1) Recently, dry cleaning with perchloroethylene has become available in Japan, and this dry cleaning has become to be used even for cleaning Japanese clothes made of silk. Two patients visited us one after another, who were engaged in cleaning Japanese clothes and thought to be poisoned by perchloroethylene. Their health states and working conditions were examined from the viewpoint of occupational hygiene.
2) The patients complained similarly of memory disturbance, easy fatigability and decrease of tolerance to alcohol after contact with perchloroethylene. The medical examination at the Nagoya University hospital revealed a slight disturbance of liver function, a slight narrowness of left visual field, and diffuse distribution of α rhythm, sporadic θ activities and mixed fast wave in EEG in the first patient. And, evident disturbance of liver function, decrease of retinal potential and diffuse distribution of a rhythm and mixed fast wave in EEG were revealed also in the second patient. Liver function and function of the central nervous system were commonly disturbed in the two patients, although the degree of the disturbance was different between them.
3) A large amount of perchloroethylene was used in the work room of the first patient, and his work room was narrow. Therefore, high concentrations of perchloroethylene were detected at the time of survey. The concentration of perchloroethylene was 30-70 ppm under his nose at washing Japanese clothes by hand brush, and 100-400 ppm near Japanese clothes wetted with perchloroethylene and hanged on.the wash-line poles.
As regards to the second patient, the work room was fairly improved after his health disturbance. But high concentrations of perchloroethylene were detected at the out of the fun for ventilation and at the exhaust opening, and this fact proposes another kind of environmental pollution problem.
4) Japanese clothes wetted with perchloroethylene were hung on wash-line poles to become dry naturally in the room so that the clothes did not become wrinkled and remain soft after cleaning. Consequently, perchloroethylene is consumed about 60 % by weight of Japanese clothes and on top of that, most of perchloroethylene is vaporized in the work room, whereas in the ordinary dry cleaning perchloroethylene is consumed at about 5% by clothes weight, most of which is exhausted from the cleaner to the outdoor. Accordingly, the concentration of perchloroethylene in the work room may become very high and the worker may have a danger to be poisoned with perchloroethylene. As there are many workers engaged in this kind of work in Japan, it is necessary to make countermeasures for them from the viewpoint of occupational hygiene.

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The daily absorption of lead through the intestinal tract has been reported to be 15-30 μg and the daily excretion in urine to be about 12 μg. On the assumption that gastrointestinal net absorption and urinary excretion of lead are almost equal to each other in adults who have reached a steady state and that lead absorption by the respiratory tract and excretion by routes other than urine or bile are negligible, lead excretion in bile was calculated to be 3-18 μg/day in adults with no known high exposure. The lead secretion in bile of 4 samples was 18 μg/day, and the difference between the last two figures is 0-15 μg/day, which is the reabsorption amount in the intestinal tract.
Since total lead absorption and excretion are almost equal to each other in adults with low level exposure, the difference of the absorption between the atmospherically exposed group and the control can be replaced by the difference of excretion. Since lead absorption via the intestinal tract in both exposed and control groups are almost equal and lead absorption via the respiratory tract during nonworking hours of the exposed group and that of the control group are the same, the difference of lead excretion (absorption) between the two groups should be equal to the lead absorption via the respiratory tract due to occupational exposure. In order to derive the detectable level of occupational respiratory absorption where the difference of the averages of blood lead concentrations of the two groups is statistically significant, the occupational respiratory absorption is replaced by the difference in lead excretion in urine and bile between the two groups. The occupational respiratory absorption of lead which theoretically indicates a statistically significant difference from the control group and the corresponding value of lead concentration in air were obtained.
The sensitivity of the statisitcal test varies according to the number of samples used. The number of samples which reflects biological significance is thirty or more. If the number of samples is about 30, the respiratory absorption of lead during working hours was calculated to be between 9 to 26 μg/day corresponding to concentrations of lead in air of 4-12 μg/m³. The values obtained by these calculations agreed fairly well with values actually obtained and reported elsewhere.

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In 1964, Bleiberg et al. reported high prevalence of porphyria cutanea tarda (PCT) among the workers in a 2, 4-D and 2, 4, 5-T producing plant. Since then, like chlorinated benzenes, some of the poly-chlorinated phenols have been suspected as a possible inducer of PCT, but the experimental evidence is as yet lacking.
A series of feeding experiments of 2, 4-di-, 2, 4, 5-tri-, and penta-chlorophenol (2, 4-DCP, 2, 4, 5-TCP, PCP) to rats was carried out in order to determine whether these chemicals themselves are really able to induce hepatic porphyria. In the first experiment, a short term experiment with a large dose, the chemicals were administered to rats in the doses of 200-1, 000 mg/kg every day for 3 weeks, and in the second a small dose of chemicals, 10 mg/day/capita (30-70 mg/kg), was administered every day for 17 weeks. All of the rats including the control were fasted for 3 days in the last week of each experiment. The results obtained are summarized as follows.
Urinary excretion of ALA and coproporphyrin did not increase, or rather decreased in the rats treated with the chlorinated phenols during the course of both experiments. No uroporphyrinuria was found in all of the rats. In the groups treated with each of the chlorinated phenols, the average values of urinary PBG and fecal porphyrin showed no significant increase compared with those in the control. Abnormal accumulation of porphyrins in the liver and kidneys was not observed in all of the rats, and uroporphyrin contents in these organs were under the limit of detection. Histologic examination revealed only a slight liver damage with vacuole degeneration and intralobular leucocytic infiltration in about half of the rats treated with chlorinated phenols.
From these results, it seems unlikely that the poly-chlorinated phenols have potency to induce hepatic porphyria. However, it should be noted that improvement and control of working environment are necessary in the factories producing these organochloric herbicides because there are some possibilities of the presence of highly hepatotoxic chemicals having the induction potency of porphyria, such as chlorinated benzenes and tetrachlorodibenzo-p-dioxin, in their synthesizing process as pre-compounds or by-products.

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