[in Japanese]

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In order to determine both the distributional variation of heavy metals and the relationship between lead and essential metals in rats poisoned by lead, a study was undertaken using atomic absorption spectrophotometry.
The cerebral lead concentration increased according to the amount of lead administered. The distribution patterns of lead in seven regions of the brain were significantly different between lead-treated animals and controls. In the latter, the differences in lead concentration among the individual regions were statistically significant, with the lowest levels reported for the cortex. In contrast, the cortex and hippocampus had the higher concentration in rats to which 45μg/g or 90μg/g of lead had been administered. Those given 180μg/g body weight showed uniform accumulations in all cerebral regions.
Iron concentrations were highest in the hippocampus, while zinc and copper concentrations were distributed almost uniformly. No statistically signigicant loss of essential elements was recorded from the brains of lead-treated animals, but significant decreases of copper from the liver and of iron from the whole blood were found.

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Cadmium concentrations in rice were employed as an index of cadmium exposure. Samples of unpolished rice were collected from 727 households in 40 villages along the cadmium-polluted Jinzu River basin and analyzed for the metal. The prevalence of itai-itai disease was used as the index of the effects of cadmium.
A close relationship between cadmium exposure and its effect on health was found when disease patients were stratified according to cadmium concentration per village, demonstrating that doseresponse relationships did in fact exit.

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The increase in the standard population death rate from pulmonary cancer warrants attention. Three factors can be attributed to this increase: air pollution, cigarette smoking, and occupational exposure to carcinogens. The present paper reports on the results of a study of the relationship between air pollution and pulmonary cancer. Rats, mice, and hamsters were subjected to up to 12 months exposure to diluted gasoline engine exhaust containing 300±50ppm CO, 0.21ppm NO, 0.08ppm NO₂, 28ppmC hydrocarbon in the form of methane and 32ppb O₃. Further experimentation consisted of combined treatments with carcinogens-rats with diisopropanolnitrosamine, mice with ethylcalbamate, and hamsters with diethylnitrosamine to determine whether the incidence of tumors would increase. No animals exposed exclusively to exhaust gas diveloped pulmonary tumors, indicating that exhaust caused no lung tumorigenesis. However, the frequency of pulmomary tumors increased in animals subjected to combinations of exhaust and carcinogens. The incidence of malignant pulmonary tumors in the rats group exposed for 12 months to carcinogens only was 8.7%, while that in the group exposed to the combination was 30.3%, with the rates for mice 72.7% as against 91.7%, and for hamsters, 3.8% as against 10%. The results indicate that gasoline engine exhaust increases the development of lung tumors, and that exhaust plus other carcinogens significantly increases the risks.

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The effect of noise on the psychomotor activity of rats was measured using cages equipped with rotating wheels. (CLEA, Type LC-900, Tokyo)
Sixty-four Wistar male rats were divided into 4 age groups-4, 7, 10, and 15 weeks old.
Subjects were exposed to wide octave-band noise at 100dB (C), continuously for 13-14 days. The control group 32 rats was kept less than 40dB (A), i.e., “silent conditions”.
The following result were obtained;
1. No signifficant difference in rat body weight was observed between the exposed and control groups at the end of the experiments.
2. Exposure to noise inhibited spontaneous activity in the 4- and 7-week-old groups, but activity increased in the 10- and 15-week-old groups.
3. It seems likely that noise effects psychomotor activity beginning between the eighth and tenth week in rats.

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Fish generally contain high levels of methylmercury, which may be due to the specific metabolism of mercury compounds. This paper attempts to clarify metabolic differences for mercury compounds in mice, rats and carp. Biological half-lives (BHL) throughout the body and in individual organs, and the distribution of mercury compounds injected intraperitonially were investigated by using radioactive mercury (²⁰³Hg). The following results were obtained.
1. The disappearance patterns differed according to the animal species. Methylmercuric chloride disappeared rapidly and in a linear progression in mice. The BHL in mice was 7.8 days, and in rats also a relatively short 51 days, but the compound disappeared very slowly in carp with the BHL of 230 days in theory and more than 400 days in practice.
2. There were low levels of mercuric chloride in tissues other than rat and carp kidneys, but there were high levels of methylmercuric chloride not only in the kidneys but in the blood, brain, liver, spleen, muscle and hair of all three animals. Accumulative distributions in carp muscle and excretive distributions in mouse and rat hair were found for methylmercuric chloride.
3. The individual BHLs of mercuric chloride and methylmercuric chloride in rat liver, brain, spleen, blood, muscle and testicles were the same about 15 days, but differed from those in kidneys and hair, which had the same days as the BHLs in rat bodies. In animal bodies covered with hair as in the case of rats and mice, individual BHLs in hair affected the total BHL of methylmercuric chloride, a substance which is likely to be deposited in the hair.
Differential metabolism of mercury compounds has been demonstrated in mice, rats and carp. Accumulative distributions of methylmercury in carp muscle in particular may cause the longer BHLs and support the high levels of methylmercury in fish.

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Twenty-four hour polygraphs were performed to obtain distributions of REM and stage 4 sleep during 2-hour sleep periods in eight different time zones. The time zones differed on the basis of time when sleep onset occurred and the length of preceding awakeness. Eight healthy males, averaging 23. 3 years old, were studied. The experiments ran after the end of a usual night's sleep (00:00-07:00). The eight periods were divided into 4 advanced and 4 delayed shifts based on time of retiring-i. e., A₄-10:00, A₃-15:00, A₂-20:00, A₁-22:00, D₁-02:00, D₂-04:00, D₃-06:00, D₄-10:00.
1) Total sleep time was shorter for the advanced, and longer for the delayed shifts.
2) REM latency was longest for A₂, and shorter in A₄, A₃ and D_1-4. It became more significant for the periods farther away from A₂ in either direction, with an inverse tendency observed for initial REM duration.
3) REM at onset (SOREMp) was observed only for early morning periods, A₄, D₃ and D₄.
4) The amount of REM sleep was greatest in A₄ and considerably less in the order of A₃ and A₂. It then increased in the following order, A₁, D₁, D₂, D₃ and D₄. Mean rectal temperature during sleep was found to be in an inverse order.
5) Stage 4 sleep increased as follows: A₄<A₃<A₂<A₁<D₁<D₂<D₃<D₄, with significant differences between each two periods.
The above findings indicate the presence of a conspicuous circadian rhythm in REM sleep, and the dependence of stage 4 sleep on the length of the preceding period of wakefulness.

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Pulmonary function tests were performed on elderly men and women. Various pulmonary function test parameters were analyzed using flow-volume curves.
The following results were obtained.
1. Normal values for all groups over age 60 were recorded for pulmonary function data of all those subjects with %FVC>80% and FEV_1.0%>70%.
The FVC, FEV_1.0 and PFR values for the 70-79 and 80-89 groups were significantly lower than for those in the 60-69 age group.
2. The V₅₀/H and V₂₅/H values for smokers were lower than those for nonsmokers.
3. Following a principal component analysis, a varimax rotation was applied to 9 pulmonary function test parameters to statistically assess their significance.
Parameters which revealed obstructive factors were FEV_1.0%, V₅₀/H, MMF and V₂₅/H. Lung volume was determined by %FVC, FVC and FEV_1.0.
4. The coefficients of variation for PFR, MMF, V₇₅/H, V₅₀/H and V₂₅/H were significantly greater than those for %FVC, FVC, FEV_1.0 and FEV_1.0%.

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Long-term effects of barbital were examined, using (C57BL/6 x C3H/He) F1 mice to which the compound MTD (0.5% diet) was orally administered daily for 120 weeks. Tumors of the thymus, lymph nodes, lungs, liver and mammary glands developed, but there were no group differences in terms of rates of incidence, except in the liver. Statistically higher incidences of liver tumors were observed for the treated mice (50% in females and 57% in males) over the controls (3% in females and 19% in males). Twenty-two percent of the liver tumors in all treated mice of both sexes were diagnosed as hepatocellular carcinoma, but no metastasis was found. Thus, barbital MTD caused almost no tumors in other organs where spontaneous tumors do not generally develop in the mouse. It was assumed, therefore, that the tumorigenic activity of barbital in mouse liver can be attributed to a promoting property.

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A bicycle ergometer (50W and 100W for 2 hours) was used to study the effects of physical exercise on the rate of bacteria dispersal from individuals in a model laboratory with a ventilation rate of 1.2 times/hr. The mean halflife of airborne bacteria was found to be 3.3/hr, whether the person was at rest or during physical exercise, and the loss due to sedimentation was calculated at 2.1/hr. However, the bacteria dispersal per person tended to increase during the 50W period which became significant at 100W, over the rate at rest. The results suggest that the level of exercise effects the bacteria dispersal rate from humans and the amount of bacterial contamination of indoor air.

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