Finally, the measurement of cell phone use in most studies has been crude. Most have been case-control studies, which have relied on people’s memories about their past cell phone use. In these types of studies, it can be hard to interpret any possible link between cancer and an exposure. People with cancer are often looking for a possible reason for it, so they may sometimes (even subconsciously) recall their phone usage differently than people without cancer.
A study by the Corporate EME Research Laboratory and Motorola Florida Research Laboratories tested 9 different cell phone radiation shields, 5 of which claimed to block 99% of cell phone radiation. The other 4 shields tested claimed to emit a reverse radiation that would cancel out the harmful radiation from cell phones. The study found that all of the radiation shields had no effect on the amount of radiofrequency radiation a cell phone user is exposed to from their phone.
The Stewart report recommended that children should only use mobile phones in emergencies. The recommendation was based on the theory that children could be more at risk from the radiowaves emitted by mobile phones. This is because their brains are still developing and their skulls are thinner, making it easier for the radiowaves to penetrate them. Also if they start using mobiles at a young age, their cumulative lifetime use will be higher than adults. According to the Advisory Group on Non-Ionising Radiation, “little has been published specifically on childhood exposures” since 2000. As a result, children are still advised only to use mobile phones in emergencies. However, surveys suggest that many children are ignoring the advice. A survey of 1,000 British children, carried out in 2001, found 90% of under-16s own a mobile and one in 10 spends more than 45 minutes a day using it.
In subsequent analyses of Interphone data, investigators addressed issues of risk according to specific location of the tumor and estimated exposures. One analysis of data from seven of the countries in the Interphone study found no relationship between brain tumor location and regions of the brain that were exposed to the highest level of radiofrequency radiation from cell phones (9). However, another study, using data from five of the countries, reported suggestions of an increased risk of glioma and, to a lesser extent, of meningioma developing in areas of the brain experiencing the highest exposure (10).
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.