
Dental X-Rays linked to Brain Tumors - ck2
http://www.washingtonpost.com/blogs/the-checkup/post/study-links-dental-x-rays-to-brain-tumor-risk/2012/04/09/gIQALz8k6S_blog.html
======
irons
_The study found at a general level that people with meningioma were more than
twice as likely as people without the brain tumor to have had a bitewing X-ray
sometime in their life._

Running a story like this using relative percentages, but no absolute values,
is absurd and contemptible.

I'm not finding any absolute values for meningioma rates in any other stories
about this particular study, but old pal wikipedia says:

<http://en.wikipedia.org/wiki/Meningioma>

 _Many individuals have meningiomas but remain asymptomatic (no symptoms) for
their entire life, so the meningiomas are not discovered until after an
autopsy. 1-2% of all autopsies reveal meningiomas which were unknown to the
individuals during their lifetime, since there were never any symptoms. In the
1970s, tumors causing symptoms were discovered in 2 out of 100,000 people,
while tumors discovered without causing symptoms occurred in 5.7 out of
100,000, for a total incidence of 7.7/100,000. With the advent of modern
sophisticated imaging systems such as CT scans, the discovery of asymptomatic
meningiomas has tripled._

I think I'll worry about something else.

~~~
ck2
You don't feel 40 to 90 percent higher risk from bitewings is statistically
significant?

~~~
johngalt
Statistically significant yes. But 90 percent more of 0.00002 is 0.000038. It
would be like avoiding conductive jewelry because you're worried about
lightning.

------
ck2
Now just imagine the proof in 20 years about TSA radiation exposure.

The lawyers will get billions, the victims will get $20, while the taxpayers
get to pay for the machines now and the settlement later.

~~~
grecy
haha, no.

A law would be passed removing the ability to sue the TSA for giving you
cancer.

------
polyfractal
To put various radiation exposures in perspective (not entirely certain of the
validity of the link, it doesn't cite sources):

<http://www.physics.isu.edu/radinf/dental.htm>

> _A typical dental x-ray image exposes you to only about 2 or 3 mrem. The
> National Council on Radiation Protection (NCRP) says that the average
> resident of the U.S. receives about 360 mrem every year from background
> sources. This comes from outer space, radioactive materials in the earth,
> and small amounts of radioactive material in most foods we consume._

> _Some typical sources that may expose you to radiation also include smoke
> detectors (less than 1 mrem per year), living in a brick house instead of a
> wood one (about 10 mrem per year due to radioactive materials in the
> masonry), cooking with natural gas (about 10 mrem per year from radon gas in
> the natural gas supply), reading a book for 3 hours per day (about 1 mrem
> per year due to small amounts of radioactive materials in the wood used to
> make the paper), and even from flying in an airplane (about 5 mrem for one
> cross-country flight because of the increased altitude.)_

~~~
psyklic
Radiation concentrated in one place (such as with xrays) is a lot more harmful
than general radiation.

~~~
polyfractal
Yep, I agree. I just wanted to put up a list of common exposures so people
have some bearing on the level of radiation that we are talking about :)

------
acro
Some perspective from XKCD: <http://xkcd.com/radiation/>

------
wcoenen
In the study, people were asked if they remembered having such an X-ray any
time during their life. And people who had a brain tumor were more likely to
answer yes.

I wouldn't be surprised if that just means that people are likely to forget
about such exams, unless they get a brain tumor and start fretting about what
might have caused it. Maybe they'll even start "remembering" radiation
exposure in their youth that never actually happened. The study itself may
produce such false memories by suggestive questioning.

I'll take note if the link can be shown with real data rather than
questionnaires. Until then, I'm sceptical.

------
omgsean
I think I just had one of these done in 2011. Nice to have more fuel for my
hypochondria fire.

~~~
makmanalp
"The exposures to dental X-rays in the study took place in the 1960s, when
dental X-rays delivered higher doses of radiation than today’s do."

Phew?

------
rdl
The lowest radiation doses for dental x-ray are from modern digital systems,
so if you care, it might be worth asking your dentist if he would upgrade.
(The digital ones also give better images, are easier to work with if you need
to send the x-ray offsite, etc.

This particular cancer is probably a non-risk, but there are a lot of reasons
to go digital.

------
jessriedel
Does anyone know how much lower the doses are from modern dental x-rays
compared to the ones several decades ago which make up most of the study? Is
it a difference of 20%, or a factor of 20?

------
clumsysmurf
I thought this would add another interesting wrinkle to the conversation. It
is from a few years ago, but I found it counterintuitive and interesting (as a
lay reader).

"The safety of routine X-rays has been called into question following the
unexpected discovery that cells exposed to low doses avoid or delay repairing
damaged DNA."

[http://www.newscientist.com/article/dn3568-routine-xray-
safe...](http://www.newscientist.com/article/dn3568-routine-xray-safety-
called-into-question.html)

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evoxed
If only I could use this as my excuse for "missing" the dentist these past
couple years...

