In recent years peripheral nervous discorders have been noticed in the intoxication caused by n-hexan, or stylene. The author have assumed that the peripheral neuromuscular system must also be damaged in toluene intoxication. And the following experiments were made in order to investigate the electrophysiological changes of neuromuscular function of rats exposed to toluene vapor for a long term, The animals used were male rats of Donryu strain. The animals divided into three different exposure groups were exposed to the respective concentrations of pure toluene vapor 8 hours a day, 6 days a week uniformly, but, for 8, 16 or 41 weeks in 2000 ppm group, and for 49 weeks in 100 ppm and 200 ppm groups (Tables 1, 2). Electric threshold values of neuromuscular excitation were measured after exposure for 8, 16 and 41 weeks in 2000 ppm group and its control, and after exposure for 49 weeks in 100 ppm, 200 ppm groups and their control. And strength-duration curves and ratios of the threshold of the extensor muscle to that of the flexor were obtained. Maximal conduction velocities (motor nerve) were measured by the modification of Kaeser and Lambert's method in 100 ppm, 200 ppm and the control groups. The strength-duration curve did not show any notable change in all the groups (Figs.3-6). But the ratio of the threshold stimuli increased in 2000 ppm group after exposure for 41 weeks (p<0.05). This may be due to the influence of toluene on the nervous system (Figs.7, 8). The maximal conduction velocity decreased more in 200 ppm group than in 100 ppm and the control groups (Fig.9). Latency from the application of stimuli at the upper point of femur to the appearance of twitch of the sole muscle was much longer in 200 ppm group than in the other groups (p<0.05). There was no noticeable difference in three groups on latency in the same sense from the knee point to the sole muscle as well as the upper point of ankle to the sole muscle (Fig.10). So, the peripheral nervous disorders may not be dominant in the distal region.

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For the protection of workers against risks of occupational cancer, the most important and fundamental principle is to eliminate carcinogenic agents from the work environment. In iron and steel industries, various substances with unknown components are used for coating the inside surface of ingot case. In order to know whether they are carcinogenic or not, the author carried out biological and chemical assays on nine commercial brands of ingot case coating materials. The results obtained are as follows: (1) Animal experiments: thirty % toluene solution of the test materials and toluene used as control were painted on the shaved skin of 20 male and 20 emale ddN mice, aged 7-9 weeks, thrice weekly until death. The mice treated with materials A, B, C, D, E and F yielded skin tumors, including squamous cell carcinomas at the application site, while no tumor was found in the groups receiving G, H and I. Material A seemed to be most carcinogenic since 17 mice bore skin tumors including 11 carcinoma cases with shortest latent period of 10 weeks. Materials B and C were similar but slightly weaker than A, because tumor bearing mice were 13 (6 cancers) for B and 11 (8 cancers) for C, the latent periods being 20 and 28 weeks, respectively. Materials D and F induced a rather small number of cases of tumor, Namely 5 (3 cancers) and 5 (1 cancers), respectively. Carcinogenicity of E was obscure because of only two papillomas yielded. (2) Chemical analysis: Each of the materials, 0.25-5.0g, was charged on a column of 20-100g of activated aluminum and developed with n-hexane containing increasing amount of benzene up to 30%. 15-30 fractions obtained from each material were examined for absorption spectrum and those with similar spectra were combined, making 10-15 fractions. Each of them was subjected to thin layer chromatographic separation; plates composed of two adsorbent layers (26% acetylated cellulose and aluminum oxide G) and methanol-ether-water (4: 4: 1) being used as developer. Fluorescent spots on the plate were eluted with benzene. Absorption spectroscopy of such elutes yielded approximate amounts of hydrocarbons by means of Cooper's base line technique. Materials which were hard to separate chromatographically were subjected to two additional alumina column chromatographies. Recovery rates for benzo[a]pyrene as determined by the above analytical method but the use of radioactive and non-radioactive benzo[a]pyrene were 67 to 74%. Large amounts of polycyclic aromatic hydrocarbons were detected in materials A, B and C, slightly smaller in D, and small amounts in E and F. Benzo[a]pyrene was 340, 175, 235, 45 and 2 μg/g for A, B, C, D and F, respectively. In G, H and I, no hydrocarbons were found. The results of the chemical analysis were thus very similar to those of the animal experiments. It is highly desirable from the findings of this study that use of carcinogenic ingot case coating materials should be discontinued.

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1)自験例14例をふくむ本邦の文献症例57例を検討しメチルブロマイド中毒症の病型分類を試みた.軽症型急性中毒,重症型急性中毒,激症型急性中毒,および慢性中毒の4型である. 複雑で多彩な病像を呈する本中毒症のすべてに共通する検査法がない今日,病像の把握と診断にこの病型分類が有用であろう. 2)メチルブロマイド中毒症の各臨床病型について,潜伏期,主症状,予後はつぎの通りであった. 潜伏期は,軽症型急性中毒では数分から数時間であり,重症型急性中毒では主症状の発現迄に初発症状より数時間を要した.激症型急性中毒は数時間以内に発症している. 主症状は,軽症型急性中毒では頭痛,めまい,悪心,嘔吐(初発症状群)であり,重症型急性中毒では昏睡と全身痙攣,激症型急性中毒では急性肺浮腫,慢性中毒では歩行失調であった. 予後は軽症型急性中毒は数週以内に全治し,重症型急性中毒は半永久的後遺症を残し,激症型急性中毒は48時間以内に死亡し,慢性中毒は軽快までに数カ月以上を要した. 3)本邦症例の臨床病型の内わけはつぎのごとくであった.軽症型急性中毒5例,重症型急性中毒3例,激症型急性中毒2例,および慢性中毒15例. 自験例では軽症型急性中毒4例.重症型急性中毒2例,慢性中毒8例であった. 4)急性中毒の積重ねのない慢性中毒症と思われる症例は,本邦例では6例(40%)だが,自験例では1例(13%)のみであった.

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55才男子.昭和30年よりスチレンモノマーを架橋用にしたポリエステル樹脂槽の製造に従事した.作業は素手で行ない,流涙,鼻汁を頻回に経験していた.3年後黄疸にて入院治療をうけたが,この頃より頭重感,不眠,全身倦怠感,四肢のしびれ感,筋肉痛が始まり,時には激しい苦痛を訴えた.昭和44年5月当科ヘ入院した.入院時現症では痩せ,および上下肢,躯幹の表皮が萎縮性を示し,四肢,躯幹に軽度の筋萎縮を認めた.四肢の腱反射の亢進があり,知覚検査で両側上下肢のしびれ感,両側下腿に冷感覚の低下を認めた. 入院時検査成績では,皮膚生検上中等度の表皮の萎縮を認め,筋生検および筋電図は神経原性の変化を示した.尿中クレアチン排泄量は187mg/dayと増加が認められたが,尿中馬尿酸排泄量は0.28&#8764;0.32g/dayと正常であった.肝機能,血算,血液生化学,血清反応,尿検査には異常を認めなかった. 入院および経過約1年の観察で,症状はほとんど不変であり,心季亢進,呼吸困難,不眠,頭痛ならびに食思不振を伴う高度の不安神経状態が出没した. 汎発性強皮症が鑑別の対象になったが臨床ならびに組織学的所見より除外された. スチレン中毒症と考えられる症例は文献上Carpenter(1944), Barsotti(1952), Klimkova-Deutschova(1962), Praatt-Johnson(1964), Stewart(1968),松下(1968),原(1970)-以上神経障害例-,およびKatz(1962,肝,脾,血液障害例)らの報告をみる.これらの症例の臨床所見は必ずしも一致していないが,われわれの症例は,末梢性の神経障害,腱反射亢進,ならびに精神症状を示した点が,Klimkova-Deutschova,松下の報告と共通であり,さらに皮膚および筋萎縮の存在が新知見であった.

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Deposition of lead in the kidney of rats suffered from lead poisoning were examined by the use of both light and electron microscopes. Chronic lead poisoning of rats was attained by 13 successive intraperitoneal injections with 1 ml of 1% lead acetate solution once in two weeks over a period of 26 weeks. Subacute lead poisoning of rats was attained by 3 intraperitoneal injections with 1 ml of 5% lead acetate solution once in two weeks over a period of 6 weeks. Light microscopic observations on the kidneys from chronically lead-poisoned rats showed that proximal tubules were atrophic with a concomitant increase and swelling of the interstitial tissue, or dilatated with flattened and atrophic epithelia. Most glomeruli appeared intact. The presence of dense concretions and nuclear inclusion bodies in the epithelial cells of the proximal tubules was dominant in this case. The dense concretions were different from the inclusion bodies, spherical or ovoid in shape, and varied in size, of which diameter ranged up to 50 μm. In subacutely lead poisoned rats, the concretions usually appeared in the lumen of the proximal tubule. A hydrogen sulfide test for identification of lead by Iwahashi strongly suggested that the concretions contained lead. From the electron microscopic observations, the concretions were shown to be the complexes of needle-like components less than 100 Å in width and electron-dense material. The needle-like component were usually organized into concentric lamellae, on which the dense material deposited. The concretions were never found in nuclei. Besides, the concretions were clearly surrounded by a single membrane. Inclusion bodies were found in the enlarged nuclei of proximal tubule cells as complexes of filament of 70-170 Å in width and electron-dense substance. From these fidings, it was suggested that exogenous lead deposited in the concretions enclosed by the limiting membranes which may be a form of lysosome.

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