Exposure to extremely low frequency magnetic fields among primary school children in Spain.

Epidemiological studies have found an increased leukaemia risk in children with high residential exposure to extremely low frequency electromagnetic fields (ELFEMF). Two recent independent reanalyses of published epidemiological studies 2 found statistically significant increased risks in children with average residential exposures equal or above 0.3 or 0.4 μT (micro teslas, the unit of measurement of magnetic field density). An IARC working group (June 2001) evaluated that these findings were unlikely to be attributable to chance, but could be affected by selection bias. Therefore this association between childhood leukaemia and high residential magnetic field strengths was judged limited evidence for excess cancer risk in exposed humans. Exposure at school could significantly contribute to children’s overall exposure, but only few epidemiological studies incorporated such measurement. We evaluated level of exposure to ELF-EMF in primary schools in the city of Oviedo and the province of Barcelona, the second region being one of the most industrialised areas of Spain.