electromagnetic radiation and health electromagnetic radiation and health electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 ev energy to ionize atoms or break chemical bonds. extreme ultraviolet and higher frequencies, such as x-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning. this article is about the health effects of non-ionizing radiation. for the negative health effects of ionizing radiation, see radiation poisoning. types of radiation in the electromagnetic spectrum part of a series onpollutionair pollution from a factory air acid rain air quality index atmospheric dispersion modeling chlorofluorocarbon exhaust gas haze indoor air internal combustion engine global dimming global distillation ozone depletion particulates persistent organic pollutant smog aerosol soot volatile organic compound biological biological hazard genetic introduced species (invasive species) digital information electromagnetic light ecological overillumination radio spectrum natural ozone radium and radon in the environment volcanic ash wildfire noise transportation land water air rail sustainable transport urban sonar marine mammals and sonar industrial military abstract noise control radiation actinides bioremediation depleted uranium nuclear fission nuclear fallout plutonium poisoning radioactivity uranium electromagnetic radiation and health radioactive waste soil agricultural herbicides manure waste pesticides land degradation bioremediation defecation electrical resistance heating soil guideline values phytoremediation solid waste biodegradable waste brown waste electronic waste battery recycling food waste green waste hazardous waste biomedical waste chemical waste construction waste lead poisoning mercury poisoning toxic waste international waste industrial waste lead smelting litter mining coal mining gold mining surface mining deep sea mining mining waste uranium mining municipal solid waste garbage nanomaterials plastic microplastics packaging waste post-consumer waste waste management landfill thermal treatment space satellite thermal urban heat island visual air travel advertising clutter overhead power lines traffic signs vandalism war chemical warfare herbicidal warfare (agent orange) nuclear holocaust (nuclear fallout - nuclear famine - nuclear winter) scorched earth unexploded ordnance war and environmental law water agricultural wastewater diseases eutrophication firewater freshwater groundwater hypoxia industrial wastewater marine debris monitoring nonpoint source see misc section nutrient ocean acidification oil spill pharmaceuticals freshwater salinization septic tanks sewage septic tanks pit latrine shipping stagnation sulfur water surface runoff turbidity urban runoff water quality misc point source area source legacy pollution lists diseases law by country most polluted cities least polluted cities by pm2.5 treaties categories by country environment portal ecology portal the most common health hazard of radiation is sunburn, which causes between approximately 100,000 and 1 million new skin cancers annually in the united states. in 2011, the world health organization (who) and the international agency for research on cancer (iarc) have classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (group 2b). hazards dielectric heating from electromagnetic fields can create a biological hazard. for example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns (the mechanism is the same as that used in a microwave oven). the heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of distance to the source. the eyes and testes are particularly susceptible to radio frequency heating due to the paucity of blood flow in these areas that could otherwise dissipate the heat buildup. radio frequency (rf) energy at power density levels of 1–10 mw/cm2 or higher can cause measurable heating of tissues. typical rf energy levels encountered by the general public are well below the level needed to cause significant heating, but certain workplace environments near high power rf sources may exceed safe exposure limits. 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. low-level exposure the world health organization (who) began a research effort in 1996 to study the health effects from the ever-increasing exposure of people to a diverse range of emr sources. in 2011, the who/international agency for research on cancer (iarc) has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (group 2b), based on an increased risk for glioma, a malignant type of brain cancer, associated with wireless phone use. epidemiological studies look for statistical correlations between em exposure in the field and specific health effects. as of 2019, much of the current work is focused on the study of em fields in relation to cancer. there are publications which support the existence of complex biological and neurological effects of weaker non-thermal electromagnetic fields (see bioelectromagnetics), including weak elf electromagnetic fields and modulated rf and microwave fields. effects by frequency warning sign next to a transmitter with high field strengths while the most acute exposures to harmful levels of electromagnetic radiation are immediately realized as burns, the health effects due to chronic or occupational exposure may not manifest effects for months or years. extremely low frequency extremely low frequency em waves can span from 0 hz to 3 khz, though definitions vary across disciplines. the maximum recommended exposure for the general public is 5 kv/m. elf waves around 50 hz to 60 hz are emitted by power generators, transmission lines and distribution lines, power cables, and electric appliances. typical household exposure to elf waves ranges in intensity from 5 v/m for a light bulb to 180 v/m for a stereo, measured at 30 centimetres (12 in) and using 240v power. (120v power systems would be unable to reach this intensity unless an appliance has an internal voltage transformer.) overhead power lines range from 1kv for local distribution to 1,150 kv for ultra high voltage lines. these can produce electric fields up to 10kv/m on the ground directly underneath, but 50 m to 100 m away these levels return to approximately ambient. metal equipment must be maintained at a safe distance from energized high-voltage lines. exposure to elf waves can induce an electric current. because the human body is conductive, electric currents and resulting voltages differences typically accumulate on the skin but do not reach interior tissues. people can start to perceive high-voltage charges as tingling when hair or clothing in contact with the skin stands up or vibrates. in scientific tests, only about 10% of people could detect a field intensity in the range of 2-5 kv/m. such voltage differences can also create electric sparks, similar to a discharge of static electricity when nearly touching a grounded object. when receiving such a shock at 5 kv/m, it was reported as painful by only 7% of test participants and by 50% of participants at 10 kv/m. the international agency for research on cancer (iarc) finds "inadequate evidence" for human carcinogenicity. shortwave shortwave (1.6 to 30 mhz) diathermy (where em waves are used to produce heat) can be used as a therapeutic technique for its analgesic effect and deep muscle relaxation, but has largely been replaced by ultrasound. temperatures in muscles can increase by 4–6 °c, and subcutaneous fat by 15 °c. the fcc has restricted the frequencies allowed for medical treatment, and most machines in the us use 27.12 mhz. shortwave diathermy can be applied in either continuous or pulsed mode. the latter came to prominence because the continuous mode produced too much heating too rapidly, making patients uncomfortable. the technique only heats tissues that are good electrical conductors, such as blood vessels and muscle. adipose tissue (fat) receives little heating by induction fields because an electrical current is not actually going through the tissues. studies have been performed on the use of shortwave radiation for cancer therapy and promoting wound healing, with some success. however, at a sufficiently high energy level, shortwave energy can be harmful to human health, potentially causing damage to biological tissues, for example by overheating or inducing electrical currents. the fcc limits for maximum permissible workplace exposure to shortwave radio frequency energy in the range of 3–30 mhz has a plane-wave equivalent power density of (900/f2) mw/cm2 where f is the frequency in mhz, and 100 mw/cm2 from 0.3 to 3.0 mhz. for uncontrolled exposure to the general public, the limit is 180/f2 between 1.34 and 30 mhz. radio and microwave frequencies