COPENHAGEN, Denmark, Oct. 21 (UPI) -- A study involving more than 358,400 people in Denmark finds no increase of tumors after prolonged cellphone use, an international team researchers concluded.
The study participants -- age 30 and older, and born in Denmark after 1925 -- were subdivided into subscribers and non-subscribers of cellphones before 1995.
Patrizia Frei of the Institute of Cancer Epidemiology, Danish Cancer Society in Copenhagen, and colleagues
said those with central nervous system tumors were identified from the complete Danish Cancer Register.
In the follow-up period, 1990 to 2007, there were 10,729 cases of tumors of the central nervous system.
When restricted to individuals with the longest cellphone use -- cellphone subscription of 13 years and more -- the incidence rate ratio was 1.03 in men and 0.91 in women.
Among those with subscriptions of 10 years and more, ratios were 1.04 in men and 1.04 in women for glioma (brain tumor) and 0.90 in men and 0.93 in women for meningioma (in which tumors grow from the layers of tissue covering the brain and spinal cord).
There was no indication of dose-response relation either by years since first subscription for a cellphone or by anatomical location of the tumor -- that is, in regions of the brain closest to where the handset is usually held to the head.
The study, published in the British Medical Journal, found no increased risks of tumors of the central nervous system, providing little evidence for a causal association.