According to American Academy of Pediatrics President Dr. Robert Block, when cell phones are used by children, "the average RF energy deposition is two times higher in the brain and 10 times higher in the bone marrow of the skull," than for adults.  A July 2008 peer-reviewed study shows that children under the age of eight absorb twice the amount of radiation into their brain tissue as adults due to their lower skull thickness. 
According to a peer-reviewed Dec. 2006 study of 420,095 cell phone users in Denmark, the results showed a "reduced brain tumor risk" among long-term subscribers.  Two other peer-reviewed studies also found that cell phone users had a slightly decreased risk of developing brain tumors. A July 20, 2005 Danish study  found a "decreased risk for high-grade glioma," a malignant brain tumor, and a 2005 Swedish study  also found a "decreased odds ratio" for developing glioma as well as meningioma, another type of brain tumor.
Carlo’s October 7, 1999, letters to wireless-industry CEOs are the smoking-gun equivalent of the November 12, 1982, memo that M.B. Glaser, Exxon’s manager of environmental-affairs programs, sent to company executives explaining that burning oil, gas, and coal could raise global temperatures by a destabilizing 3 degrees Celsius by 2100. For the tobacco industry, Carlo’s letters are akin to the 1969 proposal that a Brown & Williamson executive wrote for countering anti-tobacco advocates. “Doubt is our product,” the memo declared. “It is also the means of establishing a controversy…at the public level.”18
Joel Moskowitz (@berkeleyprc) of the University of California, Berkeley School of Public Health, US, says: “This is the largest technological experiment in the history of our species, with potential health risks we still know next to nothing about.” This view is shared by Denis Henshaw, professor of human radiation effects at Bristol University, UK, who said: “Vast numbers of people are using cell phones and this could be a time bomb of health problems.”