Exposure to cellular telephone relay stations was assessed by the surrogate base station coverage. The municipalities were classified into three categories:
1) no base station coverage: the distance of all base stations was more than 400 m to the municipality area, or the operating time of the base station was less than 5 years;
2) moderate base station coverage: operating time at least 8 years and at least 15 % of the municipality area was in the distance of 400m or less to the next base station; or, the operating time lasted 5 to 7 years and at least 30 % of the municipality area in the distance of 400m or less to the next base station;
3) low base station coverage: municipalities that could not be assigned to the other categories.
|Reference group 1||no base station coverage|
|Group 2||low base station coverage|
|Group 3||moderate station station coverage|
242508 person years
1116 malignant tumors were registered in the observed municipalities.
No elevated cancer incidence was found in municipalites with cellular telephone relay stations. The cancer incidence was highly variable in areas without any cellular telephone relay station. No association between base stations and the occurence of tumor types thought to be sensible for radiation effects was observed.
The authors concluded that the high variance of cancer incidence in towns without a cellular telephone relay station qualifies reports about local cancer clusters in the surrounding of such base stations.