Mesothelioma in Sweden: Dose-Response Analysis for Exposure to 29 Potential Occupational Carcinogenic Agents.

BACKGROUND: There is little information on the dose-response relationship between exposure to occupational carcinogenic agents and mesothelioma. This study aimed to investigate this association as well as the existence of agents other than asbestos that might cause mesothelioma. METHODS: The Swedish component of the Nordic Occupational Cancer (NOCCA) study consists of 6.78 million individuals with detailed information on occupation. Mesothelioma diagnoses recorded in 1961-2009 were identified through linkage to the Swedish Cancer Registry. We determined cumulative exposure, time of first exposure, and maximum exposure intensity by linking data on occupation to the Swedish NOCCA job-exposure matrix, which includes 29 carcinogenic agents and corresponding exposure for 283 occupations. To assess the risk of mesothelioma, we used conditional logistic regression models to estimate hazard ratios and 95% confidence intervals. RESULTS: 2,757 mesothelioma cases were identified in males, including 1,416 who were exposed to asbestos. Univariate analyses showed not only a significant excess risk for maximum exposure intensity, with a hazard ratio of 4.81 at exposure levels 1.25-2.0 fb/ml but also a clear dose-response effect for cumulative exposure with a 30-, 40-, and 50-year latency time. No convincing excess risk was revealed for any of the other carcinogenic agents included in the Swedish NOCCA job-exposure matrix. CONCLUSION: When considering asbestos exposure, past exposure, even for short periods, might be enough to cause mesothelioma of the pleura later in life.

Occupational Risk for Oral Cancer in Nordic Countries.

AIM: To evaluate occupational risk for cancer of the tongue, oral cavity or pharynx after adjustment for alcohol and tobacco use. MATERIALS AND METHODS: The data covered 14.9 million people and 28,623 cases of cancer of the tongue, oral cavity and pharynx in the Nordic countries 1961-2005. Alcohol consumption by occupation was estimated based on mortality from liver cirrhosis and incidence of liver cancer. Smoking by occupation was estimated based on the incidence of lung cancer. RESULTS: Only few occupations had relative risks of over 1.5 for cancer of the tongue, oral cavity and pharynx. These occupations included dentists, artistic workers, hairdressers, journalists, cooks and stewards, seamen and waiters. CONCLUSION: Several occupational categories, including dentists, had an increased relative risk of tongue cancer. This new finding remains to be explained but could be related to occupational chemical exposures, increased consumption of alcohol and tobacco products, or infection with human papilloma virus.

Occupational exposure to solvents and acute myeloid leukemia: a population-based, case-control study in four Nordic countries.

OBJECTIVE: The aim of the current study was to assess the relation between occupational exposure to solvents and the risk of acute myeloid leukemia (AML). METHODS: Altogether, this study comprises 15 332 incident cases of AML diagnosed in Finland, Norway, Sweden and Iceland from 1961-2005 and 76 660 controls matched by year of birth, sex, and country. Occupational records were linked with Nordic Occupational Cancer Study job exposure matrix (JEM) to estimate quantitative values for 26 occupational exposure factors. Hazard ratios (HR) with 95% confidence intervals (95% CI) were estimated by using conditional logistic regression models. RESULTS: We did not observe statistically significantly increased risk for exposure to any of the solvents. HR estimates for high levels of toluene (HR 1.35, 95% CI 0.74-2.46), aromatic hydrocarbon solvents (ARHC) (HR 1.18, 95% CI 0.76-1.86), and moderate-to-high levels of trichloroethylene were slightly but non-significantly elevated. We did not observe an association between benzene exposure and AML in this study. CONCLUSIONS: This study did not provide clear evidence for an association between occupational solvent exposure and AML. There was some indication for an excess risk in the groups of workers exposed to toluene, trichloroethylene and ARHC.

Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies.

BACKGROUND: In 2012, the International Agency for Research on Cancer classified tetrachloroethylene, used in the production of chemicals and the primary solvent used in dry cleaning, as "probably carcinogenic to humans" based on limited evidence of an increased risk of bladder cancer in dry cleaners. OBJECTIVES: We assessed the epidemiological evidence for the association between tetrachloroethylene exposure and bladder cancer from published studies estimating occupational exposure to tetrachloroethylene or in workers in the dry-cleaning industry. METHODS: Random-effects meta-analyses were carried out separately for occupational exposure to tetrachloroethylene and employment as a dry cleaner. We qualitatively summarized exposure-response data because of the limited number of studies available. RESULTS: The meta-relative risk (mRR) among tetrachloroethylene-exposed workers was 1.08 (95% CI: 0.82, 1.42; three studies; 463 exposed cases). For employment as a dry cleaner, the overall mRR was 1.47 (95% CI: 1.16, 1.85; seven studies; 139 exposed cases), and for smoking-adjusted studies, the mRR was 1.50 (95% CI: 0.80, 2.84; 4 case-control studies). CONCLUSIONS: Our meta-analysis demonstrates an increased risk of bladder cancer in dry cleaners, reported in both cohort and case-control studies, and some evidence for an exposure-response relationship. Although dry cleaners incur mixed exposures, tetrachloroethylene could be responsible for the excess risk of bladder cancer because it is the primary solvent used and it is the only chemical commonly used by dry cleaners that is currently identified as a potential bladder carcinogen. Relatively crude approaches in exposure assessment in the studies of "tetrachloroethylene-exposed workers" may have attenuated the relative risks.

Occupational exposure to trichloroethylene and perchloroethylene and the risk of lymphoma, liver, and kidney cancer in four Nordic countries.

OBJECTIVES: Trichloroethylene (TCE) and Perchloroethylene (PER) are two chlorinated solvents that are applied widely as degreasers of metal parts, and in dry cleaning and other applications. In 2012, the International Agency for Research on Cancer classified TCE as carcinogenic to humans and PER as probably carcinogenic to humans. We explored exposure-response relations for TCE and PER and non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), and cancers of the kidney and liver in the Nordic Occupational Cancer cohort. METHODS: The cohort was set up by linking occupational information from censuses to national cancer registry data using personal identity codes in use in all Nordic countries. Country, time period, and job-specific exposure estimates were generated for TCE, PER and potentially confounding occupational exposures with a job-exposure matrix. A conditional logistic regression was conducted for exposure groups as well as for continuous cumulative exposure. RESULTS: HRs for liver cancer, NHL and MM but not kidney cancer were slightly elevated in groups with high exposure to PER (compared to occupationally unexposed subjects). HRs for liver cancer and NHL also increased with increasing continuous exposure to PER. We did not observe evidence for an association between exposure to TCE and NHL, MM or liver and kidney cancer. CONCLUSIONS: Although this study was subject to limitations related to the low prevalence of exposure to PER and TCE in the Nordic population and a limited exposure assessment strategy, we observed some evidence indicative of an excess risk of cancer of the liver and NHL in subjects exposed to PER.

Risk of death among persons with Alzheimer's disease: a national register-based nested case-control study.

Few studies have reported the risk of death related to Alzheimer's disease (AD) in large population-based cohorts. The objective of this study was to analyze the impact of AD on all-cause mortality in a nationwide sample of persons with AD. Community-dwelling persons with AD and an equal number of individually matched (age, gender, and region of residence) control persons without AD were identified from the registers of Social Insurance Institution of Finland at the end of 2005. Deaths in this sample (n = 56,041, mean age 79.7 years, 67.8% women) during a 57-month follow-up period were recorded. Using a nested case-control design, unadjusted and adjusted (cardiovascular disease, cancer, diabetes, and asthma and/or COPD) hazard ratios (HR) with 95% confidence intervals (CI) were computed using proportional hazards regression. The results were categorized according to age at death (<80, 80 to 89, ≥ 90 years) and duration of AD (≤ 3, 4 to 6, ≥ 7 years). The unadjusted HR for death associated with AD was 2.03 (95% CI: 1.97 to 2.09). The HR was highest in the youngest age category [HR = 3.46 (95% CI: 3.18 to 3.77)], and still significantly elevated in the oldest age category [HR = 1.50 (95% CI: 1.41 to 1.60)]. Comorbidity adjustments did not change the HRs, and even a short duration of AD (≤ 3 years) was associated with a significantly increased risk of death. In conclusion, AD was associated with an increased risk of death that was more pronounced at younger ages and existed even after a recent diagnosis of AD.

Occupational exposure to wood dust and formaldehyde and risk of nasal, nasopharyngeal, and lung cancer among Finnish men.

Controversy exists over whether or not occupational inhalation exposure to wood dust and/or formaldehyde increases risk for respiratory cancers. The objective of this study was to examine the risk of nasal, nasopharyngeal, and lung cancer in relation to occupational exposure to wood dust and formaldehyde among Finnish men. The cohort of all Finnish men born between the years 1906 and 1945 and in employment during 1970 was followed up through the Finnish Cancer Registry for cases of cancers of the nose (n = 292), nasopharynx (n = 149), and lung (n = 30,137) during the period 1971-1995. The subjects' occupations, as recorded in the population census in 1970, were converted to estimates of exposure to wood dust, formaldehyde, asbestos, and silica dust through the Finnish job-exposure matrix. Cumulative exposure (CE) was calculated based on the prevalence, average level, and estimated duration of exposure. The relative risk (RR) estimates for the CE categories of wood dust and formaldehyde were defined by Poisson regression, with adjustments made for smoking, socioeconomic status, and exposure to asbestos and/or silica dust. Men exposed to wood dust had a significant excess risk of nasal cancer overall (RR, 1.59; 95% confidence interval [CI], 1.06-2.38), and specifically nasal squamous cell carcinoma (RR, 1.98; 95% CI, 1.19-3.31). Workers exposed to formaldehyde had an RR of 1.18 (95% CI, 1.12-1.25) for lung cancer. There was no indication that CE to wood dust or formaldehyde would increase the risk of nasopharyngeal cancer. Occupational exposure to wood dust appeared to increase the risk of nasal cancer but not of nasopharyngeal or lung cancer. The slight excess risk of lung cancer observed for exposure to formaldehyde may be the result of residual confounding from smoking. In summary, this study provides further evidence that exposure to wood dust in a variety of occupations may increase the risk of nasal cancer.

Increased incidence of Merkel cell carcinoma among younger statin users.

BACKGROUND: Statins (HMG-CoA-reductase inhibitors) are suggested to act as a predisposing factor for autoimmune diseases, have immunomodulatory effects, and possibly prevent some cancer types - the sum of these effects is unknown in cancers of viral aetiology, such as Merkel cell carcinoma (MCC). Aim of our study was to find out whether statin users in Finland have an increased incidence of MCC. PATIENTS AND METHODS: A cohort of 224715 male and 230220 female statin users during 1994-2007 was identified from the Prescription Register of the National Social Insurance Institution. This cohort was followed up through the Finnish Cancer Registry for MCC up to 2009. RESULTS: There were altogether 50 cases of MCCs, while the expected number of cases, calculated on the basis of the MCC incidence in comparable Finnish population, was 39.9 (SIR 1.25, 95% CI 0.93-1.65). The standardized incidence ratio (SIR) for MCC in ages <60 years was 3.16 (95% CI 0.65-9.23), in ages 60-74 years 1.94 (95% CI 1.23-2.90) and in ages ≥75 years 0.89 (95% CI 0.57-1.31). The relative risk of MCC decreased significantly, 0.79 fold (95% CI 0.67-0.92), at each 5 year step when moving towards older age groups. There was no significant variation in SIR related to years since starting the statin use, or between the genders. CONCLUSIONS: MCC is the first neuroendocrine cancer linked to statin use. The association is statistically significant and biologically plausible through immunomodulatory effects of statins. The excess of MCCs was observed in atypically young patients, a similar phenomenon as noted earlier in patients with immunocompromising states.

Risk of liver cancer and exposure to organic solvents and gasoline vapors among Finnish workers.

We investigated the association between exposure to various groups of solvents and gasoline vapors and liver cancer. A cohort of economically active Finns born between 1906 and 1945 was followed up during the period 1971-1995. The incident cases of primary liver cancer (n = 2474) were identified in a record linkage with the Finnish Cancer Registry. Occupations from the 1970 census were converted to exposures using a job-exposure matrix. Cumulative exposure was calculated as the product of estimated prevalence, level and duration of exposure, and we used Poisson regression to calculate the relative risks (RR). Among the occupations entailing exposure to organic solvents, an elevated liver cancer incidence was observed in male printers, and varnishers and lacquerers. Among men, the risk was increased in the highest exposure category of aromatic hydrocarbons [RR 1.77, 95% confidence interval (CI) 1.30-2.40], aliphatic/alicyclic hydrocarbons (RR 1.47, 95% CI 0.99-2.18), chlorinated hydrocarbons (RR 2.65, 95% CI 1.38-5.11) and "other solvents" (RR 2.14, 95% CI 1.23-3.71). Among women, the risk was increased for the group "other solvents" that includes mainly alcohols, ketones, esters and glycol ethers (RR 2.73, 95% CI 1.21-6.16). Our finding of an increased risk among workers exposed to chlorinated hydrocarbons is in line with several earlier studies on trichloroethylene. The results also suggest a link between exposure to other types of solvents and the risk of liver cancer. The possibility that alcohol consumption contributes to the observed risks cannot be totally excluded.

Postmenopausal hormone drugs and breast and colon cancer: Nordic countries 1995-2005.

OBJECTIVES: The purpose of this study was to utilize the variation in the level and timing of the change in postmenopausal hormone therapy (HT) use between the Nordic countries to assess the population-level impact of decline in HT use on the breast and colon cancer incidences. METHODS: Nationwide HT-sales data in defined daily doses (DDDs) per 1000 inhabitant in 1995-2005 in Finland, Iceland, Norway and Sweden were obtained from drug control authorities. Breast and colon cancer incidence data by 5-year age-groups were obtained from the National Cancer Registers. By time series analysis we estimated in each age-group and country how much a change in HT-sales changes cancer incidence. RESULTS: The decline of HT-sales varied; the decline from the highest sales was 61% in Sweden, 51% in Norway, 43% in Iceland and 25% in Finland. With the exception of Finland, the breast cancer incidence increased from 1995 to the year following the year with maximum HT-sales and decreased after that year. In the model combining countries and years, changes in HT-sales predicted the change in breast cancer incidence, an average 7% for each 10 DDD units of HT-sales. No clear association between HT-sales and colon cancer incidence was found. CONCLUSIONS: The time and country specific data suggest, that on the population level, a notable drop from high level of HT use somewhat decreases breast cancer incidence or breaks its increasing trends. The suggested protective effect of HT for colon cancer was not seen.

Night-time work predisposes to non-Hodgkin lymphoma.

Our aim was to find out whether non-Hodgkin lymphoma (NHL) was more common than expected among night-time shift workers. The Finnish job-exposure matrix (FINJEM) provided estimates of the proportion of exposed persons and the mean level of exposure among the exposed in each occupation. The probability of night-time work in each occupation was assessed, the observed and expected numbers of cancer cases in a cohort of persons born in 1906-1945 during the years of 1971-1995 were calculated, and the cumulative index of night-time work was scored. The cohort compromised of 1,669,272 persons of whom 6,307 (3,813 men and 2,494 women) had NHL during the follow-up. Night-time work increased significantly (p = 0.01) the risk of NHL in men, the overall relative risk being 1.10 (95% confidence interval of 1.03-1.19). Using the lag period of 10 years, the risk ratio was 1.28 (1.03-1.59) for men who worked in night-time shifts to a high degree as compared with those who had not been exposed to night-time work. Night-time workers are cancer prone and have a greater risk of NHL than population on average.

Scholastic achievement of children with lymphoma or Wilms tumor at the end of comprehensive education--a nationwide, register-based study.

Cancer treatment may affect school performance. School report grades after childhood lymphomas and Wilms tumor have not been previously reported. All Finnish patients with Wilms tumor (N = 74), Hodgkin lymphoma (HL) (N = 99) and non-Hodgkin lymphoma (NHL) (N = 94) who were born in 1974-1986 and had achieved the age of 16 years were identified from the Finnish cancer registry. Population controls (N = 1329) were matched for age, gender and residence. Their 9th grade school reports were obtained from Statistics Finland. The overall average and grades for mother tongue, first foreign language, mathematics and physical education were compared between the patients and their controls. Almost all the patients (>98%) had finished their comprehensive school. NHL patients had lower overall averages than their controls (difference -0.27 grade units; 95% CI -0.39, -0.15). Irradiation or age at diagnosis did not explain this difference in NHL patients. The grades of NHL patients were significantly lower than those of their controls in each academic school subject, especially in mathematics (-0.45; 95% CI -0.63, -0.27). In mother tongue, girls with irradiation had greatest difference (-0.66, 95% CI -0.99, -0.34) to their controls. Patients with HL and Wilms tumor performed similarly or even better than their controls in all academic subjects. Grades for physical education were impaired in Wilms tumor patients (-0.20; 95% CI -0.33, -0.06). Impairment of school report grades was observed in patients with NHL. The difference to controls was greatest in mathematics. The patients with HL and Wilms tumor, who had not received any central nervous system directed therapy, achieved equally good grades as their controls in all the academic subjects.

Occupational exposure to solvents and gasoline and risk of cancers in the urinary tract among Finnish workers.

BACKGROUND: Bladder cancer (BC) is generally considered as an occupational disease, and some chemical exposures may also be associated with renal cell cancer (RCC). The aim of this study was to estimate the risk of cancers of the urinary tract in relation to occupational exposure to solvents and gasoline. METHODS: A cross-sectional cohort of all economically active Finns from the 1970 population census was followed up for BC (10,277 cases) and RCC (9,954 cases). Census occupations were assigned estimates of exposure to hydrocarbon (HC) solvents and gasoline with a job exposure matrix. Relative risk (RR) estimates were defined using Poisson regression models, adjusted for smoking and obesity. RESULTS: Exposure to solvents was positively associated with the incidence of BC in women but not in men. The RR estimates were above 1.2 in nearly all exposure categories of all exposures studied but a statistically significant excess was only seen for middle levels of chlorinated HC solvents (1.7; 95% CI = 1.2-2.5) and a low level of aromatic HC solvents (1.6; 95% CI = 1.3-2.1). The RR estimates for RCC were close to unity in all categories of exposure. CONCLUSIONS: Our findings suggest that occupational exposure to certain solvents may have an impact on BC risk. The risk of RCC does not appear to be altered by exposure to HC solvents or gasoline.

Cancer of the mouth and pharynx, occupation and exposure to chemical agents in Finland [in 1971-95].

The objective of this article was to find associations between cancer of the mouth and pharynx, occupation and chemical exposure. A cohort of Finns born between 1906 and 1945 was followed-up for 46.8 (21.5 in males and 25.3 in females) million person-years during 1971-95. Incident cases of cancer of the mouth and pharynx (n = 2,708) were identified in a record linkage with the Finnish Cancer Registry. The Census occupations in 1970 were converted to chemical exposures with a job-exposure matrix (FINJEM). Cumulative exposure (CE) was calculated as the product of prevalence, level and duration of the exposure. Standardized incidence ratio (SIR) was calculated for each of the 393 occupations, and for CE categories of the 43 chemical agents, using total Finnish population as reference. Relative risks (RR) comparing various CE-categories with unexposed ones were defined for selected agents by Poisson regression analysis. Elevated SIRs were observed among lawyers, authors, journalists, performing artists, musicians, electronics and telefitters, painters (building), building hands, dockers, unskilled labourers and hotel porters in males and private secretaries, dressmakers, shoemakers and cobblers, waiters, pursers and stewardesses in females. The multivariate analyses showed high RRs for high exposure to aliphatic and alicyclic hydrocarbons, pesticides and alcohol. In conclusion, occupations with high SIRs were mostly the ones with high consumption of alcohol. Exposure to solvents and possibly to pesticides, engine exhaust, textile dust and leather dust may increase the risk of cancer of mouth and pharynx.

Exposure to iron and welding fumes and the risk of lung cancer.

OBJECTIVES: Exposure to iron fumes and dust and welding fumes is widespread and may increase the risk of lung cancer. The aim of this study was to identify associations between exposure to iron and welding fumes and the incidence of lung cancer among Finnish men. METHODS: The cohort of all economically active Finnish men, born in 1906-1945, who participated in the national census in 1970 was followed through the Finnish Cancer Registry for lung cancer cases (N=30,137) during 1971-1995. Their census occupations in 1970 were converted to estimates of cumulative exposure to iron and welding fumes with the Finnish job-exposure matrix on the basis of likelihood, average level, and estimated duration of exposure. Relative risk estimates for categorized cumulative exposure were defined by a Poisson regression, adjusted for smoking, socioeconomic status, and exposure to asbestos and silica dust. RESULTS: The relative risks for lung cancer increased as the cumulative exposure to iron and welding fumes increased. Relative risks in the highest exposure category was 1.35 [95% confidence interval (95% CI) 1.05-1.73] for iron and 1.15 (95% CI 0.90-1.46) for welding fumes. The respective relative risks estimated for squamous-cell carcinoma of the lungs were 1.94 (95% CI 1.35-2.78) and 1.55 (95% CI 1.08-2.24). There was no excess risk of small-cell carcinoma in any exposure category. CONCLUSIONS: Occupational exposure to iron and welding fumes was associated with an increase in lung cancer risk, mainly that of squamous-cell carcinoma. The simultaneous exposure to both of these agents and other potential work-related carcinogens complicates the interpretation of the independent roles of the risk factors.

Scholastic achievements of childhood leukemia patients: a nationwide, register-based study.

PURPOSE: Studies concerning the scholastic achievement of survivors of childhood leukemia have yielded controversial results. We studied the school marks of childhood leukemia survivors in a register-based study. PATIENTS AND METHODS: Three hundred seventy-one patients with a diagnosis of leukemia before the age of 16 years who were born between 1974 and 1986 and alive on their 16th birthday were identified from the Finnish Cancer Registry. Five matched controls were sought for each patient from the Population Register Center of Finland. Information on the ninth-grade school report was obtained from Statistics Finland. The overall mark average and the marks (scale 4 to 10) for mother tongue, foreign language, mathematics, and physical education were compared between the patients and controls. RESULTS: The ninth-grade school report was obtained by 97.6% of the patients and 98.5% of the controls. The patients whose treatment included cranial irradiation had a lower overall mark average (mean difference, -0.24; 95% CI, -0.33 to -0.15) and lower marks for all assessed school subjects compared with their controls. Of the patients treated with chemotherapy alone, only the females with leukemia diagnosed before 7 years of age had lower school marks than their controls. The biggest difference was observed in the marks for foreign language among the irradiated females diagnosed at a young age (mean difference, -1.0; 95% CI, -1.25 to -0.74). CONCLUSION: Leukemia treatment that includes cranial irradiation impairs scholastic achievement. It is noteworthy that treatment of leukemia with chemotherapy alone impairs school performance only in females diagnosed before school age.

Incidence of ovarian cancer of grand multiparous women--a population-based study in Finland.

OBJECTIVES: Parity is known to induce protective effects on ovarian cancer. This study aimed to evaluate how far upon births the protection reaches, the effect of age at first birth, the interval between births in the whole population and the length of time from the first to the last birth and from the last birth to cancer among postmenopausal women. METHOD: The population-based cohort consisted of 87,929 grand multiparous (GM) women, i.e. women with at least 5 deliveries. Standardised incidence ratios (SIRs) were calculated by dividing the number of observed cancer cases by the expected number based on the national incidence rates, both extracted from the population-based Finnish Cancer Registry. Conditional logistic regression for the case-control design nested in the GM cohort was used to estimate proportional hazards by different factors. RESULTS: The SIR for ovarian cancer among GM women was low (418 cases; SIR 0.64, 95% confidence interval 0.58-0.69). Further births over five did not give additional protection. The relative risk did not vary significantly by age at first birth or interval between the births in any histological subtype. CONCLUSION: The risk of ovarian cancer was low in all GM women no matter how many children and at which ages they had delivered or contracted cancer.

Breast cancer in Belarus and Ukraine after the Chernobyl accident.

An increase in breast cancer incidence has been reported in areas of Belarus and Ukraine contaminated by the Chernobyl accident and has become an issue of public concern. The authors carried out an ecological epidemiological study to describe the spatial and temporal trends in breast cancer incidence in the most contaminated regions of Belarus and Ukraine, and to evaluate whether increases seen since 1986 correlate to radiation exposure from the Chernobyl accident. The authors investigated the trends through age-cohort-period-region analyses of district-specific incidence rates of breast cancer for Gomel and Mogilev regions of Belarus and Chernigiv, Kyiv and Zhytomir regions of Ukraine. Dose-response analyses were based on Poisson regression, using average district-specific whole body doses accumulated since the accident from external exposure and ingestion of long-lived radionuclides. The study demonstrated increases in breast cancer incidence in all areas following the Chernobyl accident, reflecting improvements in cancer diagnosis and registration. In addition, a significant 2-fold increase in risk was observed, during the period 1997-2001, in the most contaminated districts (average cumulative dose of 40.0 mSv or more) compared with the least contaminated districts (relative risk [RR] in Belarus 2.24, 95% confidence interval [CI] 1.51-3.32 and in Ukraine 1.78, 95% CI=1.08-2.93). The increase, though based on a relatively small number of cases, appeared approximately 10 years after the accident, was highest among women who were younger at the time of exposure and was observed for both localised and metastatic diseases. It is unlikely that this excess could be entirely due to the increased diagnostic activity in these areas.

Testicular cancer, occupation and exposure to chemical agents among Finnish men in 1971-1995.

OBJECTIVE: To find associations between testicular cancer, occupation and chemical exposure. METHODS: A cohort of all economically active Finnish men born between 1906 and 1945 was followed-up for 19.7 million person-years during 1971-1995. Incident cases of testicular cancer (n=387) were identified in a record linkage with the Finnish Cancer Registry. The Census occupations in 1970 were converted to chemical exposures with a job-exposure matrix (FINJEM). Cumulative exposure (CE) was calculated as the product of prevalence, level, and duration of the exposure. Standardised incidence ratio (SIR) was calculated for each of the 393 occupations, and for CE categories of the 43 chemical agents, using average male population as reference. Relative risks (RR) comparing various CE-categories with unexposed ones were defined for selected agents by Poisson regression analysis. RESULTS: Elevated SIRs were observed among railway traffic supervisors (5.8, 95% CI 1.6-14.7), programmers (4.3, 1.4-9.9), university teachers (4.1, 1.3-9.5) and electrical engineers (3.9, 1.1-10.1). A significant exposure-response trend (mainly contributed by seminoma) was observed for pesticides, textile dust, aliphatic and alicyclic hydrocarbons, and some other organic solvents. CONCLUSIONS: Risk of testicular cancer increased only in four occupations. Pesticides, textile dust, and some organic solvents may be related to an excess risk of seminoma.

National job-exposure matrix in analyses of census-based estimates of occupational cancer risk.

OBJECTIVES: The aim of this study was to increase the understanding of the alternative exposure metrics and analysis methods in studies applying job-exposure matrices in analyses of health outcomes, the association between crystalline silica and cancer being used as an example. METHODS: Observed and expected numbers of cancer cases during 1971-1995 among Finns born in 1906-1945 were calculated for 393 occupational categories, as defined in the 1970 population census. According to the Finnish Cancer Registry, there were 43 433 lung and 21 444 prostate cancer cases. The Finnish job-exposure matrix (FINJEM) provided estimates of the proportion of exposed persons and the mean level of exposure among the exposed in each occupation. RESULTS: The most comprehensive exposure metric included period- and age-specific estimates of exposure and an estimate of occupational stability, but also remarkably simpler metrics gave significantly elevated estimates of the risk ratio (RR) between 1.36 and 1.50 for lung cancer for occupations with the highest estimated cumulative silica exposure (> or = 10 mg/m3-years), allowing a lag time of 20 years. It proved important to adjust the risk ratios at least for the socioeconomic status and occupational exposure to asbestos. The risk ratios for prostate cancer were close to 1.0 in every model. CONCLUSIONS: The results showed that the FINJEM-based analysis was able to replicate the well-known association between exposure to crystalline silica and lung cancer. The FINJEM-based method gives valid results, and it can be used to analyze large sets of register-based data on health outcomes.