The MOBI-Kids Study Protocol: Challenges in Assessing Childhood and Adolescent Exposure to Electromagnetic Fields from Wireless Telecommunication Technologies and Possible Association with Brain Tumor Risk

The rapid increase in mobile phone use in young people has generated concern about possible health effects of exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF). MOBI-Kids, a multinational case-control study, investigates the potential effects of childhood and adolescent exposure to EMF from mobile communications technologies on brain tumor risk in 14 countries. The study, which aims to include approximately 1,000 brain tumor cases aged 10-24 years and two individually matched controls for each case, follows a common protocol and builds upon the methodological experience of the INTERPHONE study. The design and conduct of a study on EMF exposure and brain tumor risk in young people in a large number of countries is complex and poses methodological challenges. This manuscript discusses the design of MOBI-Kids and describes the challenges and approaches chosen to address them, including: (1) the choice of controls operated for suspected appendicitis, to reduce potential selection bias related to low response rates among population controls; (2) investigating a young study population spanning a relatively wide age range; (3) conducting a large, multinational epidemiological study, while adhering to increasingly stricter ethics requirements; (4) investigating a rare and potentially fatal disease; and (5) assessing exposure to EMF from communication technologies. Our experience in thus far developing and implementing the study protocol indicates that MOBI-Kids is feasible and will generate results that will contribute to the understanding of potential brain tumor risks associated with use of mobile phones and other wireless communications technologies among young people

Validating self-reported mobile phone use in adults using a newly developed smartphone application

OBJECTIVE: Interpretation of epidemiological studies on health effects from mobile phone use is hindered by uncertainties in the exposure assessment. We used a newly developed smartphone application (app) to validate self-reported mobile phone use and behaviour among adults. METHODS: 107 participants (mean age 41.4 years) in the Netherlands either downloaded the software app on their smartphone or were provided with a study smartphone for 4 weeks. The app recorded the number and duration of calls, text messages, data transfer, laterality and hands-free use. Self-reported mobile phone use was collected before using the app and after 6 months through an interviewer-administered questionnaire. RESULTS: The geometric mean ratios (GMR, 95% CI) and Spearman correlations (r) of self-reported (after 6 months) versus recorded number and duration of calls were: GMR=0.65 (0.53 to 0.80), r=0.53; and GMR=1.11 (0.86 to 1.42), r=0.57 respectively. Participants held the phone on average for 86% of the total call time near the head. Self-reported right side users held the phone for 70.7% of the total call time on the right side of the head, and left side users for 66.2% on the left side of the head. The percentage of total call time that the use of hands-free devices (headset, speaker mode, Bluetooth) was recorded increased with increasing frequency of reported hands-free device usage. DISCUSSION: The observed recall errors and precision of reported laterality and hands-free use can be used to quantify and improve radiofrequency exposure models based on self-reported mobile phone use

Maternal Early-Pregnancy Vitamin D Status Is Associated With Maternal Depressive Symptoms in the Amsterdam Born Children and Their Development Cohort

Objective: To examine low maternal vitamin D status as a potential risk factor for high levels of depressive symptoms in a pregnant population. Methods: In the Amsterdam Born Children and Their Development cohort, maternal serum vitamin D (n = 4236) was measured during early pregnancy (median, 13 weeks) and labeled "deficient" ( = 80 nM). Maternal depressive symptoms were measured by the Center for Epidemiological Studies Depression Scale at 16-week gestation. The association of vitamin D status with high levels of depressive symptoms (Center for Epidemiological Studies Depression score >= 16) was assessed by multivariate logistic regression (final sample, 4101). Results: Overall, 23% of women had vitamin D deficiency, and 21% of women had vitamin D insufficiency. Women with high levels of depressive symptoms (28%) had lower vitamin D concentrations than women with low levels of depressive symptoms (p <.001). After adjustment for constitutional factors, life-style and psychosocial covariates, and sociodemographic factors, vitamin D deficiency (odds ratio [OR], 1.48; 95% confidence interval [Cl], 1.13-1.95) and insufficiency (OR, 1.44; 95% Cl, 1.12-1.85) were significantly associated with high levels of depressive symptoms. Additional analyses revealed a linear trend, with an OR of 1.05 (95% Cl, 1.02-1.08) for each 10-nM decrease in vitamin D status. Conclusions: In this study, low early-pregnancy vitamin D status was associated with elevated depressive symptoms in pregnancy. Further research, using a randomized controlled design, would be required to confirm the causality of this association and the potential benefits of higher vitamin D intake for psychosocial healt

Ethnic differences in term birthweight: the role of constitutional and environmental factors

It is not clear to what extent ethnic differences in the term birthweight distribution are constitutional or pathological. This study explored term birthweight heterogeneity between ethnic groups and the explanatory role of constitutional and environmental factors. As part of a prospective cohort study, the Amsterdam Born Children and their Development study, 8266 pregnant women filled out a questionnaire during early pregnancy. Ethnic groups were categorised as: native Dutch group; first and second generation Surinamese, Antillean, Turkish, Moroccan, Ghanaian and other non-Dutch groups. Only singleton livebirths with >or=37.0 weeks of gestation and with complete data were included for analysis (n = 7118). We performed linear regression analyses to estimate the association between ethnicity and, for gestational age, standardised birthweight at term, adjusted for constitutional (fetal gender, parity, maternal age, maternal height) and environmental (education, cohabitation status, maternal body mass index, smoking, alcohol consumption, depression, work stress) determinants respectively. Mean birthweight ranged from 3223 g (second generation Surinamese newborns) to 3548 g (Dutch newborns). Adjustment for constitutional factors substantially reduced the ethnic differences in birthweight, while adjustment for environmental factors provided little additional explanation. Surinamese [first generation: regression coefficient (b) = -98.3 g, P < 0.001; second generation: b = -159.3 g, P < 0.001], first generation Antillean (b = -102.0 g, P = 0.037), and Ghanaian newborns (b = -120.7 g, P = 0.001) remained significantly smaller than Dutch newborns after adjustment for all determinants. Term birthweight differences between Dutch newborns and Turkish, Moroccan and other non-Dutch newborns were largely explained by constitutional rather than environmental determinants, limiting the need for prevention. Surinamese, Antillean and Ghanaian (mainly black) newborns remained unexplainably smaller after adjustment, leaving the possibility of either unknown constitutional or pathological underlying mechanism

Maternal Depressive Symptoms in Relation to Perinatal Mortality and Morbidity: Results From a Large Multiethnic Cohort Study

Objective: To explore whether 1) maternal depressive symptoms during pregnancy are associated with preterm birth (PTB), small for gestational age (SGA), a low Apgar score and child loss; 2) maternal smoking mediates the associations; and 3) the associations differ by ethnic background. Methods: Pregnant women in Amsterdam were approached during their first prenatal visit to participate in the Amsterdam Born Children and their Development study. They filled out a questionnaire covering sociodemographic data, life-style, and (psychosocial) health. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression scale. The baseline sample consisted of 8,052 women; the main ethnic groups were: Dutch, Creole, Turkish, and Moroccan. Results: The prevalence of perinatal outcomes was: 5.4% (PTB); 12.3% (SGA); 11.5% (low Apgar score); and 1.4% (child loss). The prevalence of high depressive symptomatology was 30.6%. After adjustment for maternal age, parity, education, ethnicity, prepregnancy body mass index, hypertension, alcohol and drug use, and a small mediation effect of maternal smoking, high versus low levels of depressive symptoms were associated with SGA (odds ratio [OR], 1.19; p = .02) and a low Apgar score (OR, 1.74; p = .01), but not with PTB (OR, 1.16; p = .18) and child loss (OR, 1.28; p = .24). Stratified analyses by ethnic background showed a tendency toward higher risks, although insignificant, among Creole women. Conclusions: Several pathways may explain the detrimental effects of maternal depressive symptomatology on perinatal health outcomes, including a psychoendocrinological pathway involving the hormone cortisol or mediation effects by maternal risk behaviors. Further research should explore the underlying pathways, in particular among ethnic subgroup

Using software-modified smartphones to validate self-reported mobile phone use in young people : A pilot study

A newly developed smartphone application was piloted to characterize and validate mobile phone use in young people. Twenty-six volunteers (mean age 17.3 years) from France, Spain, and the Netherlands used a software-modified smartphone for 4 weeks; the application installed on the phone recorded number and duration of calls, data use, laterality, hands-free device usage, and communication system used for both voice calls and data transfer. Upon returning the phone, participants estimated their mobile phone use during those 4 weeks via an interviewer-administered questionnaire. Results indicated that participants on average underestimated the number of calls they made, while they overestimated total call duration. Participants held the phone for about 90% of total call time near the head, mainly on the side of the head they reported as dominant. Some limitations were encountered when comparing reported and recorded data use and speaker use. When applied in a larger sample, information recorded by the smartphone application will be very useful to improve radiofrequency (RF) exposure modeling from mobile phones to be used in epidemiological research. Bioelectromagnetics. 36:538-543, 2015. © 2015 Wiley Periodicals, Inc

Recall of mobile phone usage and laterality in young people: The multinational Mobi-Expo study

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Patterns of cellular phone use among young people in 12 countries : Implications for RF exposure

Characterizing exposure to radiofrequency (RF) fields from wireless telecommunications technologies during childhood and adolescence is a research priority in investigating the health effects of RF. The Mobi-Expo study aimed to describe characteristics and determinants of cellular phone use in 534 young people (10-24years) in 12 countries. The study used a specifically designed software application installed on smartphones to collect data on the use of wireless telecommunications devices within this age group. The role of gender, age, maternal education, calendar period, and country was evaluated through multivariate models mutually adjusting for all variables. Call number and duration were higher among females compared to males (geometric mean (GM) ratio 1.17 and 1.42, respectively), among 20-24year olds compared to 10-14year olds (GM ratio 2.09 and 4.40, respectively), and among lowest compared to highest social classes (GM ratio 1.52 and 1.58, respectively). The number of SMS was higher in females (GM ratio 1.46) and the middle age group (15-19year olds: GM ratio 2.21 compared to 10-14year olds) and decreased over time. Data use was highest in the oldest age group, whereas Wi-Fi use was highest in the middle age group. Both data and Wi-Fi use increased over time. Large differences in the number and duration of calls, SMS, and data/Wi-Fi use were seen by country, with country and age accounting for up to 50% of the variance. Hands-free and laterality of use did not show significant differences by sex, age, education, study period, or country. Although limited by a convenience sample, these results provide valuable insights to the design, analysis, and interpretation of future epidemiological studies concerning the health effects of exposure resulting from cellular phone use in young people. In addition, the information provided by this research may be used to design strategies to minimize RF exposure

Recall of mobile phone usage and laterality in young people: The multinational Mobi-Expo study

OBJECTIVE: To study recall of mobile phone usage, including laterality and hands-free use, in young people. METHODS: Actual mobile phone use was recorded among volunteers aged between 10 and 24 years from 12 countries by the software application XMobiSense and was compared with self-reported mobile phone use at 6 and 18 months after using the application. The application recorded number and duration of voice calls, number of text messages, amount of data transfer, laterality (% of call time the phone was near the right or left side of the head, or neither), and hands-free usage. After data cleaning, 466 participants were available for the main analyses (recorded vs. self-reported phone use after 6 months). RESULTS: Participants were on average 18.6 years old (IQR 15.2-21.8 years). The Spearman correlation coefficients between recorded and self-reported (after 6 months) number and duration of voice calls were 0.68 and 0.65, respectively. Number of calls was on average underestimated by the participants (adjusted geometric mean ratio (GMR) self-report/recorded = 0.52, 95% CI = 0.47-0.58), while duration of calls was overestimated (GMR=1.32, 95%, CI = 1.15-1.52). The ratios significantly differed by country, age, maternal educational level, and level of reported phone use, but not by time of the interview (6 vs. 18 months). Individuals who reported low mobile phone use underestimated their use, while individuals who reported the highest level of phone use were more likely to overestimate their use. Individuals who reported using the phone mainly on the right side of the head used it more on the right (71.1%) than the left (28.9%) side. Self-reported left side users, however, used the phone only slightly more on the left (53.3%) than the right (46.7%) side. Recorded percentage hands-free use (headset, speaker mode, Bluetooth) increased with increasing self-reported frequency of hands-free device usage. Frequent (≥50% of call time) reported headset or speaker mode use corresponded with 17.1% and 17.2% of total call time, respectively, that was recorded as hands-free use. DISCUSSION: These results indicate that young people can recall phone use moderately well, with recall depending on the amount of phone use and participants' characteristics. The obtained information can be used to calibrate self-reported mobile use to improve estimation of radiofrequency exposure from mobile phones