Hutter HP, Moshammer H, Wallner P, Cartellieri M, Denk-Linnert DM, Katzinger M, Ehrenberger K, Kundi M. Tinnitus and mobile phone use. Occup Environ Med. Ahead of print June 23, 2010.
Subjective tinnitus is a sensation of a sound that is unrelated to an external source. The mechanism of tinnitus is not fully understood, and its treatment is problematic. Therefore, it is important to identify risk factors for tinnitus and to focus on prevention. Because during mobile phone use the electromagnetic energy is absorbed in the cochlea and along the auditory pathway, it is theoretically possible that exposure to mobile phones is a risk factor for tinnitus.
The objective of this study was to determine whether mobile phone use increases the risk of tinnitus.
This was a hospital-based case-control study. Cases were 16-80 year old patients with acute and chronic tinnitus consecutively presented over 1 year at the outpatient unit. Each case completed a standardized questionnaire (Structured Tinnitus Interview, STI). In addition, a medical interview was conducted. The patients were subjected to a clinical examination and to a diagnostic test battery. Patients for whom an underlying disease could be established were excluded from the study. Controls (patients without any condition related to tinnitus) were randomly selected from the same outpatient department and matched to cases for age, gender and ethnic group. The controls were evaluated following the same procedure except for the STI and the clinical tinnitus examination. A standardized questionnaire based on the protocol of the WHO interphone study was used to assess the mobile phone use.
The odd ratios (ORs) for mobile phone use were moderately but not significantly increased. For mobile phone use at the side of the tinnitus (ipsilateral), OR=1.37 (95% CI 0.73-2.57) for ever vs. never use, OR=1.71 (95% CI 0.85-3.45) for average daily use of 10 minutes or more, OR=1.57 (95% CI 0.78-3.19) for cumulative hours of use of 160 or more. The OR was significantly elevated for duration of ipsilateral mobile phone use of 4 years or more: OR=1.95 (95% CI 1.00-3.80). There was a significant trend for duration of mobile use (p=0.046). For mobile phone use opposite to the side of the tinnitus (contralateral) the ORs were similar except there was no increase in the category of mobile phone use of 4 years or more: OR=0.91 (95% CI 0.39-2.09).
Interpretation and Conclusion
The authors have discussed potential biases and confounders and have come to the conclusion that the observed increase in risk of tinnitus associated with long-term use of mobile phones is unlikely to be a spurious result. This association requires further investigation.