Regular use of a mobile phone was defined as at least once a week for at least six months.
|Reference group 1||never or nonregular use|
|Group 2||regular use|
|Group 3||years since first use: 0.5 - 4 years|
|Group 4||years since first use: 5 - 9 years|
|Group 5||years since first use: 10 - 14 years|
|Group 6||years since first use: ≥ 15 years|
|Group 7||lifetime years of use: 0.5 - 4 years|
|Group 8||lifetime years of use: 5 - 9 years|
|Group 9||lifetime years of use: 10 - 14 years|
|Group 10||lifetime years of use: ≥ 15 years|
|Group 11||cumulative number of calls: < 5350|
|Group 12||cumulative number of calls: 5350 - 16062|
|Group 13||cumulative number of calls: > 16062|
|Group 14||cumulative hours of use: < 284|
|Group 15||cumulative hours of use: 284 - 1156|
|Group 16||cumulative hours of use: >1156|
|Participation rate||50 %||75 %|
Overall, no association was found between regular mobile phone use and the risk of leukemia (OR 1.06, CI 0.76-1.46). Analysis of risk in relation to years since first use, lifetime years of use, cumulative number of calls and cumulative hours of use produced no significantly elevated risks. Only in the subgroup of people who first used a mobile phone 15 or more years ago, a non-significantly raised risk was observed (OR 1.87, CI 0.96-3.63).
The authors conclude that the use of mobile phones does not increase the risk of leukemia although the possibility of an effect after long-term use, while biologically unlikely, remains open.