Relationship between distance to overhead power lines and calculated fields in two studies

Estimation of the general population and children under five years of age in France exposed to magnetic field from high or very high voltage power line using geographic information system and extrapolated field data

BACKGROUND

The effects of extremely low-frequency magnetic fields, especially their long-term health effects, including childhood leukaemia, remain elusive. The International Agency for Research on Cancer has classified the exposure to magnetic fields >0.4 μT as 'possibly carcinogenic to humans (group 2 B)' for childhood leukaemia. However, the number of exposed individuals, particularly children, remains poorly documented in international literature. The objective of this study was to estimate the number of individuals living near a high or very high voltage line in France (≥63 kV), among the general population and children under the age of five years.

METHODS

The estimate considered different exposure scenarios depending on the line voltage and the distance of the housing from it, and whether the line is overhead or underground. The exposure scenarios were obtained using a multilevel linear model created from a measurement database published by "Réseau de transport d'électricité", the operator of the French electricity transmission network.

RESULTS

Between 0.11% (n = 67,893) and 1.01% (n = 647,569) of the French population and between 0.10% (n = 4712) and 1.03% (n = 46,950) of children under five years of age were estimated to be living in an area potentially exposed to a magnetic field, depending on the exposure scenario (>0.4 μT and >0.1 μT, respectively).

CONCLUSIONS

By making it possible to estimate the total number of residents, schools, and health institutions near high-voltage power lines, the proposed methodology can help identify potential co-exposures near high-voltage power lines, which are regularly cited as a possible explanation for contradictory results from epidemiological studies.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

Humans are exposed to a complex mix of man-made electric and magnetic fields (MFs) at many different frequencies, at home and at work. Epidemiological studies indicate that there is a positive relationship between residential/domestic and occupational exposure to extremely low frequency electromagnetic fields and some types of cancer, although some other studies indicate no relationship. In this review, after an introduction on the MF definition and a description of natural/anthropogenic sources, the epidemiology of residential/domestic and occupational exposure to MFs and cancer is reviewed, with reference to leukemia, brain, and breast cancer. The in vivo and in vitro effects of MFs on cancer are reviewed considering both human and animal cells, with particular reference to the involvement of reactive oxygen species (ROS). MF application on cancer diagnostic and therapy (theranostic) are also reviewed by describing the use of different magnetic resonance imaging (MRI) applications for the detection of several cancers. Finally, the use of magnetic nanoparticles is described in terms of treatment of cancer by nanomedical applications for the precise delivery of anticancer drugs, nanosurgery by magnetomechanic methods, and selective killing of cancer cells by magnetic hyperthermia. The supplementary tables provide quantitative data and methodologies in epidemiological and cell biology studies. Although scientists do not generally agree that there is a cause-effect relationship between exposure to MF and cancer, MFs might not be the direct cause of cancer but may contribute to produce ROS and generate oxidative stress, which could trigger or enhance the expression of oncogenes.

3D GIS for surface modelling of magnetic fields generated by overhead power lines and their validation in a complex urban area

Residential exposure to magnetic fields generated by overhead high-voltage power lines, continues to be a matter of social concern and, for the scientific community, a challenge to model this exposure accurately enough to reliably detect even small effects in large populations complexes. In any expression of the magnetic field intensity, the source-receiver distance is a determining variable, especially in an environment closer to the electrical installation and critical with the existence of significant unevenness in the terrain. However, MF exposure studies adopt, due to their complexity, simplifications of reality where even sometimes the terrain relief and the buckling of the line are not considered. The application of 3D techniques with Geographic Information Systems (GIS) allows us to address this problem. This article presents a model for generating magnetic field intensity surfaces from high-precision terrain elevation data. The series expansion of the Biot-Savart law to an infinite rectilinear conductor with variable height according to the catenary described by the cables using ArcGIS software is applied to calculate the magnetic field. For the validation, 69 control points (1035 field measurements) were used in a free urban area and another 28 points (420 field measurements) in a built-up urban area with complex relief. Good estimates were obtained, although with differences in both areas. With MAPE 9.65% and 19.51%, R2 = 0.922 and 0.949, RMSE = 0.154 and 0.094 μT, respectively. Furthermore, 86% of the points were correctly classified according to usual exposure percentiles. However, the use of a 5 m resolution digital terrain model to obtain high-precision elevation data was an indispensable condition for the good performance of our model. The result as a continuous surface of magnetic field values at the real elevation of the ground can contribute significantly to the development of new environmental and public health studies.