 years and enumerated in 1983: (i) cases identified prospectively in 73,080 radiologic technologists who were free of thyroid cancer at the baseline survey and completed a second questionnaire a decade later (N = 121), and (ii) cases occurring prior to cohort enumeration among 90,245 technologists who completed the baseline survey and were thyroid cancer free 2 years after certification (N = 148). Survival analyses estimated risks associated with employment as a radiologic technologist, including duration of employment, period of employment, types of procedures and work practices. The only occupational history characteristic associated with prospectively identified thyroid cancer was a history of holding patients for X-ray procedures at least 50 times (HR = 1.47, 95% CI = 1.01-2.15). Total years worked as a radiologic technologist, years performing diagnostic, therapeutic, and nuclear medicine procedures, employment under age 20 and calendar period of first employment were not associated with thyroid cancer risk. Risk of thyroid cancers diagnosed before the baseline questionnaire was inversely associated with decade first employed as a technologist, and was elevated, albeit imprecisely, among those working more than 5 years prior to 1950 (HR = 3.04, 95% CI = 1.01-10.78). These data provide modest evidence of an association between employment as a radiologic technologist and thyroid cancer risk; however, the findings require confirmation with more accurate exposure models.     

Cancer epidemiology in the paper and pulp industry

Several studies of pulp and paper workers have demonstrated increased risks for certain cancer sites, e.g. tumours of the lymphatic and haematopoietic system as well as stomach cancer. An impressive lung cancer excess was found among paper and board mill workers in Finland, but not in studies elsewhere. Individual exposures have not been estimated, neither has a job-exposure matrix been applied in any of the studies. Therefore, it is impossible to link any of the excesses to specific single compounds or mixtures, of which there are a multitude in the pulp and paper industries. Although there are high quantities of organic chlorine compounds in the process mixtures and waste, the compounds have low volatility and occupational exposures are not necessarily high. Estimations of individual occupational exposure should be mandatory in future epidemiological studies in this industry.     

Cancer mortality among men occupationally exposed to dichlorodiphenyltrichloroethane

Several studies have evaluated cancer risk associated with occupational and environmental exposure to dichlorodiphenyltrichloroethane (DDT). Results are mixed. To further inquire into human carcinogenicity of DDT, we conducted a mortality follow-up study of 4,552 male workers, exposed to DDT during antimalarial operations in Sardinia, Italy, conducted in 1946 to 1950. Detailed information on DDT use during the operations provided the opportunity to develop individual estimates of average and cumulative exposure. Mortality of the cohort was first compared with that of the Sardinian population. Overall mortality in the cohort was about as expected, but there was a deficit for death from cardiovascular disease and a slight excess for nonmalignant respiratory diseases and lymphatic cancer among the unexposed subcohort. For internal comparisons, we used Poisson regression analysis to calculate relative risks of selected malignant and nonmalignant diseases with the unexposed subcohort as the reference. Cancer mortality was decreased among DDT-exposed workers, mainly due to a reduction in lung cancer deaths. Birth outside from the study area was a strong predictor of mortality from leukemia. Mortality from stomach cancer increased up to 2-fold in the highest quartile of cumulative exposure (relative risk, 2.0; 95% confidence interval, 0.9-4.4), but no exposure-response trend was observed. Risks of liver cancer, pancreatic cancer, and leukemia were not elevated among DDT-exposed workers. No effect of latency on risk estimates was observed over the 45 years of follow-up and within selected time windows. Adjusting risks by possible exposure to chlordane in the second part of the antimalarial operations did not change the results. In conclusion, we found little evidence for a link between occupational exposure to DDT and mortality from any of the cancers previously suggested to be associated.     

Occupational risks of bladder cancer in the United States: II Nonwhite men

Occupational risks of bladder cancer among nonwhite men were assessed based on interviews with 126 cases and 383 controls conducted during the National Bladder Cancer Study, a population-based, case-control study conducted in 10 areas of the United States. Our findings indicated that nonwhite men who were ever employed as auto workers have an elevated risk of bladder cancer [relative risk (RR) = 2.3; 95% confidence intervals (CI) = 0.8-6.4] with a significant positive trend in RR with increasing duration of employment (P = .017) and with the RR rising to 4.7 for those employed at least 10 years. Dry cleaners, ironers, and pressers also experienced increased bladder cancer risk (RR = 2.8, CI = 1.1-7.4). Nonsignificant excesses of similar magnitude to those seen among white men were found for nonwhite men employed in several other occupations. Overall, our findings suggest that the risk of occupational bladder cancer among white and nonwhite men is similar. When inconsistencies between whites and nonwhites did occur, they appeared either due to chance or possibly racial differences in exposure among men within the same industry and occupation. In all, we estimate that the population attribute risk for occupation among nonwhite U.S. men is 27% (CI = 9% to 56%), which is slightly higher than the estimate of 21% to 25% previously reported for white U.S. men, although this difference was not statistically significant.     

Cancer incidence among medical diagnostic X-ray workers in China, 1950 to 1985

A second follow-up of 27,011 diagnostic X-ray workers in China revealed a 21% greater incidence of cancer than expected based on the experience of 25,782 physicians who did not routinely use X-rays (RR = 1.21; 95% Cl: 1.08 to 1.35). This risk is lower than the 50% excess reported previously and reflects, in part, the reduced risk among workers first employed after 1965, when hospital exposures to radiation probably were lower than in earlier years. The X-ray workers were employed between 1950 and 1985 and followed for an average of 16.1 years. Significantly elevated risks were seen for leukemia (RR = 2.4, n = 34 cases), and cancers of the esophagus (RR = 5.2, n = 19), liver (RR = 1.8, n = 65), and skin (RR = 2.8, n = 9). Cancers of the breast (RR = 1.5, n = 20), thyroid (RR = 1.7, n = 8), and bone (RR = 7.6, n = 4) also occurred more often than expected. Non-significant deficits were observed for cancers of the oral cavity and pharynx (RR = 0.6, n = 16), colon and rectum (RR = 0.8, n = 20), stomach (RR = 0.8, n = 36), and lung (RR = 0.9, n = 45). Excess risks for leukemia and esophageal cancer were seen among men but not among women. The RR for leukemia was higher for X-ray workers who began employment before 1970 than for those who started more recently and also for those who were young when employment began. The patterns of risk associated with duration of work, and with age and calendar time of initial employment, suggest that the excesses of leukemia and skin cancer, and, possibly, cancers of the breast and thyroid, were due to occupational exposure to X-rays. However, there was little evidence that radiation contributed to the increased occurrences of liver or esophageal cancers.     

A cohort study of tobacco use,diet, occupation,and lung cancer mortality

In 1966, a cohort of White males aged 35 or over, who were policy-holders with the Lutheran Brotherhood Insurance Society (United States), completed a mail questionnaire on tobacco use, diet, and demographic characteristics. During the 20 years of follow-up, 219 lung cancer deaths occurred. Besides the strong relationship with cigarette smoking, we observed an effect on lung cancer risk among current users of cigars or pipes who were nonsmokers of cigarettes (relative risk [RR]=3.5, 95 percent confidence interval[CI]=1.0–12.6) or who were past/occasional users of cigarettes (RR=2.7, CI=1.4–5.3). In addition, elevated risks (from 1.5 to 2.6) of lung cancer were found among craftsmen and laborers, with the highest risks among subjects who worked in the mining or manufacturing industry. No association between current (as of 1966) use of beer or hard liquor and lung cancer was observed, although past users were at elevated risk. An inverse association between lung cancer and intake of fruits was observed, and risks of lung cancer were lower among persons in the highest dietary intake quintiles of vitamins A and C. Except for oranges, however, none of the inverse associations with fruits or dietary nutrients had statistically significant trends. The findings from this cohort study add to the evidence of an adverse effect of cigar/pipe smoking and possibly protective effect of dietary factors on lung cancer risk.