労働科学のバックナンバー
2007/11/10発売号 (83巻4号)

出版社：労働科学研究所
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■労働科学の目次

白土男女幸，宮本直和，濱田明美，饗庭照美，飯　聡，西村由二三，仲井朝美，宇治橋貞幸，芳田哲也
包丁研ぎにおける熟練者と非熟練者の動作分析と筋活動様式の比較
労働科学，83（4），139～150，（2007）

　本研究では，熟練者2名と非熟練者1名を対象とし，包丁研ぎ動作の3次元動作解析，筋電図計測，および包丁の刃先評価を行った。その結果，以下のことが明らかとなった。
熟練者は非熟練者と比較すると，全身を使った研ぎ動作を行い，1研ぎの動作範囲が大きく動作時間も短かった。また，それらの再現性も熟練者において高かった。
熟練者は尺側手根屈筋を用いて包丁を上からしっかりと押さえつけるながら研ぎ，手前に引く際，三角筋後部で肘を後方に引いていた。
熟練者によって研がれた包丁の刃は刃先および中央部において凹凸形状に変化したが，非熟練者によって研がれた刃には変化が見られなかった。（図10）　（自抄）
キーワード：バイオメカニクス，筋電図，熟練者および非熟練者，包丁研ぎ，刃先形状

Minayuki SHIRATO, Naokazu MIYAMOTO, Akemi HAMADA, Terumi AIBA,
Akira II, Yoshifumi NISHIMURA, Asami NAKAI, Sadayuki UJIHASHI, Tetsuya YOSHIDA
Comparison of Body Movement and Muscle Activity Patterns During Sharpening a Kitchen Knife Between Skilled and Unskilled Subjects
THE JOURNAL OF SCIENCE OF LABOUR，83（4），139～150，（2007）

The purpose of the study was to investigate the differences between skilled and unskilled subjects in the motion and muscle activity patterns during sharpening a kitchen knife. Two skilled subjects and an unskilled subject conducted sharpening of a kitchen knife at a freely chosen pace. The shape of the knife blade sharpened by each subject was examined under a microscope. The motions were recorded by four cameras (60 Hz) and surface electromyograms of four muscles of the upper limbs were recorded. The skilled subjects had shorter motion durations, longer motion pathways and higher reproducibility of strokes than the unskilled subject. In each stroke, prominent EMG activities were observed in the flexor carpi ulnaris and posterior deltoid muscles in the case of skilled subjects. The front edge and the central region of the knife sharpened by the skilled subjects changed to be odd-shaped, while those of the knife sharpened by the unskilled subject remained unchanged.
Key words: Biomechanics, Electromyography, Expert and non-expert, Sharpening kitchen knife, Shape of kitchen knife-edge

木村菊二，島影喜久子
綿を取扱っている作業場における綿塵について
労働科学，83（4），151～168，（2007）

米国で綿塵の測定に使用されているVE sampleとほぼ同じ捕集特性を持つTR samplerを試作し，さらに作業者に装着して個人曝露濃度が測定可能なTR 個人サンプラーの開発を行った。
　綿塵の調査を実施した作業場は，中小企業の綿の打ち直し，タオルの製造，太糸の紡績工場等の4社，および，大企業の紡績工場２社について実施した。
　中小企業の綿を直接取り扱っている作業場の綿塵濃度は許容濃度の値をかなり超えていた。タオルの製造，紡績等では許容濃度の値前後の濃度であった。
　大企業の紡績工場では，混綿，梳綿，精紡と工程がすすむに従って綿塵濃度は低下していた。R綿塵濃度は，いずれも1mg/m3 以下であった。
　採取した粒子を顕微鏡によって観測した結果，混綿では土砂の外，葉，茎の砕片などの夾雑物が多数認められ，精紡では夾雑物はほとんど認められなかった。
　フィルター上に採取したサンプルを過熱処理して不燃性物質を求めた結果，かなりの不燃性物質が含まれているところもあった。（図12，表7，写真28）（自抄）
キーワード：綿塵；綿肺症；吸入性粉塵；垂直型分粒装置付き綿塵サンプラー；綿塵用TRサンプラー；綿塵用TR個人サンプラー

Cotton Dust Concentrations in Workplaces Treating Cotton
Kikuzi KIMURA , Kikuko SHIMAKAGE
THE JOURNAL OF SCIENCE OF LABOUR，83（4），151～168，（2007）

Byssinosis suffered by workers at workplaces dealing with cotton has been a serious social issue in many industrialized countries including Japan. A special committee on guidelines for suppressing cotton dust was organized in 1977 in Japan, and the one of the authors was in charge of developing measuring methods of airborne cotton dust concentrations and investigating the actual situation in workplaces dealing with various kinds of cotton materials.
A new device for measuring cotton dust concentrations in the air was developed that had the same dust collection efficiency as a vertical elutriator cotton dust sampler (VE sampler) used in the United States for measuring cotton dust. This new device was called a total and respirable cotton dust sampler (TR sampler), and based on the method of this device, a total and resprable cotton dust personal sampler was also developed and put into use.
The TR sampler could collect cotton dust by first collecting particles of 15 μm or more in hydrodynamic diameter on an impact glass plate coated with silicone oil and by collecting remaining particles through a glass fiber filter. The weight of the impact plate and that of the glass fiber filter were measured before and after dust collection, the differences in weight divided by the volume of suction air giving the dust concentrations. The particles collected by the glass fiber filter corresponded to respirable dust and the sum of the respirable dust and the dust collected on the impact plate gave the amount of total dust.
The cotton dust concentrations measures by the TR sampler were compared with those obtained by a VE sampler at the same workplaces. The dust levels measured by the TR sampler ranged between 110-120% of those obtained by the VE sampler. When the differences in measurement conditions were taken into account, we may assess that both these samplers give the approximately same dust concentrations for cotton dust.
Cotton dust concentrations were measured in four small and medium-sized companies undertaking purifying cotton materials, wadding cotton into futons, manufacturing towels and spinning coarse yarns as well as in two large cotton spinning mills. The measurements at the small and medium-sized companies were done in 1981, while those at the large mills were done in 1978-1979. The results showed that cotton dust concentrations in workplaces dealing directly with cotton as in the case of purifying cotton materials were much higher than the permissible concentration for cotton dust. The cotton dust concentrations in workplaces for manufacturing towels, and for carding or fine spinning of cotton were around the permissible concentration. The cotton dust concentrations in large spinning mills were becoming lower as the spinning process proceeded from blending and carding cotton to fine spinning, with repirable cotton dust concentrations of less than 1 mg/m3.
The coarse particles collected on the impact plate of the TR sampler in cotton blending sections mainly consisted of foreign substances such as earth or sand particles and contained only a small amount of long fibers. On the contrary, particles collected in carding and fine spinning sections comprised a large number of long cotton fibers. This was presumably because noncombustible particles such as earth and sand particles had been removed when cotton materials were pneumatically transported from the blending section to the subsequent sections.
The microscopic observation of the particles collected on the impact plate of the TR sampler revealed, in addition to earth and sand particles, a large amount of foreign substances such as leaves and stalks as well as bacteria and spores sometimes. The air in carding sections contained a less amount of such substances than that in blending sections, while the air in fine spinning sections contained numerous fragmented cotton fibers with a very small amount of foreign substances.
The proportion of non-combustible substances determined by superheating respirable dust collected by the TR sampler was considerably high in the workplaces of the small and medium-sized companies, as high as 70% in extreme cases. The proportion of non-combustible substances was 20% in carding sections, and only 2 % in the case of fine spinning. In large spinning mills, the corresponding proportion was the highest in blending sections at 37% and lower as the spinning process proceeded, with the lowest 2% in fine spinning sections.
The results indicated the need for protecting workers dealing with cotton against both large and respirable particles commonly seen in their workplaces. Large particles of 15 μm or more in diameter contained organic debris particles and foreign substances that could cause allergic diseases. The effects on health of cotton dust were found to depend on the dust contents, and this should be taken into account in protecting the workers. The TR sampler has made it possible to measure concentrations of both large and respirable particles, and has proven suitable for assessing the cotton dust concentrations.
Keywords：Cotton dust; Byssinosis; Respirable dust; Vertical elutriator cotton dust sampler; Total and respirable cotton dust sampler; Total and respirable cotton dust personal sampler