Life expectancy after the first suicide attempt.

OBJECTIVE: To assess excess mortality among suicide attempters compared to the general population. METHOD: Remaining life expectancy was calculated for a nationwide cohort of all 187 894 persons 18 years or older hospitalised for the first time attempted suicide in Sweden in 1971-2010. RESULTS: Life expectancy was shortened throughout the lifespan for both men and women debuting with suicide attempt. The reduction in life expectancy for men debuting with a suicide attempt at 20 years of age was 18 years while the reduction for men debuting at 50 years of age was 10 years. For women attempting suicide, the life expectancy was shortened by 11 and 8 years respectively. The gender difference in life expectancy attenuated in patients making their first suicide attempt at age 70 years or older. Suicide deaths explained about 20% of the total mortality within 10 years of the suicide attempt and 5% in those with duration of four decades since the first suicide attempt. CONCLUSION: The life expectancy is dramatically reduced in patients attempting suicide. With most excess deaths being due to physical health conditions, public efforts should be directed both towards improving physical health and to prevent suicide.

Atopic conditions and brain tumor risk in children and adolescents--an international case-control study (CEFALO).

BACKGROUND: A number of epidemiological studies indicate an inverse association between atopy and brain tumors in adults, particularly gliomas. We investigated the association between atopic disorders and intracranial brain tumors in children and adolescents, using international collaborative CEFALO data. PATIENTS AND METHODS: CEFALO is a population-based case-control study conducted in Denmark, Norway, Sweden, and Switzerland, including all children and adolescents in the age range 7-19 years diagnosed with a primary brain tumor between 2004 and 2008. Two controls per case were randomly selected from population registers matched on age, sex, and geographic region. Information about atopic conditions and potential confounders was collected through personal interviews. RESULTS: In total, 352 cases (83%) and 646 controls (71%) participated in the study. For all brain tumors combined, there was no association between ever having had an atopic disorder and brain tumor risk [odds ratio 1.03; 95% confidence interval (CI) 0.70-1.34]. The OR was 0.76 (95% CI 0.53-1.11) for a current atopic condition (in the year before diagnosis) and 1.22 (95% CI 0.86-1.74) for an atopic condition in the past. Similar results were observed for glioma. CONCLUSIONS: There was no association between atopic conditions and risk of all brain tumors combined or of glioma in particular. Stratification on current or past atopic conditions suggested the possibility of reverse causality, but may also the result of random variation because of small numbers in subgroups. In addition, an ongoing tumor treatment may affect the manifestation of atopic conditions, which could possibly affect recall when reporting about a history of atopic diseases. Only a few studies on atopic conditions and pediatric brain tumors are currently available, and the evidence is conflicting.

Patterns of exposure to infectious diseases and social contacts in early life and risk of brain tumours in children and adolescents: an International Case-Control Study (CEFALO).

BACKGROUND: Infectious diseases and social contacts in early life have been proposed to modulate brain tumour risk during late childhood and adolescence. METHODS: CEFALO is an interview-based case-control study in Denmark, Norway, Sweden and Switzerland, including children and adolescents aged 7-19 years with primary intracranial brain tumours diagnosed between 2004 and 2008 and matched population controls. RESULTS: The study included 352 cases (participation rate: 83%) and 646 controls (71%). There was no association with various measures of social contacts: daycare attendance, number of childhours at daycare, attending baby groups, birth order or living with other children. Cases of glioma and embryonal tumours had more frequent sick days with infections in the first 6 years of life compared with controls. In 7-19 year olds with 4+ monthly sick day, the respective odds ratios were 2.93 (95% confidence interval: 1.57-5.50) and 4.21 (95% confidence interval: 1.24-14.30). INTERPRETATION: There was little support for the hypothesis that social contacts influence childhood and adolescent brain tumour risk. The association between reported sick days due to infections and risk of glioma and embryonal tumour may reflect involvement of immune functions, recall bias or inverse causality and deserve further attention.

Extremely low-frequency magnetic fields and survival from childhood acute lymphoblastic leukemia: an international follow-up study.

A previous US study reported poorer survival in children with acute lymphoblastic leukemia (ALL) exposed to extremely low-frequency magnetic fields (ELF-MF) above 0.3 µT, but based on small numbers. Data from 3073 cases of childhood ALL were pooled from prospective studies conducted in Canada, Denmark, Germany, Japan, UK and US to determine death or relapse up to 10 years from diagnosis. Adjusting for known prognostic factors, we calculated hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival and event-free survival for ELF-MF exposure categories and by 0.1 µT increases. The HRs by 0.1 µT increases were 1.00 (CI, 0.93-1.07) for event-free survival analysis and 1.04 (CI, 0.97-1.11) for overall survival. ALL cases exposed to >0.3 µT did not have a poorer event-free survival (HR=0.76; CI, 0.44-1.33) or overall survival (HR=0.96; CI, 0.49-1.89). HRs varied little by subtype of ALL. In conclusion, ELF-MF exposure has no impact on the survival probability or risk of relapse in children with ALL.

Incidence trends of vestibular schwannomas in Denmark, Finland, Norway and Sweden in 1987-2007.

BACKGROUND: The reported incidence rates of vestibular schwannomas (VS) vary substantially, but it is unclear as to what extent the variation reflects differences in risk or recording practices. Our aim was to describe the incidence rates of VS in Denmark, Finland, Norway and Sweden between 1987 and 2007. METHODS: Comprehensive data were available from all registries only for the period from 1987 to 2007. An analysis of a longer time period (1965-2007) was conducted with the Norwegian and Swedish data. RESULTS: The average age-standardised incidence rates during 1987-2007 varied from 6.1 per 1,000,000 person-years (95% confidence interval (CI), 5.4-6.7) among Finnish men to 11.6 (95% CI, 10.4-12.7) in Danish men, and from 6.4 per 1,000,000 person-years (95% CI, 5.7-7.0) among Swedish women to 11.6 (95% CI, 10.5-12.8) among Danish women. An overall annual increase of 3.0% (95% CI 2.1-3.9) was observed when all countries and both sexes were combined, with considerable differences between countries. However, the practices of both reporting and coding VS cases varied markedly between countries and over time, which poses a challenge for interpretation of the results. CONCLUSION: The overall incidence of VS increased in all the four Nordic countries combined between 1987 and 2007, with marked differences between countries. However, the incidence rates more or less stabilised in the late 1990s, showing relatively constant incidence rates and even some decline after 2000.

A pooled analysis of extremely low-frequency magnetic fields and childhood brain tumors.

Pooled analyses may provide etiologic insight about associations between exposure and disease. In contrast to childhood leukemia, no pooled analyses of childhood brain tumors and exposure to extremely low-frequency magnetic fields (ELF-MFs) have been conducted. The authors carried out a pooled analysis based on primary data (1960-2001) from 10 studies of ELF-MF exposure and childhood brain tumors to assess whether the combined results, adjusted for potential confounding, indicated an association. The odds ratios for childhood brain tumors in ELF-MF exposure categories of 0.1-<0.2 µT, 0.2-<0.4 µT, and ≥0.4 µT were 0.95 (95% confidence interval: 0.65, 1.41), 0.70 (95% CI: 0.40, 1.22), and 1.14 (95% CI: 0.61, 2.13), respectively, in comparison with exposure of <0.1 µT. Other analyses employing alternate cutpoints, further adjustment for confounders, exclusion of particular studies, stratification by type of measurement or type of residence, and a nonparametric estimate of the exposure-response relation did not reveal consistent evidence of increased childhood brain tumor risk associated with ELF-MF exposure. These results provide little evidence for an association between ELF-MF exposure and childhood brain tumors.

Determinants of mobile phone output power in a multinational study: implications for exposure assessment.

OBJECTIVES: The output power of a mobile phone is directly related to its radiofrequency (RF) electromagnetic field strength, and may theoretically vary substantially in different networks and phone use circumstances due to power control technologies. To improve indices of RF exposure for epidemiological studies, we assessed determinants of mobile phone output power in a multinational study. METHODS: More than 500 volunteers in 12 countries used Global System for Mobile communications software-modified phones (GSM SMPs) for approximately 1 month each. The SMPs recorded date, time, and duration of each call, and the frequency band and output power at fixed sampling intervals throughout each call. Questionnaires provided information on the typical circumstances of an individual's phone use. Linear regression models were used to analyse the influence of possible explanatory variables on the average output power and the percentage call time at maximum power for each call. RESULTS: Measurements of over 60,000 phone calls showed that the average output power was approximately 50% of the maximum, and that output power varied by a factor of up to 2 to 3 between study centres and network operators. Maximum power was used during a considerable proportion of call time (39% on average). Output power decreased with increasing call duration, but showed little variation in relation to reported frequency of use while in a moving vehicle or inside buildings. Higher output powers for rural compared with urban use of the SMP were observed principally in Sweden where the study covered very sparsely populated areas. CONCLUSIONS: Average power levels are substantially higher than the minimum levels theoretically achievable in GSM networks. Exposure indices could be improved by accounting for average power levels of different telecommunications systems. There appears to be little value in gathering information on circumstances of phone use other than use in very sparsely populated regions.

Occupational exposure to UV light and mortality from multiple sclerosis.

BACKGROUND: The etiology of multiple sclerosis (MS) is largely unknown; low exposure to ultraviolet (UV) light has been a suggested risk factor. The aim of this study was to investigate whether occupational exposure to UV light reduces the risk of death from MS. METHODS: The cohort was based on all individuals in the Swedish census in 1980. All MS-related deaths were identified in the national registry of causes of death. A job-exposure matrix was developed to classify the occupational exposure to UV light. RESULTS: MS was recorded as a cause of the death for 839 individuals. The risk of MS-related death decreased with increasing occupational exposure to UV light. The relative risk adjusted for age, sex, and socioeconomic status was 0.48 (95% CI 0.28-0.80) in the high-exposure group and 0.88 (95% CI 0.73-1.06) in the intermediate-exposure group. CONCLUSIONS: Occupational exposure to UV light was associated with a reduced risk of MS. Our findings are corroborated by previous observations that UV light has a preventive role in the development of MS, although the possibility of reversed causality cannot be completely ruled out.

Future needs of occupational epidemiology of extremely low frequency electric and magnetic fields: review and recommendations.

The occupational epidemiological literature on extremely low frequency electric and magnetic fields (EMF) and health encompasses a large number of studies of varying design and quality that have addressed many health outcomes, including various cancers, cardiovascular disease, depression and suicide, and neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis (ALS). At a 2006 workshop we reviewed studies of occupational EMF exposure with an emphasis on methodological weaknesses, and proposed analytical ways to address some of these. We also developed research priorities that we hope will address remaining uncertainties. Broadly speaking, extensive epidemiological research conducted during the past 20 years on occupational EMF exposure does not indicate strong or consistent associations with cancer or any other health outcomes. Inconsistent results for many of the outcomes may be attributable to numerous shortcomings in the studies, most notably in exposure assessment. There is, however, no obvious correlation between exposure assessment quality and observed associations. Nevertheless, for future research, the highest priorities emerge in both the areas of exposure assessment and investigation of ALS. To better assess exposure, we call for the development of a more complete job-exposure matrix that combines job title, work environment and task, and an index of exposure to electric fields, magnetic fields, spark discharge, contact current, and other chemical and physical agents. For ALS, we propose an international collaborative study capable of illuminating a reported association with electrical occupations by disentangling the potential roles of electric shocks, magnetic fields and bias. Such a study will potentially lead to evidence-based measures to protect public health.

Meningioma and mobile phone use--a collaborative case-control study in five North European countries.

BACKGROUND: Use of mobile telephones has been suggested as a possible risk factor for intracranial tumours. To evaluate the effect of mobile phones on risk of meningioma, we carried out an international, collaborative case-control study of 1209 meningioma cases and 3299 population-based controls. METHODS: Population-based cases were identified, mostly from hospitals, and controls from national population registers and general practitioners' patient lists. Detailed history of mobile phone use was obtained by personal interview. Regular mobile phone use (at least once a week for at least 6 months), duration of use, cumulative number and hours of use, and several other indicators of mobile phone use were assessed in relation to meningioma risk using conditional logistic regression with strata defined by age, sex, country and region. RESULTS: Risk of meningioma among regular users of mobile phones was apparently lower than among never or non-regular users (odds ratio, OR = 0.76, 95% confidence interval, CI 0.65, 0.89). The risk was not increased in relation to years since first use, lifetime years of use, cumulative hours of use or cumulative number of calls. The findings were similar regardless of telephone network type (analogue/digital), age or sex. CONCLUSIONS: Our results do not provide support for an association between mobile phone use and risk of meningioma.

Medical history, cigarette smoking and risk of acoustic neuroma: an international case-control study.

Acoustic neuroma (vestibular schwannoma) is a benign tumor of the vestibulocochlear nerve. Its recorded incidence is increasing but risk factors for this tumor have scarcely been investigated. We conducted a population-based case-control study of risk factors for acoustic neuroma in the UK and Nordic countries, including 563 cases and 2,703 controls. Tumor risk was analyzed in relation to medical history and cigarette smoking. Risk of acoustic neuroma was significantly raised in parous compared with nulliparous women (OR = 1.7, 95% CI: 1.1-2.6), but was not related to age at first birth or number of children. Risk was not associated with a history of allergic disease, past head injury, past diagnosis of a neoplasm or birth characteristics, but was significantly raised for past diagnosis of epilepsy (OR = 2.5, 95% CI: 1.3-4.9). Tumor risk was significantly reduced in subjects who had ever regularly smoked cigarettes (OR = 0.7, 95% CI: 0.6-0.9), but the reduction applied only to current smokers (OR = 0.5, 95% CI: 0.4-0.6), not ex-smokers (OR = 1.0, 95% CI: 0.8-1.3). The reduced risk of acoustic neuroma in smokers and raised risk in parous women might relate to sex hormone levels, or smoking might suppress tumor growth, but effects of parity and smoking on timing of diagnosis of the tumor are also a potential explanation. The raised risk in relation to past diagnosis of epilepsy might be a surveillance artefact or imply that epilepsy and/or antiepileptic medication use predispose to acoustic neuroma. These findings need replication by other studies and possible mechanisms need to be clarified.

Epilepsy as a risk factor for cancer.

AIM: Epilepsy and long term use of antiepileptic drugs have been suggested to be associated with an increased risk of cancer. The authors therefore set out to analyse previous diagnosis of epilepsy as a risk factor for certain cancer forms in a case control study. METHODS: Incident cases of leukaemia, lymphoma, myeloma, and pancreatic cancer were identified from the Swedish Cancer Registry 1987-99, a total of 52 861 cases. Controls (n = 137 485) were randomly selected from the Swedish Population Registry stratified on age, sex, and year of cancer diagnosis. Cases and controls were linked to the Swedish Hospital Discharge Registry for 1969-99 to identify individuals with first time hospital discharge for epilepsy. RESULTS: While an epilepsy diagnosis the same year as a cancer diagnosis carried an increased risk of non-Hodgkin's lymphoma (OR = 2.89, 95% CI 1.89 to 4.41), Hodgkin's disease (OR = 4.77, 95% CI 1.77 to 13.30), leukaemia (OR = 2.55, 95% CI 1.50 to 4.32), acute myeloid leukaemia (OR = 3.65, 95% CI 1.68 to 7.93), and pancreatic cancer (OR = 2.05, 95% CI 1.22 to 3.45), the authors found no support for an association between discharge with a diagnosis of epilepsy two years or more before the diagnosis of cancer and an increased risk of any of the types of cancer included in this analysis. The lack of association was also evident for individuals with an epilepsy diagnosis preceding malignancy/reference year by >10 years. CONCLUSIONS: Clinical examinations prompted by seizure onset probably mainly explain the observed association between epilepsy diagnoses the year before a cancer diagnosis. However, these results lend no support to the suggestion that epilepsy, and presumably long term exposure to antiepileptic drugs, is associated with an increased risk of the types of cancer included in the present study.

Validation of short term recall of mobile phone use for the Interphone study.

AIM: To validate short term recall of mobile phone use within Interphone, an international collaborative case control study of tumours of the brain, acoustic nerve, and salivary glands related to mobile telephone use. METHODS: Mobile phone use of 672 volunteers in 11 countries was recorded by operators or through the use of software modified phones, and compared to use recalled six months later using the Interphone study questionnaire. Agreement between recalled and actual phone use was analysed using both categorical and continuous measures of number and duration of phone calls. RESULTS: Correlations between recalled and actual phone use were moderate to high (ranging from 0.5 to 0.8 across countries) and of the same order for number and duration of calls. The kappa statistic demonstrated fair to moderate agreement for both number and duration of calls (weighted kappa ranging from 0.20 to 0.60 across countries). On average, subjects underestimated the number of calls per month (geometric mean ratio of recalled to actual = 0.92, 95% CI 0.85 to 0.99), whereas duration of calls was overestimated (geometric mean ratio = 1.42, 95% CI 1.29 to 1.56). The ratio of recalled to actual use increased with level of use, showing underestimation in light users and overestimation in heavy users. There was substantial heterogeneity in this ratio between countries. Inter-individual variation was also large, and increased with level of use. CONCLUSIONS: Volunteer subjects recalled their recent phone use with moderate systematic error and substantial random error. This large random error can be expected to reduce the power of the Interphone study to detect an increase in risk of brain, acoustic nerve, and parotid gland tumours with increasing mobile phone use, if one exists.

Mobile phone use and risk of acoustic neuroma: results of the Interphone case-control study in five North European countries.

There is public concern that use of mobile phones could increase the risk of brain tumours. If such an effect exists, acoustic neuroma would be of particular concern because of the proximity of the acoustic nerve to the handset. We conducted, to a shared protocol, six population-based case-control studies in four Nordic countries and the UK to assess the risk of acoustic neuroma in relation to mobile phone use. Data were collected by personal interview from 678 cases of acoustic neuroma and 3553 controls. The risk of acoustic neuroma in relation to regular mobile phone use in the pooled data set was not raised (odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7-1.1). There was no association of risk with duration of use, lifetime cumulative hours of use or number of calls, for phone use overall or for analogue or digital phones separately. Risk of a tumour on the same side of the head as reported phone use was raised for use for 10 years or longer (OR = 1.8, 95% CI: 1.1-3.1). The study suggests that there is no substantial risk of acoustic neuroma in the first decade after starting mobile phone use. However, an increase in risk after longer term use or after a longer lag period could not be ruled out.

Output power levels from mobile phones in different geographical areas; implications for exposure assessment.

BACKGROUND: The power level used by the mobile phone is one of the most important factors determining the intensity of the radiofrequency exposure during a call. Mobile phone calls made in areas where base stations are densely situated (normally urban areas) should theoretically on average use lower output power levels than mobile phone calls made in areas with larger distances between base stations (rural areas). AIMS: To analyse the distribution of power levels from mobile phones in four geographical areas with different population densities. METHODS: The output power for all mobile phone calls managed by the GSM operator Telia Mobile was recorded during one week in four defined areas (rural, small urban, suburban, and city area) in Sweden. The recording included output power for the 900 MHz and the 1800 MHz frequency band. RESULTS: In the rural area, the highest power level was used about 50% of the time, while the lowest power was used only 3% of the time. The corresponding numbers for the city area were approximately 25% and 22%. The output power distribution in all defined urban areas was similar. CONCLUSION: In rural areas where base stations are sparse, the output power level used by mobile phones are on average considerably higher than in more densely populated areas. A quantitative assessment of individual exposure to radiofrequency fields is important for epidemiological studies of possible health effects for many reasons. Degree of urbanisation may be an important parameter to consider in the assessment of radiofrequency exposure from mobile phone use.

Occupational magnetic field exposure among women in Stockholm County, Sweden.

BACKGROUND: Most epidemiological studies on adverse health effects among women in relation to occupational magnetic field exposure have been based on information about men's exposure. AIMS: To create a job-exposure matrix for occupational exposure to extremely low frequency magnetic fields among women. METHODS AND RESULTS: Measurements were performed using personal magnetic field meters (Emdex Lite) carried by the subjects for 24 hours on a normal workday. Subjects were volunteer women working in the occupations identified as common among women in Stockholm County based on the 1980 census. A total of 471 measurements were made in 49 different occupations, with a minimum of 5 and a maximum of 24 measurements in each occupation. The included occupations cover about 85% of the female population gainfully employed in 1980. Parameters representing average and peak magnetic field exposures, temporal change in the exposure, and proportion of time spent above certain exposure levels were calculated both for the workday and for the total 24 hour period grouped by occupational titles. The occupations with higher than average exposure were cashiers, working proprietors in retail trade, air stewardesses, dental nurses, cooks, post-office clerks and kitchen maids. CONCLUSIONS: This new job-exposure matrix substantially increases the knowledge about magnetic field exposure among women and can be used for exposure assessment in future studies.

Occupational sunlight exposure and cancer incidence among Swedish construction workers.

We studied sunlight exposure from outdoor work in relation to cancer, using data from 323,860 men participating in an occupational health service program of the Swedish construction industry. An experienced industrial hygienist assessed the exposure for 200 job tasks. We estimated relative risks (RRs) adjusted for age, smoking, and magnetic field exposure. There was an increased RR in the high-exposure group for myeloid leukemia [RR = 2.0, 95% confidence interval (95% CI) = 1.1-3.6] and lymphocytic leukemia (RR = 1.7, 95% CI = 0.9-3.2). For non-Hodgkin's lymphoma there was a 30% increase in risk in the high-exposure group (95% CI = 0.9-1.9). There was no increased risk of malignant melanoma, except for tumors of the head, face, and neck in the high-exposure group (RR = 2.0, 95% CI = 0.8-5.2), and we also found an increased risk for malignant melanoma of the eye in this group (RR = 3.4, 95% CI = 1.1-10.5). Outdoor workers had no increased risk of nonmelanoma skin cancer. Nevertheless, the RR for lip cancer (squamous cell carcinoma) among the high-exposure group was estimated at 1.8 (95% CI = 0.8-3.7). Among other sites, an increased risk of stomach cancer was suggested in this group (RR = 1.4, 95% CI = 1.0-1.9). The results for lymphoma, leukemia, and possibly also for stomach cancer might reflect a suppression of the immune system from ultraviolet light in outdoor workers.

Fatty fish consumption and risk of prostate cancer.

Consumption of fatty fish might reduce the risk of prostate cancer, although epidemiological studies of fish consumption are rare. We studied the association between fish consumption and prostate cancer in a population-based prospective cohort of 6272 Swedish men. During 30 years of follow-up, men who ate no fish had a two-fold to three-fold higher frequency of prostate cancer than those who ate moderate or high amounts did. Our results suggest that fish consumption could be associated with decreased risk of prostate cancer.

Physical activity and risk of renal cell cancer.

The relation between physical activity and renal cell cancer is unclear. High occupational physical activity has been associated with a decreased risk of renal cell cancer among men-but not among women-in two previous studies, while no association has been found for leisure time physical activity. Our aim was to investigate the association between occupational and leisure time physical activity in a prospective cohort of 17,241 Swedish twins. Information on physical activity and a wide range of potential confounding factors was obtained through a mailed questionnaire. During follow-up from 1967 through 1997 we identified 102 cases of renal cell cancer. We found no evidence of an inverse association between either occupational or leisure time physical activity and risk of renal cell cancer in this prospective cohort.