[ RadSafe ] Myth or Fact? (Dental dose)

[Otto Raabe]

At 08:40 PM 8/24/2006, Peter Thomas wrote:

>Entrance skin  4.71 mGy
>Thyroid 0.0215 mGy
>Salivary Glands 0.275 mGy
>
>The main contributors to the effective dose are the dose to the thyroid
>and the dose to the salivary glands (0.025 weighting factor under ICRP60
>rules where a remainder tissue has a higher does than any of the tissues
>with individual weighting factors).
****************************************************
8/25/06

The remainder tissues include the sum of all tissues of the body other than 
those with specified weighting factors. The reminder weighting factor does 
not apply specifically to the salivary glands. The weighting factor for the 
salivary glands cannot be 0.025 since that is higher than for tissues with 
specified weighing factors such as bone surfaces.  A weighting factor of 
0.025 for salivary glands would predict that 2.5% of all A-bomb induced 
cancers were salivary gland cancers. According to BEIR V "...the 
susceptibility of the salivary gland  to radiation carcinogenesis is 
relatively low in comparison with other organs." Although there is known 
that high ionizing radiation doses can increase the risk of salivary gland 
tumors, the BEIR V report notes that in A-bomb survivors "....mortality 
from salivary gland tumors has not been detectably affected...." Therefore, 
the tissue weighting factor for salivary glands must be quite small, 
certainly much smaller than 0.025.

OItto


**********************************************
Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140
***********************************************