Answer to Question #11975 Submitted to "Ask the Experts"

Category: Micro/Radio Waves, Radar & Powerlines — Microwaves and Radiofrequency

The following question was answered by an expert in the appropriate field:


I am generally worried by radiation, and I don't understand what it is. I'm concerned for my children and try to stay away from things that might eventually turn out dangerous for their health in years to come. I bought a toy that they've had for a couple of years, and now I understand it uses radiofrequency (RF) to talk to the other toys!? When I bought it, I asked what the technology was, but I think they probably fobbed me off as I asked if it sent waves between the toys, since one reacts to the presence of the others. I just wondered if this is radiation? It's been in my son's bedroom. I won't even have a cordless phone or a microwave, but I do have Wi-Fi. Could you please explain this to me as I don't understand what this is. Is it the same as the remote control or walkie-talkies or a cell/mobile phone?


The United States and other countries have safety limits that are designed to avoid known hazards of RF energy with large safety factors. I am quite sure that your exposure to RF energy from Wi-Fi and other wireless devices in your home is far below these safety limits.

Technically, "radiation" refers to energy that propagates through space. X rays from a dental x-ray unit, light from a lightbulb, and RF energy from the wireless key fob that you use to unlock your car are all forms of electromagnetic radiation. Human bodies themselves emit RF and other forms of electromagnetic radiation (known as blackbody radiation) as a consequence of being at body temperature. An infrared fever thermometer measures the level of infrared radiation emitted by the body.

Consequently there is nothing intrinsically threatening about radiation. The potential hazards of electromagnetic radiation depend on its intensity and the part of the electromagnetic spectrum in which it occurs. Ionizing radiation, such as x rays, has sufficient energy in its photons to break chemical bonds, which is a potent cause of damage to tissue. RF energy is nonionizing—its photons have insufficient energy to disrupt chemical bonds. The established hazards of RF energy are chiefly related to excessive heating of tissue. For example, workers on towers near high-powered broadcast antennas can face significant occupational hazards from RF overexposure.

There are many AM, FM, and TV broadcast transmitters in the environment, some operating at very high power levels, and they have contributed to background levels of RF signals in the environment for decades. The number of wireless-connected devices on the consumer market has exploded since the early 2000s. Most noticeable to citizens is the increase in the number of cell phones and cellular base stations; now most citizens in developed countries have cell phones. In addition, there has been a tremendous increase in Wi-Fi and Bluetooth-enabled devices and an increasing number of household devices such as bathroom scales, electric power outlets, and light fixtures are now outfitted with Wi-Fi interfaces. One industry source (the Wi-Fi Alliance) recently noted that 9 billion Wi-Fi connected devices are anticipated to be in use around the world this year.

As a practical matter, it is impossible to avoid such devices and still live in modern society. All of these wireless devices operate at low power levels, and their RF exposure levels, even considering the cumulative exposure from all of the devices in an individual's environment, are invariably far below U.S. safety limits (limits of the Federal Communications Commission [FCC]), which are similar to limits adopted elsewhere in the world.

I looked up the toy that you mentioned. According to FCC documents, that game uses wireless Bluetooth links to control accessory parts of the toy. Documents for one toy in that series states that the power levels at their peak transmissions are about 1 milliwatt (mW), which is similar to that used by my cordless mouse and electronic watch. The levels of RF exposure produced by such a device would be very tiny compared to safety limits, certainly below the exposure to an individual from using a cell phone and probably lower than the exposure produced when a bystander uses a cell phone in his/her vicinity.

To be sure, one can find exaggerated claims on the internet about possible health risks of low-level RF energy. However, health agencies such as World Health Organization and many national health agencies have consistently concluded that exposures to RF energy below internationally accepted limits has no demonstrable health risk. Research is still ongoing about possible health and safety issues that might be caused by low-level exposures to RF signals, but in the opinion of health agencies no health problems have been established by many research projects so far. Speaking for myself, I am more concerned about nonhealth RF issues, including threats to privacy from use of wireless devices, material inappropriate for children freely available on the internet, and traffic accidents caused by use of wireless devices while driving.

Kenneth R. Foster, PhD

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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