Comprehensive personal RF-EMF exposure map and its potential use in epidemiological studies

Highlights

• Personal RF-EMF exposure was measured in the city of Albacete (Spain).

• A lattice map was prepared with the city's administrative regions.

• Spatial randomness of mobile phone antennas and personal exposition were analysed.

• Spearman correlation between antennas and intensities was studied.

Abstract

In recent years, numerous epidemiological studies, which deal with the potential effects of mobile phone antennas on health, have almost exclusively focused on their distance to mobile phone base stations. Although it is known that this is not the best approach to the problem, this situation occurs due to the numerous difficulties when determining the personal exposure to the radiofrequency electromagnetic fields (RF-EMF).

However, due to the rise of personal exposimeters, the evolution of spatial statistics, the development of geographical information systems and the use of powerful software, new alternatives are available to deal with these epidemiological studies and thus overcome the aforementioned difficulties. Using these tools, this paper presents a lattice map of personal RF-EMF exposure from exterior mobile phone base stations, covering the entire 110 administrative regions in the city of Albacete (Spain). For this purpose, we used a personal exposimeter, Satimo EME Spy 140 model, performing measurements every 4 s The exposimeter was located inside the plastic basket of a bicycle, whose versatility permitted the access to all the zones of the city.

Once the exposure map was prepared, its relation with the known antenna locations was studied. The 64 mobile telephone antennas of the city were also georeferenced; the randomness of both variables (exposure and antennas) were studied by means of the Moran's I test. Results showed that the distribution of the antennas follows a grouped pattern (p<0.001), while the distribution of the average exposure values have a random distribution (p=0.618). In addition, we showed two Spearman correlation studies: the first between the average exposure values and the number of mobile telephone antennas per administrative region, and the second, also considering the antennas of the neighbouring regions. No substantial correlation was detected in either of the two cases.

This study also reveals the weaknesses of the epidemiological studies, which only take into account the distance to the antennas, which would provide a new approach to the problem. By precisely knowing the resident population of each administrative region of the city, this proves to be highly useful to rely on a prepared aggregate data map based on the mean exposure values to RF-EMF in these sections. The displayed map would permit the execution of more accurate epidemiological studies, since it would be possible to compare the exposure measurements with the incidence data of a disease.

Introduction

During recent decades, the emission of waves produced by radiofrequency electromagnetic fields (RF-EMF) has undergone a major increase (Calvente et al., 2010, Joseph et al., 2008). Recently, the development of personal exposimeters (PEM) has permitted a detailed description of the electromagnetic radiation spectrum to which the population has been subjected and the contribution of each frequency band: radio, television, mobile phone antennas, wireless telephony or Wifi networks in diverse European cities (Bolte and Eikelboom, 2012, Bolte et al., 2011, Frei et al., 2009b, Joseph et al., 2010a, Juhasz et al., 2011, Markakis and Samaras, 2013, Thomas et al., 2008, Thuroczy et al., 2008, Viel et al., 2009, Viel et al., 2009).

Simultaneously with the increased exposure to RF-EMF, the population's concerns have grown with regards to the potential effects on health (Röösli et al., 2010). Among the emission sources, we highlight the mobile phone antennas due to their high number, which have been the object of numerous studies (Röösli et al., 2010). However, almost the majority of these studies, which have dealt with the potential effects of the emitted radiation on health, have focused on the location of the antennas and exclusively in the proximity of the cases of disease (Atzmon et al., 2012, Dode et al., 2011, Elliott et al., 2011, Elliott et al., 2010, Shahbazi-Gahrouei et al., 2014, Stewart et al., 2012). Although the use of the distance to the antenna as an exposure indicator has been questioned in several work papers (Foster and Trottier, 2013), few alternatives have been presented for the execution of epidemiological studies on the potential effects of the RF-EMF generated by the telephone antennas.

Fortunately, the use of personal exposimeters, the development of spatial data analysis, modern geographic information systems (GIS) and the software such as R (Bivand et al., 2013), could provide solutions in future investigations.

Studies with PEM mainly have the following aims: first, to characterize the personal exposure of population and secondly, to measure typical exposure levels in different micro-environments, such as public transportation, outdoor urban areas, other zones inside houses, etc. (Frei et al., 2009b). These two objectives must be clearly differentiated because they have major implications on the methodology of the study (Joseph et al., 2008). In addition, several of the problems to be taken into account in these types of studies by means of PEM, include: the anisotropy (Knafl et al., 2008) , the effect of the body (Joseph et al., 2010b; Nájera et al., 2015; Panagopoulos et al., 2013), the sensitivity of the device (Röösli et al., 2008), measurement errors (Bolte et al., 2011, Knafl et al., 2008, Neubauer et al., 2007) and the fading (temporary reduction of the wave intensity), an essential feature of the RF-EMF which undergo reflections in the buildings and in other structures (Larcheveque et al., 2005). On the other hand, the mobile monitoring of mobile phone base station radiation using PEM is useful because of the high repeatability of exposure levels (Urbinello et al., 2014a). Finally, several studies suggest alternatives to assess the exposure in different micro-environments, through the use of different models prepared based on specific measurements (Aerts et al., 2013a, Beekhuizen et al., 2013, Frei et al., 2009a).

The main objective of this paper was to prepare a lattice map, of the exposure to RF-EMF emitted by mobile phone base stations, through the use of PEM, in the city of Albacete (Spain) as the basis for the execution of future epidemiological studies.

Likewise, the relation was analysed between the exposure and the antenna locations in the entire city. It was determined if the zones with more antennas; inside the city correspond to the zones with the highest intensities and vice versa. For this purpose, we have studied the spatial randomness of the antennas and the measured intensities, as well as the correlation between both variables.