Would your head glow in the dark if you got 100 dental x-rays?

These are the questions that keep me up at night.  Strange, I know.

“Let’s irradiate your head, but don’t worry, we’ll protect your shoulders”

But with all the talk about Japan’s nuclear power plant mishap and with everything I am reading about radiation in cell phone use, I thought I would do some extensive research on the subject.  (hmm…I wonder if sitting in front of my computer is radiating me….)

Radioactivity. What is it?

There is radioactivity all around us and even inside our own bodies.  Our blood and bones contain Potassium 40, Carbon 14, and Radium 226.   Ever hear of “carbon 14 testing” on bones found in an archeological site?  They are measuring the amount of radioactive Carbon 14 in the bones which has a half-life (the amount of time it takes for half of the substance to degrade) of 5730 years.  (And just in case you ever make it to Final Jeopardy, the half life of Uranium 238 is 4.5 billion years.)

There is also radiation that comes naturally from the soil and the air, which finds its way into our food.

Non-ionizing radiation refers to waves that travel through the air, but do not have enough energy to damage atoms, and ultimately, living cells.  Some types of non-ionizing radiation include the sun, microwaves, radio waves and infa-red waves.  That’s why the sun feels hot.  This form of radiation can do damage, but it is in the form of heat damage (burns), not cell destruction and cancer.

Ionizing Radiation is what we think of when we think of nuclear radiation.  This is the kind that can cause damage to the body’s cells and can cause cancer.  We aren’t aware of exposure to these types of rays.  This type of radiation is cumulative, that is, exposure adds up over your lifetime.  Ionizing radiation can be found in x-rays and nuclear radiation exposure.  It is also all around us in the environment.

So how much is too much?

When we talk about “damage” and “harmful radiation” we want to know how much can I get and still be sure I won’t grow another pinky finger.  The answers on safety will vary.

There are many ways of measuring radiation.  For this post, I used units called sieverts (Sv). For the purpose of discussing radiation to humans we have to make the unit smaller.  Milliverts (mSv) are 1/1000 of a sievert (don’t worry, there’s no test on this).  For example, one chest x-ray gives you 0.1 mSv.  You may also hear of “rems” or “rads”, but we will use the international standard of sieverts for this post.

We know, from Japanese victims of Hiroshima, unfortunately, that sudden exposure (all at once, not over the course of a lifetime) to levels of radiation produce the following effects:

  • 500 mSv – nausea
  • 700 mSv – vomiting
  • 750 mSv – hair loss in 1 – 2 weeks
  • 900 mSv – diarrhea
  • 1000 mSv – internal bleeding
  • 4000 mSv – death within 2 months
  • 10,000 mSv – death in 1 – 2 weeks
  • 20,000 mSv – death within hours
So we know what levels are harmful, but it’s a bit trickier to determine what levels are “safe”.
The general population is exposed to about 3 mSv/year through building materials, radon, soil, and foods grown in that soil.  We know that these constant low levels of exposure are not harmful.
But what about diagnostic medical testing? I agree that safety must be a priority, but the risk has to be weighed against benefit.  When considering a medical diagnostic test, for example, is it really safer to forgo a mammogram (0.7 mSv) once a year because you are worried about radiation exposure?  I was diagnosed with Stage III breast cancer from a mammogram at 41.  I would never have seen the age of 50 if I was concerned about radiation levels.
x-ray
However, repeated CT scans that can expose your body to 20-40 mSv at a time can put you at risk of developing cancer later in life.  Unfortunately, in the US, doctors are so “lawsuit conscious” that they often go overboard with diagnostic testing, checking and rechecking to make sure they haven’t missed something that could lead to a lawsuit down the road.
Researchers found a population of 25,000 Japanese post-atomic-bomb survivors who were exposed to roughly the same amount of radiation as two CT scans. Based in part on those studies, the Food and Drug Administration estimates that an adult’s lifetime risk of developing radiation-induced cancer from a CT scan is roughly 1 in 2,000. Worse, the risk for children is even higher because kids are more sensitive to the harmful effects of radiation.
When considering a CT scan or any diagnostic test that uses radiation, you need to ask yourself and the doctor if this is really necessary and if there are other tests such as MRI or Ultrasound tests that would give the same information as a CT scan.  MRI’s and Ultrasounds do not use any ionizing radiation, and when looking at soft tissue in the body, can give the same information as CT scans (but not always).
I know, as a cardiac nurse, that stress echocardiograms (using sound waves, no radiation, to look at heart function) will give better and more accurate information about the function of the heart than a nuclear cardiac stress test which exposes the patient to 40 mSv!  But because stress echocardiograms are not always covered by insurance (and cost 1/6 of a nuclear scan), cardiologists are less likely to order them.You can use this handy Radiation Risk Calculator to check the levels of radiation of different diagnostic tests and to calculate your risk of cancer so far from the tests that you have had.  Have fun! :)
So what about cell phones? 

cell phones cancer
When you hear about cell phone radiation, they are talking about non-ionizing radio frequency radiation. This is the  type  that can produce heat like from  a microwave.However, a new announcement was just released in May 2011 by the World Health organization stating that it now puts cell phone use in the same cancer causing category as lead.  A team of 31 scientists from 14 countries including the US made this decision after reviewing up to date studies on cell phone use and cancer risk.  What they found was an increase in certain types of brain tumors in those with longterm cell phones use.You may see articles giving you the SAR or Specific Absorption Rate for certain cell phone models.  SAR is the unit of measure that was given to cell phone radiation.  But it doesn’t matter if you are using the lowest level phone, because it all depends on the amount of time you spend on it.
It is also thought that when your phone is trying to get a signal, it emits higher levels of radiation and should be held away from your head during this time.When you look at cancer development — particularly brain cancer — it takes a long time to develop. I think it is a good idea to give the public some sort of warning that long-term exposure to radiation from your cell phone could possibly cause cancer,” said Dr. Henry Lai, research professor in bioengineering at University of Washington who has studied radiation for more than 30 years.
Read more here.
It would behoove you (yes, I said behoove) to be on the safe side of cautious when it comes to prolonged cell phone use.  Using a headset or using the speaker function instead of holding the phone to your head for hours will help. (but using the speaker function around me would be very bad for your health)
So what should I do with all this information? 

In short, you would benefit from being aware of your levels of radiation and make an informed choice before exposure.  Obviously if you are an airline pilot, you will get more radiation at your job.  So you need to be extra diligent in limiting your exposure in other areas like unnecessary medical exams.
The federal limits of radiation (above the natural 3 mSv/year)  are as follows:
astronauts………………250 mSv/year (but with the cuts in the US space program, we won’t have to worry about that anymore)
adults…………………….50 mSv/year
children under 18……..5 mSv/year
fetus………………………0.5 mSv/month
Exposure also is affected by a person’s weight.  A larger person would be less affected by 1 mSv than a smaller person.
Here is a list of common sources of ionizing radiation and the amounts of exposure:
  • air travel ———————————-  0.003 – 0.009 mSv/hour
  • dental bitewing x-rays – —————— 0.01 mSv
  • chest x-ray———————————-0.1 mSv
  • Cardiac CT scan—————————-16 mSv
  • smoking————————————-53 mSv/year (1 pack/day.  Tobacco contains radioactive polonium-201 and lead-210 which has a half-life of 22.3 years.  Want to quit? )
  • airport scanner—————————–.005 mSv
  • normal exposure from environment——3 mSv/year
  • mammogram——————————–0.4-0.7 mSv
  • watching 4 hours of TV/day for a year—–0.02 mSv
Small changes for a healthier life.
Please note: In researching this post, there were many incorrect facts in many of the articles I read.  Some of this stemmed from the use of the radiation unit of measure.  Some information sites used mrem and some used mSv.  1 mSv is equal to 100 mrem.  Some of the levels of radiation had mixed up units of measure and the articles made it seem like the exposure to certain things were far more than they were.  I made sure to triple check my facts to give you the most accurate post. 



Categories: cancer prevention, health, health and safety

Tags: , , , , ,

2 replies

  1. Thanks for this. So straight forward.
    I had my thyroid removed due to cancer 7 years ago. The docs said the cancer was most likely caused by radiation, but never specifically answered my questions about where/how I was exposed. I had a radioactive CT scan when I was 16-cancer diagnosis 23 years later. And I have always wondered about x-rays…

    • Sorry about your thyroid cancer. We can go crazy trying to figure out what “caused” our cancer. I have finally stopped looking.
      I told my doctor once that I was taking mushroom supplements.
      “I don’t think that is smart because we don’t know how it will affect your breast cancer.”
      “Can you tell me how I got the cancer?” I ask
      “No” she says
      “Then how can you tell me the supplements will affect it?”
      She didn’t say anything.
      The best thing we can do now is just take what we know and move forward.

      Thanks very much for reading and I wish you well!

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