The “tatami” mat production is one of the most important farming in Japan. It is all year domestic labor, being consisted of rush cultivating and “tatami” mat weaving process. From the industrial health point of view the working process have several problems. 1. Rush harvesting process Rush is reaped for 3 weeks in July. The process, cutting, smearing, drying and storing, is hard physical work and energy consumption was estimated 3500-4500 kcal. per day. The workers are exposed to the scorching heat of the sun and the average value of WBGT-index of the working times a day was culculated 29.3°C. The process requires 5-10 co-workers per each household. The reaped rush bundles are carried hand in hand with each workers from the field to the storing room. The workers are exposed to dense concentrated dusts of “sendo” used for “dorozome”, smearing rushes into mud in order to keep it's color unfaded. Especially, in the process of drying to storing, for 1-3 hours per day, over 100mg/m3 of dusts was observed. And average values of the working space was 44mg/m3 for male and 41mg/m3 for female during 7: 00-18: 00. Seventy eight percent of particles of the floating dusts in the working space were under 5μ in diameter. The “sendo” is clayey dust mixed with quartz, chlorite, kaolin, sericite and other minerals and contains 20-30% of free silica. 2. “Tatami” mat weaving process The stored rushes are weaved into “tatami” mat domestically for all seasons. It contains the process of sorting length of rushes and weaving. The intensity of works are relatively low, but it's compulsory working times are very long. The workers are exposed chronically for long-term to low dencity (1-5mg/m3) of “sendo” dusts through the process. And occasionally, the workers are exposed to relatively dense concentrated dust (15-25mg/m3) in the storing process. Seventy five to eighty five percent of the floating dusts were under 5μ in diameter.
Farmers engaged in rush cultivating and “tatami” mat weaving process are exposed daily to “sendo” dusts. We conducted a health survey of the rush farmers. The results are as follows. Forty four cases, 32 males and 12 females, of slight fibrosis (PR 1) were devided from 326 subjects examined, 179 males and 147 females, by chest roentogenograms. And 37 cases, 17 males and 20 females, were suspicious (RX) of pneumoconiosis. The longer the working periods in rush labor, the higher prevalence of chest roentogenogram findings were found. And other factors on rush managements also related to the prevalence. The severity of pneumoconiosis is still in early stage and almost PR 1 cases were classified as “the first division of health control” settled by “the Act of Pneumoconiosis” in Japan. But, those subjects examined had complaints of some respiratory symptoms higher percentages than that of farmers not engaged in rush labor. Furthermore, in those subjects relatively high percentages of the cases were defined as impaired lung function, especially with air way obstruction. The results suggest that the prevalence of respiratory findings of rush farmers relate to the amount of inhaled particles of “sendo” dusts.
Farmers engaged in “tatami” producing process are exposed to “sendo” dusts. “Sendo” means dyeing materisl being used for the process of. “dorozome”. to keep rushes' and “tatami” products' color unfaded. It is clayey dust and contains 20-30% free silica. 1. “Sendo” The experimental study on fibrogenesity to rat's lung by intratraheal infusion of 3.5% and 10% suspension of “sendo” dusts was made. The results are as follows. Evident dust foci and slowly but steadily progressed collagenous fibrogenic reaction were observed histologically in the lung tissue of rats treated “sendo” at 3 to 6 month after infusion. This suggests that rush farmers' pneumoconiosis raise due to long-term inhalation of “sendo” dusts. 2. Substitute materials for “sendo”: eight trial productions. The exploitation of substitute materials for “sendo” has been made. And eight kinds of trial productions, consisting of TiO2, ZnO, MgO, CaCO3 and some amount of “sendo”, were provided. These materials were examined fibrogenesity to lung tissue with comparison of “sendo” by same method of former experiment. The results are as follows. These materisls showed less stronger fibrogenetic reaction to lung tissue than that of “sendo” histologically. And contents of hydroxyproline of lung tissue of rats were estimated 4.0-5.5mg per total dry weight of right lung at 6 month after infusion. On the contrally, 6.0-7.0mg were the controlled lungs treated by “sendo”, quartzsands and kaolin. But these materials contain some amount of “sendo” and/or TiO2 which fibrogenesity to lung tissue has been already observed. So the further study were undertaken. 3. Substitute materials for “sendo”: three markettable goods. Three kinds of new substitute materials for “sendo”, mainly consisting of ZnO+CaCO3+BaSO4 or MgO+CaCO3, were provided for rush farmers. Contents of free silica of these new materials were 0.0-1.0%. And experimental study showed these materials relatively weak fibrogenesity to lung tissue than that of “sendo” histologically, and tissue hydroxyproline of right lungs were estimated 3.5-4.5mg. This suggests that these three kinds of new substitute materials for “sendo” were available for the dust control of rush labor.
In application of organophosphorus pesticides (800-fold dilution of Sumithion and 1500-fold dilution of Diazinon) for the control of disease and insect damages to apples, the amount of exposure to the pesticides, blood levels of the pesticides, and liver function tests of the workers engaging in the application work were observed. Its summary was as follows; 1. The concentration of pesticides inhaled by each worker engaging in the fixed piping joint control was calculated as 0.030±0.042mg/m3 (mean±S. E.). 2 Analysis of the correlation between the inhaled amounts of pesticides and the air velocity disclosed that was a statistically significant positive correlation between the two parameters. Therefore, it will be necessary for the workers engaging in the application of pesticides to amply consider the factor of wind in actual application. 3. Both the serum levels of organophosphorus pesticides and the urinary excretion of p-nitro-m-crezol measured were low. 4. In view of the above-mentioned current amounts of exposure to pesticides, no acute effects of the pesticides were manifest on the liver function tests. 5. However, because the fixed piping joint control system employs the lance application (hand application), the applicator is more liable to be exosed to large amounts of pesticides, the exposure amount being 2.7 times that of speed sprayer (SS) operator. 6. It is not rare that women and the aged engage in the fixed piping joint control; therefore, it is necessary to educate ample care in the protection of workers from exposure to pesticides.