Simulation of the incidence of malignant brain tumors in birth cohorts that started using mobile phones when they first became popular in Japan.

Over 20 years have passed since the initial spread of mobile phones in Japan. Epidemiological studies of mobile phone use are currently being conducted around the world, but scientific evidence is inconclusive. The present study aimed to simulate the incidence of malignant brain tumors in cohorts that began using mobile phones when they first became popular in Japan. Mobile phone ownership data were collected through an Internet-based questionnaire survey of subjects born between 1960 and 1989. The proportion of mobile phone ownership between 1990 and 2012 was calculated by birth cohort (1960s, 1970s, and 1980s). Subsequently, using the ownership proportion, the incidence of malignant brain tumors was calculated under simulated risk conditions. When the relative risk was set to 1.4 for 1,640 h or more of cumulative mobile phone use and the mean daily call duration was 15 min, the incidence of malignant brain tumors in 2020 was 5.48 per 100,000 population for the 1960s birth cohort, 3.16 for the 1970s birth cohort, and 2.29 for the 1980s birth cohort. Under the modeled scenarios, an increase in the incidence of malignant brain tumors was shown to be observed around 2020.