Re: Impacts of smartphone radiation on pregnancy: A systematic review. Heliyon 2022 , p.e08915.

In February 2022, El-Jarrah & Rababa published their paper “Impacts of smartphone radiation on pregnancy: A systematic review” in Heliyon [[1]El-Jarrah I. Rababa M. Impacts of smartphone radiation on pregnancy: a systematic review.Heliyon. 2022 Feb 8; e08915Abstract Full Text PDF PubMed Scopus (4) Google Scholar]. This review concluded that exposure to electromagnetic fields (EMF) is linked to various health effects and reported that women and children are at greater risk due to exposure during pregnancy. However, there are a number of methodological issues with this review that indicate the authors have not fully assessed the evidence and may have omitted evidence contrary to their conclusions. Although the authors mention that they conducted a systematic review and describe in the methods how it was conducted, this was not a properly conducted systematic review. Further, the studies are given a risk of bias (RoB) rating the full RoB analysis is not presented and we noted that the authors rate poor quality studies as being high quality, for example, rating the limited cross-sectional study by Lu et al (2017) as a high quality study [[2]Lu X. Oda M. Ohba T. Mitsubuchi H. Masuda S. Katoh T. Association of excessive mobile phone use during pregnancy with birth weight: an adjunct study in Kumamoto of Japan Environment and Children’s Study.Environ. Health Prev. Med. 2017 Dec 22; : 1-8PubMed Google Scholar]. Also, systematic reviews only include original research papers, but El-Jarrah and Rababa include a meta-analysis in the final list of included studies [[3]Tsarna E. Reedijk M. Birks L.E. Guxens M. Ballester F. Ha M. Jiménez-Zabala A. Kheifets L. Lertxundi A. Lim H.R. Olsen J. Associations of maternal cell-phone use during pregnancy with pregnancy duration and fetal growth in 4 birth cohorts.Am. J. Epidemiol. 2019 Jul 1; 188: 1270-1280Crossref PubMed Scopus (18) Google Scholar]. There was also no formal systematic review synthesis of results presented such as what is prescribed by PRISMA; the authors merely provide a narrative assessment. Further, the authors mix in vitro, in vivo, epidemiological, and human experimental studies which would require separate systematic reviews. Instead, the authors present a biased narrative review. The authors only assessed papers published in the last 5 years and there is no justification for the selection of this timeframe. This is a major source of bias as it excludes many modern high-quality papers on EMF and health. This short time frame for inclusion again highlights how the authors have ignored evidence on this topic. Additionally, the screening process as reported is flawed. The authors reportedly found 10,450 articles from 7 databases and yet only 311 articles remained after duplicates were removed meaning 10,139 articles were duplicates. This cannot be mathematically correct. This is because in the unlikely scenario that each article was duplicated across all 7 databases it is mathematically impossible for the authors to have found less than 1492 non-duplicated articles (10,450/7 = 1492). Furthermore, the search strings used for each database search are not presented, nor is the number of articles retrieved from each database. The authors’ assessment of pregnancy outcomes included nine papers. Of these, eight had clear limitations in their methods, particularly when assessing exposure that would prevent any causal association being made, and the other paper was a measurement study that was not assessing health outcomes. Other limitations in the studies included cross-sectional design and uncontrolled confounding. The authors of this review seem to have ignored these limitations when assessing the evidence of the included studies. Overall, this review by El-Jarrah & Rababa failed to fully or adequately assess the available evidence on the impact of EMF on health and pregnancy outcomes. It also relied on papers with low quality methods and poor exposure assessment. Another recent review by Ashrafinia et al (2021) included six higher quality cohort studies that assessed the impact of mobile phone exposure and adverse maternal, infant and child outcomes and reported no substantiated evidence of an impact from mobile phone exposure [[4]Ashrafinia F. Moeindarbari S. Razmjouei P. Ghazanfarpour M. Najafi M.N. Ghalibaf A.A. Abdi F. Can prenatal and postnatal cell phone exposure increase adverse maternal, infant and child outcomes?.Rev. Bras. Ginecol. Obstet. 2021 Dec 12; 43: 870-877Crossref PubMed Scopus (3) Google Scholar]. It appears that El-Jarrah & Rababa have “cherry picked” articles that suited their narrative and ignored or rejected papers that didn’t, as studies that did not find an association included in the Ashrafinia et al review were not included in this review despite being within the dubious 5-year timeframe [[4]Ashrafinia F. Moeindarbari S. Razmjouei P. Ghazanfarpour M. Najafi M.N. Ghalibaf A.A. Abdi F. Can prenatal and postnatal cell phone exposure increase adverse maternal, infant and child outcomes?.Rev. Bras. Ginecol. Obstet. 2021 Dec 12; 43: 870-877Crossref PubMed Scopus (3) Google Scholar]. The particular papers that have been inexplicably excluded from the El-Jarrah & Rababa review but are present in the Ashrafinia et al review include Sudan et al (2016), Papadopoulou et al (2017), and Choi et al (2017) [[5]Sudan M. Olsen J. Arah O.A. Obel C. Kheifets L. Prospective cohort analysis of cellphone use and emotional and behavioural difficulties in children.J. Epidemiol. Community Health. 2016 Dec 1; 70: 1207-1213Crossref PubMed Scopus (28) Google Scholar,[6]Papadopoulou E. Haugen M. Schjølberg S. Magnus P. Brunborg G. Vrijheid M. Alexander J. Maternal cell phone use in early pregnancy and child’s language, communication and motor skills at 3 and 5 years: the Norwegian mother and child cohort study (MoBa).BMC Publ. Health. 2017 Dec 17; : 1Google Scholar,[7]Choi K.H. Ha M. Ha E.H. Park H. Kim Y. Hong Y.C. Lee A.K. Kwon J.H. Choi H.D. Kim N. Kim S. Neurodevelopment for the first three years following prenatal mobile phone use, radio frequency radiation and lead exposure.Environ. Res. 2017 Jul 1; 156: 810-817Crossref PubMed Scopus (21) Google Scholar]. Furthermore, recent major reviews conducted by international health authorities have also found no substantiated evidence of a health impact from EMF exposure below safety guidelines [[8]SCENIHR (Scientific Committee on Emerging and Newly Identified health risks). Potential health effects of exposure to electromagnetic fields (EMF).Eur. Commiss. Jan 2015; 2015: 1-288Google Scholar, [9]International Commission on Non-Ionizing Radiation ProtectionGuidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz).Health Phys. 2020 May 1; 118: 483-524Crossref PubMed Scopus (759) Google Scholar]. Rohan Mate, PhD candidate; Christopher Brzozek, PhD; Ken Karipidis, PhD: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.