French Geocap study

A study of childhood leukaemia and proximity to high-voltage power lines was published in April 2013.

It finds elevated risks within 50 m of the highest voltage lines, but not at greater distances, and not for the lower-voltage lines.

The results in more detail

The main results are reproduced in the following table:

 relative risks and confidence intervals in distance bands
 0-49 m50-99 m

100-199 m

200-599 m>600 m
225-400 kV lines1.7 (0.9-3.6)1.0 (0.5-2.1)0.7 (0.4-1.2)1.2 (1.0-1.4)1.0 (0.8-1.2)
63-150 kV lines1.0 (0.6-1.7)1.2 (0.7-1.9)0.8 (0.6-1.2)1.0 (0.8-1.2)1.1 (1.0-1.2)

The paper then show how this result varies in various subgroups.  The relative risk for the closest distance band, 0-49 m, and for the 225-400 kV lines, varies as follows:

With the age of the child:

 relative riskconfidence interval
0-4 years2.61.0-6.9
5-14 years1.00.3-3.3
  • 0-4 years: 2.6 (1.0-6.9)
  • 5-14 years: 1.0 (0.3-3.3)

With the size of the urban unit:

  • <5000 people: 2.5 (0.8-7.7)
  • 5000-100,000: 4.9 (1.3-19.2)
  • >100,000: 0.4 (0.1-2.9)

Finally, the study had different methods of locating the home, with different potential accuracies.  The main results are for the best estimate of the location.  For some subjects, they had the full address, which they refer to as a GIS uncertainty of 20 m (in fact, the accuracy may not necessarily be this good, for example with appartment buildings).  For others, they identified the actual home from aerial photographs or equivalent, which may be the most accurate of all.

  • Full address: 2.1 (0.9-4.7)
  • Aerial photographs: 1.3 (0.5-1.7)

So the elevated risk seems to be confined to the higher voltage lines, the younger children, and the smaller urban units.

These results are presented in the following graphs:

How the risk varies with voltage of line

 graph of geocap results by voltage

How the risk varies with age of child

 graph of geocap results by age of child

How the risk varies with size of urban unit

graph of geocap results by urban unit

The abstract in full

 

British Journal of Cancer (2013), 1–8  doi: 10.1038/bjc.2013.128
Childhood leukaemia close to high-voltage power lines – the Geocap study, 2002–2007
C Sermage-Faure, C Demoury, J Rudant, S Goujon-Bellec, A Guyot-Goubin, F Deschamps, D Hemon, and J Clavel

Background: High-voltage overhead power lines (HVOLs) are a source of extremely low-frequency magnetic fields (ELF-MFs), which are classified as possible risk factors for childhood acute leukaemia (AL). The study was carried out to test the hypothesis of an increased AL incidence in children living close to HVOL of 225–400 kV (VHV-HVOL) and 63–150 kV (HV-HVOL).
Methods: The nationwide Geocap study included all the 2779 cases of childhood AL diagnosed in France over 2002–2007 and 30 000 contemporaneous population controls. The addresses at the time of inclusion were geocoded and precisely located around the whole HVOL network.
Results: Increased odds ratios (ORs) were observed for AL occurrence and living within 50m of a VHV-HVOL (OR¼1.7 (0.9–3.6)). In contrast, there was no association with living beyond that distance from a VHV-HVOL or within 50m of a HV-HVOL.
Conclusion: The present study, free from any participation bias, supports the previous international findings of an increase in AL incidence close to VHV-HVOL. In order to investigate for a potential role of ELF-MF in the results, ELF-MF at the residences close to HVOL are to be estimated, using models based on the annual current loads and local characteristics of the lines.

They had previously published a paper giving their methods in more detail:

J Radiol Prot. 2013 Mar 13;33(2):349-365. [Epub ahead of print]
Methods used to estimate residential exposure to 50 Hz magnetic fields from overhead power lines in an epidemiological study in France.
Bessou J, Deschamps F, Figueroa L, Cougnaud D.
SourceRéseau de Transport d'Electricité (RTE), Cœur Défense, 110 esplanade du Général de Gaulle, F-92030 La Defense, France.

An epidemiological study of paediatric cancers in relation with various environmental factors is currently being carried out in France. One of these factors is the proximity of children's residences to high voltage overhead lines (63-400 kV). This possible influence will be studied following three criteria, namely 'distance', 'distance-voltage' and 'calculated residential exposure' to extremely low frequency magnetic field (ELF-MF). This paper describes methods for generating and characterising these three criteria of increasing complexity and characterises the influence of the input data in terms of uncertainties in the exposure to ELF-MF assigned to subjects. The method developed for the 'calculated residential exposure' criterion is based on a limited number of configurations of overhead lines, selected to have a representative sample of the French high voltage (HV) network. The calculated exposure is then fitted to each subject and each neighbouring overhead line, taking into account the yearly mean current flowing in the line and the distance of the residence from the power line. All variability factors introduced by this simplified representation have been analysed, classified and quantified to give the best assessment and associated confidence interval of the residential ELF-MF exposure of the subjects. The overall 1σ uncertainty of the calculated residential exposure excluding geo-coding uncertainties is around 8% for subjects living close to power lines with a known current load and 17% for the others.