Mobile phones affect multiple sperm quality traits: a meta-analysis

Introduction

Almost 10% of men of reproductive age are estimated to be subfertile¹. Owing to its complexity, even after identification of a plethora of underlying factors, etiology in almost half of the infertile subjects tested at fertility clinics remains obscure². Hence, the list of the causes of male infertility is growing by the day with recent advances in fertility research³. Though advances in assisted reproduction technologies (ARTs), especially in the form of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), have helped subfertile couples conceive offspring, it is feared that ARTs only bypasses the problem of subfertility and contributes towards hiding the underlying causes which have at times led to serious health problems in offspring^4,5. Hence, identification of unknown aetiologies would help in prescription of specific preventive measures that will ultimately decrease the incidence of male infertility.

Most nations, especially developing countries, are witnessing an increase in the use of various radiation-emitting domestic-purpose devices that could cause mild to serious health problems based on the duration and intensity of usage⁶, and reduced fertility is now recognised as one such problem⁷. Wireless mobile phones are one of the most accepted devices with a tremendous increase in usage across the world in recent times⁸. Research into the impact of ionizing radiation on the development of various types of health disorders, especially cancers, has been well established⁹. Similarly, several studies have found an increase in the risk of developing some types of tumors after long-term exposure to non-ionizing radiation from mobile phones¹⁰. Research into the effects of mobile phone radiation on male fertility, though growing, is limited and inconclusive^11,12. Recently, several case-control studies have reported results from a general population setting alongside a few studies from subfertile populations^7,13–20. Like ionizing radiation, non-ionizing radiation is also expected to affect spermatozoa, though in subtle ways²¹. The aim of this meta-analysis was, therefore, to investigate the impact of mobile phone radiation on semen parameters in vitro as well as in vivo settings in men of reproductive age from both general and subfertile populations.

Material and methods

A systematic search of an electronic database was conducted to retrieve published studies on the impact of mobile phone radiation on semen parameters in adult men. The results have been reported according to the standards of the guidelines for meta-analysis of observational studies in epidemiology²². All English language research studies published up until January 2012 in scientific journals indexed in the searched databases were included for analysis.

Inclusion/exclusion criteria and outcomes of interest: The studies on human males of reproductive age reporting the effect of mobile phone radiation on any or all measures of semen volume, total sperm count, sperm concentration, sperm motility or sperm morphology were included. All the studies that did not satisfy the inclusion criteria were excluded.

Search strategy, data extraction and meta-analysis: Google Scholar and NLM’s PubMed database were searched for articles by using different combinations of 4 mobile phone related keywords [‘mobile phone’, ‘cellular phone’, ‘radiofrequency electromagnetic waves (RF-EMW)’, ‘radiation’] with 5 sperm quality related keywords (‘spermatozoa’, ‘semen’, ‘sperm concentration’, ‘sperm motility’, ‘sperm morphology’) Data from 11 eligible studies were extracted and separated into in vitro and in vivo categories.

Effect sizes were expressed as Hedges’s g²³, separately for in vivo & in vitro studies using individual semen parameters as units of analysis (Supplementary Table 1). A random model was used to test and quantify effect size using ‘Comprehensive Meta-Analysis (v.2)’ trial version²⁴. A random effect model was preferred over a fixed effect model in order to account for differences in both effect size and sampling error²⁵.

Results

Discussion

This study was aimed to analyse the data assessing the risk of mobile phone radiation on male fertility. Our results suggest that mobile phone radiation has a tendency to significantly affect sperm quality. Based on the design of the analysed records, we divided studies into in vivo studies and in vitro studies. The effect size was significant in both the categories, suggesting that mobile phone radiation could severely compromise male fertility. This conclusion is robust, as a fail-safe test suggested that the results are not likely to be mediated by publication bias.

The number of worldwide mobile subscriptions grew from less than 1 billion in 2000 to over 6 billion in 2012⁸, with more than half of these subscribers estimated to be children and young adults. Hence, it is very likely that in the coming decades, we could witness an increase in the incidence of male infertility due to mobile phone radiation exposure, similar to growing concerns over other hazards. Although the mechanism of cell phone radiation-mediated health defects is still obscure, it is proposed that their ability to produce heat, disrupt cell membranes, affect endothelial function, alter the blood-brain barrier, and modulate neuronal excitability have the potential to affect multiple physiological functions simultaneously^28–30.

To our knowledge, this is the first meta-analysis of the effects of mobile phone radiations on various sperm quality parameters. Cellular phones have become integral part of everyday life, and newer versions of these are developed very rapidly these days. Hence, it is necessary to educate the users about the hazards of cell phones as well as test the newer versions like smartphones for health hazards.