Numerous reports have been published in the field of industrial health on biological monitoring of trichloroethylene exposure, but these studies have been confined to healthy humans. Triehloroethylene metabolism in individuals with chronic liver diseases has not been clarified. This experiment was therefore performed on rats that were administrated carbon tetrachloride subcutaneously for three months to induce chronic liver damage. The metabolism of trichloroethylene and its metabolites, chloral hydrate and trichloroethanol, were investigated using the isolated liver perfusion method. Comparing the changes of these substances in the chronically damaged liver with those in the intact liver, the following results were observed in the chronically damaged liver:
1) The conversion of trichloroethylene to trichloroethanol and trichloroacetic acid decreased.
2) The reduction of chloral hydrate to trichloroethanol increased.
3) The oxidation of chloral hydrate to trichloroacetic acid decreased.
4) The biliary excretion of trichloroethanol and trichloroacetic acid decreased.

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The high curve speed railway vehicles (HCSRVs) of the Japanese National Railway have been operating since 1973 with the aim of increasing speed on ordinary routes with many curve track sections.
Although the aim of increased speed has been attained, it has been pointed out that the swing of HCSRVs is stronger than that of ordinary-type trains and it may increase motion sickness among the passengers and conductors.
In this study, the authors examined motion sickness symptoms among 119 passengers and 100 conductors of both trains with a self-administered questionnaire, and evaluated the vibration acceleration on the floor by using the 1/3 Octave Band Analyzer and the Fast Fourier Transform method (FFT).
The results can be summarized as follows:
1) There were more passengers and conductors suffering from motion sickness riding on HCSRVs than those on the control trains.
2) HCSRVs had the peak values of vibration acceleration within the range of 0.5 Hz and 1 Hz at horizontal, although the control train showed them above 1.0 Hz.
These results suggest that the high rates of subjective complaints of passengers and conductors riding on HCSRVs were affected by vibration acceleration of frequency lower than 1 Hz.

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In recent years it has been suggested in Japan that occupational trichloroethylene exposure will induce primary pneumatosis cystoides intestinalis coli. A series of two experiments were conducted to ascertain the cause-effect relationship between trichloroethylene and pneumatosis as follows:
1) In the first experiment, 12 male rats of Fischer strain were exposed to trichloroethylene at a nearly lethal concentration for 12 wk. Five out of 12 rats died during the experiment, and body weight gain was extremely depressed. However, neither pneumatosis nor histological changes were observed. No changes were observed in 4 control rats as well.
2) In the second experiment, 38 male rats of Sprague-Dawley strain were exposed to 800, 200 or 50 ppm trichloroethylene over a period of 12 wk. Two out of 13 rats of the 800 ppm group died, and body weight gain was suppressed. Mild suppression in body weight gain was also observed in the 200 ppm group. However, pneumatosis was not observed in any rats of trichloroethylene groups. No pathological changes were observed in 13 rats of the control group.
The foregoing results suggest that trichloroethylene cannot induce pneumatosis cystoides intestinalis in rats of these two strains. Inasmuch as rats are not prone to develop pneumatosis, the possibility for trichloroethylene to induce this disease in man cannot be denied.

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The purpose of this study is to apply changes in forearm transcutaneous PO₂ (tcPO₂) during the cold water immersion test (5°C, for 10 min) to the diagnosis of vibration syndrome. Forearm tcPO₂ in healthy controls increased gradually up to 3 min after the start of the cold water immersion and decreased thereafter. It returned to almost the same level before immersion 5 min after the start. In the workers using vibrating tools manifesting Raynaud's phenomenon, forearm tcPO₂ also increased up to 3 min after the start as in healthy controls, but no change was observed thereafter. The difference between the level of forearm tcPO₂ at 3 min and that at 10 min after the start of the immersion (Forearm tcPO₂ recovery index, newly devised by authors) in workers using vibrating tools was significantly lower than that in healthy controls. Therefore, investigation of changes in forearm tcPO₂ following the cold water immersion test is considered to be a useful objective item which can contribute to the diagnosis of vibration syndrome.

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In order to determine the effect on the respiratory system of long-term inhalation of chromic acid in electroplating, histopathological examination was performed on mice (ICR, female, n=50) exposed to chromic acid mist for 12 months (30 min/d, 2 d/wk), by using the authors' miniaturized chromium electroplating system. After 12 months' exposure, the mice were kept for 6 months without exposure.
In the upper respiratory tract, round perforations were found in the nasal septums in 6 mice that were sacrificed or died after 10 months' exposure. The perforations were located near the point of the septum, the thinnest part of the nasal septum, and were of pin-hole sige.
On the epithelium of the trachea and bronchus, loss of cilia, proliferation of goblet cells or basal cells, and squamous metaplasia were observed in almost all of the exposed mice. These changes appeared to be more advanced in mice exposed for a longer period.
In the lung, development of benign adenoma was observed in one mouse in the 6- to 9-months' exposure group, in three in the 10- to 14-months' exposure group and in one in the group examined after 15 to 18 months. Furthermore, adenocarcinomas were found in two mice, one of which died at 17 months and the other was sacrificed 18 months after initiation of exposure.
In conclusion, the finding that adenomas and adenocarcinomas were observed in mice exposed to chromic acid mist suggests the need to give careful attention to the possibility of respiratory cancers in chromium electroplating workers.

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