Cutaneous melanoma in France in 2015 attributable to solar ultraviolet radiation and the use of sunbeds.

BACKGROUND: Exposure to solar ultraviolet radiation (UVR) and the use of UV-emitting tanning devices are associated with cutaneous malignant melanoma occurrence. OBJECTIVE: The aim of this study was to quantify the proportion and number of melanoma cases attributable to solar UVR exposure and sunbed use in France in 2015. METHODS: Population attributable fractions (PAFs) and numbers of melanoma cases attributable to solar UVR exposure were estimated by age and sex using the incidence rates of a 1903 birth cohort as the primary reference. Further analyses were performed using the following: (i) contemporary melanoma incidence rates in low-incidence regions within France and (ii) national melanoma incidence rates for the year 1980, as additional references. Assuming a 15-year lag period, PAF and melanoma cases attributable to sunbed use were calculated using prevalence estimates from a cross-sectional population survey and published relative risk estimates. RESULTS: In 2015, an estimated 10 340 melanoma cases diagnosed in French adults were attributable to solar UVR exposure, corresponding to 83% of all melanomas and 3% of all cancer cases in that year. PAFs for melanoma were highest in the youngest age group (30-49 years) and higher in men than in women (89% vs. 79%). A total of 382 melanoma cases occurring in French adults in 2015 were attributed to the use of sunbeds, equivalent to 1.5% and 4.6% of all melanoma cases in men and women, respectively. CONCLUSIONS: A considerable proportion of melanoma cases in France in 2015 were attributable to solar UVR exposure, suggesting that targeted prevention strategies need to be implemented.

Risk factors of thyroid tumors: role of environmental and occupational exposures to chemical pollutants.

BACKGROUND: The rising incidence of thyroid cancer observed during the last few decades in most western countries is explained in large part by increasing numbers of diagnoses due to changes in medical screening practices. However, beside radiation exposure, exposure to environmental chemicals may also play a role in thyroid cancer etiology and in the increased incidence. This paper presents the main chemicals suspected to induce thyroid tumorigenesis, and epidemiological results on the association between chemical exposure and thyroid tumors. METHODS: We reviewed experimental studies to identify the main chemicals possibly involved in thyroid tumorigenesis. We also reviewed the main epidemiological studies investigating the association between environmental chemical exposure and thyroid neoplasm in humans. RESULTS: Environmentally abundant chemicals may disrupt thyroid function and/or play a role in tumorigenesis through a variety of mechanisms. Epidemiological results provide insufficient evidence of a causal link between exposure to environmental chemicals and thyroid tumors, but raise the hypothesis of an increased risk of thyroid neoplasm for workers in the leather, wood, and paper industries, and those exposed to certain solvents and pesticides. CONCLUSION: This paper highlights the need for large epidemiological studies evaluating the exposure to various groups of environmental chemicals and its impact on the thyroid gland.

Occupational exposure to pesticides and bile tract carcinoma in men: results from a European multicenter case-control study.

OBJECTIVES: To estimate the associations between occupational exposure to pesticides and extrahepatic biliary tract carcinoma in men, a population-based case-control study was carried out. METHODS: Cases (n = 104), aged 35-70, diagnosed in 1995-1997, were sampled by active reporting systems from hospitals. Controls (n = 1,401) were a random sample of the general male population. Information on occupation and confounding factors was obtained by questionnaires. Exposures were quantified with respect to time, application methods, and use of personal protective equipment. Intensity was evaluated by using a published algorithm which weighted the exposure assigned according to the use of personal protective equipment and mode of application. Logistic regression analyses were conducted adjusted for gallstones, age, and country. RESULTS: Being ever exposed to pesticides resulted in an odds ratio (OR) of 1.0 [95%-confidence interval (CI) 0.6-1.6]. A modestly elevated risk was found for backpack mounted sprayers OR = 1.4 [95% CI 0.7-2.6] and vine farmers OR = 2.5 [95% CI 0.9-7.2]. Using time periods and exposure frequency as intensity measure, no elevated risks were found. The only exception was year of maximum exposure which yielded an OR of 1.6 [95% CI 0.7-3.5]. However, no clear trend was observed in this analysis. CONCLUSIONS: This study does not rule out that pesticide exposure represents an occupational risk factor for extrahepatic biliary tract carcinoma, but no indication of a strong association was observed. Some modes of exposure were weakly, albeit not significantly associated with carcinoma risk. The observed estimates of effects may be influenced by a lack of precise exposure assessment. Different chemical compositions of pesticides were utilized during a long time span of pesticide exposure, and it should be considered that the exposure is assessed with substantial uncertainty that could non-differential and bias results toward the null.

Glutathione S-transferase genotype and p53 mutations in adenocarcinoma of the small intestine.

Adenocarcinoma of the small intestine (ASI) is a rare disease of unknown aetiology. The glutathione S-transferase M1 (GSTM1) enzyme catalyses the detoxification of compounds involved in carcinogenesis of adenocarcinoma of the stomach, colon and lung, including constituents of tobacco smoke. We investigated a possible interaction between the lack of GSTM1 enzyme activity and the carcinogenic compounds of tobacco smoke. Based on the theory that certain carcinogens cause specific point mutations in the p53 gene we analysed by single strand conformation polymorphism (SSCP) and sequencing, p53 exon 5-8 of 52 samples of ASI collected in Sweden, Germany, France, Italy and Denmark between 1995 and 1997. The GSTM1 gene status was investigated by multiplex PCR. The prevalence of GSTM1 negative genotype among cases with ASI was 69% and higher than previous reports of 50% suggesting a higher risk of ASI among GSTM1 negative compared with GSTM1 positive subjects. A 'case-only' approach was used to address the combined association between the GSTM1 negative genotype and lifestyle exposures in patients with ASI. Using this method, heavy smokers (> 20 pack-years) with the GSTM1 negative genotype had an odds ratio of 4.8; 95% confidence interval (CI) (0.6-38.7) for ASI as compared to smokers who expressed GSTM1. No similar association between alcohol consumption and ASI was found. No p53 mutations in exon 5-8 were found in these samples, but the method may not be sensitive enough to identify smaller differences. Thus p53 does not seem to be the target of carcinogens acting in the small intestine.

Viral infection, atopy and mycosis fungoides: a European multicentre case-control study.

Mycosis fungoides (MF) is a rare disease with an unknown aetiology, although it has been suggested that infections may play a role. The present study investigates whether infections, atopic disorders and some other diseases are risk indicators for MF. A European multicentre case-control study involving seven rare cancers, including MF, was conducted from 1995 to 1998. Patients between 35 and 69 years of age diagnosed with MF (n = 140) were recruited, and the diagnoses were verified by a reference pathologist, who classified 83 cases as definitive and 35 cases as possible; 22 cases were not accepted. Of the 118 accepted cases, 104 patients were interviewed (including 76 definitive cases and 28 possible cases). These 76 definitive cases were used for this study. A common set of controls to serve all case groups were interviewed, representing a total of 4574 controls. The latter included 1008 colon cancer patients and 3566 subjects selected from population registers. Information on infections, skin pathology and clinical history 5 years before the diagnosis of MF was used to estimate odds ratios (ORs) derived from logistic regression-modelling, which included gender, age and country. The highest ORs for MF were found in patients who reported a history of psoriasis 5 years before MF was diagnosed (OR 7.2, 95% CI: 3.6-14.5). Urticaria had an OR of 1.4 (95% CI: 0.6-3.6). Infections and atopic diseases were not closely associated with MF. Some diseases correlated to MF. Whether this has a causal background or reflects early diagnostic uncertainty is not known.

Occupational risk factors, ultraviolet radiation, and ocular melanoma: a case-control study in France.

BACKGROUND: Ultraviolet radiation has been suspected as a possible cause of ocular melanoma. Because this association is controversial, we examine the role of occupational exposure to ultraviolet radiation on the occurrence of this rare cancer. MATERIAL AND METHODS: A population-based case-control study was conducted in 10 French administrative areas (départements). Cases were 50 patients with uveal melanoma diagnosed in 1995-1996. Controls were selected at random from electoral rolls, after stratification for age, gender, and area. Among 630 selected persons, 479 (76%) were interviewed. Data on personal characteristics, occupational history, and detailed information on each job held were obtained from face-to-face interviews using a standardized questionnaire. Estimates of occupational exposure to solar and artificial ultraviolet light were made using a job exposure matrix. RESULTS: Results show elevated risks of ocular melanoma for people with light eye color, light skin color, and for subjects with several eye burns. The analysis based on the job exposure matrix showed a significantly increased risk of ocular melanoma in occupational groups exposed to artificial ultraviolet radiation, but not in outdoor occupational groups exposed to sunlight. An elevated risk of ocular melanoma was seen among welders (odds ratio = 7.3; 95% confidence interval = 2.6-20.1 for men), and a dose-response relationship with job duration was observed. The study also showed increased risk of ocular melanoma among male cooks, and among female metal workers and material handling operators. CONCLUSION: Following the present study, the existence of an excess risk of ocular melanoma in welders may now be considered as established. Exposure to ultraviolet light is a likely causal agent, but a possible role of other exposures in the welding processes should not be overlooked.

Medical risk factors for small-bowel adenocarcinoma with focus on Crohn disease: a European population-based case-control study.

BACKGROUND: Crohn disease and biliary diseases have been associated with small-bowel adenocarcinoma (SBA). We examined how medical conditions affect the risk of SBA. METHODS: A population-based European multicentre case-control study during the period 1995-97 including 95 histologically verified cases of SBA along with 3335 population controls; 70 cases (74%) and 2070 (62%) controls were interviewed about previous medical conditions. RESULTS: Crohn disease was identified in two SBA cases (both located in ileum) and two controls; odds ratio (OR) 53.6 (6.0-477) (95% CI in parentheses). Only one case and no controls had had long-standing Crohn disease. Coeliac disease was associated with SBA (2 cases, 0 controls), but one of the cases was diagnosed at the same time as the SBA. Overall, people with a history of gallstones had no increased risk of SBA. The OR was exclusively increased during the 3-year period preceding the SBA diagnosis. Previous gallstone surgery, which may be a sign of severe gallstone disease, was not associated with SBA. Liver cirrhosis, hepatitis or medical treatments with radioactive substances or corticosteroid tablets were not associated with this disease. Cases with SBA had an increased prevalence of anaemia; OR 15.3 (2.5-92.1). An association between low educational level and SBA was found; OR 1.75 (1.0-3.0). CONCLUSION: This study supports Crohn disease and coeliac disease being strong but rare risk factors for SBA. Previous gallstones were unrelated to SBA, and detection bias may account for the findings in earlier studies.

Acute myeloid leukaemia in human immunodeficiency virus-infected adults: epidemiology, treatment feasibility and outcome.

The epidemiology and clinical outcome of acute myeloid leukaemia in human immunodeficiency virus (HIV)-infected adults is poorly documented. We retrospectively surveyed all French haematology centres for adult acute myeloid leukaemia (AML) cases diagnosed between January 1990 and July 1996 who were found to be HIV-seropositive before or at the time of AML diagnosis. Medical charts were reviewed to determine the stage of HIV infection, the characteristics of AML and the response of AML to chemotherapy. Sixteen cases of AML (13 men, three women) were reported by 12 haematology units. Based on assumptions on the size, age and sex distribution of the HIV-infected population in France, the estimated risk of AML in 1990 to 1996 among HIV-infected adults was twice that of the general population (standardized incidence ratio = 2.05; 95% confidence interval, 1.17-3.34). Two other cases occurring before 1990 were spontaneously notified to the authors and were included in the clinical analysis. At AML diagnosis, the median CD4+ cell count was 275 x 106/l and nine patients had acquired immune deficiency syndrome (AIDS). Fifteen patients were scheduled for remission-induction therapy of AML. No deaths were related to AML treatment. Complete remission was obtained in 11 out of 15 patients. Three patients were long-term survivors: two remain alive in complete remission at 8 years and 9 years, respectively, and the third died of AIDS at 8 years. A CD4+ cell count above 200 x 106/l at AML diagnosis was predictive of longer survival (log-rank test: P = 0.004). Like many other malignancies, the incidence of AML appears to be increased in HIV-infected patients. Our results show a twofold higher incidence, although this needs to be confirmed in a specifically designed prospective epidemiological study. Such patients, especially those with CD4+ cell counts above 200 x 106/l at AML diagnosis, should receive remission-induction therapy, which can confer long-term survival.

Are alcohol intake and smoking associated with mycosis fungoides? A European multicentre case-control study.

The incidence of mycosis fungoides (MF) is low, and the aetiology of the disease is unknown. The aim of this study was to investigate whether wine consumption protects against the disease and whether smoking constitutes a risk factor. This paper is part of the European Rare Cancers Study that tries to determine the risk factors for seven selective rare cancers, including mycosis fungoides, involved in the development of cancer. A multicentre case-control study was conducted in six European countries. Only incident cases with confirmed histology were included in the analysis which include a total of 76 cases of MF and 2899 controls. Wine intake had no protective effect; on the contrary the consumption of more than 24 g of alcohol per day was associated with a high risk of MF (odds ratio (OR)=3.02, 95% confidence interval (CI), 1.34-6.79), after adjusting for centre, country, age, sex and education. There was a dose-dependent increase in the risk of MF with increased smoking habits, albeit the observed trend was not statistically significant. A combined exposure to high tobacco and alcohol use yielded a significantly increased risk factor for MF (P=0.0073). Alcohol intake was associated with MF.

Is there an association between alcohol intake or smoking and small bowel adenocarcinoma? Results from a European multi-center case-control study.

OBJECTIVE: To discover whether tobacco smoking and intake of different types of alcoholic drinks are associated with small bowel adenocarcinoma (SBA). METHODS: A population-based European multi-center case-control study was conducted from 1995 to 1997. RESULTS: After a histological review using uniform diagnostic criteria, 47 (33%) of the 142 identified cases of SBA were excluded due to reclassification as either tumors of the papilla of Vater (n = 22), stromal tumors, or metastases; 95 cases were accepted for study. In all, 70 cases of SBA together with 2070 controls matched by age, sex, and region were interviewed. A high intake (more than 24 g alcohol per day) of beer or spirits was associated with SBA, an odds ratio (OR) of 3.5 and 95% confidence intervals (CI) of 1.5-8.0 and 3.4 (95% CI 1.3-9.2), respectively). There was no association with wine intake or total alcohol intake. Tobacco smoking was probably unrelated to SBA. CONCLUSIONS: A high intake of beer or spirits seems to be a risk factor for SBA. Since this association was not seen for wine drinkers, protective components of wine may counterbalance a carcinogenic effect of alcohol on the small bowel. Alternatively, the result may be confounded by other factors, e.g. dietary factors.

Occupation and small bowel adenocarcinoma: a European case-control study.

OBJECTIVES: Because of the rarity of small bowel adenocarcinoma (SBA), little is known about the aetiology of this disease. This study aimed to identify occupational clustering of cases SBA as a systematic approach to new hypotheses on the aetiology of this disease. METHODS: A European multicentre case-control study was conducted in 1995-7, inclusive. Incident cases aged 35-69 years with SBA (n=168) were recruited before acceptance by a pathologist. Altogether 107 cases and 3915 controls were accepted, of which 79 cases, 579 colon cancer controls, and 2070 population controls were interviewed. RESULTS: The strongest industrial risk factors for SBA taking account of 10 years' exposure lag were dry cleaning, manufacture of workwear, mixed farming (women), and manufacture of motor vehicles (men). A significantly increased risk of SBA (odds ratio (OR) and 95% confidence interval (95% CI)) was found among men employed as building caretakers, OR 6.7 (1.7 to 26.0) and women employed as housekeepers, OR 2.2 (1.1 to 4.9); general farm labourers, OR 4.7 (1.8 to 12.2); dockers, OR 2.9 (1.0 to 8.2); dry cleaners or launderers, OR 4.1 (1.2 to 13.6); and textile workers (sewers or embroiderers), OR 2.6 (1.0 to 6.8). For the last four groups, together with welders OR 2.7 (1.1 to 6.6) (men) an exposure-response pattern was found when calculating the ORs for jobs held 1-5 years and >5 years, with never having held the job as reference. The ORs (95% CIs) for 1-5 years and >5 years were 4.3 (0.4 to 44.0) and 3.5 (0.9 to 13.7), 3.0 (0.3 to 26.2) and 4.3 (0.9 to 21.2), 4.6 (0.4 to 48.1) and 11.0 (2.0 to 60.4), 1.3 (0.2 to 11.0) and 5.8 (2.0 to 17.2), and 2.8 (0.3 to 23.8) and 4.6 (1.3 to 16.6), respectively, for each of these occupations. Among welders, people performing semiautomatic arc welding (MIG/MAG) were identified as a high risk group (OR 5.0 (1.3 to 19.6)). CONCLUSIONS: This explorative study suggests an increased occurrence of SBA in certain occupations, which needs further evaluation.

Comparative analyses of the studies of magnetic fields and cancer in electric utility workers: studies from France, Canada, and the United States.

OBJECTIVES: To summarise and to facilitate comparison of three major studies of electric utility workers that examined the relation between quantitative measurements of occupational exposure to magnetic fields and risk of brain cancer and leukaemia. These studies have been interpreted as providing conflicting evidence. METHODS: A common analytical approach was applied to data from the five cohorts included in the three studies based on original data from four of the cohorts, and published data from one additional cohort. A nested case-control design with conditional logistic regression was used to estimate the relative risk/10 microtesla-years (microT-years) for each of the contributing cohorts and for the combined data. The homogeneity of these estimates among the studies was also evaluated. RESULTS: Apparent inconsistencies in the findings of these studies can be explained by statistical variation. Overall, the studies suggest a small increase in risk of both brain cancer and leukaemia. Different methodological choices had little impact on the results. Based on a combined analysis of data from all five studies, the relative risk/10 microT-years was 1.12 (95% confidence interval (95% CI) 0.98 to 1.28) for brain cancer, and 1.09 (95% CI 0.98 to 1.21) for leukaemia. CONCLUSIONS: The combined estimates seem to provide the best summary measures of the data from all studies. However, fluctuations in risks among studies may reflect real differences, and the exposure measurements in different studies may not be entirely comparable.

Occupational cancer in France: epidemiology, toxicology, prevention, and compensation.

This article is a description of the current situation in France with regard to occupational cancer: research, prevention, and occupation. Toxicologic experiments are carried out using (italic)in vitro(/italic) and (italic)in vivo(/italic) tests, particularly using transgenic mice. Several epidemiologic studies have been conducted over the last decades: population-based case-control studies; mortality studies and cancer incidence studies carried out in historical cohorts of workers employed in the industry; and case-control studies nested in occupational cohorts. French ethical aspects of toxicologic and epidemiologic studies are described. The results thus obtained are used to establish regulations for the prevention and the compensation of cancers attributable to occupational exposure. This French regulation for prevention of occupational cancer involves several partners: (italic)a(/italic)) the states authorities, including labor inspectors, responsible for preparing and implementing the labor legislation and for supervising its application, particularly in the fields of occupational health and safety and working conditions; (italic)b(/italic)) the Social Security Organisation for the analysis of present or potential occupational risks based on tests, visits in plants, complaints or requests from various sources, and statistics. These activities are performed within the framework of the general French policy for the prevention of occupational cancer. This organization includes the National Institute for Research and Safety, particularly involved in research in the various fields of occupational risks--animal toxicology, biologic monitoring, exposure measurements epidemiology, psychology, ergonomy, electronic systems and machineries, exposure to chemicals, noise, heat, vibration, and lighting; and (italic)c(/italic)) companies where the regulation defines the role of the plant manager, the occupational physician, and the Health, Safety and Working Conditions Committee (comprising the manager, employees' representatives, the occupational physician, and the safety department) in dealing with any problem regarding safety, occupational hygiene, and working conditions. These organizations along with medical practitioners are involved with the compensation of occupational cancers. The regulation for compensation includes the tables of occupational cancer, the possibility of recognition of a cancer case when the requirements of the tables are not met, and the postprofessional follow-up of workers exposed to a carcinogenic agent.

Exposure to 50-Hz electric field and incidence of leukemia, brain tumors, and other cancers among French electric utility workers.

Recent studies on the association between exposure to 50- to 60-Hz fields and cancer carried out among electric utility workers have focused mainly on the magnetic field component of exposure. The authors have investigated tumor risks specifically associated with electric fields, as this exposure is distinct from magnetic fields. The study design is a case-control study nested within a cohort of 170,000 workers employed at Electricité de France-Gaz de France (EDF) between 1978 and 1989. All incident cases of cancer and benign tumor of the brain diagnosed in 1978-1989 among workers before the age of retirement were included. Four randomly selected controls were individually matched to each case by year of birth. The exposure to electric fields was assessed from measurements collected in 850 EDF workers for a full work week. Arithmetic and geometric mean exposures were included in a job-exposure matrix to determine the cumulative exposure of the cases and the controls. Exposures to potentially carcinogenic chemicals found at the workplace were also evaluated through expert judgment. The analysis by site of tumor did not show any increased risk for leukemia (72 cases). An odds ratio of 3.08 (95% confidence interval 1.08-8.74) was observed for all brain tumors (69 cases) for exposure above the 90th percentile (> or = 387 V/m-year), and there was some indication of a dose-response relation, although the risk did not increase monotonically with exposure. No confounding from magnetic fields or from other potentially carcinogenic hazards was apparent. The observed association was somewhat stronger after allowing a 5-year latency period before diagnosis (odds ratio = 3.69, 95% confidence interval 1.10-12.43) for exposure above the 90th percentile. However, the risk of brain tumor could not be linked to a specific type of tumor. An unexpected association was also observed for colon cancer, using geometric indexes of exposure, but no other association was seen for any other type of cancer. Our study indicates that electric fields may have a specific effect on the risk of brain tumor, and that this should be taken into account in future analyses on the carcinogenic effects of 50- to 60-Hz fields.

[Cancer incidence among active male workers at Electricite de France-Gaz de France]. / Incidence des cancers dans la population masculine des salariés en activité à Electricité de France et Gaz de France.

The social security department of the French national electric and gas company has established a cancer register among a population of about 150,000 active employees based on sick leaves of both short and long duration as well as deaths recorded along with their medical cause. A first study conducted in male workers, aged 20-59, during the 1978-1989 period showed a lower cancer incidence for almost every site of cancer except for leukaemias and others reticuloses tumors of lymphoid and histiocyte tissues, compared with the French general population (SIR = 148 and 218 resp.). Between the 1978-1982 and 1983-1989 periods, a marked decrease (statistically significant) was observed in the incidence of larynx cancer and cancers of all sites usually related with excessive alcohol consumption. During the same period the incidence of pancreatic cancer has almost doubled. Large variations according to socio-economic status were observed for cancers of the lung, the pharynx, the oral cavity and the oesophagus and, also, to a lesser degree, for tumours of the testis and the bladder and leukaemias. The results suggest further studies of occupational factors. Interest and limits of such a compagny register are discussed.

Occupational respiratory cancer and exposure to asbestos: a case-control study in a cohort of workers in the electricity and gas industry.

Cancers of the pleura, lung, and larynx between 1978 and 1989 among active male workers of Electricité de France-Gaz de France were studied in association with asbestos exposure using a case-control design nested within the cohort of workers of the company. The cohort included about 1,400,000 person-years, corresponding to a mean of 117,000 men per year. Exposure to asbestos and to some potential occupational confounders selected among agents from groups I, IIa, and IIb of the International Agency for Research on Cancer was assessed by a job-exposure matrix specific to the company. During the observation period, 12 cases of pleural cancer, 310 cases of lung cancer, and 116 cases of larynx cancer were registered in the cancer register of the company social security department. Four controls per case, matched for year of birth, were randomly selected among the cohort. Conditional logistic regression was used to estimate the odds ratios. A first analysis was conducted in order to assess the validity of the job-exposure matrix by investigating already known relationships between asbestos exposure and asbestosis. For asbestosis, a strong exposure-response relation was found with an odds ratio (OR) of 57.4 [95% confidence interval (CI): 17.0-194.0] in the highest exposure group. There was an elevated risk of pleural cancer (OR, 4.8, CI, 1.2-19.8). For lung cancer, significant ORs of 2.0 (CI, 1.3-3.2) and 1.9 (CI, 1.2-3.0) were found among the two highest cumulative exposure groups; adjustement for confounders slightly decreased the ORs. Squamous cell neoplasm of the lung was associated with asbestos exposure. The association between larynx cancer and asbestos exposure showed a tendency towards a nonsignificant increase in ORs in the highest cumulative exposure categories; this tendency disappeared when adjusting for occupational confounders. This study showed that occupational exposure to asbestos could increase the risk of pleural and lung cancer in a sector in which exposure levels are not considered to be high compared with other industrial settings.

Association between exposure to pulsed electromagnetic fields and cancer in electric utility workers in Quebec, Canada, and France.

The authors report the association between exposure to pulsed electromagnetic fields (PEMFs) and cancer in a nested case-control study of electric utility workers in Quebec, Canada (follow-up, 1970-1988), and France (follow-up, 1978-1989), among whom 2,679 cases of cancer were identified. Exposures were assessed through a job-exposure matrix based on about 1,000 person-weeks of measurements from exposure meters worn by workers. Exposures were considerably higher in Quebec than in France. No association was found between PEMFs and cancers previously suspected of association with magnetic fields (leukemia, other hematopoietic cancers, brain cancer, or melanoma). However, there was a clear association between cumulative exposure to PEMFs and lung cancer, with odds ratios rising to 3.11 (95% confidence interval (CI) 1.60-6.04) in the highest exposure group (84 cases). This association with largely confined to Quebec, where there was a monotonic exposure-response relation with an odds ratio of 6.67 (95% CI 2.68-16.57) in the highest exposure group (32 cases). The association is substantial and was not explained by smoking or other occupational exposures. However, several factors limit the strength of the evidence for a causal relation: lack of precision in what the meters measured; little previous evidence for this association; and no elevated risk for lung cancer in the utility workers overall in comparison with the general population.

Cancer risks associated with occupational exposure to magnetic fields among electric utility workers in Ontario and Quebec, Canada, and France: 1970-1989.

To determine whether occupational exposure to magnetic fields of 50-60 Hz was associated with cancer among electric utility workers, the authors used a case-control design nested within three cohorts of workers at electric utilities: Electricité de France--Gaz de France, 170,000 men; Ontario Hydro, 31,543 men; and Hydro-Québec, 21,749 men. During the observation period, 1970-1989, 4,151 new cases of cancer occurred. Each participant's cumulative exposure to magnetic fields was estimated based on measurements of current exposure of 2,066 workers performing tasks similar to those in the cohorts using personal dosimetry. Estimates were also made of past exposure based on knowledge of current loading, work practices, and usage. Workers who had more than the median cumulative exposure to magnetic fields (3.1 microtesla (microT)-years) had a higher risk for acute nonlymphoid leukemia (odds ratio (OR) = 2.41, 95% confidence interval (CI) 1.07-5.44). The same observation holds for acute myeloid leukemia (OR = 3.15, 95% CI 1.20-8.27). There was also an elevated risk for mean exposure above 0.2 microT (acute nonlymphoid leukemia, OR = 2.36, 95% CI 1.00-5.58; acute myeloid leukemia, OR = 2.25, 95% CI 0.79-6.46). However, there were no clear dose-response trends with increasing exposure and no consistency among the three utilities. Men whose cumulative exposure to magnetic fields was above the 90th percentile (15.7 microT-years) had an elevated risk for brain cancer (OR = 1.95, 95% CI 0.76-5.00) that was not statistically significant. No association with magnetic fields was observed for any of the other 29 types of cancer studied, including skin melanoma, male breast cancer, and prostate cancer. Controlling for potential confounding factors did not change the results.

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.