Are Cordless phones esp. DECT 6.0 harmful?

Factual Questions
1

Greetings,
I just replaced my 2.4 V-tech generic cordless phone with a new Panasonic DECT 6.0
(KX-TG9333T) model that operates in the 1.93 Ghz range. The RF transmission power is 115 mW (max). When I placed the base unit near the radio which is right next to the bed, the radio made a crazy pitched noise that the V-tech never made.

This made me a little paranoid and lo and behold when the hand set is also brought close to the radio, the interference shows up again. Is this “new” technology possibly harmful . I did some research and some articles say that when you plug in the base unit it can be more powerful than a cell phone mast? In Europe they are designing this DECT to only transmit when the phone is in use otherwise my model is continuously sending out radio waves. Also, some sites said that digital cordless phones are just as dangerous as using a cell phone for extended periods.

Are my fears justified? What kind of waves does this DECT put out as compared to an older 2.4 GHZ range phone? Thank you for reading.

2

Yes, both cordless phones and cellphone are equally dangerous, which is to say, not at all.

There has NEVER been a study which has shown irrefutable proof that cellphones or cordless phones are dangerous.

There have been small-scale studies which seem to link wireless devices to all kinds of aliments, but, AFAIK, all of these studies fall apart when their methodologies are examined. Clearly, if cellphones are obviously dangerous, people would be dying in droves - there are literally BILLIONS of phones in use every day.

3

Good luck finding unbiased info on the internet about this. That’s like searching for one needle in about a million haystacks.

beowulff is correct. As far as we know currently, it’s not dangerous.

All of the fears about this sort of thing got their start with power lines in the late 1960’s. Some insurance guy noticed that folks who live next to power lines don’t live as long as people who don’t. Insurance guys get paid big bucks to figure stuff like this out since it affects how they set their rates, which is the basis of their entire industry.

Nobody except insurance guys really took much notice until a study came out in the 70’s linking power lines to childhood leukemia. This study was later discredited, but by then the genie was out of the bottle. There were two groups, one that believed that power lines were the spawn of satan and were killing us all, and the other that believed they were perfectly harmless and the first group was a bunch of whackos. At that point not a lot of studies had been done, so both sides had a pretty much equal amount of scientific data on their side, which is to say, none.

It didn’t take long before folks started making the obvious connection that if fields from power lines could be bad, then stuff like those new fangled cell phones (which back then were the size of a brick) must also be bad. Things went absolutely nuts in the 80’s, with folks getting paid big bucks to walk around with field strength meters and declare what areas were “safe” and what areas weren’t (even though they just pulled the “safe” limit out of their backsides - science still hadn’t caught up yet).

Fast forward a couple of decades, and now billions and billions of dollars have been poured into the subject. The result? There hasn’t been a single study yet which has stood up to peer review and follow up studies that proves any link at all between something bad (typically cancer) and either power lines or radio waves (typically meaning cell phones).

Of course, what you do have is an occasional study that does find something. At first you might think well yeah, the study funded by the Cell Phones Are The Spawn Of Satan Organization of course is going to find something bad, but actually these studies that do find links typically aren’t funded by groups with a major bias and the researchers truly are doing things right. The problem is that this is just the way science works. Sometimes you get false positives. That’s why you do peer reviews and follow up studies. The second problem is that journalistic integrity doesn’t mean squat these days, so if a report finds some sort of link, it isn’t qualified with a blurb about how this is only preliminary and more studies need to be done. Instead, the press just blasts “CELL PHONES MAKE YOUR BRAIN EXPLODE” in big letters on the front page (along with MAKE SURE YOU WATCH OUR BROADCAST AT 11 SO YOU KNOW WHAT TO DO TO PROTECT YOURSELF!!!). When follow-up studies don’t prove the link, “We didn’t find anything after all” isn’t front page news, and gets shoved to the back pages, if it gets printed at all. This leads people to think that there’s a lot more scientific evidence for cell phones, power lines, etc. causing cancer than there really is.

Here’s our current understanding of things, which all of these studies have so far been consistent with. Electromagnetic radiation is a broad range of stuff, which in order of frequency is long waves (useful for submarines to communicate through polar ice, but little else), radio waves, microwaves (which are just higher frequency radio waves), infra-red light, visible light, ultraviolet light, X-rays, gamma rays, and cosmic rays. Part way through the ultraviolet part of the spectrum, electromagnetic radiation becomes ionizing, meaning that it is high enough in frequency that it can strip the electrons off of atoms and create ions. This is bad, since ionizing radiation is well known to cause cell damage and cancers. Ionizing radiation is why X-ray techs wear lead aprons and why it is very important for suntan lotion to contain UV blockers.

Cell phones, and your cordless phone, work on frequencies on the lower end of the microwave range, which is way below the range of ionizing radiation. As your microwave oven demonstrates, if you get enough radio waves in a small area you can easily cook something and cause damage, but the same thing happens for visible light too (as anyone who has ever fried an ant with a magnifying glass and sunlight can tell you). You wouldn’t want to put your hand inside of a running microwave oven (if you could), and you wouldn’t want to stand directly in front of one of those Hollywood style spotlights either. One thing the “cell phones are evil” folks have yet to come up with is a reasonable theory about why radio waves would be harmful when similar power levels of higher frequency visible light aren’t harmful. Not only have experiments failed to show a conclusive link, but no one’s even come up with a good reason why they would be dangerous in the first place.

Basically, having your cordless phone next to you is about as dangerous as having a flashlight shine on you. Don’t worry about it.

4

^^ That post needs to be stickied, archived, or turned into a staff report or something. Excellent stuff!

5

Thank you Engineer for such a complete answer. Can you tell me what is the exact cause of why the DECT phone causes interference on the radio whereas the 2.4 does not have that effect?

6

To add to this, and to summarize what engineer_comp_geek said, there’s no plausible way that we know of, that a 115 mW signal at 1.9 GHz could possibly cause health problems. Now you can never guarantee that something is safe, but with no plausible mechanism, and no studies showing an effect, it’s pretty much a dead issue. They’re harmless.

DECT phones send data in one of 24 timeslots, so the phone is transmitting only 1/24 of the time. The max power of your phone is 115 mW, so the average power it puts out is about 1/24 of that. The frequency of its signal is way out of the FM radio band, but your radio is very sensitive and can work with radio signals that are way lower-power than what the DECT phone base puts out. Even though it should be out-of-band, there are non-linear properties of the radio’s input amplifier that make some bit of those pulses of 1.9 GHz show up in the radio receiver.

You may have noticed that GSM cell phones also cause interference with all kinds of devices, such as headsets. GSM is also pulsed in timeslots. I’m not an expert in cordless phones, but I suspect that your old 2.4 GHz phone was not pulsed like this.

7

Didn’t they end up figuring out that the link could be explained by noticing that people who live near transmission lines tend to be poorer than average? I seem to recall reading about that one as a textbook example of correlation != causation.

8

Yes, that was figured out pretty quickly, then the challenge was set for how to do studies that accounted for that socioeconomic variable. We couldn’t just dismiss the data because we’ve identified a probable confounding variable; we have to do more studies that measure and account for it. But yes, the final answer has settled on that explanation.