出版社：National Institute of Occupational Safety and Health
摘要：A ten-year observation of workers exposed to mercury has been carried out in a certain tungsten rod manufacturing factory. Atmospheric mercury levels in working places have been recorded by routinized monitoring. Periodical health checks compris-ing estimation of urinary mercury level, physical examination and interview for sub-jective complaints have been done by the same physician, one of the present authors. The tolerance to mercury vapour was variable greatly. As a factor of this varia-bility, the experience of preceding mercury exposure was depicted first, The workers experienced already a poisoning or a nearly poisoned condition could tolerate in amount far in excess of dose, to which newly employed workers could not tolerate. The second factor is the difference in individual susceptibility to mercury. Symptoms of poisoning, mainly tremor, appeared in some of the workers with above 300 μg/1 of mercury in the urine (standardized value to the specific gravity of urine, 1.024), but some other tolerated by the level of 780μg/1. There was the concurrence of elevation of urinary mercury level with appearance of symptoms in some cases, but in other cases, the independency of symptoms from change in urinary mercury levels was ob-served. By these results and literal studies, the diminution of maximum allowable concent-ration is considered being recommendable as to the urinary mercury level of workers exposed to mercury vapour.
