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Biomedical subjects

K Omae

Publications and source records attributed to K Omae.

At least 19 recordsLinked to original sources
PubMed1992

Four-year follow-up of effects of toluene diisocyanate exposure on the respiratory system in polyurethane foam manufacturing workers. I. Study design and results of the first cross-sectional observation.

A 4-year cohort study was designed to assess the exposure-effect relationship of working in polyurethane foam (PF) manufacturing factories with exposure to toluene diisocyanate (TDI) and its effects on the respiratory system. This paper describes the results of the first cross-sectional observations. The study population included 90 male workers who had been working in PF factories for 0.5-25 years (mean 13.3 years) (PF workers) and 44 reference workers in the same factories. The mean exposure concentration of TDI calculated from 129 personal samples was 3.2 ppb. Peak exposure excursions above 20 ppb occurred in 16 of 129 samples. Pulmonary function and its change during the working day as assessed by examining the forced expiratory flow-volume curve, respiratory impedance, and airway resistance and specific airway conductance were not different in the PF workers from those in the reference workers. Chest X-radiographs did not show any noteworthy radiological changes. Prevalences of "phlegm in winter," "nasal stuffiness or discharge in winter," and "irritation of eye and throat mucous membranes" were significantly higher in the PF workers. The findings indicate that TDI exposure at levels around 3 ppb may not adversely affect the pulmonary function over many years of exposure of those who are not hypersensitive to TDI. The causal chemicals inducing some respiratory and irritative symptoms could not be specifically identified since the PF workers were exposed not only to TDI but also to other irritative agents in the PF manufacturing processes.

Adolescent↗
PubMed1992

Four-year follow-up of effects of toluene diisocyanate exposure on the respiratory system in polyurethane foam manufacturing workers. II. Four-year changes in the effects on the respiratory system.

Fifty-seven polyurethane foam manufacturing workers (PF workers) and 24 reference workers were followed for 4 years to clarify the effects on pulmonary function of working in PF factories with exposure to toluene diisocyanate (TDI). No significant differences in the average annual losses (AALs) of pulmonary function for 4 years were observed among the 28PF workers whose TDI exposure levels were very low (mean = 0.1 ppb, group L), the remaining 29 PF workers with mean TDI exposure of 5.7 ppb (group H), and the reference workers. However, 15 PF workers in group H who had experienced peak exposure excursions to 30 ppb or above with a mean concentration of 8.2 ppb showed significantly larger AALs in percentage maximal mid-expiratory flow, forced expiratory volume in 1 s ratio to vital capacity (FVC), and forced expiratory flow at 25% of FVC than expected, and significantly larger AALs in some obstructive pulmonary function indices than those of the 14 remaining PF workers in group H whose peak exposure excursion levels were 3-14 ppb with a mean time-weighted average (TWA) of 1.7 ppb, group L, and the reference workers. These findings suggest that the peak exposure excursion level of TDI might be important in inducing obstructive pulmonary function changes in the PF workers rather than the TWA exposure levels, though further comparative studies of the AAL in those who are exposed to different peak exposure excursion levels but the same mean exposure levels are necessary. From the standpoint of prevention, the proposition that peak exposure excursion levels exceeding 20 ppb should be avoided is reasonable.

Adult↗
PubMed1992

Acute and subacute inhalation toxicity of silane 1000 ppm in mice.

Male ICR mice were exposed to silane 1000 ppm, a concentration 200 or 2000 times higher than the recommended occupational exposure limits by many countries and academic associations, for 1, 2, 4, and 8 h (phase I study) and for 6 h/day, 5 days/week, over 2 and 4 weeks (phase II study). Hematological and biochemical studies were performed, and the animals were examined for histopathological lesions of the cornea, nasal cavity, respiratory tract, lung, liver, kidney, spleen, pancreas, thymus, thyroid, bone marrow, salivary glands, esophagus, and testis. All mice in both studies survived until they were sacrificed. In the phase I study, no exposure-related changes were found as a result of the hematological, biochemical, or histopathological examinations. In the phase II study, hematological and biochemical examinations failed to reveal any exposure-related changes, but mild irritation, manifested in the form of a small amount of exudate (eight out of ten animals), and inflammatory cells and/or necrotic cells on the nasal mucosa (six out of ten animals) was observed in the mice exposed to silane for 4 weeks. These findings suggest that silane toxicity and irritation are not severe.

Administration, Oral↗
PubMed1992

Health profiles of workers exposed to acrylonitrile.

The objective of this study was to reveal the health effects of acrylonitrile (AN) in seven Japanese acrylic fiber manufacturing factories. The study subjects were 157 AN-exposed male shift workers who had been exposed to AN for 17 years on the average and 537 control workers whose working conditions were similar to those of the AN-exposed workers. The seven factories were classified into two groups according to their AN exposure levels in 1987, and also into three groups on the basis of 1976 exposure levels. The most highly exposed group of subjects showed a mean AN concentration of 1.13 ppm by personal sampling. Medical examination failed to detect any health effects attributable to long-term exposure to AN, although the existence of some symptoms of acute irritation could not be completely ruled out. The results of this study may provide a "no observed effects level" for human on-the-job exposure with regard to the health effects examined here.

Acrylonitrile↗
PubMed1992

Effect of chronic exposure to acrylonitrile on subjective symptoms.

A cross-sectional study was performed to clarify the relationship between exposure to acrylonitrile (AN) and its effect on subjective symptoms by using a modified Cornell Medical Index (CMI) health questionnaire. The 7 acrylic fiber manufacturing factories surveyed were classified into 3 groups, namely, group L with a mean environmental acrylonitrile concentration of 1.8 ppm, group M with 7.4 ppm, and group H with 14.1 ppm. The total number of workers engaged in acrylic fiber manufacturing processes (acrylonitrile workers) and reference workers analyzed were 504 and 249, respectively. These consisted of 92 acrylonitrile workers and 108 reference workers in group L, 304 and 102 respectively in group M, and 108 and 39 respectively in group H. The mean values for length of exposure to acrylonitrile were 5.6 years in group L, 7.0 years in group M, and 8.6 years in group H. Neurotic status as determined by Fukamachi's criteria and Cornell Medical Index profiles did not show any AN-related differences between AN workers and reference workers in any of the groups. The subjective symptoms with significantly high prevalences in AN workers were "headache", "tongue trouble", "choking lump in throat", "fatigability", "general malaise", "heavy arms", and "heavy sweating". Except for "choking lump in throat" there was no relationship between the prevalence of symptoms and the length or level of exposure to acrylonitrile. These results suggested that long-term exposure to acrylonitrile at levels up to 14.1 ppm did not induce neurotic effects in acrylonitrile workers, but might cause some reversible subjective symptoms.

Acrylonitrile↗
PubMed1992

Acute renal injury by tetraethyl orthosilicate in mice: ultrastructure, histochemistry and X-ray microanalysis.

Tetraethyl orthosilicate (Si(OC2H5)4, or TEOS) is a silicon-containing compound which has widespread industrial applications and which has been documented as biohazardous. The histopathological features and mechanism of TEOS toxicity in the kidney of ICR mice were investigated in a light and electron microscopy study, which included energy dispersive X-ray microanalysis. TEOS was given to mice as intraperitoneal injection of approximately 1,670 mg/kg body weight in experiments based on a 24 h time-scale. Tissues were examined after sampling either immediately on death if this occurred within 24 h or, in the case of surviving animals, after sacrifice at 24 h. Renal injury was considered to be the most probable cause of death, on the basis of the following main findings: 1) acute tubular necrosis (glomerular lesions were absent); 2) a dense deposit of silicon over the microvilli of dead tubular epithelial cells; 3) an abundant aggregation of hydroxyapatite crystals containing calcium in the cytoplasm and mitochondria of the dead tubular epithelial cells; and 4) abundant myelinosomes and some hydroxyapatite crystals in the cytoplasm of viable proximal convoluted tubule epithelial cells. It was speculated that silicon compounds may bind to the plasma membranes of the proximal convoluted tubule epithelial cell microvilli and damage or interfere with membrane calcium channels. The resulting calcium ion imbalance may play a role in the subsequent progression of acute tubular necrosis by TEOS.

Animals↗
PubMed1991

Effect of lead on cardiac parasympathetic function.

A cross-sectional survey was performed on 172 male, lead exposed workers to clarify the effects of lead on the cardiac autonomic nervous system expressed as the decrease of R-R interval variation on an electrocardiogram and to obviate the dose-effect relationship between blood-lead level (Pb-B) and the degree of the decrease. For 132 workers who were exposed to lead for more than one year and whose Pb-B levels were relatively stable (Pb-B variation less than 20 micrograms/dl during recent one year), a significant dose-related decrease of R-R interval variation during deep breathing was observed. Age-adjusted R-R interval variation during deep breathing in those whose Pb-B were 30 micrograms/dl or above was significantly decreased compared with those whose Pb-B levels were 20 micrograms/dl or below. This decrease was observed more clearly in younger workers. These results suggest that an effect on autonomic nervous system expressed as decrease of R-R interval variation during deep breathing might be one of the earliest effects of lead exposure.

Adolescent↗
PubMed1990

No adverse effects of lead on renal function in lead-exposed workers.

A cross-sectional study was performed on 165 male lead-exposed workers to clarify the quantitative relationships between less severe exposure to lead and its effects on renal function in 1985. Mean and range of blood lead concentration (Pb-B) were 36.5 micrograms/dl and 6-73 micrograms/dl, respectively. Duration of lead exposure was 0.1 to 26.3 years. No lead-related changes were detected in serum creatinine concentration, beta-2 microglobulin in urine, creatinine clearance, beta-2 microglobulin clearance, and uric acid clearance. Twenty of the 165 workers had been exposed to lead for more than 10 years with mean duration of 21.0 years. Average concentrations of Pb-B in each individual during 1972 to 1984 were 26.1-66.6 micrograms/dl. Renal function indices of these 20 workers were not different from those of remaining lead-exposed workers whose lead exposure duration were 10 years or less. These results suggest that long-term less severe exposure to lead up to 70 micrograms/dl of Pb-B may not cause adverse effects on renal glomerular function and proximal tubular function.

Adult↗
PubMed1989

[Healthy worker effect on Japanese industry workers: a commentary from the viewpoint of industrial health management].

Healthy worker effect (HWE), which can be described as a lower death rate within a work force when compared to the general population, has been observed in many epidemiological mortality studies on industrial work populations free of significant life-shortening hazards. The purpose of this report is to evaluate this effect on the active work populations engaged in large scale manufacturing companies in Japan, and to appreciate the possible attributable factors to this phenomenon. Standardized mortality ratios (SMRs) were calculated for workers in the member companies of The Japan Iron and Steel Federation (JISF) and The Japan Chemical Fibers and Textile Association (JCFTA), where mortality surveillance systems have been established. SMRs for all causes of death from 1969 to 1981 were within the range of 50 to 81 in JISF, and 34 to 41 in JCFTA. These results point to the existence of strong HWE, equal to or even lower than the reported values in some industrial populations in the United States. An evident HWE for cancer was also observed in the study populations, but it was reported to be of little significance, if at all, in the United States. HWE can be considered as a composite result of factors such as: (1) selection of healthier work force, (2) risk reduction due to life style modification during employment, and (3) methodological characteristics of the SMR, which are dependent on the percentage of active workers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Development of a new exposure monitoring system considering pulmonary ventilation (DEM 1).

Exposure evaluation is an essential facet in the assessment of the risks of exposure to toxic materials in the workplace. Presently, samples from the breathing atmosphere are measured in order to determine the level of individual exposure to toxic substances. This method, however, does not take into account the level of physical exertion during exposure. Physical activity is known to increase pulmonary ventilation by up to 10 times that of the level at rest. Thus, measurement of pulmonary ventilation, as well as the concentration of a toxic material in the air would provide valuable data in evaluating exposure. We have developed a device that measures and records the concentration of a toxic material in the air and pulmonary ventilation as predicted by heart rate both simultaneously and continuously. In this system, real time pulmonary ventilation is predicted from heart rate by using a regression equation that was obtained from the results of our study. The percentage error of predicted pulmonary ventilation at each heart rate is within 30%. The present study assessed the feasibility of the use of heart rate as the predictor of pulmonary ventilation. Our new exposure monitoring system is the first practical device that monitors the level of exposure dependent upon pulmonary ventilation and will be useful in the reevaluation of threshold limit values (TLV's) and in working management.

Adult↗
PubMed1988

Reevaluation of urinary excretion of coproporphyrins in lead-exposed workers.

Urinary concentrations of coproporphyrin I and III (CP I and III) were determined by high-performance liquid chromatography in 131 male workers exposed to lead, and the relationships between lead exposure and urinary coproporphyrins were reevaluated. CP I had a statistically significant correlation with lead in the blood (Pb-B), but it was not useful as an indicator of the effect of lead on heme metabolism. On the other hand, CP III had a good correlation with Pb-B and markedly increased when Pb-B levels exceeded 40 to 50 micrograms/100 ml. Both sensitivity and specificity were more than 80% when the health-based Pb-B limit and the screening level of CP III were fixed at 50 micrograms/100 ml and 50 micrograms/g creatinine, respectively. In conclusion, measurement of CP III is sufficiently sensitive and specific enough in practice for the early detection of health effects due to lead exposure in the same way as the measurement of delta-aminolevulinic acid in urine.

Adult↗
PubMed1984

Two-year observation of pulmonary function in workers exposed to low concentrations of toluene diisocyanate.

Pulmonary effects were investigated in 106 toluene diisocyanate (TDI)-exposed workers and 39 referents in 64 exposed workers and 21 referents on the 2-year follow-up study in 1982. Means of individual, time-weighted average (TWA) exposure concentrations measured by personal monitors were approximately 0.001 ppm in each year. Short-term exposure at 0.02 ppm or over was observed in 9.3% of the collected samples in 1980 and 1.9% in 1982. Pulmonary function was assessed by measurements of maximum expiratory flow-volume curve and respiratory impedance. No differences were observed in the means of the pulmonary functions and their individual daily changes between the TDI workers and the referents. Significant intra-individual, two-year decreases were observed in some pulmonary function parameters in both groups, but when the effect of aging was adjusted, the decreases disappeared. Prevalences of respiratory symptoms in the TDI workers were not significantly higher than those in the referents, except for irritating complaints of the eyes and throat probably due to peak exposure to TDI and/or co-existing irritants. Eight of the TDI workers had episodes of acute asthmatic reactions shortly after having begun their TDI jobs and most parameters in their maximum expiratory flow were significantly less than the predicted values, though exposure concentrations when the episodes occurred could not be defined. From these results, it was suggested that TDI exposure at the levels of 0.001 ppm may not induce adverse pulmonary effects when the workers are not hypersusceptive to TDI.

Adult↗