Causes of the Biliary Tract Cancer from the Point of View of Environmental Epidemiology

(1)人类胆道的Rec测定流行病学研究表明，自1958年以来，新泻县的胆道癌死亡率一直是日本最高的。为了检验新泻地区的人胆汁是否具有致突变性，我们采用rec法对新泻地区采集的胆汁进行了检测，并与日本死亡率相对较低的高知县的胆汁致突变性率进行了比较。采用枯草芽孢杆菌检测系统对人胆汁进行了孢子检测，以考察其可能的致突变性和共致突变性。在新泻县检测的65份样品中，3份（4.6%）表现出诱变活性。高知县26份样本均无致突变性。新泻县和高知县的诱变频率差异无统计学意义。(2)人胆囊胆汁中硒含量分析了人胆囊胆汁中硒的含量。共研究了37名受试者；新泻22例，高知县15例，其中胆结石13例，胆囊息肉2例。术中取胆汁5 ml，用注射器从胆囊中取出，并在-20^ cc的温度下保存，待分析。采用电子捕获检测器气相色谱仪分析，样品用量为0.2 ml。新泻地区胆汁中硒的平均含量为269 <正负>39.0（平均<正负>S.D.） ng/ml，高知地区为285 <正负>84.4ml；无显著性差异。

(1) Rec assay of human bileEpidemiological studies revealed that the death rate for the biliary tract cancer in Niigata Prefecture has been the highest in japan since 1958. In order to examine whether or not the human bile in Niigata is mutagenic, we tested the bile collected in Niigata by means of rec assay and compared with the rate of mutagenic activity of the bile in Kochi Prefecture, where the death rate has been relatively low in Japan. Spore rec assay of human bile was conducted by the Bacillus subtilis test system to examine possible mutagenicity and co-mutagenicity. Of 65 samples in Niigata Prefecture examined, 3(4.6%) Showed mutagenic activity. In 26 samples in Kochi Prefecture, none was mutagenic. There was no statistical significance in frequencies of mutagenicity between Niigata and Kochi Prefectures.(2) Selenium contents in human gallbladder bileThe selenium contents in human gallbladder bile were analyzed. Thirty- Seven subjects were studied ; 22 Patients with cholelithiasis in Niigata and 15 patients (13 with cholelithiasis and 2 with gallbladder polypus) in Kochi Prefecture. Five ml of bile was withdrawn withdrawn with a syringe from the gallbladder during the operation and stored at -20^ﾟC until analysis. For the analysis by gas chromatograph with an electron-capture detector, 0.2 ml of sample was used. The mean selenium contents in bile were 269 <plus-minus>39.0 (mean<plus-minus>S.D.) ng/ml for the subjects in Niigata and 285 <plus-minus>84.4ml in Kochi ; without significant difference.