Objective  To study the relationship between cell phone radiation and thyroid nodule and to explore the cause of high incidence of thyroid nodules.

  Methods  We conducted a survey with a self-designed questionnaire among 814 thyroid nodule outpatients randomly recruited at the First Affiliated Hospital of Lanzhou University from January 2014 to January 2016. The participants were then divided into groups according to their gender, age, and cumulative hours of cell phone use. Welch variance analysis was used to determine whether there was any difference in thyroid nodules size and other thyroid function indicators among the participants of different groups and Games-Howell test was adopted to test the difference. Specific absorption rate (SAR) of cell phone radiation in thyroid tissue was calculated with biometrics for all the participants.

  Results  There were significant differences in thyroid nodule size among the participants with different cumulative cell phone use time in different gender and age groups (P < 0.05 for all) except for the participants in male elderly group (F = 2.404, P = 0.098). The thyroid nodules size increased with the increment of cumulative cell phone use time in a dose-dependent manner. Games-Howell test demonstrated that the thyroid nodule size increased significantly by 0.254 centimeter (cm) in middle-aged males with the cumulative cell phone use time of > 2 000 hours compared to those of same group with the cumulative time of < 1 000 hours; for female participants, the thyroid nodule size increased significantly by 0.388 cm and 0.522 cm in those of young age groups with the cumulative cell phone use time of 1 001 – 2 000 hours and > 2 000 hours and increased by 0.407 cm in those of elder age group with the cumulative time of > 2 000 hours in comparison with those of same age group with the cumulative time of < 1 000 hours; same significant differences in thyroid nodules size were observed among the middle-aged female participants with different cumulative cell phone use hours (all P < 0.05). The induced current density and the results bio-electromagnetic measurements indicated that the SAR of cell phone radiation was significantly higher in thyroid tissues than in tissues of hypophysis and hypothalamus.

  Conclusion  The result of bio-electromagnetic dosiology is consistent with that of epidemiological survey and there is a significant correlation between thyroid nodule and cell phone radiation.