PURPOSE:Annual medical checkups are presumed to be important with the well-being of aged individuals. The purpose of this study was to investigate factors related to participation in medical checkups of elderly persons at home. METHODS:A survey was performed targeting so-called young elderly persons living at home in 3 regions in Hokkaido Prefecture, a large city (Sapporo), an ex-coalmining town (Yubari) and a small farming town (Takasu). The study populations were asked about medical checkups, economic status, self-rated health status, activities of daily living (ADL) and basic characteristics such as age, sex and occupation. We used the Mantel-Haenszel method for statistical analysis. RESULTS:1) Elderly males who received medical checkups within the last 1 year (participants) had a shorter period of education, were less likely to have or to have had the smoking habit, undertook more physical activity, had better eating habit, more often rated their own health as good or normal, and had a better physical ADL & instrumental ADL, than those who had never received medical checkups (non-participants). Regionally, the items that showed significant differences included: "live with the spouse", "do not smoke" and "do not have physical pain or disabilities" in Sapporo; "enjoy physical activity", "have good eating habit" and "have good instrumental ADL" in Yubari; and "engaged in agriculture/fishery work" and "had outpatient visits in the last three months" in Takasu. 2) Elderly female participants who had outpatient visits in the last three months had anxiety about their own health, significantly different from non-participants. Regionally, the items that showed significant differences included: "often drink alcohol" in Sapporo; "still working right now", "was engaged in agriculture/fishery work in the past" and "had outpatient visits in the last three months" in Yubari; and "have own house", "do not smoke" and "pay attention to eating habit" in Takasu. 3) The item which showed a significantly high rate both for male and female participants was "still working right now". CONCLUSIONS:This study indicates that medical checkups should be recommended to the elderly, taking into account not only their basic characteristics such as sex and occupation, but also lifestyle, self-rated health status and ADL, which are associated with medical checkup participation.

To investigate the threshold effects of chronic low-level occupational exposure to styrene on color vision, we examined color discrimination in 105 male workers exposed to styrene (mean age 37.7 years; mean length of exposure 6.2 years; mean urinary concentration of mandelic acid 0.21 g/L) and in 117 referents (mean age 37.7 years). We also assessed the effects of styrene by examination of the nature of the relation between disorders of nervous function and age, alcohol consumption, and other variables. A standardized questionnaire was adopted to collect information about work history, occupational or nonoccupational solvent exposure, alcohol consumption, and drug use. Color vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the color confusion index (CCI). There was a dose-dependent relationship between the urinary concentration of mandelic acid and color vision loss. The CCIs of the subgroups whose urinary mandelic acid levels were 0.1–0.2 and >0.2 g/L were significantly higher than those of each referent group (P<0.05 and P<0.01, respectively), but not in the subgroup whose urinary mandelic acid level was lower than 0.1 g/L. Our study suggests that a low level of styrene, presumably 0.1–0.2 g/L, involves the risk of inducing adverse effects on color vision. After confounding factors were adjusted for, the urinary mandelic acid level had a significant positive relationship with color vision.

The relationship between exposure to styrene and nerve conduction velocities was investigated in 32 workers occupationally exposed to styrene. There was a dose-dependent relationship between urinary mandelic acid and ulnar and peroneal motor distal latencies (MDLs). The ulnar and peroneal MDLs of subgroup B (urinary mandelic acid > or = 250 mg/l) were significantly longer than those of subgroup A (urinary mandelic acid < 250 mg/l)(p < 0.05), and the referent group (p < 0.03). After adjusting confounding factors, urinary mandelic acid had a significant positive relationship with ulnar and peroneal MDL. Our study suggests that a low level of styrene, below the 50 ppm exposure limit of the American Conference of Governmental Industrial Hygienists (ACGIH), involves the risk of inducing adverse effects on the peripheral nervous system. The study also indicated that motor distal latency is a sensitive parameter of toxic peripheral neuropathy.

OBJECTIVES:To examine the effect of occupational exposure to cyclohexane on the peripheral nervous system.METHODS:A nerve conduction study was performed on 18 workers exposed to cyclohexane in a luggage factory and on age and sex matched occupationally unexposed controls. 12 workers had been exposed to n-hexane (median 2.8 years) before the start of exposure to cyclohexane. To confirm the effect of exposure, a follow up study was performed on nine workers one year after the first study. The mean exposure to cyclohexane was 1.2 years in the first study. A symptom survey was performed. The exposure was measured by air sampling of the breathing zone of each worker. The urinary metabolite cyclohexanol was also monitored.RESULTS:The concentration of airborne cyclohexane ranged from 5 to 211 ppm. The urinary concentration of cyclohexanol ranged from 0.12 to 1.51 mg/l. There was a strong correlation between the cyclohexane exposure in personal air and urinary cyclohexanol. No differences were found in nerve conduction velocities (NCV) between workers exposed to cyclohexane and age and sex matched controls. The results of the follow up study showed significant improvements in peroneal motor NCV (P < 0.01) and sural sensory NCV (P < 0.05) and in ulnar motor distal latency (MDL, P < 0.05) and peroneal MDL (P < 0.05) compared with the first study. Although the past n-hexane exposure affected the first neurophysiological study, the effect had disappeared in the second study, one year later.CONCLUSION:Occupational exposure to the concentrations of cyclohexane experienced in this study had no adverse effects on the peripheral nervous system.

The purpose of this study was to investigate the relation between nerve conduction velocity (NCV) and some factors which affect the measurement, such as age, skin temperature, body build and alcohol consumption. Neurophysiological parameters of healthy volunteers (28 males and 27 females, aged 20-57 years) who were free from occupational exposure inducing neuropathy were determined by monitoring skin temperature. A questionnaire survey on height, alcohol and tobacco consumption was also performed. The following results were obtained: 1) Analysis of covariance to examine the relation between age groups and NCVs adjusting for skin temperature showed significant differences only in peroneal motor distal latency (MDL) and duration of sural sensory nerve action potential (SNAP) between age groups. However, there was no constant relation between these parameters and age. Multiple regression analysis showed the significant relationships between age and ulnar MDL and the duration of sural sensory nerve action potential, adjusting for sex, height, weight, BMI, alcohol intake (frequency/week, ethanol equivalent ml/week), tobacco consumption (/day), skin temperature and education years. 2) The skin temperature had significant effects on ulnar MDL, ulnar sensory NCV, duration of ulnar SNAP, sural sensory NCV and amplitude and duration of sural SNAP according to the results of multiple regression analysis and analysis of variance. 3) The body mass index had an independent effect on the ulnar nerve conduction, shortening MDL and the duration of the sensory nerve action potential. 4) Consumption of alcohol and tobacco had no significant relation to nerve conduction velocity in our study. These results show that skin temperature is a major covariate of peripheral nerve conduction and that it is very important to control skin temperature in studies on nerve conduction measurements.

OBJECTIVES:To survey the loss of colour vision among Japanese workers who have been exposed to styrene concentrations currently considered low (about 20 ppm). Also to assess the effects of styrene by examination of the nature of the relation between disorder of colour vision and age, alcohol consumption, and other variables.METHODS:Colour discrimination was examined in 64 male workers exposed to styrene (mean age; 38.0, mean exposed years; 7.0) and in 69 controls (mean age; 38.0). A standardised questionnaire was adopted to collect work history, occupational or non-occupational solvent exposure, alcohol consumption, and drug use. Colour vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the colour confusion index (CCI).RESULTS:The mean atmospheric styrene concentration was about 20 ppm. The mean urinary concentration of mandelic acid was 0.22 g/l. There was a significant difference in CCI between exposed workers and age matched controls. Colour vision of workers whose concentration of urinary mandelic acid was > or = 0.42 g/l was significantly impaired when compared with workers whose concentration was < 0.42 g/l. Multiple linear regression analysis that controlled confounding variables such as age, alcohol consumption, smoking, and educational attainment showed that the CCI was significantly related to the concentration of urinary mandelic acid. In both exposed workers and controls, the types of defects were mostly blue-yellow loss, although a few subjects showed complex loss. No one showed only red-green loss.CONCLUSIONS:These findings suggest that exposure to moderate styrene concentrations can lead to impairment of colour vision, and that there is a significant correlation with the urinary metabolite of styrene.

A survey was conducted in the second half of a working week on 33 women who either applied glue (with cyclohexane as an almost exclusive solvent component) or worked in the vicinity of glue application. Carbon cloth-equipped diffusive samplers were used for personal measurement of time-weighted average intensity of exposure to the solvent. The geometric mean and the highest cyclohexane concentration observed in air were 27 ppm and 274 ppm, respectively. Concentrations of cyclohexanol in urine samples and cyclohexane in whole blood and serum collected at the end of a shift showed significant correlations with the solvent exposure levels. Urinary cyclohexanone also correlated, but with a smaller correlation coefficient. The observation suggests that cyclohexanol in urine and cyclohexane in blood or serum collected at the end of a shift are useful indicators of occupational exposure to cyclohexane vapor. Quantitative estimation of balance at the end of the shift suggested that only a minute portion (< 1%) of cyclohexane absorbed is excreted in the urine as cyclohexanol, almost exclusively as a glucuronide. A survey of subjective symptoms revealed an increase in the prevalence of “dimmed vision” and “unusual smell”, but hematology and serum biochemistry testing did not indicate any specific signs.