Trichloroethylene has been widely used for the removal of grease in dry cleaning, plate and painting industries, in which approximately 280 thousand workers contact trichloroethylene, for example, in the United States, resulting in acute and chronic poisonings. Based on 203 papers mainly on trichloroethylene toxicity on human beings, the present review covers acute toxicity, chronic toxicity, carcinogenicity, factors modifying toxicity, metabolism, dose-response relationships and maximum allowable concentration of this chemical. 1 figure and 12 tables.

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The behavior of fluoride ion level in the urine and in the serum was measured as an index for health care of workers exposed to hydrofluoric acid, the effect of fluorine-containing foodstuff intake by the workers being considered at the same time. For this study, 250 hydrofluoric acid workers and as a control group 1, 600 non-hydrofluoric-acid workers were examined. All workers, ranging in age from 15 to 59 years old, came from the same electronics factory. Fluorides in the biological fluids were measured by using the fluoride ion-specific electrode method and the electrode potential recording method concurrently. The fluoride ion levels (geometric mean) in the urine and in the serum of the non-hydrofluoric-acid workers were determined to be 0.59 ppm and 12 ppb, respectively. Among the influences of fluorine-containing foodstuff on fluoride content in the biological fluids, the effect of black tea and/or green tea intake was particularly remarkable. In the case of the non-hydrofluoric-acid workers, the concentration increased to about double of the control value. Similarly in a diet test on volunteers, the concentration increased about six times. As for the response to tea intake with the lapse of time, the concentration in the urine specimen (spot urine, S.G. corrected: 1.024) reached the maximum value three hours after the intake. In the case of the serum specimen, the maximum value was recorded one hour after the intake, and the influence of the intake continued for several hours. These results suggest that, in the medical examination of hydrofluoric acid workers, restriction of intake of tea and in some cases even a fasting program would have to be introduced as necessary pre-conditions. Upon observation of fluorine concentration in the urine with the lapse of time of hydrofluoric acid workers restricting tea intake, it was confirmed that the trend of the day-to-day variation was small. But that of the in-a-day variation, namely, an increase in the concentration toward the end of daily working hours was obvious. By introduction of these well-regulated methods, it has become possible to properly evaluate even the infuence of hydrofluoric acid on the workers irregularly exposed to a hydrofluoric acid environment having a lower concentration than that of the threshold limit value (3ppm). However, in view of ease of collection and measurement of specimens, speed, and degree of response to the exposure, it can be concluded that the measurement of fluorine content in the urine is more advantageous as an index for the health care than that in the serum. For this reason it is desirable that the former method should be given priority from the view point of prevailing industrial hygiene laws and regulations.

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A "multipurpose" inhalation system for long-term experiments was developed to study health effects of the exposure to various kinds of aerosols appearing in general working environments as well as in the ambient atmosphere. In order to carry out a continuous inhalatlon study on animals for their life-span, at least two essential conditions should continuously be fulfilled. (1) Steady maintenance of the appropriate sanitary conditions for the animals placed in the inhalation box. (2) Constant feeding of aerosol at an appropriately regulated concentration level. The developed system described in the present paper has been proved to be satisfactory from the above viewpoints. This inhalation system was applied to an experimental study attempting to simulate the polluted lungs in the urban dwellers. Heavy oil combustion products were chosen as the inhalation material, which were made to be inhaled by the male rats of SD-JCL strain for their life-span. The present report is mainly concerned with the construction of the inhalation system including a newly devised regulation facility of the aerosol concentration. Operating characteristics and actual data obtained are described. Details of the exposure conditions and pathological findings obtained will be described in the succeeding reports.

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In attempting to establish an excretory TLV for trichloroethylene, the rates at which trichloroethylene and its metablites accumulate in the body with increasing number of exposures and their plateau values attained after repetition of an infinite number of exposures were estimated theoretically with a mathematical model. After a single inhalation exposure to trichloroethyene is over its concentration in the blood, x, and the amount of its urinary metabolites, [D]^t₀ as a function of time t are expressed as a sum of three exponentials: x=A₁e-α_lt+A₂e-α₂t+A₃e-α₃t, and [D]^t₀=D₃(1-e-k₃t)-D₂(1-e-kBt)+D₁(1-e-k_At), where A₁-A₃ and D₁-D₃ are constants depending on the inhaled air concentration of trichloroethylene, and α₁-α₂ and k_A-k₃ rate constants. When the same degree of exposure is repeated for n consecutive days, the blood concentration, t hours after the nth day's exposure, becomes [numerical formula] and the amount of metabolites excreted in urine becomes [numerical formula] From the experimental results of a single human exposure reported previously, the concentration of trichloroethylene in the blood was predicted to change only to a negligible degree after repetition of an infinitive number of exposures, whereas the amount of total urinary metabolites was predicted to increase by twice as much as that excreted after the single exposure.

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A male worker, 29 years old, was engaged in construction work of World Ocean Exposition in Okinawa Prefecture, and was diagnosed as suffering from leptospirosis in September 1973. The leptospirosis was an acute infection caused by Leptospira hebdomadis. The parasite seemed to be transmitted to him by ingestion of food and drink contaminated with the urine and excreta of the reservoir animals in the unsanitary workshop and living environment in Okinawa district. This leptospirosis was determined as an occupational disease.

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