The index of specific flow of absorption or DAS (also known under its English denomination SAR for Specific Absorption Misses) is an index which measures the level of radio frequencies emitted by the portable towards the user when it functions with full power, under the worst conditions of use. Its unit is the Watt by Kilogram (W/kg, IF $\{m^2\; s^\; \{-\; 3\}\}$). The absorption of electromagnetic fields produces a rise in temperature fabrics (heating effect). Following the publication of the decree of October 8th, 2003, the mobiles intended to be used in France must present an index DAS lower than 2 W/kg out of 10 G of human tissue than the level of the trunk and the head. The index given by the manufacturers corresponds, in general, with that on the level of the head.

Formulate

The specific flow of absorption is calculated starting from the following physical sizes:

1. the Electric field in fabrics: $SAR\; =\; \backslash \; frac\; \{\backslash \; sigma\; \backslash \; vec\; E^2\}\; \{\backslash \; rho\}$
2. density of current in fabrics: $SAR\; =\; \backslash \; frac\; \{J^2\}\; \{\backslash \; rho\; \backslash \; sigma\}$
3. rise in temperature in fabrics: $SAR\; =\; c\_i\; \backslash \; frac\; \{dT\}\; \{dt\}$

E… Electric field in V/m

J…. Density of current (unit)|With]/m ² ] , obtained starting from the magnetic fields and/or électrique.

ρ… Density of the fabric kg/m ³

σ … electric Conductivity of the fabric S/m

c_i… Heat capacity of fabric in J/(kg K)

dT/dt… derived from the Temperature of fabrics by time in K/S

Application in health

More concretely, nowadays, with some exceptions, the majority of the telephones have a DAS lower than 1 W/kg out of 10 G of fabrics. The DAS is more often located around 0.4 to 0.8 W/kg out of 10 G. Knowledge on the electromagnetic waves is today still to deepen. Many scientific studies tend to prove the harmlessness of these waves with low dose (in lower parts of 2 W/kg out of 10 G). Where none could establish this harmlessness clearly, others on the other hand highlighted dangers in the long term to the human body such as cancers or the permeabilisation of the cellular membranes, such as the hemato-encephalic Barrière.

At present, the frequent technological changes of the cellphones do not make it possible to have a reliable knowledge of the risk. Indeed, it takes several years to undertake an epidemiologic study having enough relevance to apply to low radiation dosage emitted by the portables. Thus, the studies we have today relate to only the first generations of portables. But since, the 3G develops and the frequencies evolve/move.

The French Agency of Public health of the Environment and Work (AFSSET) published in June 2005 a new opinion on the portables. On its side the European Agency for the environment, taking into account the remaining doubts, recommends the application of the precaution principle and to reduce the limits of current exposures.

According to a Swedish epidemiological study led by Kjell Mild, the intensive users of mobile phone would have a risk to be reached of a malignant tumor with the Cerveau on the side where they use their telephone 2,9 times higher, from many studies conclude at the very weak risk even with their absence.

Better is still worth to also prefer a telephone having a DAS relatively low, but as much as possible telephoning under conditions of good reception and to move away compound from the hot areas of the body at the time of a communication of the type GSM/GPRS/UMTS by using for example a pedestrian kit.

See too

Related articles

• electromagnetic Wave
• electromagnetic Spectrum
• Wave radio
• not-ionizing Radiation
• Mobile phone
• Transmission without wire and electromagnetic health
• Pollution

External documentation

Bibliography :

• European standard IN 50360 for the measurement of the DAS
• International standard CEI 62209-1 of the International Electrotechnical Commission
• Recommendation of the European Council, of July 12th, 1999, relating to the limitation of the exposure of the public to the electromagnetic fields (of 0 Hz with 300 GHz)
• Directive 2004/40/CE of the European Parliament and the Council, of April 29th, 2004, concerning the minimal regulations of safety and health relating to the exposure of the workers to the risks due to the physical agents (electromagnetic fields)
• Report/ratio of French Senators JL. Lorraine and D. Raoul
• Report/ratio Zmirou
• Article written by the students of the CFJ

external Bonds :

• Results of the study COMOBIO
• Research program ADONIS
• Study Intercom
• File mobile phone head office of slotted measuring health
• Section of the DAS of Antennessa
• Testing ground DAS Speag
• Site of the ICNIRP
• Swiss Group of research on the nonionizing radiations
• Dosimetry of the radio waves
• Mobile telephony and health: to include/understand index DAS (ZDNet)
• scientific Hoax of two Russian journalists

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