A dynamic flow type of human olfactometer was developed.
Twenty-six healthy male adults were used for testing "detection threshold" of ten kinds of standard test odorants diluted with nujol. They were β-phenylethyl alcohol, cycloten, iso-valeric acid, γ-undecalactone, skatol, exalotolide, phenol, dl-camphor, diallyl sulfide and acetic acid. Distribution of "detection threshold" of these odorants showed almost a normal curve. Exposures to β-phenylethyl alcohol and skatol showed a large coefficient of variation in "detection threshold". On the contrary, acetic acid and cycloten showed a small deviation.
Five healthy male adults were exposed to iso-valeric acid (10^-5) using the olfactometer in the odor exposure chamber, and the function of concentration maintenance (TAF), heart rate, blood pressure and brain waves were measured. The effect of NH₃ (4ppm) and H₂S (0.12ppm) on the above physiological functions was also studied. Odorant concentration in the range of "detection threshold" did not cause any significant change in TAF, heart rate, blood pressure and brain waves, but odorant concentration over "recognition threshold" affected the above physiological functions.
From these results, it may be presumed that the acceptable limit of odor concentration exhibiting the lowering of physiological functions is in the range of "recognition threshold". This limit of odor intensity may correspond to three point five according to the six-points intensity scale.

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The subjective feeling of people exposed to environmental noise is an important indicator of the assessment of noise environment. The subjective feeling under noise exposure is ordinarily surveyed on both the disturbance for health conditions and the degree of subjective noisiness or annoyance. The degree of noisiness expressed in the words for rating. If the psychophysical grade of the rating words is not measured, the interpretation on the results of survey becomes obscure. From the above mentioned viewpoint, in this paper, the psychophysical values of several rating words in the Japanese language were measured on the noisy scale.
The scales measuring the noisy degree or the quiet degree were divided into 10 equal parts. Nine rated adverbs were measured on 410 female students and 70 male students aged 19 to 22 years old.
These rating words are nearly identical with the following English words: extremely, very, hgghly, fairly, passably, relatively, rather, slightly, and barely.
The results were as follows;
1) The psychophysical values given to each of the rating words on noisy or quiet scale are given in Fig., In Fig., the modes and the ranges from 25% ile to 75% ile in the distribution are shown. The intervals between each of the values given to 9 words were unequal.
2) Each of the rating words gave similar values on the noisy scale and on the quiet scale.
3) No sexual differences were seen in the values of each word.
4) In 5 rating words, the values on the hedonic scale reported in the reference by another author were smaller than the values of 25% ile in the distribution on noisy scale.

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The development of industry in Japan has been increasing environmental pollution. Itai-itai disease is concidered to be caused by intake of foodstuffs or water containing a high concentration of cadmium. Therefore, the studies on the absorption, excretion and accumulation of cadmium were carried out.
Results were as follows:
1) Absorption rate of orally administered cadmium in mice was 2% and was not influenced by the factors of pregnancy, hunger and thirst.
2) Five mg of cadmium in drinking water was administered to a 58-year old man divided into 3 doses in 1st day. Absorption rate in this experiment was estimated to be 5.33%. When the same experiment on cadmium in rice was carried out, its value was 1.53%.
3) Biological half time in the whole body of mice was concluded to be about 60 days. In man, this value was estimated to be 3 to 8 years.
4) Food containing 10ppm cadmium was given to the mice for a long period. Accumulation rate in this experiment decreased gradually and was not influenced by sex difference, times of pregnancy and nursing.
5) Total body contents of cadmium in the human body were estimated to be 32mg in males, and 52mg in females.
6) On the sex difference in man, it became apparent that cadmium concentration in female was twice as much as that in male, in both cases of hepatic and renal diseases, a high tendency was observed in the value of the ratio in human liver and kidney.

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Work load of visual functions in visual inspection task was studied under a fairly constant working condition. This was carried out with ten subjects by measuring the work output, CFF variation, visual recognition threshold and heart beats;
The results are as follows.
1) The CFF variation rate decreased along with the work process, thereby indicating a strong tendency of work load accumulation.
2) The variation rate decreased along with the work process, thereby indicating a strong tendency of work load accumulation.
3) Negative correlation was found to exist between CFF variation and work output, but on the other hand, between visual recognition threshold and work output indicated a positive correlation. These relationships were reduced to the deterioration of visual function.
4) The number of heart beats per minute was insufficient to evaluate the work load during inspection. But many of the workers showed a tendency of heart beats increment during inspection.
Thus, the relationship among work load, CFF variation rate and visual recognition threshold have been clarified. Deterioration of visual function was thought to be due to the functional decrement of differentiation in CFF and of recognition in visual recognition threshold.

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In the study of lung retention of metallic fume, it is necessary to generate monodispersed metallic fumes whose particle sizes are variable and to which experimental animals are exposed at constant concentration for a long period.
However, an experiment of metallic fume inhalation is very difficult because there is no technique to generate metallic fumes having particle sizes as designed and to maintain a constant concentration. The author, therefore, designed and constructed a metallic fume inhalation apparatus, which consists of the monodispersed metallic fume generator and exposure chamber for rats which can be easily operated. To obtain a stable evaporation of metal in the generator, a high frequency electric furnace was used. The metallic vapour evaporated in the graphite crucible of the furnace was carried with nitrogen gas into the condenser and formed into metallic fume with small-size distribution by self-nucleation. Particle size of generated fume could be easily varied by changing flow rate of the carrier gas and temperature of the furnace. The exposure chamber was a vertical transparent polyvinylchloride cylinder with six cylindrical tubes on the wall into which rats could be inserted and fixed. A metal grid covered one end of each cylindrical tube where the head of each rat inserted into the tube, was placed, so that only the head of each rat in the exposure chamber was exposed to metallic fume.
The inhalation experiments using lead fumes were carried out in order to compare the characters of the new inhalation apparatus with the usual system in which several rats were exposed to the fume together in one cage. As results, higher lung retention rates (about 1.30 times at the aerodynamic median diameter of 0.23μm and 1.54 times at 1.7μm) and smaller variations in weights of inhaled lead fume in each rat lung were observed in the new fixed form inhalation system as compared with the usual free form inhalation system.

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The increased excretion of δ-aminolevulinic acid and coproporphyrin III in the urine in human plumbism is we11 documented. However, two questions on porphyrin metabolism in lead poisoning remain unansweres, i. g.
a) By what mechanism is coproporphyrin excreted in large amount in severe lead poisoning, despite the fact of the complete inhibition of δ-aminolevulinic acid dehydratase activity in red cell by lead?
b) Increased excretion of porphobilinogen is a prominent sequel of lead poisoning in the rabbit, but this phenomenon is not so prominent in other species including the human. Is this due to the difference of species or the amount of lead administered?
This paper describes the experiment on the excretions of δ-aminolevulinic acid, porphobilinogen, and coproporphyrin that are measured simultaneously in rats poisoned with different amounts of lead.
The following results were obtained.
1) Lead poisoned rats (A and B) were prepared by administering lead (5μmoles/kg) 40 and 50 times subcutaneously over the period of 52 and 58 days, respectively. Rats (C and D) were treated by lead (100μmoles/kg) 9 times over the period of 30 days. Porphyrins and precursors were determined continuously for 67 and 95 days (A and B) and for 60 days (C and D), respectively.
2) In cases A and B, δ-aminolevulinic acid was elevated remarkably in the urine with the increase of lead administration. Coproporphyrin was increased slightly but porphobilinogen was not increase.
3) In cases C and D, the proportions of heme precursors excreted as δ-aminolevulinic acid and coproporphyrin are remarkably increased with the slight increase of porphobilinogen. Thus, the appearance of porphobilinogen in lead poisoning is due to the large amount of lead administered.
4) δ-aminolevulinic acid dehydratase activity in red cells determined at the end of the experiments was found to be completely inhibited in both groups.
5) These results support Sho, s experiment (Jap. J. Hygiene, 29, 379 (1974)) δ-aminolevulinic acid synthetase activity is stimulated in lead poisoning, thus excessive δ-aminolevulinic acid seems to overcome the blocking of δ-aminolevulinic acid dehydratase resulting in the increased formation of coproporphyrin in lead poisoning

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Inhibition of δ-aminolevulinic acid dehydratase (δ-ALA-D) activity by lead has been generally accepted as one of the main disorders of porphyrin metabolism in lead poisoning. δ-ALA-D activity inhibited by lead in bone marrow and erythrocytes results in an increased urinary excretion of δ-ALA. If mercury or arsenite inhibits δ-ALA-D with stronger affinity for SH groups than lead, raised urinary δ-ALA concentration should be expected.
This paper reports the urinary excretion patterns of δ-ALA, PBG and coproporphyrin III in mercury or arsenite poisoned rats. The inhibitory effects of these three metals on δ-ALA-D activity in liver and erythrocyte preparations were also examined.
The following results were obtained.
1) Urinary excretion of δ-ALA in rats poisoned with mercury or arsenite was not so remarkably raised as compared with lead poisoned rats.
2) Treatment of rats with lead has been found to produce copro- and protoporphyrins in bone marrow. In mercury or arsenite poisoning bone marrow porphyrins were not elevated but small amount of porphyrins were found in liver.
3) It was found that δ-ALA-D activity in liver homogenate was partially inhibited in vitro by lead, mercury or arsenite (1×10^-5M)by approximately 10-20%. On the other hand, δ-ALA-D activity in erythrocyte hemolysate was strongly inhibited by lead but not by mercury or arsenite.

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第45回日本衛生学会総会は,昭和50年4月2日～4日の3日間,京都で開催され,渡辺厳一教授の次期会長講演と235題の一般発表が行われました。参加者は713名を数える盛況で,各会場とも活発な討論が行われ,成果をあげることができました。会員各位の御支援,御協力に厚く御礼申し上げます。座長をお引受け下さいました先生方には,学会の運営に御尽力下さいました上,御多忙中にもかかわらず,“座長のまとめ”を御執筆下さいました。ここにあらためて御礼申し上げます。
以下“座長のまとめ”を演題番号順に,掲載致します。冒頭の数字は演題番号,( )内は掲載頁(日衛誌第30巻1号)で,次に座長氏名を敬称略で記させて頂きました。

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