Objective-To investigate whether residence before and after birth near
50 Hz high voltage installations increases a child's risk of cancer a
nd whether risk correlates with the strength of the magnetic field. De
sign-A population based case-control study. Setting-Denmark. Subjects-
1707 children under the age of 15 with leukaemia, tumour of the centra
l nervous system, or malignant lymphoma diagnosed in 1968-86 and 4788
children taken from the central population register. Main outcome meas
ures-Proximity before and after birth to existing or former 50-400 kV
electrical transmission connections and substations and associated his
torical electromagnetic fields calculated on the basis of current load
on line, phase ordering of line, and distance from the dwelling. Resu
lts-A significant association was seen between all major types of chil
dhood cancer combined and exposure to magnetic fields from high voltag
e installations of greater-than-or-equal-to 0.4 muT (odds ratio 5.6).
At greater-than-or-equal-to 0.25 muT no significant association was se
en (odds ratio 1.5). A possible association was also seen with cases o
f Hodgkin's disease separately at greater-than-or-equal-to 0.1 muT. Co
nclusion-On the basis these results and additional descriptive data on
electricity consumption and incidence of childhood cancer in Denmark
since the 1940s it was concluded that the proportion of childhood canc
er possibly caused by 50 Hz electromagnetic fields must be small.