Re: Tritiated Thymidine

["Otto G. Raabe" <ograabe@UCDAVIS.EDU>]

At 10:08 AM 10/31/01 -0800, Michael Dupray wrote:

>Can anyone refer me to information or inform me of the difference

>between the hazards of tritiated thymadine as opposed to HT and HTO?

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October 31, 2001

Davis, CA



Dear Michael



Tritiated thymidine acts as a DNA nucleotide and is rapidly and

irreversible incorporated directly into cellular DNA so that the tritium

low energy beta can efficiently irradiate and damage the genetic material

of the cell. Almost all of the radiation dose is delivered to the cell

nucleus. In contrast, tritiated water is uniformly spread throughout the

body water so that the dose to cellular nuclei and DNA is limited to that

small fraction of tritiated water that is in the cell nucleus rather than

in the cytoplasm or in body fluids. Hence tritiated thymidine is

considerably more dangerous that tritiated water. HT is hydrogen gas which

is not readily taken into the body and is readily exhaled if inhaled.

Tritiated water vapor is much more readily absorbed by the body, so that

the potential radiation exposure from an atmosphere of HT is considerably

less than from water vapor. 



Otto



**********************************************

Prof. Otto G. Raabe, Ph.D., CHP

Center for Health & the Environment

(Street Address: Bldg. 3792, Old Davis Road) 

University of California, Davis, CA 95616

E-Mail: ograabe@ucdavis.edu

Phone: (530) 752-7754   FAX: (530) 758-6140

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