摘要：A smoke injury occurred in Gifu prefecture in May, 1964, by which silkworms reared with mulberry leaves around a tile factory were late in their growth, failed to cocoon or died. To find out the cause of this injury, raw materials of tile, air, flue gas, mulberry leaves, silkworms and deposited dust were analyzed. The amounts of sulfur oxides, lead and arsenic in flue gas and in mulberry leaves were too small to cause the injury. In air around the factory, fluorine was found at the rate of 0.001-0.035 mg/day/100 cm2 absorbing paper, and the amount of fluorine increased with the degree of injury to silkworms. The most contaminated mulberry leaves contained 30 mg of fluorine per 100 g of dried leaves, and the fluorine content was 15-20 times higher than the normal leaves. The fluorine contents of green body and glaze were found to be 13 and 56 mg/100 g, respectively, and 55-80% of fluorine in these raw materials was volatilized by firing in the course of tile manufacturing. From the results of this research, it is concluded that the volatilized fluorine might be the cause of the smoke injury.
