[Study on the Establishment of a Specific Similar Exposure Group (SEG) in Personal Exposure Monitoring: A Case Report of Indium Tin Oxide Target Surface Grinding Process].

Surface grinding workers of Indium Tin Oxide target material are exposed to an indium compound with high toxicity. We divided individual exposure workers into similar exposure groups (SEG) and examined the effectiveness of the classification of SEG. Sampling was carried out twice a day for a total of 10 times, in 9 of which a work environment measurement in unit work area was performed at the same time. The classification examined two methods. One method was to set all the workers in the work place as one group (SEG1), and the other was to classify them depending on whether the workers handled the target material contained indium or not (SEG2). The group handled indium-contained material was SEG2(+) n=9, and the other was SEG2(-) n=9. Only the arithmetic mean value (AM) of four groups 2.8-27.4 µg/m3 in the SEG2(+) was lower than the measurement B value of the work environment measurement, but the AM of all the groups in SEG2(+) 2.8-276.8 µg/m3 was higher than the geometric mean value of measurement A 0.4-12.3 µg/m3. The concentration range of 100 µg/m3 or more of SEG2(+) AM was 20% of the total. This range was not recognized in the other items, and the variation of SEG2(+) was small. Even though the evaluation of SEG1 is control class 2, if revaluated on SEG2(+), 50% of the SEG2(+) were evaluated as control class 3. It is possible to efficiently manage chemical substances by establishing specific SEG properly stratified.

Vitamin D Status in Japanese Adults: Relationship of Serum 25-Hydroxyvitamin D with Simultaneously Measured Dietary Vitamin D Intake and Ultraviolet Ray Exposure.

Vitamin D insufficiency/deficiency is prevalent worldwide. We investigated the effect of vitamin D intake and ultraviolet ray (UV) exposure on serum vitamin D concentration in Japan. A total of 107 healthy adult participants were recruited from Hokkaido (43°N) and Kumamoto (33°N) prefectures. All participants undertook surveys in both summer and winter. Serum 25-hydroxyvitamin D (25(OH)D3) was examined, and vitamin D intake was assessed with a diet history questionnaire. UV exposure was measured with a wearable UV dosimeter. Regression analysis was performed to investigate the relationship between these factors, with covariates such as sun avoidance behavior. The prevalence of vitamin D insufficiency (serum 25(OH)D3; 12 ng/ml (30 nmol/L) ≤ and <20 ng/ml (50 nmol/L))/deficiency (<12 ng/ml) was 47.7% in summer and 82.2% in winter. UV exposure time was short in Kumamoto (the urban area), at 11.6 minutes in summer and 14.9 minutes in winter. In Hokkaido (the rural area), UV exposure time was 58.3 minutes in summer and 22.5 minutes in winter. Vitamin D intake was significantly associated with serum 25(OH)D3, and a 1 µg/1000kcal increase in intake was necessary to increase 25(OH)D3 by 0.88 ng/ml in summer and by 1.7 ng/ml in winter. UV exposure time was significantly associated with serum 25(OH)D3 in summer, and a 10 min increase in UV exposure time was necessary to increase 25(OH)D3 by 0.47 ng/ml. Although consideration of personal occupation and lifestyle is necessary, most Japanese may need to increase both vitamin D intake and UV exposure.

Effects of sarin on the nervous system of subway workers seven years after the Tokyo subway sarin attack.

This study was designed to assess the after effects of sarin exposure on the nervous system in victims of the Tokyo Subway Sarin Attack, which occurred on 20 March, 1995. We performed a similar study 3 yr after the disaster. This time, we newly enrolled 36 staff of the Teito Rapid Transit Authority (Tokyo Eidan subway) to assess the 7 yr after effects on the nervous system, and merged previous data including unpublished data to enhance statistical power. New subjects consisted of 23 male exposed subjects and 13 referent subjects matched for age and working types. Neurobehavioral tests for psychomotor function and memory, stabilometry, and Benton visual retention test were performed. As reported previously, the exposed group performed significantly less well in the psychomotor function test (tapping) than the referent group (117.8 +/- 1.2 vs. 105.6 +/- 1.2 msec). Using merged data, this phenomenon was also observed in a dose-dependent manner and the exposed group performed significantly less well in the backward digit span test (4.47 +/- 1.17 vs. 5.11 +/- 1.65 digits). These results indicate that chronic decline of psychomotor function and memory function still exist 7 yr after the sarin exposure.

Three-dimensional analysis of nystagmus in benign paroxysmal positional vertigo. New insights into its pathophysiology.

Nystagmus is a rhythmical rotation of the eyeball. Its characteristics can be defined mathematically by the axis of rotation and the angular velocity around this axis. We analysed the axis of rotation for the nystagmus in benign paroxysmal positional vertigo (BPPV) to elucidate its pathophysiology. Thirteen patients with typical unilateral BPPV participated in the present study. The axis of rotation for the nystagmus was calculated from images recorded on digital videotape with an infrared CCD camera, using an algorithm that we developed. The patients' responsiveness to Semont's liberatory maneuver was also assessed.The results showed that patients could be assigned to one of two groups based on the rotation axis of the nystagmus. In one group of patients (n = 7; Group A), the axis of rotation was almost vertical to the plane containing the posterior semicircular canal (PSC) on the presumed affected side. In the other group of patients (n = 6; Group B), it was clustered around the naso-occipital axis. These results suggest that in the patients in Group A the responsible lesion is confined to the PSC, whereas the pathogenesis underlying the conditions in those in Group B is considered to be more complicated. This speculation was reinforced by the difference in responsiveness to Semont's liveratory maneuver. All of the patients in Group A showed remission of vertigo within 10 days (mean, 2.4 days) after onset of treatment using Semont's liberatory maneuver, whereas the patients in Group B required much longer periods of time for remission to occur (mean, 25.7 days). Our findings lead to the conclusion that by considering the spatial orientation of individual semicircular canals, in the patients in Group B the pathophysiology is not confined to the PSC, but most probably all three semicircular canals are involved.