Regression calibration of self-reported mobile phone use to optimize quantitative risk estimation in the COSMOS study.

The Cohort Study of Mobile Phone Use and Health (COSMOS) has repeatedly collected self-reported and operator-recorded data on mobile phone use. Assessing health effects using self-reported information is prone to measurement error, but operator data were available prospectively for only part of the study population and did not cover past mobile phone use. To optimize the available data and reduce bias, we evaluated different statistical approaches for constructing mobile phone exposure histories within COSMOS. We evaluated and compared the performance of four regression calibration (RC) methods (simple, direct, inverse, and generalized additive model for location, shape, and scale), complete-case (CC) analysis and multiple imputation (MI) in a simulation study with a binary health outcome. We used self-reported and operator-recorded mobile phone call data collected at baseline (2007-2012) from participants in Denmark, Finland, the Netherlands, Sweden, and the UK. Parameter estimates obtained using simple, direct, and inverse RC methods were associated with less bias and lower mean squared error than those obtained with CC analysis or MI. We showed that RC methods resulted in more accurate estimation of the relation between mobile phone use and health outcomes, by combining self-reported data with objective operator-recorded data available for a subset of participants.

Radon Exposure Concentrations in Finnish Workplaces.

ABSTRACT: The aim of this study was to obtain information on the radon concentrations to which Finnish workers are exposed. Radon measurements were conducted as integrated measurements in 700 workplaces, supplemented by continuous radon measurements in 334 workplaces. The occupational radon concentration was calculated by multiplying the result of the integrated measurements by the seasonal correction factor and the ventilation correction factor (ratio between the working time and the full-time radon concentration obtained from continuous measurement). The annual radon concentration to which workers are exposed was weighted by the actual number of workers in each province. In addition, workers were divided into three main occupational categories (working mainly outdoors, underground, or indoors above ground). Probability distribution of the parameters affecting radon concentration levels were generated to calculate a probabilistic estimate of the number of workers exposed to excessive radon levels. With deterministic methods, the geometric and arithmetic mean radon concentrations in conventional, above-ground workplaces were 41 and 91 Bq m -3 , respectively. The estimated geometric and arithmetic mean annual radon concentrations that Finnish workers are exposed to were assessed as 19 and 33 Bq m -3 , respectively. The generic ventilation correction factor for workplaces was calculated as 0.87. Assessed with probabilistic methods, there are approximately 34,000 workers in Finland whose exposure to radon exceeds the reference level of 300 Bq m -3 . Although radon concentrations are generally low in Finnish workplaces, many workers are exposed to high levels of radon. Radon exposure in the workplace is the most common source of occupational radiation exposure in Finland.

Lung cancer incidence attributable to residential radon exposure in Finland.

This study aimed to estimate (1) the number of avoidable lung cancer cases attributable to residential radon in Finland in 2017, separately by age, sex, dwelling type and smoking status, (2) the impact of residential radon alone and the joint effect of residential radon and smoking on the number of lung cancers and (3) the potential decrease in the number of radon-attributable lung cancers if radon concentrations exceeding specified action levels (100, 200 and 300 Bq m-3) would have been mitigated to those levels. Population-based surveys of radon concentrations and smoking patterns were used. Observed radon levels were contrasted with 25 Bq m-3 representing a realistic minimum level of exposure. Lung cancer risk estimates for radon and smoking were derived from literature. Lastly, the uncertainty due to the estimation of exposure and risk was quantified using a computationally derived uncertainty interval. At least 3% and at most 8% of all lung cancers were estimated as being attributable to residential radon. For small cell carcinoma, the proportion of cases attributable to radon was 8-13%. Among smokers, the majority of the radon-related cases were attributable to the joint effect of radon and smoking. Reduction of radon exposure to 100 Bq m-3 action level would eliminate approximately 30% of radon-attributable cases. Estimates were low compared with the literature, given the (relatively high) radon levels in Finland. This was mainly due to the lower radon levels and higher smoking prevalence in flats than in houses and a more realistic point of comparison, factors which have been ignored in previous studies. The results can guide actions in radon protection and in prevention of lung cancers.

IMPROVING THE ASSESSMENT OF OCCUPATIONAL EXPOSURE TO RADON IN ABOVE-GROUND WORKPLACES.

Representative sampling of radon in indoor air is difficult because the concentration often exhibits unpredictable spatial and temporal variation. In workplaces, temporal variation may be rapid, and the minimum and maximum concentration can differ by a factor of 100. In this paper, we compare methods for assessing the radon concentration in workplaces utilising the results of an initial investigation with a track-etch detector and the results of an additional continuous measurement. The recommended method is as follows: the mean radon concentration during the working hours of 1 week, as well as the weekly mean, is calculated from the continuous measurement. The ratio between these mean concentrations is multiplied by the result from the track-etch detector. The coefficient of variation of this method is assessed as 19%. If the result of 1 week of continuous measurement is used alone, the coefficient of variation is assessed as 32%.

Radon in Finnish underground mines 2011-2019.

Radon measurements in Finnish underground mines were started in 1972. Since 1992, regular radon inspections by the competent authority have been carried out in all underground mines. During these inspections, several grab samples are taken from the air, which are later measured in the laboratory. This is a follow-up survey of radon concentrations in the air of the underground mines. The average radon concentrations in the mines between the years 2011 and 2019 varied from 90 to 1100 Bq m-3. Overall, the occupational radon exposure in the Finnish underground mines has remained at a low level from the 1990s onwards. In recent years, high radon concentrations have been observed only in those mines where active mining has ceased. Compared to other recent studies in mines in other countries, radon concentrations in Finnish mines are approximately at the same level. Uncertainties relating to infrequent grab sampling have been recognised and the authority is now testing personal radon detectors that may be used for the exposure assessment in the future.

Indoor Radon Measurements in Finnish Daycare Centers and Schools-Enforcement of the Radiation Act.

BACKGROUND: Indoor radon exposure is the second leading cause of lung cancer. Finnish radiation legislation obligates employers to measure indoor radon concentrations in workplaces, including schools and daycare centers, if they are in radon prone areas. Surveillance campaigns were conducted to ensure that the required radon measurements were performed and to gain knowledge on current indoor radon levels in daycare centers and schools. METHODS: Daycare centers located in the high-radon risk municipalities were identified. Schools where indoor radon level measurements were obligatory but not performed, were identified. RESULTS: Indoor radon measurements were performed in 633 daycare centers where the mean radon concentration was 86 Bq/m3 and the median 40 Bq/m3. The radon level was greater than 300 Bq/m3 in 8% (n = 49) of daycare centers. The radon measurements were performed in 1176 schools, which is 95% of the schools to be measured. The mean radon concentration was 82 Bq/m3 and the median 41 Bq/m3. The radon levels were greater than 300 Bq/m3 in 14% (n = 169) of the schools. CONCLUSIONS: The systematic surveillance campaigns by the radiation protection authority were very efficient in order to ensure that the measurements are performed in schools and daycare centers. The campaigns also reduced the radon exposure of employees, children, and adolescents, where necessary.

Long-term effect of mobile phone use on sleep quality: Results from the cohort study of mobile phone use and health (COSMOS).

BACKGROUND: Effects of radiofrequency electromagnetic field exposure (RF-EMF) from mobile phone use on sleep quality has mainly been investigated in cross-sectional studies. The few previous prospective cohort studies found no or inconsistent associations, but had limited statistical power and short follow-up. In this large prospective cohort study, our aim was to estimate the effect of RF-EMF from mobile phone use on different sleep outcomes. MATERIALS AND METHODS: The study included Swedish (n = 21,049) and Finnish (n = 3120) participants enrolled in the Cohort Study of Mobile Phone Use and Health (COSMOS) with information about operator-recorded mobile phone use at baseline and sleep outcomes both at baseline and at the 4-year follow-up. Sleep disturbance, sleep adequacy, daytime somnolence, sleep latency, and insomnia were assessed using the Medical Outcome Study (MOS) sleep questionnaire. RESULTS: Operator-recorded mobile phone use at baseline was not associated with most of the sleep outcomes. For insomnia, an odds ratio (OR) of 1.24, 95% CI 1.03-1.51 was observed in the highest decile of mobile phone call-time (>258 min/week). With weights assigned to call-time to account for the lower RF-EMF exposure from Universal Mobile Telecommunications Service (UMTS, 3G) than from Global System for Mobile Communications (GSM, 2G) the OR was 1.09 (95% CI 0.89-1.33) in the highest call-time decile. CONCLUSION: Insomnia was slightly more common among mobile phone users in the highest call-time category, but adjustment for the considerably lower RF-EMF exposure from the UMTS than the GSM network suggests that this association is likely due to other factors associated with mobile phone use than RF-EMF. No association was observed for other sleep outcomes. In conclusion, findings from this study do not support the hypothesis that RF-EMF from mobile phone use has long-term effects on sleep quality.

Headache, tinnitus and hearing loss in the international Cohort Study of Mobile Phone Use and Health (COSMOS) in Sweden and Finland.

BACKGROUND: Mobile phone use and exposure to radiofrequency electromagnetic fields (RF-EMF) from it have been associated with symptoms in some studies, but the studies have shortcomings and their findings are inconsistent. We conducted a prospective cohort study to assess the association between amount of mobile phone use at baseline and frequency of headache, tinnitus or hearing loss at 4-year follow-up. METHODS: The participants had mobile phone subscriptions with major mobile phone network operators in Sweden (n = 21 049) and Finland (n = 3120), gave consent for obtaining their mobile phone call data from operator records at baseline, and filled in both baseline and follow-up questionnaires on symptoms, potential confounders and further characteristics of their mobile phone use. RESULTS: The participants with the highest decile of recorded call-time (average call-time >276 min per week) at baseline showed a weak, suggestive increased frequency of weekly headaches at 4-year follow-up (adjusted odds ratio 1.13, 95% confidence interval 0.95-1.34). There was no obvious gradient of weekly headache with increasing call-time (P trend 0.06). The association of headache with call-time was stronger for the Universal Mobile Telecommunications System (UMTS) network than older Global System for Mobile Telecommunications (GSM) technology, despite the latter involving higher exposure to RF-EMF. Tinnitus and hearing loss showed no association with call-time. CONCLUSIONS: People using mobile phones most extensively for making or receiving calls at baseline reported weekly headaches slightly more frequently at follow-up than other users, but this finding largely disappeared after adjustment for confounders and was not related to call-time in GSM with higher RF-EMF exposure. Tinnitus and hearing loss were not associated with amount of call-time.

An international prospective cohort study of mobile phone users and health (COSMOS): Factors affecting validity of self-reported mobile phone use.

This study investigates validity of self-reported mobile phone use in a subset of 75 993 adults from the COSMOS cohort study. Agreement between self-reported and operator-derived mobile call frequency and duration for a 3-month period was assessed using Cohen's weighted Kappa (κ). Sensitivity and specificity of both self-reported high (≥10 calls/day or ≥4h/week) and low (≤6 calls/week or <30min/week) mobile phone use were calculated, as compared to operator data. For users of one mobile phone, agreement was fair for call frequency (κ=0.35, 95% CI: 0.35, 0.36) and moderate for call duration (κ=0.50, 95% CI: 0.49, 0.50). Self-reported low call frequency and duration demonstrated high sensitivity (87% and 76% respectively), but for high call frequency and duration sensitivity was lower (38% and 56% respectively), reflecting a tendency for greater underestimation than overestimation. Validity of self-reported mobile phone use was lower in women, younger age groups and those reporting symptoms during/shortly after using a mobile phone. This study highlights the ongoing value of using self-report data to measure mobile phone use. Furthermore, compared to continuous scale estimates used by previous studies, categorical response options used in COSMOS appear to improve validity considerably, most likely by preventing unrealistically high estimates from being reported.

Risk factors for skin cancer among Finnish airline cabin crew.

Increased incidence of skin cancers among airline cabin crew has been reported in several studies. We evaluated whether the difference in risk factor prevalence between Finnish airline cabin crew and the general population could explain the increased incidence of skin cancers among cabin crew, and the possible contribution of estimated occupational cosmic radiation exposure. A self-administered questionnaire survey on occupational, host, and ultraviolet radiation exposure factors was conducted among female cabin crew members and females presenting the general population. The impact of occupational cosmic radiation dose was estimated in a separate nested case-control analysis among the participating cabin crew (with 9 melanoma and 35 basal cell carcinoma cases). No considerable difference in the prevalence of risk factors of skin cancer was found between the cabin crew (N = 702) and the general population subjects (N = 1007) participating the study. The mean risk score based on all the conventional skin cancer risk factors was 1.43 for cabin crew and 1.44 for general population (P = 0.24). Among the cabin crew, the estimated cumulative cosmic radiation dose was not related to the increased skin cancer risk [adjusted odds ratio (OR) = 0.75, 95% confidence interval (CI): 0.57-1.00]. The highest plausible risk of skin cancer for estimated cosmic radiation dose was estimated as 9% per 10 mSv. The skin cancer cases had higher host characteristics scores than the non-cases among cabin crew (adjusted OR = 1.43, 95% CI: 1.01-2.04). Our results indicate no difference between the female cabin crew and the general female population in the prevalence of factors generally associated with incidence of skin cancer. Exposure to cosmic radiation did not explain the excess of skin cancer among the studied cabin crew in this study.

Cancer incidence among Nordic airline cabin crew.

Airline cabin crew are occupationally exposed to cosmic radiation and jet lag with potential disruption of circadian rhythms. This study assesses the influence of work-related factors in cancer incidence of cabin crew members. A cohort of 8,507 female and 1,559 male airline cabin attendants from Finland, Iceland, Norway and Sweden was followed for cancer incidence for a mean follow-up time of 23.6 years through the national cancer registries. Standardized incidence ratios (SIRs) were defined as ratios of observed and expected numbers of cases. A case-control study nested in the cohort (excluding Norway) was conducted to assess the relation between the estimated cumulative cosmic radiation dose and cumulative number of flights crossing six time zones (indicator of circadian disruption) and cancer risk. Analysis of breast cancer was adjusted for parity and age at first live birth. Among female cabin crew, a significantly increased incidence was observed for breast cancer [SIR 1.50, 95% confidence interval (95% CI) 1.32-1.69], leukemia (1.89, 95% CI 1.03-3.17) and skin melanoma (1.85, 95% CI 1.41-2.38). Among men, significant excesses in skin melanoma (3.00, 95% CI 1.78-4.74), nonmelanoma skin cancer (2.47, 95% CI 1.18-4.53), Kaposi sarcoma (86.0, 95% CI 41.2-158) and alcohol-related cancers (combined SIR 3.12, 95% CI 1.95-4.72) were found. This large study with complete follow-up and comprehensive cancer incidence data shows an increased incidence of several cancers, but according to the case-control analysis, excesses appear not to be related to the cosmic radiation or circadian disruptions from crossing multiple time zones.

Reliability and validity of a bioimpedance measurement device in the assessment of UVR damage to the skin.

Ultraviolet radiation (UVR) is the primary cause of skin cancers. However, it is difficult to evaluate the amount of UVR absorbed into the skin retrospectively. Therefore, objective and non-invasive quantitative method would be valuable for epidemiological UVR exposure assessment. Photodamage reduces the amount of bound water in the skin, and thus, measuring the skin's dielectric constant can provide an opportunity for assessing the cumulative UVR exposure. The purpose of the study was to assess the reliability and validity of the bioimpedance device, Moisture Meter-D. The measurements were performed on 100 subjects at three separate measurement times. A questionnaire was used to obtain information on the host factors and on the past UVR exposure. The biological samples, to determine the elastin proportion of the dermis, were collected. Some long-term as well as seasonal variations in the dielectric constants were detected. Also, a weak relationship between the dielectric constant and the UVR exposure indicators and host factors was observed. The MoistureMeter-D appears not to measure structural alterations in the skin caused by photodamage, and thus it is not a valid instrument for the assessment of photodamage, i.e., past UVR exposure.

Early detection of skin cancer as public health policy: comparison of campaign and routine activity.

OBJECTIVE: The objective of this study was to evaluate the early detection of skin cancer, with emphasis on comparison of campaign (short high-intensity periods) and routine (continuous low-intensity) activity. METHODS: The study population consisted of 5903 campaign and 4284 routine attenders visiting a nurse at the Pirkanmaa Cancer Society between January 1, 1991, and December 31, 2000. Skin cancers were identified from the Finnish Cancer Registry. The performance of the program was evaluated in terms of sensitivity, specificity, positive and negative predictive values. RESULTS: A single lesion was more frequently examined during campaigns whereas a partial or total body were examined less frequently (p<0.001). Attenders received referral for removal of a lesion more frequently in routine activity (52% vs. 20% p<0.001), regardless of extent of the examination. The cumulative incidence of skin cancer within 24 months was 3.2% for routine and 1.6% for campaign attenders (p<0.001). Sensitivity was higher (82% vs. 59%, p<0.001), while specificity was lower (49% vs. 79%, p<0.001) for routine activity. CONCLUSIONS: Even though neither approach appears optimal, scheduled appointments with adequate time allocation per subject provided a lower threshold for detection and a higher yield of skin cancers compared to high-intensity campaigns.

Estimating the cosmic radiation dose for a cabin crew with flight timetables.

OBJECTIVE: Because of the lack of recorded flight history for cabin crew, a retrospective assessment of exposure to cosmic radiation is complicated. Our aim was to develop an assessment method for occupational exposure based on flight timetables. METHODS: The frequency of flights, aircraft types, and flight profiles from timetables were collected. The cosmic radiation dose was calculated with the EPCARD software. Based on annual doses and work history, the cumulative dose was estimated. RESULTS: The annual dose increased linearly: 0.7 milliSievert (mSv) in 1960, 1.6 mSv in 1980, 2.3 mSv in 1985, and 2.1 mSv in 1995. The median cumulative dose was 20.8 mSv (minimum 0.4 mSv, maximum 61.6 mSv). CONCLUSIONS: This method provides a simple algorithm for occupational dose assessment for cabin crew and can be used in other research settings as well.

Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence.

Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level.

Occupational radiation dose estimation for Finnish aircraft cabin attendants.

OBJECTIVES: The objective of this study was to develop a method for assessing dose radiation on the basis of individual flight history and to estimate whether this method is applicable for cabin attendants without flight log data. METHODS: Questionnaire data were collected to determine attendants' flight history covering up to three decades. Finnair timetables and an expert panel of pilots were used to determine one to four representative flights in five route categories. The cumulative career and annual doses were calculated on the basis of the flight histories and route-specific exposure data. RESULTS: Questionnaire data were obtained from 544 flight attendants. The mean number of active workyears was 10.5 (range 0-30) years, and the mean cosmic radiation dose was 3.2 (range 0-9.5) mSv per active workyear. The mean cumulative career dose for all the cabin attendants was 34.0 (range 0-156.8) mSv. CONCLUSIONS: If no flight log data are available, survey data are needed for individual dose estimation when possible radiation effects on cabin crew are evaluated in epidemiologic studies. This method provides a crude procedure for assessing cosmic radiation exposure among attendants when survey data are missing.