Cell Phone Radiations

Cell phones and cancer are in the news all the time now it seems. But almost everyone uses cell phones. All over the world, tens of millions of people are pressing them against their heads for hours every day. In the U.S. it is estimated that there were at least 100 million cell phone users, as of early 2002, and that number has continued to climb.

So what's the fuss? Is cancer caused by cell phones a serious concern, or the media's panic-du-jour?

A cell phone, and a household cordless phone, use a low level form of microwave radiation to send and receive their signals. (see "How do cell phones work" here.) Microwaves, as you know, are used to cook food. As the radiation penetrates tissue it causes it to heat.

Is this a problem for us with cell phones? That is the current debate. Let's examine the positions and the known evidence, without hype or prejudice. As always, EHSO will provide citations and links to the sources of any evidence provided, so you can verify it for yourself.

Cell phones are dangerous:

• They emit microwaves.
• You hold the source of the emission against your brain
• There are claims that people have had brain tumors in the exact size, shape and position as the antenna on their cell phone.

Cell phones are safe:

• Cell phones use a very, very low level of radio frequency (rf) energy - too low to cause damage.
• The type of energy emitted is non-ionizing - meaning it doesn't cause damage to chemical bonds or dna.
• Hundreds of millions of people have been using cell phones and cordless phones for years. If there were a problem, we would have seen it by now.

• February 2008: Tokyo Women's Medical University compared phone use in 322 brain cancer patients with 683 healthy people and found that regularly using a mobile did not significantly affect the likelihood of getting brain cancer. "Using our newly developed and more accurate techniques, we found no association between mobile phone use and cancer, providing more evidence to suggest they don't cause brain cancer," Naohito Yamaguchi, who led the research, said. His team's findings were published in the British Journal of Cancer.
• December 5, 2006 - Scientists in Denmark tracked over 420,000 cell phone users over the course of 21 years in an attempt to determine if if cell phone use causes cancer. As reported in ABC News, they found the RF energy produced by the phones did not correlate to an increased incidence of the disease. From the article: 'This so-called Danish cohort "is probably the strongest study out there because of the outstanding registries they keep,' said Joshua Muscat of Pennsylvania State University, who also has studied cell phones and cancer. 'As the body of evidence accumulates, people can become more reassured that these devices are safe, but the final word is not there yet,' Muscat added."
• April 2006 - the Swedish National Institute for Working Life issued a reportthis week, published in the International Archives of Occupational and Environmental Health, disputing two earlier studies that claimed cell phone use has no correlation to increased brain tumor risk. The researchers examined the cell phone usage of 905 adults who developed malignant brain tumors. They found that people with more than 2,000 hours of total talk time had 3.7 times the risk of developing brain cancer when compared with nonusers. 2,000 hours is about an hour of talk time every Monday through Friday for 10 years. The study, also found a 2 times increase for tumors specifically on the side of the head where the cell phone was generally used. But it should be noted that the study relied on the memory of the subjects for how long they used their phones, for as much as a decade ago, according to a Daily News interview with Dr. Lydia Zablotska, an epidemiologist at Columbia University's Mailman School of Public Health. "You're interviewing subjects in an era when everyone has a suspicion that cell phones may be harmful," Zablotska said of the study's shortcomings.
• January 2006 - A four-year long British study performed by the London-based Institute of Cancer Research and three British universities found that talking on a cell phone had no effect on tumor rates. The researchers included 966 people with glioma brain tumors and 1,716 healthy respondents. Individuals were questioned on first use, lifetime years of use, cumulative hours of use, and number of calls they made.
• March 21, 2005 - Fox news and CNN News both report that on March 16, 2005, a federal appeals court in Maryland reinstated five class-action lawsuits that allege that the cell phone industry has failed to protect consumers from unsafe levels of radiation. Fox quotes a Dr. Henry Lai, a bioengineering professor at the University of Washington, as saying that electromagnetic radiation emitted from cell phones may damage DNA and cause benign brain tumors. Dr. Lai also agrees with EHSO's recommendation to use a headset to minimize potential exposure.

• What is the radiation produced by a cell phone?

  Like televisions, alarm systems, computers, and all other electrical devices, Cell phones (also called mobile phones) are radio devices that use Radiofrequency (Rf) energy emit electromagnetic radiation. They operate at low power (less than 1 watt) by transmitting and receiving electromagnetic radiation in the radiofrequency (RF) end of the spectrum. Radiation which is called "ionizing" can be absorbed by tissue and break molecules apart, such as gamma rays and x-rays, are known to cause cancer. The concern is that the cell phone and it's antenna (the source of the radiation) are held close against the head)
  
  The damage to the dna molecules is thought to be the cause. The radiation that a cell phone uses is also part of the same electromagnetic spectrum, but is not ionizing. For this reason, the US FDA can regulate these devices to ensure that the radiation doesn't pose a health hazard to users, but only once the existence of a public health hazard has been established. (See "It's Not a Food or Medical Product, So Why FDA?") , RF energy was mistakenly thought to similarly cause cancer.
  
  

  Power

  Newer phones are digital. The older analog phones are expected to be phased out by 2006. The major difference is that analog phones use much more power than digital. Analog use about 1.3 Watts, while a digital mobile phone is designed to operate at a maximum power level of 0.6 watts (seehttp://www.telecom.globalsources.com/MAGAZINE/TS/0209/PANALOG.HTM By comparison, a household microwave oven uses between 600 and 1,100 watts.
  

  Frequency

  In the United States, mobile phones operate in a frequency ranging from about 850 to 1900 megahertz (MHz). In that range, the radiation produced is in the form of non-ionizing radiofrequency (RF) energy. This RF energy is different than the ionizing radiation like that from a medical x-ray, which can present a health risk at certain doses.
  Ionizing gamma rays and x-rays can cause cancer when their energy is absorbed by the tissue and chemical bonds are broken, damaging DNA. RF energy, on the other hand, produces heating of tissue. Although there is a small amount of experimental evidence that suggests RF energy can impact DNA in rats, this data has been contradicted by several other animal studies and is not well substantiated. Even if true, the doses administered in these animal studies were much larger than the exposure in humans and may have no relevance to cell phone use at all. So although the RF energy emitted by cell phones is in the electromagnetic spectrum, and other forms of electromagnetic radiation can cause cancer, RF energy is very different and has not been shown to cause cancer.
  At high enough levels, RF energy, too, can be harmful, because of its ability to heat living tissue to the point of causing biological damage. In a microwave oven, it's RF energy that cooks the food, but the heat generated by cell phones is small in comparison.
  A mobile phone's main source of RF energy is its antenna, so the closer the antenna is to a phone user's head, the greater the person's expected exposure to RF energy.
  Because RF energy from a cell phone falls off quickly as distance increases between a person and the radiation source (actually, by the distance squared), the safety of mobile phones with an antenna mounted away from the user, like on the outside of a car, has been presumed to be safe. The distance and the effect of the car acting as a Gaussian cage would virtually eliminate the radiation inside the car. Also not presently in doubt is the safety of those so-called cordless phones that have a base unit attached to a home's telephone wiring and operate at much lower power levels than cell phones.
  Many experts say that no matter how near the cell phone's antenna--even if it's right up against the skull--the six-tenths of a watt (typically) of power emitted couldn't possibly affect human health.
  sumber : http://dityaxavier.blogspot.fr/2009/03/cell-phone-radiations.html