1984年 · 第04卷第03期

The epidemiological study in tin mines from 1975 through 1981 showed that the incidence of lung cancer in miners was 515.40 per million and was higher than that in general population. Altogether 499 cases of lung cancer with complete occupational history and accurate diagnosis were colleceted for analysis in our survey. The average working life when lung cancer was discovered was 24 years and the relative risk was 12.48. The standard mortality rate was 14.51, and the risk proportionality constant was 6.6 × 10^-6/year/WLM. The average cumulative radon daughter exposure value for miner lung cancer was calculated and was found to be 716 WLM on an average (ranging from 18 to 1945).

Therefore, it might be concluded that the incidence of lung cancer had an occupational character and the radon and radon daughters were considered as one of the important factors in the development of lung cancer in tin miners.

In this paper the results of measurements of environmental gamma radiation in Liaoning Province and calculation of human dose are reported. The exposure rate was measured by RSS-111 high pressure ionization chamber and FD-71 portable scintillation counters. The results showed that average values of outdoor and indoor exposure rates were determined to be 7.9 µR/h and 11.7 µR/h, respectively, i.e., the indoor exposure was higher than that of outdoor by a factor of 1.5. The annual average gonad dose of the environmental gamma radiation to the inhabitants in Liaoning was about 58 mrad/y and the annual effective dose equivalent was 57 mrem (0.57 Sv) .

Intraperitoneal injection of radioprotector WR-2721 250 mg/kg in rats 30 minutes before 800 rad whole body γ-irradiation significantly ameliorated the symptoms and incidence of diarrhea, changes in intestinal weight, spontaneous contraction and contractile response of small intestine to acetylcholine and nicotine at 3rd day after irradiation. This indicates that WR-2721 can improve the functional disturbance of intestine in irradiated animals. The mechanism of protective effect of WR-2721 involves the blocking action of intrinsic parasympathetic ganglion of small intestine. The blocking strength of WR-2721 is about half of that of hexamethonium.

The treatment of a patient with plutonium-239 contaminated wound is reported. The original activity of plutonium-239 deposited on the wound was estimated to be about 470 µCi. The body burden of plutonium-239 was 6.5 Ci on the 140th day, and the total activity of plutonium-239 excreted in urine and faeces was 1.3 µCi between 20th to 140th days after the accident. Laboratory findings indicated that the lymphoctyes decreased continuously, but serum alkaline phosphatase, alkaline phosphatase of peripheral blood lymphoctye, and chromosomal aberrations all increased.

The early surgical wound excision and early DTPA-Ca administration brought about satisfactory results.

The effectiveness of a new chelating agent code-named "H-73-10" in comparison with quinamidic acid (formerly "811") was experimented in 93 healthy adult rats for removing hexavalent soluble uranium. Uranyl nitrate was given intraperitoneally to rats in doses ranging from 10.2 to 16.5mgU/kg. Immediately after the administration of uranium, a single intramuscular injection of appropriate chelating agent was given at the dosage of 0.43 or 0.70 mmol/kg. Urine and bone samples were taken and analysed for their uranium content by means of fluorometric method. The mortality rate of animals and the histopathological changes in kidneys were also investigated. The results demonstrated clearly that H-73-10 was more effective than quinamidic acid in eliminating the uranium from body, in reducing the deposition of uranium in the bone, and in lowering the mortality of the rats with acute uranium poisoning. Moreover, the swelling of kidneys in the rats treated with H-73-10 was essentially milder than that in the rats treated with quinamidic acid.

The results of 15 items of hematological examination in 49 X-ray and 235 non-X-ray medical workers of Wuhan Area are reported. It was found that the WBC count, with neutrophil count as its main part, increased in X-ray workers with 2 working years and decreased in those with more than ten working years. The percentage of lymphocytes seemed to be higher in X-ray workers, while the RBC and platelet counts as well as the hemoglobin content were lower than those in non-X-ray workers. These changes were related to the cumulative doses and the length of working life, but were still within the normal range. Although the numbers of peripheral blood lymphocytes containing Demel's body and of those having positive fluorescence were significantly higher in X-ray workers, yet no linear correlation between this change and the radiation doses could be observed. The relationship between these hematological changes and radiation doses are discussed.

Male mice were exposed to whole-bodyγ-irradiation with doses of 50,100, 200, 300 rads, and the chromosome aberrations at metaphase Ⅰ and metaphase Ⅱ in spermatocytes were scored.

Most of the aberrations were chromatid breaks and chromosome fragments. In the irradiated groups, the frequency of chromosomal aberrations was significantly greeter than that in the control group. The percentage of chromosomal aberrations in the two meiotic divisions of the irradiated animals increased with the irradiation doses. The frequency of chromosomal aberations at metaphase Ⅰ was higher than hat at metaphase Ⅱ.

Our experimental data indicated that, when irradiated at the diplotene stage, the radiosensitivity of the spermatocytes was significantly higher than irradiated at the pachytene stage. There were no relationships found between the XY disjunction rates and the irradiation doses, The chromosomal aberration frequency in spermatocytes was much higher than in oocytes.