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.
It was aimed to know what difference would occur in the amount of mercury in the brain of rabbit after administration of sublimate solution by different routes. Irrespective of dose level and time after injection, the subcutaneous injection made a higher concentration of mercury in the brain than the intravenous injection did. In the intravenous injection, the amount of mercury retained in the liver was markedly higher than in the subcutaneous injection. On the contrary, the kidney had a higher concentration of mercury in the subcutaneous injection. Possible mechanisms to produce such difference on the mercury concentrations in the brain were discussed.
The decrease in the hapatic ATP level and the increment of the fatty liver as reflected by the increase in the amounts of the total lipid and triglyceride in the mice exposed to three kinds of chlorinated hydrocarbons are in the following order, carbon tetrachloride, tetrachloroethylene and trichloroethylene. The total lipid and triglyceride contents increase proportionately to the fall in the ATP level with lapse of time in the mice before and after the exposure to three kinds of chlorinated hydrocarbons. From above results, it is inferred that there exists some close relationship between the decreased hepatic ATP levels and the development of fatty liver in the case of chlorinated hydrocarbon poisonings.
A simple diffusion cell was examined on its applicability for routine use as a gen-erator of air flow containing low concentration of organic vapor. Both the fluctuation of concentration of vapor in the air flow and the ratio of the time-averaged concentra-tion to the calculated one were observed by gas chromatographic technique at short time intervals of sampling for two hours or more. Much fluctuation of concentration in the stationary state of operation was noticed beyond certain ranges of the values of the operational conditions and structural factors of the cell. An attempt to reduce such fluctuation was made and the buffer flasks proved to absorb it effectively. The time-averaged concentrations from 0.4 ppm to 82 ppm were in good agreement with the calculated ones.
The effects of Na+, Ca2+ and Cd2+ on the surface pressure area relation of the phospholipid monolayer were studied. The metal ions expanded the monolayer. The lowest ion concentration at which the expansion of the monolayer was observed dec-reased in the order of Na+>Ca2+>Cd2+. The minimum concentration of Na+ for the saturation of the expansion was nearly equal to that of Ca2+, and was larger than that of Cd2+. From these results, it was thought that the reactivity of the metal ions to the phospholipid monolayer was in the order of Cd2+>Ca2+>Na+. In the subsolutions containing two different metal ions, these ions were in compe-tition with each other for the negatively charged sites of the phospholipid molecules. Cd2+ was the most reactive in the competition reaction. The high reactivity of Cd2+ was discussed in relation of the metal poisoning.
The fume from silver solder was examined. It contained very high percentage of cadmium (about 85%) in usual welding procedure, though original solder about 24%. The fume collected by Cascade Impactor was analysed chemically on each stage, and it was found that the cadmium content in the particles increased with the decrease of particle size. X-ray diffraction analysis of the fume showed that cadmium in the fume is the cadmium oxide. Therefore, it is assumed that workers exposed to the fume from silver solder inhale an enough amount of very small particles whose main compo-nent is cadmium oxide, and may suffer from acute cadmium poisoning.