Considerations for gamma irradiation of aquatic organisms

Document Type

Article

Publication Date

1-1-2000

Abstract

Ionizing radiation has been used for decades in studies involving aquatic organisms to produce androgenesis and gynogenesis and in attempts to produce reproductively sterile individuals. In these studies, gametes or organisms were exposed to a broad range of doses of ionizing radiation in various containers to obtain the desired results. However, there are many factors that affect irradiation levels and cause target doses and actual absorbed doses to be different. Our goal in this study was to use intensive dosimetry to determine the variation in dosage possible in irradiation of aquatic organisms. Using the Fricke dosimetry technique, we found suprisingly high levels of vertical and horizontal variation in dose rates inside of a small (but typical) container (14.5 cm high, 16.7 cm wide, and 2.8 L in volume). The presence or absence of container rotation further affected these variations. When the container was rotated, vertical variation ranged between 1% and 21%, and horizontal variation ranged between 10% and 19%. When the container was not rotated, vertical variation ranged between 6% and 28%, and horizontal variation ranged between 20% and 72%. Comparisons between air and water as a surrounding medium showed that the dose rate in air could be 42% higher than in water when the container rotated and as much as 218% higher in air when the container did not rotate. These variations would cause samples irradiated in water to receive dosages lower than desired. It is therefore crucial that careful dosimetry be performed before carrying out experiments and that they be performed in the same medium in which specimens are to be irradiated (presumably water for aquatic organisms). Such measurements are typically not reported or are not performed in irradiation studies of aquatic organisms. Experimental errors such as these would complicate comparisons among studies and organisms and hinder development and application of valuable techniques such as radiation-induced sterilization of genetically modified organisms.

Publication Source (Journal or Book title)

North American Journal of Aquaculture

First Page

95

Last Page

102

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