<P> The best understood biological effect of electromagnetic fields is to cause dielectric heating . For example, touching or standing around an antenna while a high - power transmitter is in operation can cause severe burns . These are exactly the kind of burns that would be caused inside a microwave oven . </P> <P> This heating effect varies with the power and the frequency of the electromagnetic energy . A measure of the heating effect is the specific absorption rate or SAR, which has units of watts per kilogram (W / kg). The IEEE and many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR, mainly based on ICNIRP Guidelines, which guard against thermal damage . </P> <P> There are publications which support the existence of complex biological and neurological effects of weaker non-thermal electromagnetic fields (see Bioelectromagnetics), including weak ELF magnetic fields and modulated RF and microwave fields . Fundamental mechanisms of the interaction between biological material and electromagnetic fields at non-thermal levels are not fully understood . </P> <P> Fluorescent light bulbs and tubes internally produce ultraviolet light . Normally this is converted to visible light by the phosphor film inside a protective coating . When the film is cracked by mishandling or faulty manufacturing then UV may escape at levels that could cause sunburn or even skin cancer . </P>

Effects of radio waves on the human body