20 subjects (10 men, 10 women) served as "mobile phone exposure group" and had a mean duration of mobile phone use of 12.5 years (range 8-15) and a mean time use of 29.6 hours per month (range 8-100). Deaf individuals matching in age and gender served as controls.
Mobile phone use was identified by a questionnaire.
The data showed a significant increase in all salivary oxidative stress indices studied in mobile phone users. Salivary flow was increased and total protein, albumin and amylase activity were decreased in mobile phone users.
The authors conclude, that the use of mobile phones may cause oxidative stress and modify the salivary function.
The major limitation to this study is that, under its current design, one cannot exclude the possibility that deafness itself, and not the lack of being exposed to mobile phones, was responsible for the observed reduced oxidative stress in the control group.