Re: dental x-rays

[brian whatcott <inet@INTELLISYS.NET>]

At 19:08 12/29/00 -0500, Ludwik wrote:
> > Average U.S. citizen living in average  location [gets]
> > 3.600 mSv annual dose.
>
> In my opinion 3.6 mSv is too high. True or false? If false
> where is my error?
>
> 1) I remember ~180 mrem per year (from natural sources).
> 2) 3.6 mSv translates to 360 mrem. This is twice as much.
>
> Is it possible that another 180 comes from medical uses,
> especially when therapeutic machines are also counted in
> the calculation of the average.
> Ludwik Kowalski

Two sources I checked agree with Ludwik that the
annual burden mentioned in a web source given earlier
 looks rather high:
EncBrit (15th ed.) article 'Radiation' offers
90 to 200 millirem as the annual background.

McGraw-Hill Enc Sci-Tech (5th ed,) article
'Radiation injury - biology' offers the following budget:
Natural
 cosmic                  28 millirad/yr
 local gamma             47
  radon in air            1
Internal sources
 potassium-40            19
carbon-14                 1
 radon and products       2

Human made contributions
 mwedical radiology     100
 shoe-shop fluoroscopes   1
 luminous clock dials     1
 occupational             2
TV sets                   1
Weapon fallout            1

Total                   204 millirad/yr

[From a UN report 1958, & MRC (UK) report 1956 hence the
hazards like shoe shop fluoroscopes have vanished, and the
dose has increased with higher anode voltages for TV color tubes,
and an increased contribution from cumulative bomb test fallout
and accidental nuclear power plant releases]







brian whatcott <inet@intellisys.net>  Altus OK
                Eureka!