Effects of four kinds of chelating agents, Ca-DTPA (calcium diethylenetriaminepentaacetic acid), Ca-EDTA (calcium ethylenediaminetetraacetic acid), CBMIDA [catechol-3, 6-bis(methyleiminodiacetic acid)] and Zn-DTPA (zinc DTPA), on bone metabolism were examined in beagle dogs by bone histomorphometry and measurement of serum biochemical constituents related to bone metabolism. Ca-DTP, Ca-EDTA or CBMIDA (150μmol/kg) was injected intravenously to dogs for 1 month, respectively. Three doses (30, 150 and 300μmol/kg) of Zn-DTPA were administered orally to dogs for 1 month respectively. All dogs received twice tetracycline hydrochloride infections at an interval of 7 days before the beginning of administration of chelating agents and also twice calcein injections at the same time schedule prior to sacrifices for analyzing bone dynamics. Bone samples were obtained from ilium and undecalcified bone sections were made. Bone histomorphometry of cancellous bone area of ilium was performed using an image analyzer. Bone volume and mean trabecular thickness did not change in any of the groups. Osteoid volume in the CBMIDA group increased (p<0.05). Osteoid volume and mean osteoid thickness in the 150μmol/kg of Zn-DTPA group decreased (p<0.05 and p<0.01). Mineral apposition rate and bone formation rate did not change in any groups except the CBMIDA and 150μmol/kg of Zn-DTPA groups, in which fluorescent bone labeling was absent or obscure, revealing inhibition of bone mineralization. Serum total calcium levels did not change in any of the groups. Serum phosphorus level decreased significantly in the 30μmol/kg dose of Zn-DTPA group (p<0.05). Parathyroid hormone level increased in the 30μmol/kg dose of Zn-DTPA (p<0.05), while it decreased in the 150μmol/kg dose of Zn-DTPA group (p<0.05). The results suggest that the protracted therapy using the above four kinds of chelating agents may incur damages of bone such as decrease of bone volume and inhibition of mineralization.
Absorbed dose rates in air at 40 sites throughout Osaka Pref. were measured by TLDs and a relationship between the dose rates and the rates estimated from concentrations of natural radionuclides in the surface soils collected at the sites was studied. The highest and lowest values of air absorbed dose rates obtained in Osaka Pref. were 114.1±1.0, 66.3±2.3nGy/h, respectively, and the former value was obtained at granite zone and the latter at andesite zone. It was found that soil particles smaller than 10 mesh contribute to the dose rates more significantly than those larger than 10 mesh. We found a fairly good correlation between the dose rates and the concentrations of 40K in the surface soils at the sites.
Comparisons of natural radiation at the new and the old campus of Fukushima Medical College have been made for three types of measurement: (1) gamma dosimetry using photon-counting thermoluminescent dosimeter; (2) gamma spectrometry using germanium semiconductor detector; (3) measurement of atmospheric radon daughter concentrations using alpha spectrometry and G. M. tube. After our college moved, the gamma dose was reduced. Total counts and each peak count in gamma spectrum also were reduced except for thoron daughter peaks. Indoor atmospheric radon daughter concentrations were drastically reduced, while the outdoor concentrations remained the same level. Indoor G. M. tube background also was reduced. Annual effective dose equivalent from gamma rays and radon daughters was estimated to be 1.14mSv and 0.57mSv for the new and the old campus, respectively.
In decontamination of hot cells, the workers should wear suitable protective clothing to protect them from internal exposure and skin contamination. But such protective clothing causes some work strain, especially heat-stress. As a simple method to evaluate quantitative work strain, we used sweat rates of the wearers. In the previous paper, sweat rates for workers with two types of protective clothing were reported. In the present paper, sweat rates under severer working conditions are measured for three types: (1) pressure ventilated blouse; (2) full-face mask & polyethylene coverall; (3) full-face mask & vinyl anorak. The measured values for 65 subjects widely scatter from 0.2 to 2.5l/h for all the protective clothing. Based on these values, the effects of protective clothing and working conditions (ambient temperature and humidity) on work strain are discussed.
A series of environmental radiation surveys was carried out from the viewpoint of characterizing the natural radiation dose rate distribution in the living environment, including natural and artificial ones. Through the analysis of the data obtained at numbers of places, several aspects of the radiation field in living environments were clarified. That is, the gamma ray dose rate varies due to the following three dominant causes: 1) the radionuclide concentration of surrounding materials acting as gamma ray sources, 2) the spatial distribution of surrounding materials, and 3) the geometrical and shielding conditions between the natural gamma ray sources and the measured point; whereas, the cosmic ray dose rate varies due to the thickness of upper shielding materials. It was also suggested that the gamma ray dose rate generally shows an upward tendency, and the cosmic ray dose rate a downward one in artificial environment. This kind of knowledge is expected to serve as fundamental information for accurate and realistic evaluation of the collective dose in the living environment.