The validity of function tests on the upper extremities as prognostic tools in vibration syndrome was evaluated over a sequence of observation periods. The subjects examined were 672 forest workers using chain saws who had had some complaints and who had shown abnormal findings in the function tests. The function tests consisted of peripheral circulatory and sensory tests, including cold provocation and motor tests of functional capacity in the upper extremities. From the results of testing, 23 variables were selected and examined by multivariate analysis. The four principal components were extracted by principal component analysis, and the factor score of the peripheral circulatory disturbances component was found to be highly correlated with the severity of VWF (Vibration-induced White Finger). The course of VWF and the nail compression test had high standard regression coefficients with the severity of vibration syndrome. The courseof finger numb-ness, pinching power, pain threshold, skin temperature and X-ray findings in the elbow joints had high discriminant function values for the evaluation of the severity of vibration syn-drome.
A mortality study has been made to assess the carcinogenic effect of arsenic exposure by analyzing a group of certified chronic arsenic poisoning patients at a small mining village in Japan. When compared with expected number of deaths, based on sex-, age-specific mortality of Japanese in 1975, '80 and '85, all cancer, cancer of respiratory system and cancer of bladder, kidney and other and unspecified urinary organs showed a significant excess over the expected number. Divided by employment history, death due to all cancers, to respiratory cancer and to urinary tract cancer showed a significant excess among former workers of the mine. Classified into four cohorts by both employment history and smoking habit, death from respiratory cancer showed a significant excess only in the cohort respiratory cancer showed a significant excess only in the cohort of former workers with smoking history, suggesting an interaction between exposure to arsenic and smoking. Eight cases among ten respiratory cancers and two urinary tract cancer cases were ac-companied by cancer of other organs, including Bowen's disease.
Rabbits were divided to groups of 3, and injected either 9.9 mg of tetramethyllead (Me4Pb)/kg of body weight (7.7 mg Pb/kg) or 39.7 mg/kg (30.8 mg Pb/kg) into the ear vein once only, respectively, and urinary and fecal excretionsof lead were studied for chemical species and total lead during the following 7 days. In the group injected 9.9 mg/kg, the urinary total lead excretion was composed of about 73% dimethyllead (Me2Pb2+), about 19% trimethyllead (Me3Pb+), about 6% inorganic lead (Pb2+), and about 2% Me4Pb on the day following the injection, and 100% Me3P13+ 7 days after the injection. In the group injected 39.7 mg/kg, the urinary total lead excretion was composed of about 67% Me2P132+, about 14% Me3Pb+, about 17% P132+, and about 2% Me4Pb on the day following the injection, and about 8% Me2Pb2+, about 74% Me3Pb+, about 17% Pb', and about 1% Me4Pb 7 days after the injection. In both groups, the fecal total lead excretion during 7 days after the injection was entirely composed of Pb2+. During the 7 days, 1-3% of either administered dose was excreted in the urine, and 7-19% in the feces. The urinary total lead excretion in the rabbits injected Me4Pb was similar to that in the rabbits injected tetraethyllead, but the fecal total lead excretion in the former was extremely smaller. This extremely small fecal excretion of total lead appeared to have resulted from the less elimination of lead into the bile of Me4Pb-injected rabbits.
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 μg/ dl and 6-73, μg/d1, respectively. Duration of lead expusure was 0.1 to 26.3 years. No lead-related changes were detected in serum creatinine concentration, beta-2 microgloburin in urine, creatinine clearance, beta-2 microgloburin 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, μg/d1. 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, μg/d1 of Pb-B may not cause adverse effects on renal glomerular function and proximal tubular function.
To objectively detect the lowering in mental activity during mental tasks, twenty-five male students were given the calculating tasks of adding or subtracting two 2-digit numbers at three grades of task load for 1 hr each. At any task load there was little variation in the percentage of correct responses in successive 5-min periods. There was no difference among the three task loads in the mood states of stress or arousal rated at the end of the task. Among the six bands in eight leads the amplitude of the beta-2 band in the Oz-A1 lead (0zβ2) showed the greatest fall corresponding to a drowsy state in one subject. It was judged from this pattern that mental activity might decrease sporadically in half of the subjects, irrespective of the task load. The mean Ozβ2 amplitudes for all the task loads decreased with work time.
Contingent negative variations (CNV) were recorded during the S1-S2 interval of two simple and one discriminative task at Fz, Cz and Pz of 12 physically-trained college athletes and 12 non-trained students. The reaction time to S2 was also measured. The whole mean CNV amplitude averaged over the 2 sec S1-S2 interval and the segmented CNV amplitudes of the 250 msec epochs were submitted to 4-way ANOVA (physical training × task × electrode position × gender), while the mean reaction time was analyzed by 3-way ANOVA. The whole mean CNV amplitude and all the segmented CNV amplitudes were greater in the physically-trained group than in the non-trained group. In all tasks the mean reaction times of the physically-trained group were significantly shorter than those of the non-trained group. The main effect of gender was not statistically significant with respect to the CNV amplitudes and the mean reaction time. The increased CNV amplitude and the shortened reaction time of the physically-trained group were discussed in relation to the reported psychophysiological correlates of CNV. The present study shows that CNV provides a technique of possible value for assessing attention and motor preparation of workers engaged in vigilance tasks.