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Cell Phones and Cancer

  1. Nov 20, 2007 #1
    The spectrum for cell phones is typically in the 850 MHz range. E=hv yields around 3.515E-6 eV. The lowest natural state electron binding energy is on the order of 10 eV >> 3.515E-6. Is this enough to dispel the "correlation"? Are there any other particle interaction mechanisms that would allow for ionization to take place with more significant quantum mechanical probabilities?

    Granted, the exact mechanism for cancer propagation is not known.
     
    Last edited: Nov 20, 2007
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  3. Nov 20, 2007 #2

    Dale

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    The radiation from cell phones is definitely not ionizing, but that is not sufficient to eliminate the possibility of other effects. I am skeptical about a connection, but it is still possible.
     
  4. Nov 20, 2007 #3

    mgb_phys

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    The MIG-25's foxfire radar was at a lot lower frequency but could legendarily kill rabbits at a range of a mile!
     
  5. Nov 20, 2007 #4
    So?
    Did they physically harm rabbits at any range?
     
  6. Nov 20, 2007 #5

    Dale

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    Sure, but it didn't give them cancer. At RF you generally only worry about heating.
     
  7. Nov 20, 2007 #6

    mgb_phys

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    It puts about 500KW - instant rabbit fricassee. Probably didn't do any ground staff standing in front of it any good either!

    I was just making the point it's not necessarily the frequency of photons, the number matter aswell.
     
  8. Nov 20, 2007 #7
    It puts out a pulse, which has an intensity of 500KW for a short time only; the average output is far smaller (otherwise imagine the generator it would need).

    You ought to know that nothing can be "instantly" cooked, hence arbitrarily high intensities are completely safe (especially at such long wavelengths) for sufficiently short periods. Whether the periods (ie. duty cycle) was short enough, apparently neither of us know. Do you have any evidence that a single rabbit was ever affected by the MIG-25's radar?

    The fact that people worried (enough to spread rumours) about the radar is irrelevant to whether radar and mobile phones are safe.
     
  9. Nov 20, 2007 #8

    mgb_phys

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    Well the generator is a pair of the most powerful engines fitted to a fighter.
    I said 'legendary' because I don't think the former soviet union filed enviromental impact assesments - but India, which still operates the aircraft does require the radar not to be operated on the ground. Interestingly the radar used valves because it wasn't possible to produce that much power in transistors at the time.

    Yes the radar is irrelevant - my point was that you can't consider only frequency.
    There was a thread about a month ago when I discussed how you test the safety of cell phones but I can't find it on the search.
     
  10. Nov 21, 2007 #9
    definitely not even close to ionizing, but there may be other effects... i don't exactly know what could go wrong, but... you still have oscillatory electric field from the wave, is it possible that it could "drive" charged particles like electrons in some resonance frequency for some mode or something? or is the E field way too weak?
    I just read the other day that they did show a correlation between extremely prolonged use and some forms of cancer or something... no clue on details. I'm still skeptical anyway
     
  11. Nov 21, 2007 #10

    mgb_phys

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    You can do simple calculations to set a level of heating so low it couldn't do any damage and use this as the safety level. But you don't know if there is something , a particular chemical reaction or cellular/organ structure, that is especially sensitive to heating or electircal fields so that it could be damaged at a level below your estimated heating threashold.

    The alternative is mass studies, but then you have to be sure that you can find a control group who don't use whatever it is you are studying and the only difference between them is the thing that you are studying. This is largely impossible.

    Imagine a study to check long term cell phones usage is harmfull - you pick a group that have used cell phones since they were first available = Wall St. traders, then you pick a group that don't use cell phones = Amish farmers. You discover that the traders have higher blood pressure - does this prove that cell phones caused it ?
     
  12. Nov 21, 2007 #11

    Dale

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    The usual "safety level" for RF energy is measured by a parameter called SAR (specific absorption rate) which is measured in W/kg and generally averaged over some period of time. The only known effect in this frequency range is heating. For example, in MRI (magnetic resonance imaging) we use RF magnetic fields at about 64 MHz or 128 MHz. The FDA limits the whole-body exposure to 4 W/kg averaged over 15 minutes. Since the tissues in the head are considered more sensitive to heating the head-only exposure is limited to 3 W/kg averaged over 10 minutes.

    At other frequencies you can also get other effects in addition to straight thermal energy deposition. E.g. in the audio frequency range you can get stimulation of electrically excitable tissues such as nerves and cardiac muscle and in the UV or higher range you can get ionization.
     
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