A Report on Non-Ionizing Radiation

SAR: Microwave News Article Archive (2004 - )

September 22, 2017

Apple has released the RF exposure numbers —SARs, or specific absorption rates— for its new Series 3 Watches. These are the first wristwatches that can connect to cellular networks without being tethered to an iPhone.

The highest exposures, according to Apple, occur when the new watches are placed next to the head. The SAR measurements are based on a 10mm separation distance. The Model A1860 entails the highest exposure: 0.53 W/Kg averaged over 1g of tissue (0.52 W/Kg for the A1861).

The...

April 4, 2010

The bone marrow of young pigs has a higher water content than adult bone marrow and, as expected, Peyman and Gabriel found that it has a higher conductivity. A little math might help understand why a higher water content in tissues this leads to higher SARs. Start with the basic equation for calculating the SAR:

SAR = σ E2 / ρ

where σ = conductivity of the tissue; E = electric field, ρ = density of the tissue

More simply, this means that the SAR is proportional to the conductivity:

SAR σ

and therefore as the conductivity increases, so does the SAR.

May 28, 2006

Metal earrings can spark hotter hot spots in the heads of cell phone users. A team of Spanish scientists has found that the peak SAR —a measure of the energy delivered to human tissue— can be up to 25% higher when a 900 MHz phone is pressed up to an ear pierced with a metallic object. In a paper that will appear in a future issue of Bioelectromagnetics, David Sanchez-Hernandez and coworkers at the Polytechnic University of Cartagena don't say exactly where such hot spots may turn up nor whether this type of magnification will also occur with 1800 MHz phones, but they do advise that this finding merits "special attention."   

January 14, 2005

As the aftershocks from the Stewart report continue to reverberate, the telecom industry is brazenly moving forward with its plan for a major relaxation of the US limit for radiation exposures from cell phones. Yesterday and today, some members of the IEEE International Committee on Electromagnetic Safety (ICES) are meeting to hammer out their revision of the IEEE RF safety standard (known as C95.1).

One of the major planned changes is to replace the current SAR limit of 1.6 W/Kg, averaged over 1g of tissue, with a standard of 2.0 W/Kg, averaged over 10g.

July 22, 2004

The brains of young children absorb twice as much as RF energy from a cell phone as those of adults, according to a set of new calculations carried out by Joe Wiart's research group at France Telecom in the suburbs of Paris.

May 12, 2004

After testing 25 different models of mobile phones, TCO Development, an arm of the Swedish white-collar union TCO based in Stockholm, is recommending only six of them. Seven of the phones failed to meet TCO's SAR standard of 0.8 W/Kg averaged over 10 g of tissue (see MWN, J/F01, p.6).

TCO Development states that its SAR limit is less strict than the Federal Communications Commission's (FCC) SAR standard for certifying phones for sale in the U.S. (It is not clear how many of these models are available in the U.S. marketplace.) 

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