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Those crazy rays

  1. Jun 26, 2004 #1
    All those sources of all sorts of potentialy healthfull but also potentialy deadly rays - I mean: natural ones (like sun (ozon holes)) and artificial - like - Roentgen machine, lightning rods with radioactive elements, or those that are here due tu people not having any idea what they did (like buildings made with use of materials like marble that have radioactive elements inside)...

    Question: Just how much UV, X-ray, Gama (and other...) radiation is actualy enough to cause cancer (what are the parameters?); and what are the sources that we should be potentialy afraid of??? (?)
  2. jcsd
  3. Jun 27, 2004 #2
    Nobody knows for certain the answer to this question. As you say, UV, x-ray, gamma radiation all elevate the risk of developing cancer, but no one knows how much of it is necesary. Actualy, it is a probabilistic thing.

    Cancer (I'm no expert so the best thing is geting a copy of Harrisons at your local library) occurs when a special type of gene mutates. This type of gene is called oncogene. Since there are so many cells in our body, the probability of an oncogene mutating is extremely small. But the more times you throw the dice, the more likely it is you get a 3. Translated into genetics, the more times your DNA replicates, the more likely it is that an oncogene mutates. There are many ways of speeding up metabolism (and thus replication), but the main one is INFLAMATION. When tissues respond to external aggressions (toxic, biologic or whatever), the metabolism speeds up due to imflamation and it is more likely for one of the oncogenes to mutate.

    Prolonged exposure to cigarrete smoke produces irritation and inflamation of the throat, bronchi, lungs, pleura. UV radiation heats up the skin.

    If you want to minimize your risc of suffering cancer, you should firstly, not smoke, not go to the beach, and move next to a nuclear power plant (place where radiation is lowest).

    My explanation is part speculation and part comes from authorized journals that I can't cite because it's been over a few years. I hope some one can correct me. I know even less medicine than physics!!
  4. Jun 27, 2004 #3


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    Now, could you explain why next to nuclear power plant is the "place where radiation is lowest"?
  5. Jun 27, 2004 #4
    Well, because its core and other places that contain radioactive material are heavily shielded. There are only traces of radiation immediately outside the plant. Radiation is much higher near large cities. All this info was given to me by a nuclear engineer at Vandellós 2, a nuclear plant near Barcelona, Spain. Of course this could only be propaganda but he sounded quite convincing at the time. This doesn't justify our reliance on nuclear energy, although. Cheers!
  6. Jun 27, 2004 #5
    It's been a few years since I took a class in the biology of cancer. So, I am not a speciallist either. But I also read science magazines frequently which kind of updates my knowledge of the subject.
    I don't remember reading about the connection between inflamation and cancer, although I do remember that people with some inflamatory processes such as irritable bowel disease, are at a higher risk. As far as a higher reproduction rate of the cells being linked to cancer, the only reference to that that I remember was in some cancers typical of children, in which it was speculated that the reproduction rate of the cells was connected with the elevated risk for those cancers.
    One of the concepts I vagely remember from my class, was that cancer is a complex process that takes many steps to complete. With respect to cancer agents, I remember talk about a promoter and an initiator. One of these kind of created the conditions necessary for development of cancer and the other trigered the process. I think I remember then talking about a one-two punch.
    I also remember that there was something that was considered as a background cancer rate, which was not attributed to artificial causes. As Tavi says, there seem to be insuficient or no studies segregating the different causes of this background rate. I don't remember if a genetic predisposition was included in that rate or excluded. Things like cosmic rays, to which we are all subject, would definitely contribute to the background cancer rate.
    Talking about causes, it appears that oxidative (free radicals) can be a cause of cancer and this is one of the reasons a lot of attention has recently been given to antioxidants. (green tea, vitamins C,E , lipoic acid, flax seed, fruits and vegies). Oxidative damage, together with inflamation has also been linked to artherosclerosis and diseases of the brain such as alzheimer's and parkinson's.
    With respect to radiation, I think I read recently that slow electrons can produce a lot of damage ( this would be from a new study). I think it was previously thought that in order for a free electron to produce damage it needed greater energy.
    So, in summary, an electron, a cosmic ray or ionizing electromagnetic radiation (X-ray, gamma) can somehow damage the DNA, producing a mutation that initiates the cancerous process. But it looks like chemical agents that produce oxidative damage are as important or maybe more important than radiation in their oncogenic properties.
    It looks like the cells have mechanisms to repair the damage to the DNA. This mecahnism does not always work. But a good intake of antioxidants may help.
    It may be very hard to avoid radiation. In the case of the sun, the most dangerous type of skin cancer is melanoma, which is often the result of bad sunburns when you are young. There is a debate between dermatologists and other doctors as to how much sun exposure to get. It happens that, especially for people with dark skin and those living at high latitudes, a lack of sun may be even more negative because it results in a deficiency in vitamin D. There are recent studies that suggest a dafficiency of vitamin D has vast consequences for your health which were not recognized before.
    I think it is always good to be informed about possible environmental dangers for your health, including sources of radiation. But it may be best not to worry too much about this as in most cases there is little we can do about it. But we can try to eat a healthy diet that includes fruits and vegetables (read about those that offer more cancer protection, such a broccoli) , take a multivitamin suplement, exercise and avoid cigarette smoke. (passive smoking may be as bad as smoking the cigarettes yourself). And don't forget that heart disease is the main disease causing death. A healthy diet and exercise will protect you from both to a certain extent.
    Last edited: Jun 27, 2004
  7. Jun 29, 2004 #6
    So complicated, but I'm ceratin that answer can be much, much easier. I remember (from my electrotechincs class) that they were talking about electro-magnetic field and how human must not be exposed to EM field greater than certain value of EM flux (Vebers or Teslas or somethin'). I mean - there must be some dose of UV, X-ray, gama that is not harmful. For example UV rays - it won't hurt if intensity is lower (I guess - photon is a photon - it is just a matter of how much photons per unit of surface we are exposed to)... I guess that there is some number that must not be exceded - or the probability is just too great.

    What are all the sources of slow electrons (they are produced by heated metal shining them out along the electromagnetic field, aren't they?). TV/monitor cathodes produce electrons to lighten phosphor dots on the screen - does this mean that we can be iradiated by it?

    And I've also seen (on the internet) that thre are some tools for stripping insulation from wires using UV rays; UV flashlights; and have you seen that article about those nano-carbon-pipes that can chanel electrons and cause X-ray radiation so they use it for X-ray photography (they invented the portable version of Roentgen machine) - aren't those potentialy dangerous sources of radiation? Can they cause cancer?
  8. Jun 29, 2004 #7
    I don't know the answer to all those questions you ask. You can research each source of radiation or type of radiation separately in google and see what you find. Cancer is a complex process, and you can't oversimplify it or you run the risk of getting wrong conclusions. There are many types of radiation for which nobody knows for certain how much of a cancer risk they represent. There are sources of radiation for which scientists have changed their opinion as new studies are published.
    For some time there was a debate about a higher leukemia rate for children that live near high-voltage power lines. More recently there has been talk that cell phones may produce brain tumors. Last week someone published a study linking cell-phone use to lower reproductive rate (not cancer related).
    There are many gadgets that were producing considerable levels of EM radiation and that the government has come up with regulations to reduce that level. But in many cases the safe level has never been determined with certainty.
    One source of radiation that might be quite dangerous would be radon gas filtering form the soil into the foundation and into your house. This only happens in certain moountainous areas in some countries. I live in California and here it is a problem. There are safe levels (which is somewhat subjective) that have been determined. And people sometimes use detectors to find out how much radon there is in the house.
    I think you should not worry too much about being exposed to radiation and focus your attention to improving your diet and exercising. But that's just my opinion. I on the other hand, you really want to find out the cancer risk posed by the different sources of radiation, you'll have to do your own search. There is a lot of info in the Web.
    If I come accross anything, I'll post it here.
  9. Jun 30, 2004 #8
    Reply: OK.

    (PS: have you noticed that personal message here must be above 10/12 letters (or something)? (the reason im writing this question :tongue2: ))
  10. Jun 30, 2004 #9


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    Yeah, I've noticed. Why?
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