Electromagnetic radiation and health

Electromagnetic environmental compatibility ( EMC-E ) refers to the compatibility of the emissions of electromagnetic fields (EMF ) on the environment, especially the people and sets limits to ensure safety and prevent possible damage to health. The topic has been for decades under the parent term of the electromagnetic compatibility (EMC ) is a central topic in electrical engineering. The EMF should be considered a branch of EMC with a focus on environmental impacts.

By contrast, the wider definition electrosmog refers to both the associated manifestations of the electromagnetic fields, as well as the electric and magnetic fields will be awarded where a harmful or a Ausgesetzsein (like smog) as well as any unwanted same effectiveness on living organisms.

• 4.1 levels of RF systems
• 4.2 Limit values ​​for low-frequency installations 4.2.1 Limits for medium frequency systems

Causes

Electric and magnetic fields are generated ( electric voltage and magnetic voltage) or a difference in charge (electric charge ) between two locations, due to a potential difference. A distinction

• Electric fields ( alternating electric field and electrostatic field ). Electrostatic fields occur for example when DC powered trams and suburban trains outside of acting as Faraday cages vehicle cabins by currents in the catenary wire and reverse currents or stray currents ( within occur only magnetic fields ).
• Magnetic fields ( alternating magnetic field and dc magnetic field) and
• Electromagnetic fields.

Alternating magnetic fields and electromagnetic fields are generated by current flow in electrical conductors caused ( electrodynamics), wherein when conductor and return conductor are brought close to each other, can reverse the magnetic effects. In electrical equipment and devices and in their vicinity and the leads currents cause low-frequency magnetic and radiofrequency electromagnetic fields, such as:

• Within Converter systems, switches and dimmers
• Electrical appliances: electric blankets, aquarium pumps, electric hi-fi equipment and clocks, clock radios, two-wire device connection cable without a protective conductor, unshielded cables, energy saving lamps, fluorescent lamps, baby monitor, heated water beds, electric adjustable beds, electric boilers, computers, kitchen appliances ( irons and ironing machines, sewing machine ) fuse boxes, and many more.
• Outgoing short range of low and high voltage cables of all kinds, whether from stray electromagnetic fields backflow < / ref >. Where the magnetic field strength is in the higher tracks, drive or accelerate the more trains in the route section (higher current consumption ) and power consumption of electrosmog in, on and through the web, accessed December 17, 2011 < / ref >
• Equalizing currents on data cables, protective conductors and gas, water, district heating, heating and underfloor heating pipes

• These include non-directional antenna transmitting equipment, such as radio stations or mobile phone base station, satellite TV and GPS, mobile phones, Wi-Fi, Bluetooth and cordless phones,
• And directional antennas for radar, car radar and radio, electronic article surveillance monitoring

• Microwave ovens generate electromagnetic fields in their cooking space, a safe lower portion of these so-called " radiation leakage " in the near vicinity,
• Induction
• Different welding processes such as resistance welding, arc stud welding, magnetic forming and Electrofusion.

• Induction hobs and ordinary electric hotplates generate alternating magnetic fields.
• Household Heat Sealers

• Electro-medical treatment procedures, magnetic resonance imaging

Effects

Starting from the definition of the electric field (which is the ability of the electric field to exert force on charge ) can be anywhere, where an electric field is detected, applied forces on charges. It is essential, whether it comes to effects on living tissue.

Electromagnetic fields have been used since 1764 in medicine, mainly for heating and circulation increase, associated with it to improve wound and bone healing, but also now as a scalpel substitute in HF surgery for transection of tissue or in the desolation of Arrhythmiezentren in the heart ( radiofrequency ablation ). Intensively researched and used therapeutically in medicine is mainly explained below thermal effects of high frequency electromagnetic alternating fields.

Low-frequency electric fields, in particular, the electrostatic field of the earth to penetrate in the case of equilibrium is not in a conductive body, but instead ends, according to the electrostatic induction of its surface, for example on the surface of the human body, plants or buildings, other than magnetic fields, which is also the body penetrate. High frequency capacitive current, however, can penetrate the body and flows mainly in the upper layers of the skin as a line current through the blood vessels and blood vessels. Extremely high frequency electromagnetic fields such as X-ray or gamma radiation can penetrate deeply.

Thermal effect

The heat input into tissue via the dielectric heating at a molecular level, depending on the resonance of the molecules, the energy transfer gives rise to an attenuation of the electromagnetic wave. Depending on what molecule directly (or whatever neighboring molecule by thermal convection ) is concerned, there are different effects. The thermal effect can lead to protein degradation in concentrated exposure when the local temperature exceeds a threshold of about 40 ° C. To temperature changes some cell types and tissues are more sensitive. Tissue with high cell division such as bone marrow, intestinal epithelium and embryonic tissues contain highly sensitive cell types, muscle and nerve tissues are relatively resistant. If the performance of the body's own repair systems is given, damage to individual cells is not a problem, otherwise, mutations accumulate.

Transmitted electromagnetic waves with wavelengths longer than about 0.5 microns too little energy to break molecular bonds chemically stable, but can disrupt hydrogen bonds in water and biomolecules, which induces the denaturation and inactivation of biomolecules. Likewise, the charges existing radicals (molecules with reactive electrons) can be rearranged to polarization effects, creating new reaction products may arise.

The heat input into biological tissue depends on many factors:

• The power density of the electromagnetic field at the location of the exposed person affected by the power ( and directional characteristics ) of the radiation source,
• Absorption, reflection, diffraction and scattering of radiation between radiation source and radiation sensor;
• Distance of the radiation detector
• And of the duration of action

• Of the resonance frequencies of the addressable molecules ( vibrational excitation of molecules with dipole moments, excitation to the rotation ),
• Of the frequency or the resonance range for or the body dimensions,
• Of the electrical material properties, electrical conductivity and dielectric strength of the tissue
• The water content of the tissue,
• Of body dimensions with respect to the wavelengths for which the body serves as a receiving antenna in association with the
• Alignment of the body in the field,
• Occurring absorption peaks caused by meetings held in the body or outside the body reflection, diffraction or scattering or when the individual cells of the body are not moving and always meet loads the same cell cluster.
• Induced eddy currents

Because of the numerous factors limit setting is not easy. The heat effect is influenced also

• The sensitivity of the tissue or cells for heat
• By the cooling due to the circulation
• Of the body mass,

Systems in which this limit is exceeded, are shielded (about microwave ovens ) or before access protected ( transmitters). Due to leakage radiation at poorly shielded equipment with high power ( about industrial plastic welding equipment) can limits be exceeded.

The thermal load by mobile takes in areas with well-developed GSM or UMTS radio networks tend to decline because the body-worn mobile phones there require a lower transmit power and ( the radio masts ) negotiate this with the base station through the transmission protocol as well. The field strengths emanating from the radio masts are negligible because of the comparison with the mobile phone great distance of the transmission towers on the body of the exposed person. One can assume that the limits of mobile phones are met and exceeded, even in relatively poor radio networks, where high transmission power of the phones is set.

A curiosity is the Frey effect is a phenomenon that occurs in the vicinity of high-performance wireless systems with pulsed radiation such as radar installations: It takes a person who is in the immediate vicinity of the antenna in the transmit beam, seeming clicking sounds true that sync with the pulsed beam occur. The Frey effect is considered to be a generally scientifically accepted phenomenon, triggered in the cochlea in the inner ear, without pathological significance.

Non-thermal effects

One must distinguish between non-thermal effects that occur at higher radiation intensities, although a relevant heating was prevented by cooling, and non-thermal effects that occur at low levels of radiation, the cause of no relevant increases in temperature. Non-thermal effects do not occur in the entire high frequency range, but only at specific resonance frequencies, radiation strengths and Timeline of the radiation.

In high-frequency fields, a plurality of nuclei and compounds are due to nuclear magnetic resonance excited (see nuclear magnetic resonance spectroscopy and magnetic resonance imaging ), the energy received at the resonance frequency is not converted into thermal energy, but re-emitted in the form of electromagnetic energy.

Other effects

In a study from 2009 was found in the analysis of satellite photos that cattle, deer and deer preferentially graze in north-south direction, its orientation but is altered by high-voltage lines. According to the authors, the electromagnetic fields from power lines influence the " inner compass " of these animals. However, a 2011 publish work with larger data base could not detect any dependence of the orientation of the animals of the earth's magnetic field. Accordingly, the authors consider it absurd to start from a disturbance of the magnetic sense of cattle and interpret the results of the previous work as errors in the data analysis. The extent to which such electromagnetic fields affect the behavior of animals that have a magnetic sense ( migratory birds, bees and pigeons ), has not yet been investigated. The orientation of living beings in a magnetic field was also detected in bacteria, green algae and plants, see Magnetotaxis.

Legal framework

Since the adoption of the 26th Ordinance on the Implementation of the Federal Pollution Control Act ( Ordinance on electromagnetic fields - 26 BlmSchV ) of 16 December 1996, this field is subject to a statutory provision in Germany. Compliance with the relevant limit values ​​shall be verified by the system operator at the Environment Agency prior to commissioning.

At European level, there is the Council Recommendation of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz ) (1999/ 519 / EC). In it, the relevant physical quantities are defined in the context of EMF exposure in Part A above. In Part B of the recommendation, the distinctions of the basic restrictions and reference levels following use shall be explained. The accompanying notes are the recommended basic restrictions and reference levels

Limits

In Germany, the protection of the population to be controlled from electromagnetic fields and radiation by frequency-dependent limits with the 26th Ordinance on the Implementation of the Federal Pollution Control Act. This Regulation shall apply to fixed installations. For mobile devices, the R & TTE applies i.V.m. with the harmonized standard DIN EN 50360 and Annex II of the Council Recommendation 1999/519/EC. For EM fields in the workplace, there is also the BG accident prevention regulation BGV B11. All of these standards are based on recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP ), a World Health Organization Expert Advisory Panel.

The Ordinance on electromagnetic fields recorded two frequency ranges:

In the 26th BlmSchV only for two technical -used frequencies ( 50 Hz power system, traction power supplies ) are thus limits specified for the low frequency range. These apply to all areas where people reside permanently.

For other frequencies in the frequency range up to 300 GHz, the ICNIRP has issued recommendations (ICNIRP guidelines 1998), for the public at large in the EU Directive 1999/519/EC and for the range of jobs in the EU Directive 2004/ 40 / EC were taken. So that no limits apply for the private sector. For the scope of the EU preorder apply to 100 kHz only limits for thermal effects according to Ohm's law. Only from 100 kHz are determined SAR values.

Levels of RF systems

The Ordinance on electromagnetic fields specifies the following limits:

Rms value of the field strength, square averaged over six-minute intervals ( frequency f used in MHz)

Representative values ​​of high-frequency radiation sources are specified by the Federal Office for Radiation Protection as follows:

Limits for low frequency systems

RMS values ​​of the electric field strength and magnetic flux density after 26 BlmSchV:

Representative values ​​of magnetic flux densities of household appliances are specified by the Federal Office for Radiation Protection as follows:

The values ​​apply to a measurement distance of 30 centimeters.

Limits for medium-frequency systems

So far, the frequency range between 50 Hz and 10 MHz is not covered by the current 26 BlmSchV or a valid European regulation. Low-frequency and medium-frequency electromagnetic fields above 50 Hz are ubiquitous ( Atmospheric disturbances ).

The recommendation of the ICNIRP applies to all technically usable frequencies. The 26th BlmSchV in the current 1996 version does not call the area between the mains frequency of 50 Hz and the lower limit for high frequency at 10 MHz. For the lower frequency range below 10 MHz, the technical regulations for electromagnetic compatibility must be maintained.

Origin of the limits

Before limits are defined and adopted in regulations, there are recommendations, for example by the ICNIRP.

The current recommendation of the ICNIRP applies to electromagnetic fields from 0 Hz to 300 GHz.

The recommendation is generally referred to Ohm's law in vector form, which is based the implementation of electromagnetic fields in tissue at the scalar conductivity. The technical limits for field strengths are therefore derived by calculation of basic restrictions. These basic restrictions related to the excitation of electric currents in the body ( affecting the nervous activity ) and to the maximum allowable temperature rise of individual body regions. The excitation of electric currents in the body, a non- thermal effect occurs at frequencies from 0 Hz to 10 MHz. At higher frequencies, the human body is a poor conductor by the high water content. The heating effect is significant at frequencies above 100 kHz. Dissociative ( separating ) radiation, the tissue immediately destroyed by decomposition of the structures and separation of molecules is effective at higher frequencies.

While currents and temperature increase are not directly measurable in the living body, it is in the derived limits to directly measurable field quantities. In compliance with the derived limits is ensured that the basic restrictions are met. Depending on the frequency of an external field causes a certain force to different strong effects in the body. Therefore, the derived limits are frequency dependent. For example, the field strength of wireless transmission equipment of the frequency must remain below 935 MHz 42.0 V / m (or 0.11 A / m or 4.76 W / m²). For an FM radio station ( 87.5 to 108 MHz), a limit of 28 V / m is considered.

Compliance with the statutory limits is monitored by the relevant pollution control authorities of the countries and by the Federal Network Agency for Electricity, Gas, Telecommunications, Post and Railways. Compliance with the technical limits must be responsibly ensured by the manufacturers and operators of technical equipment. Specified in product standards based limits of radiated field strength or power density apply to all technical devices, also for household appliances such as microwave ovens and mobile phones to do so.

Swiss limits

In Switzerland, since 2000 there is the Regulation on protection against non- ionizing radiation (see ionizing radiation), which limits the emissions of precaution. Thus, to apply generally recommended by the WHO limits. For places of sensitive use, such as bedroom, living room, school, and hospital rooms, in addition Precautionary emission limits are set. They amount, in simple terms, 10 % (high frequency) or 1% (low- frequency magnetic field ) of the general limits. In calculating the value of the Swiss pension building attenuation is taken into account, because it involves the protection of the interior. This system limits relate to a system, they can be so exceeded in total. An installation comprises all transmission antennae which are in close proximity to each.

Other recommendations for limits

There are a number of recommendations for limit values, which are not based exclusively on the established health effects. They come from associations and movements that critical of the mobile technology and assume risks in the range of valid values ​​. Therefore give out their own pension values ​​. An example is the ECOLOG Recommendation 2003 for UMTS / E network / D network ( 900-2100 MHz ) with 2 V / m (10 mW / m² = 10,000 uW / m²).