Can cellphone radiation cause cancer in humans? There’s no scientific consensus on this issue, but there is “some evidence” that exposure to radiation equivalent to that emanating from 1990s-era cellphones is associated with brain tumors in male rats, according to results of a US National Toxicology Program (NTP) study released last week (November 1). 
None of the three cases contain metallic parts, which are known to affect SAR, but all increased the user’s radiation exposure. The effect on radiation exposure would likely vary with each of the hundreds of cases on the market, and each would have to be tested individually to come up with an exact measure. The results in Table 1, however, are believed to reflect the range of radiation increases.
Specific Absorption Rate (SAR) is an indicator for calculating the level of radiation absorbed in the body. This indicator represents the rate of energy absorption by the tissue and is expressed in units of Watt/kg. The Consumer Protection Regulations (information on non-ionizing radiation from mobile phones) of 2002, stipulate the duty to label the product, specifying the radiation level of the phone’s model and the maximum permitted radiation level. This regulation allows to compare the emitted radiation level between different instruments and to take this into consideration when weighing the factors determining the choice of a new instrument at the time of its purchase.
But manipulation by the industry had begun almost immediately at the start of research. While Dr. Carlo and his team had never defined their research as being done to prove the safety of cell phones, the industry internally defined it as an insurance policy to prove that phones were safe. From the outset, what was being said by the cell phone industry in public was different from what was being said by the scientists behind closed doors.
The energy of electromagnetic radiation is determined by its frequency; ionizing radiation is high frequency, and therefore high energy, whereas non-ionizing radiation is low frequency, and therefore low energy. The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation. More information about ionizing radiation can be found on the Radiation page.