Valentini E, Ferrara M, Presaghi F, Gennaro LD, Curcio G. (2010). Systematic review and meta-analysis of psychomotor effects of mobile phone electromagnetic fields. Occup Environ Med. 67(10):708-16.
Studies on psychomotor effects of radiofrequency electromagnetic fields (RF-EMFs) emitted from mobile phones have produced inconclusive results. These studies used different protocols (double vs. single-blind), variable exposure parameters, and often different experimental tasks for assessing the same cognitive function. The systematic review and meta-analysis have been conducted in order to contribute to establishing environmental health criteria on exposure to RF-EMFs by the World Health Organization (WHO).
Original articles published between 1999 and 2008 reporting on experimental studies of behavioural outcomes in relation to acute GMS/UMTS-like exposures were searched in several professional literature databases. Twenty-four studies meeting the selection criteria were identified. Performance in the following 11 cognitive tasks was analyzed: two- and ten-choice reaction time tasks (2CRT and 10CRT), vigilance tasks (VIG) and the trial making test (TMT part B) for divided and sustained attention; simple reaction time tasks (SRT) for attention and speed processing; N-back tasks (0-Back, 1-Back, 2-Back and 3- Back) and subtraction task (SUB) for working memory; verification task (VER) for semantic memory. Standardized mean difference (SMD) was used as the effect size measure. Publication bias was assessed graphically (funnel plots) and by formal tests. The impact of funding source was explored by meta-regression analysis.
Three of the 11 cognitive tasks (2-Back, 3-Back and SRT) showed significant heterogeneity. The statistical significance disappeared when studies with extreme Standardized mean difference were excluded. A significant effect of sponsorship (industry and public/charity funding) was seen for the 2-Back task. For two cognitive tasks (SRT and SUB), there was evidence for a publication bias.
Interpretation and Conclusion
The authors have concluded that their study provides no evidence for an effect of GSM-like low intensity EMFs on cognitive and psychomotor functions. The heterogeneity of results may be due to differences in methodology, statistical power, and interpretation criteria. Sponsorship and publication bias may affect understanding of the phenomenon. Development of official research standards and guidelines in this area of research is warranted.