Mapping of static magnetic fields near the surface of mobile phones

Zastko, L., Makinistian, L., Tvarožná, A. et al. Mapping of static magnetic fields near the surface of mobile phones. Sci Rep 11, 19002 (2021). https://doi.org/10.1038/s41598-021-98083-9

Abstract

Whether the use of mobile phones (MP) represents a health hazard is still under debate. As part of the attempts to resolve this uncertainty, there has been an extensive characterization of the electromagnetic fields MP emit and receive. While the radiofrequencies (RF) have been studied exhaustively, the static magnetic fields (SMF) have received much less attention, regardless of the fact there is a wealth of evidence demonstrating their biological effects. We performed 2D maps of the SMF at several distances from the screen of 5 MP (models between 2013 and 2018) using a tri-axis magnetometer. We built a mathematical model to fit our measurements, extrapolated them down to the phones’ screen, and calculated the SMF on the skin of a 3D head model, showing that exposure is in the µT to mT range. Our literature survey prompts the need of further research not only on the biological effects of SMF and their gradients, but also on their combination with extremely low frequency (ELF) and RF fields. The study of combined fields (SMF, ELF, and RF) as similar as possible to the ones that occur in reality should provide a more sensible assessment of potential risks.

Figure 1

Experimental set up. (a) A mobile phone is placed on top of a stack of 5 mm thick PMMA spacers, just below a pane of PMMA which serves as the mapping level. Spacers are also placed above the mobile phone to better guarantee the desired distance and parallelism to the mapping level. On top of the mapping level a grid (b) is placed to assist the (manual) placing of a sensor connected to a PC through an ARDUINO board. After all points of the grid are measured with the 3-axis sensor, three maps are generated (one for each of the field’s components, Bx, By, and Bz) and the map for the magnitude, |B|, is calculated (c). Then one (or more) spacer(s) is(are) removed, so the phone descends 5 mm (or more), increasing its distance from the mapping level, and the procedure of mapping is repeated. Before any phone was placed in site, the ambient background field was mapped. All mappings, for the background and for each value of z (15, 20, 25, 30, and 55 mm) (d) were done in triplicate.

https://www.nature.com/articles/s41598-021-98083-9

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