Radiation Risk: Are CDMA Cellphones More Dangerous Than GSM?

[ravi_patent 28]

Natalie Wolchover, Life's Little Mysteries Staff Writer

Date: 23 June 2011 Time: 04:04 PM ET

Last month, the International Agency for Research on Cancer, a branch of the World Health Organization, declared cellphone radiation "possibly carcinogenic to humans." The scientific evidence linking cellphone use to brain cancer isn't conclusive, the agency said, but there is some evidence that brain cancer rates are higher among people with the highest levels of cellphone exposure, and cellphone users should take precautions until more is known.

Now, some scientists are claiming that certain types of cellphones could be more "possibly carcinogenic" than others.

"I've been telling friends and family members to seriously consider switching to CDMA [cellphones] if they're using GSM cellphones," said Joel Moskowitz, the director of the Center for Family and Community Health at the University of California, Berkeley.

CDMA, or Code Division Multiple Access, is the type of cellular network used by the phone companies Verizon and Sprint. GSM, or Global System for Mobile Communications, is the type used by AT&T and T-Mobile.

Higher power

There is accumulating evidence that cellphones that operate on GSM networks emit significantly more radiation than do cellphones operating on CDMA networks. This is not apparent when you look at a phone's specs, Moskowitz said, because phone companies are required to list only the "specific absorption rate" (SAR) — the measure of the rate at which energy from a radio frequency electromagnetic field is absorbed by the body — of a phone at its maximum radiation output. "The SAR can be misleading as it measures the maximum radiation a cellphone emits and does not reflect the average amount of radiation it emits," Moskowitz told Life's Little Mysteries.

Several recent studies have shown that CDMA phones normally emit a small fraction of their maximum radiation output, while GSM phones emit, on average, half the maximum, he explained. This comes down to the different radio frequency (RF) bands that the two networks operate on, and the different methods by which the two networks carry phone transmissions.

"When a GSM phone transmits, it immediately goes to the peak power, and then the power control circuitry ratchets down the power to an acceptable level," explained Mark McNeeley, an electrical engineer at Exponent Engineering and Scientific Consulting services and co-author of a recent study comparing GSM and CDMA networks. "CDMA networks share the same frequency among many different phone calls, so all phones transmit at the lowest possible power level necessary to maintain the fidelity of the call." It's like people talking quietly at a party, he said.

The radiation spikes at the beginning of GSM phone calls means that they emit, overall, up to 28 times more radiation than CDMA phones, according to a study co-authored by McNeeley and published last year in the Journal of Exposure Science and Environmental Epidemiology.

There are exceptions. If you have a CDMA phone in a rural area and the nearest CDMA cellphone tower is far away, then you have to broadcast at a radiation level that is equal to or greater than GSM to reach the tower, McNeeley said. If there is a GSM tower much nearer to you, you might be better off going with a GSM network, he said; but in most parts of the country, where both CDMA and GSM towers are ubiquitous, CDMA phones will emit less radiation than GSM phones.

What does radiation do to the brain?

Although dozens of international studies have been conducted over the past decade, some of which point to higher incidences of certain types of brain cancers in people who use cellphones heavily, the negative side effects of cellphone usage remain undetermined.

A possible consequence of the higher radiation output of GSM phones was seen in a study published in the International Journal of Science Technology & Management in April. Researchers compared brain scans of people talking on GSM phones and CDMA phones and found that the former stimulated much more brain activity than the latter.

Although it's still unclear what that extra brain activity is, how it's caused or whether it's bad, other studies have also shown varying health consequences of using GSM versus CDMA phones. Of 37 studies that have examined GSM phones, 43 percent have found harmful biological effects from the phones — such as a decrease in the expression of genes that help suppress tumors — Moskowitz said, while only 15 percent of the 33 studies that looked at CDMA phones have identified harmful effects.

When reached for comment on the possible hazards of GSM phones, AT&T referred to previous statements by the Federal Communications Commission and the Food and Drug Administration that said the available scientific evidence shows no proven health risk of radiofrequency (RF) energy. The FDA states: "Although evidence shows little or no risk of brain tumors for most long-term users of cellphones ... people who want to reduce their RF exposure can: reduce the amount of time spent on the cellphone, and use speaker mode or a headset to place more distance between the head and the cellphone." T-Mobile did not return telephone calls or emails.

What to do?

GSM and CDMA networks work so differently that a phone built for one cannot operate on the other. Furthermore, AT&T and T-Mobile cellular networks, which are GSM, cannot simply switch and become CDMA networks. Given these facts, if you own a GSM phone, should you switch to a carrier that supports CDMA? Experts have mixed opinions.

It is difficult to say whether higher radiation output is bad, simply because the jury is still out on whether cellphone radiation is bad in the first place, says Ken Foster, a professor of bioengineering at the University of Pennsylvania who has been studying the effects of radiofrequencies for 40 years. The radiation level of cellphones — all cellphones — is so low it is considered "non-ionizing." It isn't powerful enough to knock electrons off atoms in cells and potentially change the structure of DNA molecules, which is the way that ionizing radiation (like gamma-rays and X-rays) causes harmful mutations. No one knows by what mechanism non-ionizing radiation, such as RF from cellphones, could possibly damage DNA, Foster says.

Though Foster grants that consumers could probably reduce their exposure by choosing CDMA rather than GSM phones, he doesn't think it's likely a higher radiation output actually makes GSM phones more hazardous than CDMA phones. The radiation levels of both phone types are so low, he said, that there is no known way they could harm DNA.

"If you take a shower at 160 degrees Fahrenheit, that could burn you. But I personally don't fear a shower at 65 degrees Fahrenheit more than one at 63 degrees — neither temperature is dangerous," he said. In his view, cellphone radiation on either type of network is as harmless as two cold showers of slightly different temperatures.

If cellphones are a biohazard, Foster said, that can't be related to the amount of the radiation they emit. "Presumably, some parameter other than [radiation output] would be involved." No one has identified what aspect of cellphone radiation is dangerous, Foster said, so there is no way of knowing whether GSM phones are worse for you than CDMA phones, or vice versa. [Read: What Everyday Things Around Us Are Radioactive?]

Hazardous frequencies

However, according to other scientists, there is some evidence that the potentially hazardous aspect of cellphone radiation may be the way in which transmissions are modulated — the way individual pulses of radiation are constructed out of a range of frequencies. The modulation pattern is different for CDMA and GSM phones, and some scientists think GSM pulse modulations may have adverse biological effects.

A review article in the April issue of the journal BioElectroMagnetics by Jukka Juutilainen and colleagues at the University of Eastern Finland suggested that specific types of RF modulation may well have biological consequences.

"While the majority of recent studies have reported no modulation-specific effects, there are a few interesting exceptions indicating that there may be specific effects from amplitude-modulated RF fields on the human central nervous system. These findings warrant follow-up studies," the researchers wrote.

According to Moskowitz, the study found that GSM phones contain radiation at a frequency of 8 hertz, or 8 cycles per second, which "is in the range of 'possibly carcinogenic' because our cells have processes on that frequency level, with which the phone radiation may be interfering," he said.

Foster, on the other hand, thinks there is no robust evidence that one type of modulation is more dangerous than the other. "To my knowledge, nothing shows a clear effect of pulse modulation," he said.

Wanted: more evidence

Do some mobile phone networks pose more of a health risk than others? Though some researchers suspect so, it is too soon to say for sure. "Clearly more comparative studies are needed," Moskowitz said.

At this point, all cellphone users should be cautious. "My first recommendation is to keep a safe distance from your phone. Text instead of calling. Use the speakerphone. Use a headset," Moskowitz said. Radiation levels fall off rapidly with distance — so rapidly that you can decrease your brain's exposure to a negligible level simply by keeping your phone antenna just a few inches away.

Moskowitz also thinks people should avoid keeping their cellphones on in their pockets. "There's accumulating evidence of a risk to sperm and male fertility," Moskowitz said. "People are forgetting where they're keeping their cellphones all day long."

Foster doesn't believe cellphone radiation poses a significant danger, but he still suggests that people take precautions if they're worried, just for peace of mind. "My best advice to consumers: If they are concerned about possible radiation risks from cellphones, use a hands-free kit, which actually does reduce exposure and costs very little."

http://www.livescience.com/14755-radiation-risk-cellphones-dangerous.html

[anandjm 3]

As far as I know and I agree with the article on this, CDMA phones are less dangerous than GSM ones. There are two reasons for this

1. Power consumption is less during standby because CDMA phones check with the cell tower every few seconds (Slot Cycle Index) unlike GSM phones.

2. The use of spread spectrum communication ensures that the energy is spread over frequencies and requires lesser energy to transmit.

Edited June 24, 2011 by anandjm

[raccoon 53]

Not sure how accurate this statement is (GSM Vs. CDMA). There are way too many variables. For eg. CDMA here works on 800 MHz and both my GSMs work on 1800 MHz. No marks for saying GSM scores big time on this parameter alone. Further, battery consumption on CDMA is higher, suggesting that overall net radiation *may* be higher. You cannot emit radiation energy out of nothing. CDMA phones have significantly lower stand by times compared to GSM phones, suggesting they emit more on standby too. Further, they generally transmit to towers further away (fewer towers) hence would need to operate in higher power mode. Many more factors...

Edited June 24, 2011 by raccoon

[digitalnirvana 646]

As far as I know and I agree with the article on this, CDMA phones are less dangerous than GSM ones. There are two reasons for this

1. Power consumption is less during standby because CDMA phones check with the cell tower every few seconds (Slot Cycle Index) unlike GSM phones.

2. The use of spread spectrum communication ensures that the energy is spread over frequencies and requires lesser energy to transmit.

1. CDMA phones use more power because of the reason you mentioned.

2. Spread spectrum means theoretically infinite users have full access to entire bandwidth using pseudorandom codes unlike GSM/UMTS which is FDMA+TDMA. But this code is effectively noise to all other channels other than the receiver which has the pseudorandom code. This is why it needs more power and power control is main issue in CDMA.

Power and radiation/frequency are not same issue, this topic talks about radiation comparison which is determined by what frequencies these systems use.

Edited June 24, 2011 by dipanlahiri

[anandjm 3]

My comparison was for a given frequency. Not all GSM operators operate on 1800MHz. Many also operate on 900MHz. On dual network phones that support both CDMA and GSM but not both simulateously, I have consistently observed higher standby times on CDMA than on GSM. But when it comes to talk time things are reversed. In the case of GSM the energy is more focussed in particular frequency bands depending on the cell configuration. The possibility of interference is higher in GSM networks and hence there is a limit on the number of active callers a tower can handle. In CDMA however, the use of spread spectrum communication uses more energy overall, but is distributed across frequencies. Thus the radiation levels are lower but the energy levels are higher. I forgot to complete the second argument in favor of CDMA. Because the energy is spread over frequencies, it requires lesser energy to transmit in the presence of interference/noise. UMTS networks based on WCDMA also exhibit similar features due to the use of spread spectrum techniques unlike GSM.

As far as I know and I agree with the article on this, CDMA phones are less dangerous than GSM ones. There are two reasons for this

1. Power consumption is less during standby because CDMA phones check with the cell tower every few seconds (Slot Cycle Index) unlike GSM phones.

2. The use of spread spectrum communication ensures that the energy is spread over frequencies and requires lesser energy to transmit.

1. CDMA phones use more power because of the reason you mentioned.

2. Spread spectrum means theoretically infinite users have full access to entire bandwidth using pseudorandom codes unlike GSM/UMTS which is FDMA+TDMA. But this code is effectively noise to all other channels other than the receiver which has the pseudorandom code. This is why it needs more power and power control is main issue in CDMA.

Power and radiation/frequency are not same issue, this topic talks about radiation comparison which is determined by what frequencies these systems use.

Edited June 24, 2011 by anandjm

[kshah 452]

Gsm is TDMA

UMTS is wcdma

Reason for lesser radiation absoerption is true for cdma till phone is dormant. When in dormant cdma phone wakeup every 1 to 8 SCI (each SCI is 1.28 seconds, operators usually , keep SCI of 2 means 2.56 seconds)

But when in call cdma radiates more than GSM. In CDMA phone radiation increases as load on BTS increases. So as far as my information is concerned CDMA radiates more than GSM. May be same as wcdma.

Sent from my SPH-D700 using Tapatalk

[digitalnirvana 646]

In the case of GSM the energy is more focussed in particular frequency bands depending on the cell configuration. The possibility of interference is higher in GSM networks and hence there is a limit on the number of active callers a tower can handle. In CDMA however, the use of spread spectrum communication uses more energy overall, but is distributed across frequencies. Thus the radiation levels are lower but the energy levels are higher. I forgot to complete the second argument in favor of CDMA. Because the energy is spread over frequencies, it requires lesser energy to transmit in the presence of interference/noise. UMTS networks based on WCDMA also exhibit similar features due to the use of spread spectrum techniques unlike GSM.

Hi Anand,

Now your statements are valid point taken. Inherently CDMA is better technology than FDMA/TDMA, only if the power control could be better this would be the best there is. TDLTE is the next world beater.

[drmadhu 87]

Personal experience is that when I am talk in GSM phone more than 10min I am facing headache problem, not facing headache problem in cdma,

Other when some one calling on ur gsm phone near by landline phone showing disturbance in phone there are not a problem in CDMA,

So as far my personal experience CDMA less radiation.

Edited June 24, 2011 by vijaymalhotra_2007

[santanu@impaq 16]

GSM RF output are pulsating in nature which induces headache in some people and also the intermodulation noise we hear from all kind of audio equipment nearby.

CDMA RF is a continuous output and so does not cause disturbance in audio equipment.

Also inspite of more power output from CDMA handset, though the ear feels warm, the typical headache is not profound in CDMA

[anandjm 3]

Except when it comes to the RUIM based handset options available in India

.. the typical headache is not profound in CDMA ..

Edited June 24, 2011 by anandjm

[drabhayshah76 7]

Even i get a typical type of headache if i talk on gsm for more time but on cdma i do not get such headache and heaviness in the ear.

Regards.

GSM RF output are pulsating in nature which induces headache in some people and also the intermodulation noise we hear from all kind of audio equipment nearby.

CDMA RF is a continuous output and so does not cause disturbance in audio equipment.

Also inspite of more power output from CDMA handset, though the ear feels warm, the typical headache is not profound in CDMA

[Venkatagiri 53]

GSM or CDMA use mobile phone when you are on move. Otherwise use radiation free wired landline

[raccoon 53]

Thats the best solution, but the issue is that it is now a lot more costly to use the landline than mobile (in most cases).

[Venkatagiri 53]

More magazines are writing that CDMA phones are comparatively safer than GSM phones on radiation.This could mean cautious people will shift to CDMA from GSM now that more CDMA OMH phones are available.

[city02 63]

... GSM networks and hence there is a limit on the number of active callers a tower can handle.

i thought that there was a limit for CDMA also - no tower can handle unlimited active callers regardless of any future technology.

its possible the limit for CDMA is higher than the limit for GSM or

that CDMA slowly degrades voice quality while with GSM its all or nothing for tower congestion.

[digitalnirvana 646]

^

There is no technology to provide unlimited calls without increasing BTS. CDMA has better channel utilization than GSM because it is a spread spectrum technology using pseudorandom code unlike GSM which is FDMA/+TDMA. But the flipside is there is more noise in the channel so mobiles need more power to communicate with BTS.

[Venkatagiri 53]

One more article on what Ravi_patent described.

http://www.livestrong.com/article/490704-health-effects-of-gsm-vs-cdma/

Bottomline: Moskowitz suggests that you switch to CDMA-based cell phones

[santanu@impaq 16]

In India, the CDMA operators have deployed much less BTS forcing the handsets to operate at higher power level to overcome the noise floor as clearly mentioned in deepan's earlier post.

So the point that CDMA is less dangerous does not hold ground in India,

CDMA networks like verizon have very high BTS density in US and there the fact is true that verizon subscribers have to suffer less radiation that AT&T GSM counterparts.

But this analogy is not true for india.

In the most cities of India, GSM micro site density is very high and GSM handsets operate at lower average RF Power ( except for few period of call inititation and also while call hand off between BTS ). GSM Subscribers who are at a spot where there is continuous handoff between BTS ( at fringes ) may experience increased RF power and consequently low backup and associated headaches.

[sathishq 27]

Simple Test

1. Place GSM Phone near to CRT TV / Monitor and call to that number , You can see that disturbances visually because of Radio Waves.

2. Try the same with CDMA Mobile, It wont cause any disturbances

Conclusion : CDMA is the best Human Friendly Technology

[ni0987 179]

Check this article:

http://inderscience.metapress.com/content/d46r4h6125385301/