SAR (Specific Absorption Rate)

[Karthik R 246]

To communicate with the network, mobile phones emit low levels of radio waves (also known as radiofrequency or 'RF' energy) when being used. SAR stands for Specific Absorption Rate, which is the unit of measurement for the amount of RF energy absorbed by the body when using a mobile phone.

The SAR is determined at the highest certified power level in laboratory conditions.

A SAR value is a measure of the maximum energy absorbed by a unit of mass of exposed tissue of a person using a mobile phone, over a given time or more simply the power absorbed per unit mass. SAR values are usually expressed in units of watts per kilogram (W/kg) in either 1g or 10g of tissue.

You should also be aware that the SAR values shown are maximum values and in practice emissions from mobile phones will normally be lower than these figures. The emissions depend on factors such as distance from a transmission mast, whether the phone is used indoors or outdoors, how close the phone is held to the ear and other operating factors. It is important to realise that a phone with a high SAR rating may actually operate with much lower emissions in practice, and conversely a phone with a lower SAR rating may operate with emissions higher than a high SAR phone in practice. You should not rely on a low SAR rating to guarantee your health.

Exposure Limits

• North American and Australian Standard - The SAR limit for mobile phones used by the public is 1.6 watts/kilogram (W/kg) averaged over one gram of body tissue.
  
• European Standard - The SAR limit for mobile phones used by the public is 2.0 watts/kilogram (W/kg) averaged over ten grams of body tissue.
  

To compare relative radiation of different mobile phones, only compare phones using the same standard.

Does the SAR for a mobile phone vary when in use?

Yes. Although the SAR is determined at the highest certified power level in laboratory conditions, the actual SAR level of the phone while operating can be well below this value. This is because mobile phones use adaptive power control to reduce the transmitted power to the minimum possible whilst maintaining good call quality.

Once a call is established the mobile phone will power down to the minimum level required. Therefore, the closer you are to a base station and the better the reception, the lower the actual SAR level.

Does SAR vary between mobile phones?

Yes. The maximum SAR level for different mobile phone models can vary and this is primarily due to where the antenna in the phone is located.

Where can i find the SAR and safety information for mobile phones?

There are many ways to find SAR information for mobile phones.

• Check the phone handbook or user manual – look under safety or specifications
  
• Search the manufacturer’s web site for your phone model and SAR – it is usually listed under safety, or product specifications.
  
• If everything fails, Google it
  

How is SAR measured for mobile phones?

Specialised laboratory test equipment is used for conducting SAR measurements. The equipment consists of a ‘phantom’ (human or box), precision robot, RF field sensors, and mobile phone holder. The phantom is filled with a liquid that represents the electrical properties of human tissue.

Head Measurements - SAR test inside a head phantom:

1. The mobile phone is positioned against the phantom head and switched on to full power.
   
2. The precision robot moves the RF probe throughout the phantom head measuring the radio signal level in the head phantom.
   
3. The computer analysing the data converts the radio signal levels into SAR (W/kg).
   
4. The full test is conducted at all operating frequencies and using different phone positions.
   
5. The maximum level measured is recorded as the SAR value against the head.
   

Body Measurements - SAR test inside a body (box) phantom:

1. The mobile phone is positioned against the phantom body and switched on to full power.
   
2. The precision robot moves the RF probe throughout the phantom body measuring the radio signal level in the body near the phone.
   
3. The computer analysing the data converts the radio signal levels into SAR (W/kg).
   
4. The maximum level measured is recorded as the SAR value against the body.
   

Check out the SAR measurement video here !

Is there a separation distance from the body required for mobile phones?

Mobile phones generally get better reception when used away from the main part of the body. Some mobile phones are designed to have a small minimum separation from the body when in use, typically 15 – 25mm depending on the phone. The minimum separation often represents the spacing created by a phone holder or clothing. This is to ensure the phone operates more efficiently and also meets the SAR requirements.

A mobile phone can always be used up against the head without separation. This is because the antenna in the phone is designed to be far enough away from the head to meet SAR requirements and operate most efficiently.

Am I at risk by not using a separation distance?

Separation distances are used for more efficient operation of the phone and for SAR compliance. If a separation distance is specified and not adopted then the phone is possibly being used in a non-compliant position. However this does not compromise safety as the international exposure guidelines have large built-in safety margins.

How to reduce your exposure to phone radiation

• Use a hands-free headset.
  
• Do not use your phone more than necessary and keep your calls short
  
• Send a text instead of making a call
  
• Try to avoid using your phone if the signal strength is low - find a better location to make a call
  
• Try to use the phone outdoors rather than inside, or move close to a window to make a call
  
• Keep the phone (and particularly the aerial) as far as possible from your head
  
• Avoid touching the aerial while the phone is turned on, and keep the phone away from areas of the body such as eyes, testicles, breasts and internal organs
  
• Women - Limit usage as much as possible if pregnant
  
• Switch off your phone when not in use
  

MMF (Mobile Manufacturer Forum) has recently released a video on the issue, you can view it here

Samsung users check your SAR value here

Nokia users can check their phone's SAR value here

Motorola here

Sourced part of the info from EMF Explained. Image courtesy - Think Digit.

[Honest 836]

Very informative thread Karthik Bhai. +1

[ani_meher 42]

Very informative! One Qustion: The phone shouldn't be kept near breasts or testicles, so shirt and pant pockets are gone. Then where to store it on person?

[Karthik R 246]

WHO : Cell phone use can increase possible cancer risk

(CNN) - Radiation from cell phones can possibly cause cancer, according to the World Health Organization. The agency now lists mobile phone use in the same "carcinogenic hazard" category as lead, engine exhaust and chloroform. Before its announcement on Tuesday, WHO had assured consumers that no adverse health effects had been established.

A team of 31 scientists from 14 countries, including the United States, made the decision after reviewing peer-reviewed studies on cell phone safety. The team found enough evidence to categorize personal exposure as "possibly carcinogenic to humans."

What that means is they found some evidence of increase in glioma and acoustic neuroma brain cancer for mobile phone users, but have not been able to draw conclusions for other types of cancers.

"The biggest problem we have is that we know most environmental factors take several decades of exposure before we really see the consequences," said Dr. Keith Black, chairman of neurology at Cedars-Sinai Medical Center in Los Angeles.

The type of radiation coming out of a cell phone is called non-ionizing. It is not like an X-ray, but more like a very low-powered microwave oven. "What microwave radiation does in most simplistic terms is similar to what happens to food in microwaves, essentially cooking the brain," Black said. "So in addition to leading to a development of cancer and tumors, there could be a whole host of other effects like cognitive memory function, since the memory temporal lobes are where we hold our cell phones."

Wireless industry responded to Tuesday's announcement saying it "does not mean cell phones cause cancer." CTIA-The Wireless Association added that WHO researchers "did not conduct any new research, but rather reviewed published studies."

The European Environmental Agency has pushed for more studies, saying cell phones could be as big a public health risk as smoking, asbestos and leaded gasoline. The head of a prominent cancer-research institute at the University of Pittsburgh sent a memo to all employees urging them to limit cell phone use because of a possible risk of cancer.

"When you look at cancer development -- particularly brain cancer -- it takes a long time to develop. I think it is a good idea to give the public some sort of warning that long-term exposure to radiation from your cell phone could possibly cause cancer," said Dr. Henry Lai, research professor in bioengineering at University of Washington who has studied radiation for more than 30 years.

Results from the largest international study on cell phones and cancer was released in 2010. It showed participants in the study who used a cell phone for 10 years or more had doubled the rate of brain glioma, a type of tumor. To date, there have been no long-term studies on the effects of cell phone usage among children. "Children's skulls and scalps are thinner. So the radiation can penetrate deeper into the brain of children and young adults. Their cells are at a dividing faster rate, so the impact of radiation can be much larger." said Black of Cedars-Sinai Medical Center.

In February, a study by researchers at the National Institutes of Health, revealed radiation emitted after just 50 minutes on a mobile phone increases the activity in brain cells. The effects of brain activity being artificially stimulated are still unknown. Neurosurgeon and CNN chief medical correspondent Dr. Sanjay Gupta says Tuesday's announcement, "dealt a blow to those who have long said, 'There is no possible mechanism for cell phones to cause cancer.' By classifying cell phones as a possible carcinogen, they also seem to be tacitly admitting a mechanism could exist."

Manufacturers of many popular cell phones already warn consumers to keep their device away from their body and medical experts say there other ways to minimize cell phone radiation. The Apple iPhone 4 safety manual says users' radiation exposure should not exceed FCC guidelines: "When using iPhone near your body for voice calls or for wireless data transmission over a cellular network, keep iPhone at least 15 millimeters (5/8 inch) away from the body." BlackBerry Bold advises users to "keep the BlackBerry device at least 0.98 inch (25 millimeters) from your body when the BlackBerry device is transmitting."

The logic behind such recommendations is that the further the phone is from the body, the less radiation is absorbed. Users can also use the speakerphone function or a wired earpiece to gain some distance. Users can text instead of talk if they want to keep the phone away from their faces. Finally, cell phones emit the most radiation when they are attempting to connect to cellular towers. A moving phone, or a phone in an area with a weak signal, has to work harder, giving of more radiation. So users can avoid using their cell phones in elevators, buildings and rural areas if they want to reduce their exposure, experts say.

Courtesy : CNN

[Venkatagiri 53]

Times of India has listed 10 phones with highest radiation

Link: http://timesofindia.indiatimes.com/itslideshow/12571133.cms

[krishnendu halder 24]

nice article!+1

how will dual sim handsets perform?

[ni0987 179]

Friends please clarify me on this:

in which condition would the same mobile phone will have higher SAR value:

1. when this phone is being used with GSM 900 or
   
2. when this phone is being used with GSM 1800
   

Keeping all other conditions same.

[KumaarShah 143]

For more SAR details on the top 20 mobiles :

http://reviews.cnet.com/2719-6602_7-291-2.html

Sent from my MB855 using Tapatalk

Edited April 11, 2012 by KumaarShah

[KumaarShah 143]

BTW, Photon 4G (as many users are here at RW already) has a SAR of 0.93 (head) and 0.91 (body)

Sent from my MB855 using Tapatalk

Edited April 12, 2012 by KumaarShah

[Venkatagiri 53]

For more SAR details on the top 20 mobiles :

http://reviews.cnet....02_7-291-2.html

Thanks for the link. The site also has Top 20 LOW RADIATION phones (US)

Many Samsung models come under low radiation

Link of Low radiation handsets: http://reviews.cnet.com/2719-6602_7-291-3.html?tag=

[kshah 452]

For more SAR details on the top 20 mobiles :

http://reviews.cnet.com/2719-6602_7-291-2.html

Sent from my MB855 using Tapatalk

Why motorola phones have high SAR than other brands?

[ni0987 179]

@kshah thanks for bringing up this thread.

Friends please clarify me on this:

in which condition would the same mobile phone will have higher SAR value:

• when this phone is being used with GSM 900 or
• when this phone is being used with GSM 1800

Keeping all other conditions same.

I couldn't find a reply for this question yet.

Please friends, share your thoughts on this.

[KanagaDeepan 1,084]

^^^^

Yes sir, thatz one way to catch network signals better than other phones, imho...

[kshah 452]

I thought so. But other thought was when testing conditions are standard why more radiation? My friend from medical equipment (xray) manufacture says it could be because of either poor placement of antenna (rather better placement - so as to catch best possible reception at same power conditions) or poor shielding. Shielding require heavy metals hence heavier phones.

I am unable to understand any thing.

[kshah 452]

@ni

As far as I understand power output is constant regardless of frequency of transmission.

[drabhayshah76 7]

What about Dual Sim phones? Do the emit double the radiation? Also what about the SAR value in dual sim phones?

[city02 63]

no mobile emits a fixed amount of 'radiation' - there is a min / max level which depends on usage

[standby vs calling] and its proportional to the distance from the nearest tower

[technically the square of the distance to be precise]

so a dual sim close to a tower may use less power to emit radio signals than a single sim far away.

radiation itself is misleading since all mobiles emit NON-IONIZING radiation as opposed to x-rays / UV

[this rant has been building up for sometime due to the media frenzy over mobile safety]

there is so much fear around mobile radiation that most people forget a single xray is equivalent to almost a decade of daily mobile use in terms of altering your dna!

even a single cigarette in your life can increase your chances of cancer beyond any mobile in use presently.

since there is NO scientific study establishing ANY link between mobile use and cancer after a decade of research by the WHO,

until there is some medical proof - just use simple [common sense] precautions like i do:

1. when near any landline, avoid using your mobile

[during normal; office hours i always ask any incoming calls to call back at my work number instead]

my office number automatically fwd to my mobile if not answered to reduce the hassle of calling different numbers to get in touch with me

2. get any headset / handsfree kit to increase the distance between your skull and the antenna

3. if your BT earpiece is not available / out of charge - use the speakerphone if possible

4. send text / sms / mails from your phone instead of calling to the extent practical

unfortunately flip phones have gone out of style but due to the angle away from your head, they only provide about half the intensity into your brain as regular bar / touchscreen phones

celebs like juhi chawla are doing a great disservice try to get mobile towers demolished / banned since simply by stepping outside their houses people are breathing polluted air which has a significantly greater risk of causing pollution realted illnesses including cancer than a life time of mobile use

you must be aware of RELATIVE risk:

can excessive mobile use kill you? probably

but its over a million times more likely you will die just by crossing the road so do you stop crossing ALL streets?

for the rest of your life?

can mobiles cause cancer? again possibly

the food you eat, the air you breathe, stepping outdoors during the day [without sunscreen of SPF 30 at least]

all have PROVEN links to cancer while cell towers do not after over a dozen international studies that span a decade of usage across multiple countries

eating meat causes cancer,

eating organic food increases risk of ecoli contamination and related illness by 2-3x over non-organically [inorganic?] grown fruits / veggies

repeated ingestion of contaminated food triggers certain forms of gastro-intestinal cancer!

are you going to stop eating all organic food?

just be sensible before jumping to conclusions

focus on your most significant risks to health first

here's a novel idea:

simply ignore all SAR numbers on any handset!

its irrelevant to your health compared to talking even ONCE while driving...

in your life!

or speeding above the legal limit.

[drabhayshah76 7]

Rightly said Sir.

[city02 63]

i forgot to add that a low SAR phone far from the tower can emit HIGHER radiation than a high SAR mobile close to a tower

so it makes NO sense to base ANY purchase decisions on SAR until you can

control / FIX your distance from the nearest tower!