The chronic side effects of Ca-DTPA and Zn-DTPA were examined in Wistar rats. Ca-DTPA were administered orally to rats for 3 months and Zn-DTPA for 6 months, with 1 or 10 H. D. (H. D.=human dose, 1 H. D.=30μmol/kg body weight), respectively. The hemorrhage or congestion with increase of eosinophils in the lamina propria of the jejunum and ileum was observed in the Ca-DTPA groups at the 1st month after the beginning of administration. On the other hand, no untoward findings were observed in the Zn-DTPA groups throughout the experimental period. As a result, the oral administration of 1 H. D. Zn-DTPA for a long term could estimated to have no side effects in humans from the results in this study.
For evaluating weak leakage gamma-ray exposure a new method without background measurement has been developed. In a previous report the principle of this method was described in detail with a few examples under usual environment. In this report the method was examined under different environments, that is, environment consisting of high atomic number medium, geometric distribution of natural radioactivities, and the leakage gamma-ray of high energy. It was necessary to make small corrections for the results measured in the room whose wall was covered with such a material as lead sheet. It was found that there are no practical problems of this method under the environment with larger geometric factor of natural radioactivity distribution than π in a solid angle. With the present technique the dominant energy of leakage gamma-ray was necessary to be lower than 1.46MeV, that of primary gamma-ray of K-40.
In using CR-39 plastics for individual neutron dosimeters, changes of etching efficiency cause significant error in dose estimation. Etching efficiency is subject to a number of parameters. In this study the influences of the parameters were examined by measuring the diameters of etch-pits formed by alpha-particles and enlarged by aqueous solutions of 25-35% KOH at 55-65°C for 4hr. It has been observed that diameter changes at the rate of 8.3%/°C in temperature, 8.2%/wt% in concentration and -0.60%/day in time after preparation of etchant. The diameter is unaffected by the supplying of up to 280ml/l, of distilled water for evaporation of etchant or by increase up to 5g/l of CR-39 dissolved in etchant. The magnitude of possible error has been estimated by parameter as well as ingeneral, so as to obtain suggestions for improving etching treatment.
In order to evaluate filter performance more accurately, penetration of submicron DOP (Dioctyl Phthalate) particles through a medium efficiency air filter were determined simultaneously by means of two different laser aerosol spectrometers, the PMS ASAS-X and the Royco LAS-236. In the measurement with the ASAS-X, it was found that the maximum penetrating particle size through the filter was approximately 0.15μm and maximum penetration was (5.7±1.1)×10-2. On the other hand, the LAS-236 could not clarify the existence of the maximum penetrating particle size. For particles in the first channel of the LAS-236 corresponding to the 0.15μm particle, penetration was determined to be (6.3±1.0)×10-2 by the LAS-236 measurement. Penetration obtained by the two instruments showed good agreement within the experimental error in the neighborhood of the size of maximum penetration.