Takamoto Uemura

Effects of SO2 on respiratory system of adult Miyakejima resident 2 years after returning to the island.

Effects of SO2 on Respiratory System of Adult Miyakejima Resident 2 Years after Returning to the Island: Satoko Iwasawa, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University

Uptake of cadmium in meals from the digestive tract of young non-smoking Japanese female volunteers.

Uptake of Cadmium in Meals from the Digestive Tract of Young Non‐smoking Japanese Female Volunteers: Yuriko Kikuchi, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University

Cadmium concentration in current Japanese foods and beverages

Cadmium Concentration in Current Japanese Foods and Beverages: Yuriko Kikuchi, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University—

Cross sectional observation of the effects of carbon disulphide on arteriosclerosis in rayon manufacturing workers.

OBJECTIVE: A prospective cohort study was designed to clarify the relations between occupational exposure to carbon disulphide (CS2) and its effects on arteriosclerosis in workers in 11 Japanese rayon manufacturing factories. This report is a cross sectional baseline observation in the first study year. METHODS: Study subjects were 432 male rayon workers (mean (range) age 35.5 (19.1-47.8); duration of exposure 13.4 (0.3-29.0)) and 402 male referent workers (age 35.8 (18.9-49.8)). Exposure to CS2 was assessed by determining the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. Mean (SD) TTCA was 3.42 (2.73) mg/g creatinine (Cr) (n = 422). About a quarter of the urine samples were > 5 mg/g Cr, a biological exposure index recommended by the American Conference of Governmental Industrial Hygienists. Health effects on arteriosclerosis were evaluated by measuring blood pressure, serum lipids, pulse wave velocity of the aorta, stiffness and blood flow of the carotid artery, and blood coagulation and fibrinolysis indices, and by use of brain magnetic resonance imaging, electrocardiogram (at rest and after exercise), ophthalmograph, and Roses questionnaire. Information on potential confounding factors was collected by self administered questionnaire. RESULTS: Prevalence of microaneurysm of the retinal artery was significantly higher in workers exposed to CS2 (8.1%) than in referent workers (3.4%), and increased with age. Other examinations did not show any differences between the two groups even after allowance for confounding factors. CONCLUSIONS: Significant effects of CS2 on arteriosclerosis were not found in current rayon manufacturing workers, with the exception of induction of microaneurysm of the retinal artery.

Effects of intratracheally administered indium phosphide on male fischer 344 rats

Effects of Intratracheally Administered Indium Phosphide on Male Fischer 344 Rats: Takamoto Uemura, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University—Objective—To examine the effects of intratracheally administered indium phosphide (InP) and distribution of indium on male Fischer 344 rats. Materials and methods—Rats were intratracheally given 0, 1, 10 or 100 mg/kg of InP with a mean diameter of 0.8pm and observed for 1 and 7 days. The bronchoalveolar lavage fluid (BALF) was examined biochemically and cytologically. Serum biochemical, hematological and histopathological examinations were done, and the indium concentration in organs and serum was determined. Findings—The number of neutrophils in BALF remarkably increased in a dose‐effect manner 1 and 7 days after administration and InP particles were phagocytized in the macrophages. Total protein (TP), lactate dehydrogenase (LDH), total phospholipid (TPL) and total cholesterol (T‐Cho) in BALF showed a clear dose‐effect relationship 7 days after administration. Indium was detected in the liver and spleen and increased in a dose‐related manner on the next day and 7 days after administration. Serum indium was detected in the group given more than 10 mg/kg but did not reveal a dose relationship. Histopathological examination of the lungs showed phagocytized InP particles in the macrophages and the migration of neutrophiles in the alveoli. InP particles remained in the bronchioles and alveoli until 7 days after. No histopathological changes were detected in the liver or spleen. A hematological study did not reveal significant findings, interpretation—Intratracheally administered InP particles cause pulmonary inflammation and those particles remain in the lower airways for at least 7 days. Phagocytosis of macrophages may contribute to their disposal and distribution to the liver and spleen. Further study is required with particles with a lower toxic activity than InP and with the same particle size as the InP used in this study, to clarify their specific toxicity. Simultaneously longer observation is needed to assess toxicity in the other organs after distribution.

In Vitro Solubility and In Vivo Toxicity of Indium Phosphide.

In Vitro Solubility and In Vivo Toxicity of Indium Phosphide: Isamu Kabe et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University—This study was designed to clarify the in vitro solubility and the in vivo basic toxicity of indium phosphide (InP). InP powder was clearly soluble in synthetic gastric fluid and quite insoluble in saline or synthetic lung fluid. Male ICR mice (SPF grade) were given InP at the doses of 0, 1,000, 3,000, and 5,000 mg/kg, intraperitoneally (i. p.) or orally (p. o.). During a 2‐week observation, no mice died. In i. p. treated mice, the serum indium concentration showed a dose‐dependent increase, and indium mainly accumulated in the lungs and liver. Dose‐dependent increases in lung and spleen weight were observed. Black granules of InP were deposited in the lymph nodes, spleen, lungs, and liver. Extramedullary granulopoiesis was observed. And eosinophilic exudates and mononuclear cells were seen in the pulmonary alveoli. Considering these findings, InP particles were presumably transferred to the spleen, liver, and lungs by way of lym‐ phokinetics, causing reticuloendothelial responses. Hematological examination showed increased proportions of stab cells and monocytes in 5000 mg/kg i.p. dosed mice. The p. o. administered mice showed no clear relationship between the dose and biological effects.

Visceral fat thickness in overweight men correlates with alterations in serum fatty acid composition.

BACKGROUND We examined relationships between visceral fat amount and alterations in serum fatty acid composition, both of which represent critical factors in the development of metabolic syndrome. METHODS Correlations were analyzed between visceral fat thickness as measured by ultrasonography and proportions of individual fatty acids in 21 normal-weight and 24 overweight Japanese men. RESULTS Significant associations were identified in overweight subjects. Visceral fat thickness displayed positive correlations to levels of palmitic acid and saturated fatty acids (r=0.475, P<0.05 and r=0.545, P<0.01, respectively); and negative correlations to levels of linoleic acid and polyunsaturated fatty acids (r=-0.513, P<0.05 and r=-0.428, P<0.05, respectively). Visceral fat thickness was also correlated with estimated desaturase activities, with positive correlations to Delta9- and Delta6-desaturase activities and negative correlations to Delta5-desaturase activity (r=0.580, P<0.01, r=0.669, P<0.01 and r=-0.559, P<0.01, respectively). No significant associations were identified in normal-weight subjects. CONCLUSIONS Significant associations between visceral fat amount and alterations in serum fatty acid composition were identified, but only in overweight individuals.

Toxicity of Silicon Compounds in Semiconductor Industries

Toxicity of Silicon Compounds in Semiconductor Industries: Hiroshi Nakashima, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University—The toxicities of silane (SiH4), tetraethoxysilane (Si(OC2H5)4, TEOS) and dichlorosilane (SiH2CI2, DCS) were reviewed in order to compare the toxicological properties of silicon compounds used in the semi‐conductor industry. Silane and TEOS showed similar toxicities, characterized by nephrotoxicity. Mice subjected to silane (2500, 5000 and 10000 ppm) or TEOS (1000 ppm) acute exposure developed acute tubular necrosis. Tubulo‐interstitial nephritis was seen in mice which were subjected to an acute inhalation study and survived 2 wk of the observation period or those subjected to subacute inhalation studies of TEOS (100 and 200 ppm for 2 or 4 wk). Silane and TEOS, however, differed in the concentration at which they showed signs of toxicity. This may be due to their solubility in water and other metabolic factors, but their metabolic pathways have not yet been elucidated. TEOS injured nasal mucosa (1000 ppm for 2 h or more and 50, 100 and 200 ppm for 2 or 4 wk). It was observed at a lower concentration than nephrotoxicity in the 50 and 100 ppm subacute inhalation study. On the other hand, silane caused nasal mucosal lesions only at 5000 or 10000 ppm for acute inhalation, and those of subacute inhalation were mild (1000 ppm for 2 or 4 wk). DCS showed another type of adverse effect. It was an irritant and/or a corrosive agent to the respiratory tract in the acute (64 ppm for 1, 2, 4 or 8 h) and subacute (32 ppm for 2 or 4 wk) inhalation study. The fate of DCS in air was also studied and it was shown to form small particles including silicon and chlorine (Cl) atoms. Cl seems to play an important role in the toxicity of DCS.

A six year follow up study of the subclinical effects of carbon disulphide exposure on the cardiovascular system

Aims: A six year prospective cohort study was conducted to clarify whether the current carbon disulphide (CS2) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the effects on the cardiovascular systems. Methods: The study subjects were 432 male workers exposed to CS2 and 402 non-exposed workers in Japan, all of whom were examined in 1992–93. A total of 251 CS2 exposed, 140 formerly exposed, and 359 non-exposed workers participated in the follow up survey (follow up rate 89.9%) in 1998–99. Mean duration of exposure was 19.3 years at the end the study. Mean CS2 and 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations were 5.0 ppm and 1.6 mg/g creatinine. Health items examined were serum biochemical indices including lipids and coagulation-fibrinolysis factors, blood pressure, aortic stiffness, ophthalmography, and electrocardiography at rest and after Master’s double 2 step test. Potential confounding factors were adjusted for. Results: Incidence of ischaemic findings, defined as Minnesota codes I, IV1–3, V1–3 (at rest and after the load), or receiving treatment for ischaemia, was significantly higher in the exposed workers, especially for the spinning/refining workers (adjusted OR 2.1; 95% CI 1.1 to 4.0) or the highest quartile of six year mean TTCA (adjusted OR 3.9; 95% CI 1.8 to 8.7), although the observed increase in risk was diminished when rigorous ECG criteria were applied. Incidence of retinal microaneurysm was increased with marginal significance. Among cardiovascular risk factors we examined, only blood pressure values were significantly increased in the exposed workers. Conclusions: Increased risk of ischaemic electrocardiogram findings among Japanese viscose rayon workers was observed. Although its clinical significance is to be discussed, the current Japanese occupational exposure limit for CS2, 10 ppm, would be high to prevent subclinical cardiovascular effects in this study population.

Lack of Relationship between Occupational Exposure to Carbon Disulfide and Endocrine Dysfunction: A Six-year Cohort Study of the Japanese Rayon Workers

Lack of Relationship between Occupational Exposure to Carbon Disulfide and Endocrine Dysfunction: A Six‐year Cohort Study of the Japanese Rayon Workers: Toru Takebayashi, et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University