In Japan, there were about 12, 000 workers awarded compensations for total disability due to pneumoconiosis in December 1977. The number of new cases showed to be on the increase year by year, especially from the year 1971 onward. The purpose of this study was to interpret more accurately characteristics and factors of the incidence of pneumoconiosis. Questionnaires were mailed to 3, 400 cases awarded compensations for total disability due to pneumoconiosis out of which 2, 991 were completed and returned. The results were as follows: 1) Of the 2, 991 cases, 47% were certified at some time after having left dusty occupations. Perecentage of the cases by succeeding periods of year certified showed to increase, 17% from September 1955 to March 1960, 52% from April 1960 to March 1978 and 69% from April 1978 to June 1979. 2) The length of the period from the separation from dusty occupations to the certification for compensation showed to increase. Percentage of the cases certified after ten years and over from the separation was 2% from September 1955 to March 1960, 21% from April 1960 to March 1978 and 33% from April 1978 to June 1979. 3) Mean age of the cases certified after having left dusty occupations was higher than that of the cases certified within the period employment of the dusty occupations. 4) Of 1, 402 cases certified after having left dusty occupations, 49% were coal workers, 28% metal miners and 10% tunnel workers and those in construction. 5) Mean age of the coal workers certified was the highest among those 1, 402 certified cases. Regarding the reasons of separation of coal workers who were certified after having left, discharge was 40%, age-limit 28%, aggravation of physical conditions 19% and other 13%. 6) Mean age of the tunnel workers and those in construction who were certified was the lowest and the mean duration of the service was the shortest among those 1, 402 certified cases. Regarding the reasons of separation of these workers, aggravation of physical condition was 57%, discharge 14%, age-limit 0%, transference 16% and others 13%.

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In Japan, in the last several years, mail matters increased so remarkably that motorcycles came to be used for their speedy and efficient delivery and gathering. Moreover, enlargement and speedup of motorcycles proceeded. So much so that, many mailmen have come to us complaining of numbness or waxy white attack of their hands fingers. Frequent outbreaks of these complaints of mailmen were suspected to be caused by motorcycle riding. The authors made the present study in order to make clear the mailmen's vibration hazards induced by motorcycle riding. Since 1977, the authors have made the studies on the following three items in their respective ways. (1) Investigations on the subjective complaints The authors obtained informations through questionnaires from about 2, 700 outdoor labourers of post offices in Shizuoka Prefecture, concerning subjective complaints and labour conditions. The withdrawal was about 95.9%, and collected answers were analyzed. Subjective complaints in the group using only motorcycles and the group using both motorcycles and bicycles were generally much more in the percentage than those in the group using only bicycles (Table 2). (2) Objective examinations on the health status Physical examinations of the peripheral blood circulatory system and the peripheral nervous system were made on 120 outdoor workers of post offices in S. and N. Prefectures. Of these, 100 were motorcycle riders, and 20 bicycle riders. These 100 motorcycle riders were divided into 3 groups (Table 5). Measured items were temperature of the finger skin, nail press test, vibratory sense threshold, and pain sense threshold. The difference in the values of peripheral circulatory and nervous systems by cooling between the groups using motorcycles, especially the group with waxy white fingers, and the group using only bicycles was often found statistically significant (Table 7). (3) Time studies on the outdoor working hours By pursuing four mailmen riding motorcycles from the beginning to the end of outdoor working, their riding hours a day for mail delivery and gathering were analyzed, in order to make clear their vibration exposure time. It was found that the vibration exposure time per day for the mailmen by motorcycle riding were over two hours (Table 8). It has been reported that the maximum vibration acceleration level exceeds the exposure guidelines of ISO, at the handle-bars of a motorcycles running on the paved road. Then, from the results above described, it is surmised that the mailmen's vibration hazards induced by motorcycle riding are widely occurring in our country.

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Rabbits were dosed with tetraethyl lead at 12 mg/kg; their organs, bloods, urines and feces were then assayed for tetraehyl lead, triethyl lead, diethyl lead, inorganic lead and total lead, and the chemical species of the lead excreted in the urines and feces were also studied. 1) One day after the dosing, the total lead in the urine was made up of about 69% diethyl lead, about 27% inorganic lead and about 4% triethyl lead. This ratio of the chemical species of lead to total lead remained unchanged even 7 days after the dosing. 2) Two days after the dosing, the total lead in the feces consisted of about 85% inorganic lead, about 9% diethyl lead and about 6% triethyl lead. Seven days after the dosing, the total lead in the feces comprised about 95% inorganic lead, about 4% triethyl lead and about 1% diethyl lead. 3) Intravisceral levels of lead were also measured 24 hours after the dosing. Triethyl lead accounted for about 84% of the total lead in the liver, about 68% in the kidneys, and about 59% in the blood. 4) Lead levels in B bile and intestinal contents were determined 24 hours after the dosing. Diethyl lead accounted for about 93% of total lead in B bile, while inorganic lead made up about 90% of the total lead in the cecal, the colonic and the rectal contents. 5) Conversion of diethyl lead by intestinal contents was studied in vitro by adding diethyl lead to the intestinal contents of normal rabbits. Incubation of the mixtures in the presence of N₂ at 38°C for 180 minutes resulted in the conversion of 16% of the diethyl lead into inorganic lead in the cecal, the colonic and the rectal contents. The conversion of diethyl lead into inorganic lead in the cencal contents was followed up and it was found that the inorganic lead output increased with the passage of time. Diethyl lead proved to be the principal chemical species of lead that is eliminated into the urine and bile after dosing rabbits with tetraethyl lead. However, inorganic lead accounted for the major portion of the lead excreted into the feces. This finding suggested that the diethyl lead eliminated into the bile could be converted into inorganic lead in the intestines.

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The aim of this study was to identify a specific substance [a Low-Molecular-Weight Chromium binding substance (LMW Cr)] in normal urine and also to clarify the various factors affecting chromium to bind to this substance in urine. The results obtained were as follows: 1. Normal human and rat urines contained unsaturated LMW Cr similar to that found in the liver or other organs of rabbits and dogs. The amount of chromium bound in vitro to the unsaturated LMW Cr in normal human urine was 14.81±1.84μg/ml urine when urine was incubated with trivalent chromium for 30 minutes at 37°C. 2. Higher amounts of chromium were bound to LMW Cr in normal urine a 37°C than at 24°C, in acidic state of urine than in alkaline state, and when trivalent chromium was added to the incubation mixture than when hexavalent chromium was added. Chromium contained in LMW Cr was supposed to be trivalent. Furthermore, boiling urine at 100°C for 10 minutes did not reduce the chromium binding capacity of LMW Cr in urine. These results indicate that LMW Cr in urine binds chromium by a chemical reaction. 3. Amounts of chromium bound to LMW Cr in urine obtained 3 hrs after intraperitoneal injection of 200μmole K₂Cr₂O₇ to a rat were much higher than amounts of chromium bound in vitro to LMW Cr in normal urine during 3 hrs incubation of the urine with K₂Cr₂O₇. This suggests that most of excessively absorbed chromium is excreted into urine after being bound to LMW Cr in organs. 4. Urine from patients with chronic nephritis excreted a part of added chromium bound to high molecular weight fractions corresponding to peaks of UV absorption.

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The influences which are known to be caused by styrene on the human body stimulation of the mucosal membrane and atrophy of the central nervous system. There are several clinical reports and animal experiments concerning the stimulation of the mucosal membrane, and styrene is presumed to stimulate the mucosal membrane of the nose. To the best of our knowledge, however, there have been no reports describing histological pathology of the mucosal membrane of the nose induced by exposure to styrene. Accordingly we made animal experiments using rats in order to see influences of styrene on the mucosal membrane of the upper and lower respiratory tracts including the mucosal membrane of the nose, and could confirm the following changes electron-microscopically: 1. Increases in the amount of mucous adhering to cilia, 2. Occasional formation of compound cilia, 3. Appearance of substances having a higher electron-microscopic density within the cytoplasm of various epithelial cells, 4. Degeneration of secretory granules of goblet cells-changes in electron-microscopic density, appearance of cores with a higher electron-microscopic density, 5. Nuclear pyknosis, 6. Vacuolization of various epithelial cells, and 7. Separation and falling-off of the epithelial cell layer.

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Dentists are usually obliged to take an unstable posture during dental diagnosis and treatment. And the value of the relative metabolic rate is at a low level of about 1.0, but it has been reported that the fatigue of hands, arms, shoulders, etc. is severe because of the successive statical muscle strains during work. The authors experienced one case of a dentist with cervicobrachial syndrome with tendo-vaginitis of both thumbs and of the right forefinger and articurationitis of both thumbs. This cace is a married female dentist of 26 years old. She was employed at a dental clinic in April, 1975 and began dental work. From February to April, 1976, 3 dentists among 8 of the clinic retired, and then the amount of the daily work much increased. After that she began to feel severe dullness and eye fatigue. Moreover, in May of the year, 2 dentists tool holidays due to their health disorder, and after that she began to complain of the pain at the right shoulder, left thumb and both hands, then visited a medical clinic. In July and August, she could not continue the work because she felt severe stiffness at the occipital part of the head, neck and shoulders, and pain and numbness of fingers and hands, and of fore and upper arms. The results of medical examinations at the clinic were as follows. Results of the examinations on blood, urine and clinical biochemistry were not abnormal, but swelling, redness and heating were at articulatio interpharyngea of the right thumb. On roentgenological examination, hiatuses of both thumbs were slightly narrowed, and punched-out shadows and the straight neck were found. On electro-myographical examinations, high amplitude voltage was seen in the right hypothenar muscles, and sensory conduction velocity was somewhat lower. Thus it was confirmed that there were distal nervous disturbances. There was also a slight lowering of the strength of muscles of the right hand and arm. Reflexes of Eaton, Morley and Allen were disordered on the right side. These facts mentioned above show that this case is one of the cervicobrachial syndrome occasioned by the labor of dental work. If the labor conditions of the dentist is not good, more such cases will occur. So, much care is necessary. At the time of the planning of the labor conditions of a dental clinic, these considerations must be taken into account.

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脂肪族アミンは化学工業などで頻用されているが,とくに近年,エポキシ樹脂硬化剤としてその使用量がふえるとともに,作業者の皮膚障障などの人体影響も問題になってきている.この脂肪族アミンを始め,今日増加をつづけ膨大な量と種類に達した化学物質が,人間の健康に及ぼす影響を早期に知ることは,今日の産業衛生の緊要の課題である.そのため毒性に対する知見の整理と,より迅速簡便な検査方法の開発が望まれている. 1960年代Hanschと藤田によって提唱され,ドラッグデザインの領域でめざましい発展をとげている構造活性相関の考え方は,生物学的反応(B.R.)を分配系数などの化学物質の物性のパラメーターで量的に表現しようというもので,化学物質の毒性の評価にも有用であることは明らかである.しかし実験の化学物質への適用にあたっては,生物学的反応(LD₅₀など)の指標と化学物質側のパラメーター(とくに分配係数)のどちらも,それを求めるのは簡単ではない. われわれはまず,Hanschらの式の左辺にあたる毒性の指標を迅速に得るために,培養細胞を用い,マイクロタイター法で脂肪族アミンの細胞毒性を検査した.本方法は血清学的診断で頻用されるマイクロテストプレートの各wellに細胞を播種し,トランスファープレート上で倍数希釈系列を作った化学物質を加えて,細胞の生着・増殖におよぼす化学物質の影響を見る方法である.細胞はヒト由来線維芽細胞のIMR-90を用い,脂肪族アミンはモノアミン,ジアミンそしてエチレンアミンの3グループに分けて検討した.結果の判定は,72時間の培養後プレート底面に単層で増殖した線維芽細胞の量をギムザ染色により観察して最小細胞増殖阻止濃度(MIC)を求めた. MICをアミンのグループごとにアミン分子中のアルキル鎖の炭素数(n)に従って配列すると,一定の関係が認められた.電子計算機を用い重回帰分析を行なうとモノアミンは,log(1/MIC)=-0.016n²+0.435n-2.185.ジアミンでは,log(1/MIC)=0.018n²-0.074n-0.531と,互いに向きの異なる2次曲線が得られ,回帰係数はそれぞれr=0.960とr=0.979であった. 次にHanschらの式の右辺すなわち,化学物質のパラメーターとしての分配係数を迅速に求めるために,水-オクタノールを用いたFlask-shaking法でなく,クロマトグラフィー法を用いた.すなわち,高性能薄層クロマトグラフィー(HPTLC)を用い,先の実験に使用したアミンのR_Fを求めて,疎水性パラメーターのR_M(=log(1/R_F-1))を各アミンについて算出した.HPTLCを用いることにより,物質側パラメーターの算出は極めて容易,かつ迅速にすることができた.そうして得られたR_Mはモノアミンとジアミンではnと高い相関を示し,MICに対してそれぞれ次のような回帰式を得た.モノアミン: log(1/MIC)=-19.900R_M²-3.481R_M+1.117,(r=0.969).ジアミン: log(1/MIC)=-1.304R_M²+2.594R_M-0.823,(r=0.984). 一方エチレンアミンにおいては,R_Mはnの変化に対して,変化が乏しくほぼ一定であったが,MICも同様にほぼ一定であった.これらの結果から,R_Mを用いて化学物質の毒性の予測をすることの可能性が示唆された. 以上,脂肪族アミンを材料とし,マイクロタイター法とHPTLCを用いて構造毒性相関の検討を行なったところ,非常に迅速・簡便に良い相関を得ることができ,R_Mを用いた毒性予測の可能性も示唆された.今後とくに,スクリーニングテストの手段として,他の化学物質での応用が望まれる.

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