Using software-modified smartphones to validate self-reported mobile phone use in young people: A pilot study.

A newly developed smartphone application was piloted to characterize and validate mobile phone use in young people. Twenty-six volunteers (mean age 17.3 years) from France, Spain, and the Netherlands used a software-modified smartphone for 4 weeks; the application installed on the phone recorded number and duration of calls, data use, laterality, hands-free device usage, and communication system used for both voice calls and data transfer. Upon returning the phone, participants estimated their mobile phone use during those 4 weeks via an interviewer-administered questionnaire. Results indicated that participants on average underestimated the number of calls they made, while they overestimated total call duration. Participants held the phone for about 90% of total call time near the head, mainly on the side of the head they reported as dominant. Some limitations were encountered when comparing reported and recorded data use and speaker use. When applied in a larger sample, information recorded by the smartphone application will be very useful to improve radiofrequency (RF) exposure modeling from mobile phones to be used in epidemiological research.