Biology ETDs

Publication Date



Ruthenium-106 is an abundant fission product radionuclide in the nuclear fuel cycle which has potential for release as ruthenium tetroxide. This study was designed to provide additional data needed to adequately assess the risk for humans potentially exposed to 106RuO4vapor. Fiscner-344 rats were given a nose-only exposure to 106RuO4 vapor to determine its distribution and retention patterns. The largest percentage of the initial body burden was found in the nasopharyngeal region of the respiratory tract. Ruthenium-106 deposited in this region was rapidly cleared and excreted in the feces. Less than 1% of the initial body burden was deposited in the pulmonary region of the respiratory tract and was essentially cleared by one day after exposure. Ninety-eight percent of the body burden was cleared within 15 days after exposure and the remaining burden cleared with a biological half-time of 69 days. The fecal excretion was 5 times the 106Ru activity in the urine after the initial clearance of the upper respiratory tract. The gastrointestinal absorption was less than 1% and the data from this study indicated nasal absorption would be less than 1%. Current International Committee on Radiation Protection (ICRP) recommendations consider the lung and gastrointestinal tract as critical organs for radiation damage from inhaled particulate radioactive ruthenium. The deposition and retention pattern for ruthenium tetroxide in the nasopharynx indicates that the nasopharynx should be reconsidered as the critical region for this material for human inhalation exposures.

Project Sponsors

Contract EY-76-C-04-1013 between the Lovelace Biomedical and Enviromental Research Institute and the U.S. Department of Energy



Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Roger Orville McClellan

Second Committee Member

Marvin LeRoy Riedesel

Third Committee Member

Gordon Verle Johnson

Fourth Committee Member

Morris B. Snipes

Included in

Biology Commons