Several large-scale studies have been conducted to investigate this issue:
INTERPHONE Study: This international study found no significant increase in brain cancer risk among cell phone users. However, it did suggest a potential increased risk for the heaviest users. Danish Cohort Study: This study followed over 358,000 cell phone users and found no link between cell phone use and brain tumors. National Toxicology Program (NTP) Study: This U.S.-based animal study found "clear evidence" of tumors in the hearts of male rats exposed to high levels of RF radiation, but the implications for humans are still uncertain.
