The question of whether cellphones can cause cancer became a popular one after the dramatic increase in cell phone use since the 1990s. Scientists’ main concern is that cell phones can increase the risk of brain tumors or other tumors in the head and neck area – and as of now, there doesn’t seem to be a clear answer.
Cell phones give off a form of energy known as radiofrequency (RF) waves. They are at the low-energy end of the electromagnetic spectrum – as opposed to the higher-energy end where X-rays exist – and they emit a type of non-ionizing radiation. In contrast to ionizing radiation, this type does not cause cancer by damaging DNA in cells, but there is still a concern that it could cause biological effects that result in some cancers.
However, the only consistently recognizable biological effect of RF energy is heat. The closer the phone is to the head, the greater the expected exposure is. If RF radiation is absorbed in large enough amounts by materials containing water, such as food, fluids, and body tissues, it produces this heat that can lead to burns and tissue damage. Still, it is unclear whether RF waves could result in cancer in some circumstances.
Many factors affect the amount of RF energy a person is exposed to, such as the amount of time spent on the phone, the model of the phone, and if a hands-free device or speaker is being used. The distance and path to the nearest cell phone tower also play a role. The farther a way a person is from the tower, the more energy is required to get a good signal on the phone. The same is true of areas where many people are using their phones and excess energy is required to get a good signal.
RF radiation is so common in the environment that there is no way to completely avoid it. Most phone manufacturers post information about the amount of RF energy absorbed from the phone into the user’s body, called the specific absorption rate (SAR), on their website or user manual. Different phones have different SARs, so customers can reduce RF energy exposure by researching different models when shopping for a phone. The highest SAR in the U.S. is 1.6 watts/kg, but actual SAR values may vary based on certain factors.
Studies have been conducted to find a possible link between cell phone use and the development of tumors. They are fairly limited, however, due to low numbers of study participants and risk of recall bias. Recall bias can occur when individuals who develop brain tumors are more predisposed to recall heavier cell phone use than those who do not, despite lack of true difference. Also, tumors can take decades to develop, and given that cell phones have only been in use for about 20 years, these studies are unable to follow people for very long periods of time. Additionally, cell phone use is constantly changing.
Outside of direct studies on cell phone use, brain cancer incidence and death rates have changed little in the past decade, making it even more difficult to pinpoint if cell phone use plays a role in tumor development.
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