Whenever I see the phrase "think about it," I anticipate some crazed conspiracy theory that's likely to follow.
Walkie Talkies also send out radiation for miles. As do ham radios. Lanterns send out radiation in the form of light. It's all in the dose, and although it's not conclusive, it seems that for most people in most use-scenarios there is not enough radiation to raise one's cancer risk significantly (particularly above other environmental risks).
Cigarette smoking exploded in the US with the invention of the machine rolled cigarette and the free distribution of cigarettes to WW 1 soldiers as part of their rations. It peaked in the late 1950s, early 1960 which was just after the UK version of the Surgeon General Report came out which implicated smoking as the main cause of lung cancer (the US version would come out a few years later). The increase in lung cancer rates, a formerly rare disease, paralleled the increase in smoking at a 20 year lag.
Nearly everyone in the world owns a cellphone. Per capita cellphone ownership is higher (near 100%) than peak smoking rates. This trend started heading upward around the mid 1990s. One would expect, some 20 years later, to see a corresponding explosion of brain cancer.
"FORTUNE — During the 1980s, just as Americans began pumping low-frequency radiation through their skulls with cell phones, brain cancer rates in the U.S. slowly increased. At the beginning of the decade, doctors delivered the devastating diagnosis of brain cancer to 63 out of every 1 million Americans every year; by 1990 that number had risen to 70 per million. And that’s when cell phone usage really took off.
"Yet while the link between phones and tumors may have seemed certain to grow, a strange thing happened. Beginning in 1991 the rate of brain cancer incidence reversed course and began to slowly fall. By 2008, the last year for which the National Cancer Institute has data, 65 out of every 1 million Americans got a brain cancer diagnosis annually."
So brain cancer rates have not changed significantly over the same period. (And I wonder whether the downward trend of smoking among women beginning in the late 1960s, early 1970s -- their peak years -- accounts for some of the 20-year-later downward trend of brain cancer.)
Study cited in wikipedia:
In 2006, a large Danish group's study about the connection between mobile phone use and cancer incidence was published. It followed over 420,000 Danish citizens for 20 years and showed no increased risk of cancer.
[22] A 2011 follow-up confirmed these findings.
[23]
You can read more studies below. Most find no association. A few do. Like I said, it's not conclusive but you're probably more at risk for dying from heart disease and/or diabetes from the typical American diet than brain cancer from typical cellphone use.
https://en.wikipedia.org/wiki/Mobile_phone_radiation_and_health#Cancer