Article Preview
TopIntroduction
In 2011, there were 6 billion mobile subscriptions, equivalent to 87% world's population (The International Telecommunication Union, 2011). Mobile subscribers in developed countries have reached a saturation point with at least one cell phone subscriptions per person, while mobile subscriptions in developing countries grow rapidly. The United Nations reported that cell phones have spread faster than any other information technologies and can improve the living standard of the poorest people in developing countries (Lynn, 2010).
However, people have been concerned about whether the radio frequency waves emitted by cell phone would bring adverse effects to human health, especially brain cancers (International Agency for Research on Cancer, 2011). According to the Central Brain Tumor Registry (CBTRUS, 2012), the incidence of both benign (i.e., curable) and malignant (i.e., hardly curable) brain tumors was 13.4 per 100,000 in 1995 and increased to 19.9 per 100,000 in 2008. Questions were thus raised to consider whether fast increasing cell phone use indeed increases the risk of brain tumors. In particular, over 75% of American adolescents aged between 12-17 had cell phones in 2009, while only 45% had cell phones in 2004 (Lenhart et al., 2009). Young people will have longer time to expose to cell phone radiation and might have a higher risk of developing brain tumors.
Cell Phone Radiation
Cell phones emit a special type of radiation concerning radio frequency electromagnetic field (RF-EMF) in the microwave range (Corle et al., 2012; Feychting, Ahlbom, & Kheifets, 2005). RF-EMF is the combination of the electric field and magnetic field. When an electric current flows in a conductor, like an antenna or a circuit inside the cell phone, it generates RF-EMF. RF-EMF is strongest at the source and weakens exponentially in regard to the distance from the source. It belongs to non-ionizing radiation, which means not having sufficient energy to ionize an atom. RF-EMF has enough energy to change the rotational, vibrational, or electronic valence configurations of molecules and atoms. When a person uses a cell phone, RF-EMF is highly concentrated on the temporal lobe, an important brain region dealing with auditory perception and memory, on both sides of head near ears, especially the same side of head with a cell phone use (i.e., ipsilateral). Hence, cell phone use is considered having a higher risk of absorption of RF-EMF than radio, television, and computer use because cell phone is close to one's head (Corle et al., 2012).
Specific absorption rate (SAR) is used to measure the rate at which cell phone radiation is absorbed by the human body (FCC Encyclopedia, n.d.; Mobile Phones UK, n.d.). Many countries have set maximum levels for cell phones. In the U.S.A., the Federal Communications Commission (FCC) has set a SAR limit of 1.6 watts per kilogram (1.6W/kg), averaged over a volume of 1 gram of tissue for the head. In Europe, the limit is set to be 2 W/kg, averaged over a volume of 10 grams of tissue for the head.