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Dental X-Rays Linked To Common Brain Tumor
redletterdave writes "A new study suggests people who had certain kinds of dental X-rays in the past may be at an increased risk for meningioma, the most commonly diagnosed brain tumor in the U.S. Dr. Elizabeth Klaus, the study's lead author and a professor at the Yale School of Medicine, discovered that dental X-rays are the most common source of exposure to ionizing radiation — which has been linked to meningiomas in the past — and that those diagnosed with meningiomas were more than twice as likely as a comparison group to report ever having had bitewing images taken. And regardless of the age when the bitewings were taken, those who had them yearly or more frequently were between 40 percent and 90 percent higher risk at all ages to be diagnosed with a brain tumor."
My father was a dental technician (he made dental crowns) and he always refused to get x-rays when he went in for his check-ups. My physics professor in undergrad told me the same thing - only get dental x-rays when absolutely necessary. Bone does a good job of scattering x-rays all over the place, and your skull and jaw, believe it or not, are composed of a great deal of dense bone.
They give you this big heavy blanket (lined with lead? I dunno) to lay across your body when they do the x-ray. They seem to think it's important to block off the areas they're not actually imaging. So why don't they give you something similar to lay across the top half of your face and head? Obviously it wouldn't stop everything, but you'd think it would help at least a little.
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Any word on whether there was a decline in this type of tumor when CMOS x-ray imaging started being used in dentistry? Using CMOS rather than film supposedly requires less exposure time or less x-ray intensity in order to obtain an image comparable to film. I see the article does comment on the decreased intensity of x-ray source now as compared to a decade or so ago, but unless they couldn't readily identify this type of tumor back then, then I would expect to have seen a decline in this type of tumor as well.
Mobile phones do not release Ionizing Radiation. They release Radio Waves. These are different things. Really... You can take off your tin foil hat to make calls again.
Well, I know that it is uncommon on /. to actually RTFA, but:
>>
The lack of association with full-mouth X-rays led one expert to question the connection.
"They found a small risk (from) a pair of bitewings, but not a full mouth series, which is multiple bitewings. That inconsistency is impossible to understand to me," said Dr. Alan Lurie, president of the American Academy of Oral and Maxillofacial Radiology.
>>
So a small risk (increase from 15/10,000 to 22/10,000) caused by a pair of bitewings disappears when you do more?
I don't think so...
This is a very flawed study that doesn't account for many things including a) It's based on patients "memories" of when they got x-rays and not actual dates b) Doesn't account for the dramatic reduction in amount of rays needed for the images in the last 20-30 years.
Proof? Check this far better article http://articles.boston.com/2012-04-10/metro/31313701_1_x-rays-tumor-risk-radiation-exposure
Supposing this is true, it took this long because everybody thought that dental X-ray was harmless.
(tumor growth in less than 1:4.000.000 images, regardless of the type of tumor.)
Dental X-ray uses less than 0.01 mSv per image.
You absorb 200 times this amount every year, year in, year out. all your life. And if you live in a place with higher background radiation, this number goes up quickly.
So it is hard to prove these tumours are caused by the exams.
Lets wait and see what comes out of this.
Usually these kind of studies have some form of bias thats not adequately corrected for.
Why are other peoples sig's always more witty ???
While we take dentistry for granted, an infection driven by a bad tooth used to be a common cause of death. Bad teeth are still a common driver to the ER for many uninsured. Remember Tom Hanks knocking his bad tooth out with an ice skate and a rock on the island? Not going to the dentist for your lifetime has a greater chance of killing you than a rare cancer from a few low dose x-rays. That said, it never hurts to make sure you dentist is using modern low dose digital equipment and not taking any unnecessary images.
I'm a dental student, and I have been taught that - with modern equipment - exposure to radiation from 2 bitewings is about the same as half a day of ski holiday.
These comparisons are always misleading, because they ignore the density of the radiation received. Radiation from half a day of ski holiday is diffused over your entire body. The radiation from bite wing X-rays is concentrated on your teeth and skull. The concentration matters.
Let's use a better analogy. The energy at the focal point of a magnifying glass might be one-hundredth the amount of energy you get from standing out in the sunshine. But because that energy is concentrated into a small point, it will burn your skin.
We survive nature not because it isn't powerful, but because its power is spread out. That power gets dangerous when mankind focuses and purifies it.
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Because it is true. The term "ionizing radiation" is not just causal lingo, it is very specifically defined as radiation that is capable of liberating an electron from an atom thus producing an ion. This is not the case for lower frequency electromagnetic radiation such as that produced by mobile phones. Any potential health effects resulting from mobile phone use would have to be due to an entirely different mechanism.
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Modern techniques only use 1/100th the amount of radiation of machines from only a decade ago.
I guess my question is how does the new tech affect people. If the old tech only doubled the tumor rate, reducing the amount of radiation by two magnitudes should lower your risk quite a bit.
Also, the machine at my Dentists doesn't do the whole head, but has a VERY focused output that pressed up against your cheek. You place a digital x-ray sensor between your teeth and it works as a "film".
They're like, "we don't even have to leave the room anymore". They stand right behind the machine.
So, not that huge an increase. Actually 46% is a huge increase.
They never seem to show the error bars. We are looking at a sample of 15. Not knowing anything else, one might assume Poisson statistics in which case the 1 sigma error is 1/sqrt(sample), so about 25%.
This means that 66% of the time, if one were to run the exact same test, one would get results that varied by plus or minus 4 events. The difference between a sample of 15 and a sample of 21 can be expected about half the time.
It really takes the urgency out of - OMG a factor of 46%.
http://en.wikipedia.org/wiki/Poisson_distribution.
According to the EPA (and other places), radio waves are firmly in the non-ionizing range whereas x-rays are definitely in the ionizing range. You'll have to provide some evidence that near field effects increase radio wave energy sufficiently to shift the radiation into the ionizing range with cell phones; I couldn't find any, and it's a strong claim to make. Considering the lack of unambiguous cell phone/cancer links I doubt such evidence exists.
I'm not trying to marginalize your point, but at the same time? It seems to me that dentistry is one of the areas of medicine with the least amount of oversight or "checks and balances" to ensure patients are getting what they pay for.
For example, I went to a dentist as a teenager to have an impacted wisdom tooth extracted. The oral surgeon recommended that I have "all 4 wisdom teeth pulled at the same time, since there was a good chance the others weren't all going to come in properly anyway - and it would be less painful if I only went through one extraction". I went with his recommendation, only to find that a couple years later, I had cavities in the back of a couple of my teeth, where they faced those wisdom teeth. Apparently, their enamel was damaged in the tooth extraction process, causing them to get cavities. So then I had those filled, but I remembered thinking the whole process was a bit questionable at the time, because he had a young dental assistant working with him, who he asked to mix up the amalgam filling material for him. I remember him looking at it and questioning her about whether she mixed something up enough because it didn't look quite right, stirring it around a bit in the container she was holding, and ultimately going ahead and using it on my teeth. Well, fast forward a couple more years, and I start having a bad toothache. I go to a dentist (totally different place!) and I'm informed that tooth has a big hole in the back of it (where the filling material had obviously fallen out) and the tooth isn't even salvageable anymore!
I look at all of this and have to wonder if I would have been better off if I had only opted to have the bare minimum work done in the beginning? Seems like all these dentists did was create more problems for other dentists to correct, at my expense!
And my daughter is further making me question some of these dentists.... When she was 8 years old, the pediatric dentist commented that "he saw something on the x-rays that concerned him" and "she might need some dental work, but we'll see". The next time she came in for a checkup, he wanted to schedule an expensive dental surgery procedure for her because he claimed a tooth wasn't going to come in right, etc. etc. Well, I didn't have the money so I kept putting it off.... I did send her to the next scheduled checkup though, where they declared "She doesn't need that surgery after all!" (Really?! WTF?!)
Oh, and then there's my younger brother, who had all kinds of dental problems after his dentist screwed up a procedure -- but of course, denies any of it was his doing.
The shit got modded +5 because...lo and behold...RF from a mobile phone is non-ionizing radiation. I agree that the term "radio waves" could have been better. But it would take tens of thousands of RF photons simultaneously striking the same exact electron at the same exact time to give it enough energy to break free from the atomic bond it has formed. It only takes one photon from an x-ray to do the same.
Go ahead. Do the math. Look up the energy it takes to ionize an atomic bond. Calculate the energy in an RF photon at 2.4 GHz. Calculate the energy in a photon of an dental x-ray (not sure what frequency they use). And then marvel at the four orders of magnitude between the two. I did this once, and maybe I should have saved a copy of the results so that I could paste it into the discussion every time some tin foil hatter thinks that 2.4 GHz "radiation" will give you cancer.
The primary mode of action for RF energy on biological tissue is in the form of heating. Just like your microwave. The electric field causes the dipole water molecules to rattle around, and the increased friction results in heat.
In fact, if you get an MRI, they make sure that for example your thighs are not touching each other. Because if they are, your flesh forms a loop antenna that can pick up the RF energy in the magnet room...which will cause localized heating and burns.
http://www.mrisafety.com/safety_article.asp?subject=17
"-Prepare the patient for the MR procedure by using insulation material (i.e., appropriate padding) to prevent skin-to-skin contact points and the formation of “closed-loops” from touching body parts."
:(){
That's a total lie. They use exactly half. Source: I'm a certified dental x-ray technician.
'New' digital sensors require the same amount of X-Ray radiation, but for half the amount of time (for bitewings, that's about 100ms instead of 200ms), but since they're so quick to scan in (i.e. the Dentist doesn't have to wait for them to develop), if they aren't exactly perfect, dentists will often ask for re-takes. The average was 5 or 6 images on each patient. I was pretty good and usually only had a re-take every 3rd patient or so, but the other x-ray technician I worked with would often take 4 or 5 re-takes on a single patient. All-in-all, that means they got more radiation than if they had just gotten the traditional x-rays.
I should point out, though, that the Dentist told every patient (and told us to tell them, as well) that they only get 1/100th of the radiation. It's just a party lie.
As far as the 'pointed beam' you're talking about, that hasn't been improved, ever. The cone is just as large as it's always been. If the technician stands in the room (as my co-worker often did), they're just stupid. In fact, according to ADA recommendations, X-Ray techs are supposed to wear dosimeters. Most dentists are too cheap to buy them, though.
The 'Bitewing' x-rays that this article is about are exactly the kind that are close to your cheek. There are 3 types of dental x-rays: Bitewings, which shoot the radiation between your molars and premolars, and are used to diagnose cavities between yoru teeth. PA's, which are used to view your entire tooth, including the entire root and an area of bone beyond it. These are useful for diagnosing a toothache, because if the toothache is caused by an infection at the apex of your root, it will be visible. That, in turn, means a root canal. The third is a Panoramic, which is the kind that wraps around your entire head, and shows all of your teeth in one shot. These are beneficial for things like getting an 'aerial view'; they don't show a lot of detail (not enough to diagnose a cavity), but will show things like impacted wisdom teeth, and are useful for Orthodontists.
I think you will find that people died of brain tumours even before the mobile phone was invented. What was your point?
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>> I'm a dental student, and I have been taught that - with modern equipment - exposure to radiation from 2 bitewings is about the same as half a day of ski holiday.
>These comparisons are always misleading, because they ignore the density of the radiation received. Radiation from half a day of ski holiday is diffused over your entire body. The radiation from bite wing X-rays is concentrated on your teeth and skull. The concentration matters. Let's use a better analogy. The energy at the focal point of a magnifying glass might be one-hundredth the amount of energy you get from standing out in the sunshine. But because that energy is concentrated into a small point, it will burn your skin.
Unsurprisingly, the dental student's professor knows more about this than you do. The professor's analogy is the correct one. Yours is the incorrect one.
When x-rays cause cancer, it's a statistical process. Each x-ray photon has some small probability P of damaging a cell's DNA in such a way as to make it cancerous.
When you go skiing in the mountains, you're exposing yourself to more cosmic rays than you get at sea level. These are high-energy charged particles, not x-ray photons, but the statistical nature of the process is the same.
When you burn your skin with a magnifying glass, there is nothing statistical about the process. The outcome is deterministic. You're simply transporting x amount of energy into a certain piece of your flesh, raising its temperature by y degrees.
In case it matters, I have a PhD in physics, my field is nuclear physics, and I have worked with ionizing radiation a lot.
The only thing I would add to the correct information that the GP related from his/her professor is that in addition to the possibility of causing cancer, radiation can also make you healthier, via a well-documented effect called radiation hormesis. The usual interpretation (which is hard to test empirically) is that the radiation stimulates your cells' damage-control mechanisms. At the very low doses we're talking about, the evidence from controlled animal studies is that the net effect on your health is positive, because the hormesis effect is orders of magnitude stronger than the negative effects of the radiation.
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A valid reason to avoid the dentist
Here is a better reason.
Faster! Faster! Faster would be better!
In case it matters, I have a PhD in physics, my field is nuclear physics, and I have worked with ionizing radiation a lot.
Masters' in physics here with a similar background to yours.
My point is that the statistical likelihood of damage due to radiation depends upon its flux. For the same amount of incident energy, the flux you receive across your entire body is lower than if the same energy were collimated and aimed at your skull. The same number of photons in a smaller area increases the risk in that area. So saying that a dental X-ray has the same energy as a full-body soak in low-level radiation is deceptive. The dental X-ray is over a much smaller area, has a higher incident flux, and therefore has a larger chance to cause damage in that specific region.
The only thing I would add to the correct information that the GP related from his/her professor is that in addition to the possibility of causing cancer, radiation can also make you healthier, via a well-documented effect called radiation hormesis. The usual interpretation (which is hard to test empirically) is that the radiation stimulates your cells' damage-control mechanisms. At the very low doses we're talking about, the evidence from controlled animal studies is that the net effect on your health is positive, because the hormesis effect is orders of magnitude stronger than the negative effects of the radiation.
And this makes me suspicious of your credentials, because hormesis is an effect usually only talked about by snake oil salesmen. It's not a reliable effect, and there's a good bit of argument against it existing at all. Even if it does exist it is not something you want to play with, as a very small change of dose can drive your exposure from 'beneficial' to 'really dangerous'. If you're relying on hormesis to keep you safe then you are begging for disaster.
Genocide Man -- Life is funny. Death is funnier. Mass murder can be hilarious.