Anoxia in radiobiology

Abstract

The letter by Gillespie and Unsworth (1968) has raised again the important question of how long it takes to remove oxygen from the nutrient medium in which cells are grown or irradiated, whether in suspension or attached to a solid surface. Gillespie and Unsworth draw attention to the fact that the oxygen depletion time varies with the square of the depth of medium and suggest that many apparently discordant results can be expained in this way. They quote, among other data, the letter by Michael, Scott and Révész (1966) giving measurements of the rate of oxygen loss from a 3 mm deep layer of distilled water in a Petri dish exposed to an atmosphere of nitrogen, and comment that the rate loss agreed reasonably well with diffusion calculations over the first few hours. In the original letter, one of us (J.W.B.) was responsible for the inaccurate statement that the shape of this curve agreed well with diffusion theory. It now seems likely that incorrect boundary conditions were used in the check calculation made at that time.