After analyzing dozens of peer-reviewed mobile phone security studies in 2011, the group concluded that mobile phones are “carcinogenic” and that these devices can be just as harmful as some chemicals used in chemical cleaning and pesticides. (Note that the group hedged its findings with the word “possible”). 

A group of researchers from the World Health Organization concluded that the farther the device is from the head, the lower the level of its harmful effects on the user's body - so text messages or web surfing will not be as dangerous as calls from a mobile phone when the device as close as possible to the brain.

(That's why there were serious concerns about Google Glass, when their release to the market was first announced, and why we particularly use hands-free devices when talking on mobile phones). 

An analysis conducted by a group of European researchers led by Dr. Lennart Hardell, a professor of cancer research and epidemiology at the University Hospital Orebro in Sweden, concluded that talking on a mobile or wireless phone could triple the risk of developing brain cancer.

There are, of course, directly opposite studies of this question. But some of them were partly sponsored by mobile phone companies or shopping groups.

In particular, some argue that when it comes to wearable devices, most scientists, engineers, and health care institutions hold the position that they emit such low levels of electromagnetic radiation (usually two orders of magnitude less than a mobile phone) that they do not pose a danger to health in general. Some, however, still adhere to the position “forewarned is forearmed”.

One example is the international study Interphone, which was published in 2010, and according to the data of this study, a close relationship between mobile phone use and an increased risk of brain tumors has not been identified. In 2014, the Centers for Disease Control and Prevention came to the conclusion that “more research is needed to establish the degree of relationship between the use of mobile devices and the possible development of diseases affecting the normal functioning of the brain.

Another study on the use of mobile applications by subscription also did not reveal an increase in the risk of developing brain cancer or cancer. Nevertheless, even here, a team of Danish experts recognized the likelihood of a "slight or moderate increase" in cancer risk among active mobile phone users.

But what does all this research say to users who are unconditionally believing Apple ideologists who want to buy Apple Watch faster, or Google and Windows fanatics who want to own alternative smart watches?

Dr. Joseph Mercola, a doctor who specializes in alternative medicine and wrote a lot about the potential harmful effects of mobile phones on the human body, said that as long as the wearable device does not have a built-in 3G connection, the harmful effects are minimal, if any.

“The radiation really comes from a 3G connection on a mobile phone, so devices such as Jawbone Up and Apple Watch should be safe,” said Dr. Mercol in a telephone interview. "But if you buy a watch with an integrated cellular communications chip, you have, in essence, the same mobile phone attached to your wrist." And that, he says, is a bad idea. 

(Apple Watch uses Bluetooth and Wi-Fi to get data, and researchers say there is no proven harm to these frequencies when wearing devices on the body. Wearable devices with built-in 3G or 4G connections, including Samsung Gear S, may be more harmful. Apple declined to comment on this article, and Samsung just didn’t make contact to comment on this situation.

The researchers also expressed concern about high-power batteries that are in close proximity to important organs for long periods of time. Some reports over the past few decades have raised the question of whether they can cause leukemia.

What do users do? Perhaps we can see how the researchers themselves cope with their smartphones. 

While Dr. Mercola is an ardent supporter of mobile phone security, he recommended contacting him on a mobile phone to arrange an interview. When asked if he was lecmerising in his statements, he said: “Technology is a part of life, and I use its achievements with utmost caution.” As an example, he said that during a call, he uses a Bluetooth headset.

At the same time, people who are concerned about the possible side effects of smart watches should avoid placing them in close proximity to the brain (this looks a bit strange). However, children are at particular risk. 

While researchers argue about how harmful mobile phones and wearable computers really are, most agree that children should exercise caution when working with such devices. 

Dr. Hardell analyzed the results of a study illustrating that a child’s skull is thinner and smaller than that of an adult, which means that the brain tissue of children is more susceptible to certain types of radiation, in particular, that coming from a mobile phone.

Doctors say that children should talk as little as possible on a mobile phone. And if they have smart watches, they should take off their watches for the night and in no case put them under the pillow. Doctors also warn that pregnant women should be very careful when using not only smart technologies, but gadgets in general.

But what about adults? After examining this column, talking with experts and examining dozens of scientific papers, it is safe to talk about the dangers of using mobile phones for a long time and the need to use a headset to minimize the effects of radiation on the brain structure.

At the same time, when it comes to wearable laptops or tablets, you should not write off Apple Watch accounts, but you should not bring them close to your head. Also try not to let your own or other people's children to such devices, do not let them play with them for a long time.