Cellular Phone User's Age or the Duration of Calls Moderate Autonomic Nervous System? A Meta-Analysis

The European Health Risk Assessment Network on Electromagnetic Fields Exposure (EFHRAN) reported in 2012: "Children and adolescents represent the first generation of Europeans to be exposed to diffuse EMF since their conception and birth, thus, they are expected to be more sensitive to these fields." On the other hand, the body's physiologic processes are regulated by the autonomic nervous system (ANS) in a way that warrants further elucidation.

Age and duration of exposure are investigated for modifying the variance of the reported effects of mobile/cellular phone call (CPC) on ANS indexed, herein, by the heart rate variability (HRV).

Five studies targeted to 124 healthy subjects (aged 15.3-28.4 years (24.3 ± 5.2), who have been recorded in supine position before and/or sham versus real exposure (to a CPC lasting 5-32 minutes), are included in this meta-analysis. Age and duration of a CPC are evaluated as predictors in two separate meta-regressions.

The meta-analysis identified a heterogeneity I² = 63.2% for all outcomes and I² = 65.2% for sympathovagal balance. Thus, we performed meta-regressions: for the sympathovagal balance rather than the combined parameters effect, the goodness of fit model presents significance only for age - the residual sum of squares compared to chi-square distribution (Q_R) is 4.24 for age (p = 0.12) - while, for minutes of exposure, Q_R = 8.2805 (p = 0.016).

The sympathovagal balance - indispensible for health/homeostasis maintenance - is strongly predicted by age. Minutes of exposure did not affect overall HRV or sympathovagal balance. The results endorse/validate the EFHRAN 2012 suggestion for future research targeting to youngsters.