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Takeuchi A.,Osaka Occupational Health Service Center | Sakano N.,Kagawa University | Miyatake N.,Kagawa University
Industrial Health

This study describes an ecological study that evaluated the combined effects of working hours, income, and leisure time on suicide in all 47 prefectures of Japan. In men, the age-adjusted rate of suicide (per 100,000 population) was significantly correlated with working hours (r=0.587, p<0.0001) as well as significantly and negatively correlated with income (r=-0.517, p=0.0002) and times for the leisure activities of self-education (r=-0.447, p=0.0016) and hobbies (r=-0.511, p=0.0002). In addition, a stepwise multiple regression analysis identified time for leisure social activities as a determining factor in suicide rate, even after adjusting for working hours and income. However, the impact of time for leisure social activities on suicide rate was smaller than that of working hours and income. In contrast, none of these factors affected suicide rate in women. These results suggest that increasing leisure time may be useful for preventing suicide among men in Japan. © 2014 National Institute of Occupational Safety and Health. Source

Eitaki Y.,Keio University | Kawai T.,Osaka Occupational Health Service Center | Omae K.,Keio University
Journal of Occupational Health

Objectives: In order to measure occupational exposure concentrations of ethyl tertiarybutyl ether (ETBE), we developed a diffusive sampling method for monitoring ETBE and performed an ETBE exposure assessment. Methods: The applicability of diffusive samplers was examined by exposing the samplers to ETBE vapor in test chambers. The personal exposure levels of workers and airborne concentrations were measured at 4 gas stations. Results: The ETBE sampling rate for the diffusive samplers (VOC-SD, Sigma-Aldrich Japan) was 25.04 ml/min (25°C). Compared with the active sampling method, the diffusive samplers could be used for short-term measurements and in environments containing a mixture of organic solvents. The geometric mean (GM) of TWA-8h ETBE was 0.08 ppm (0.02-0.28 ppm) in 28 gas station workers and 0.04 ppm (0.01-0.21 ppm) in 2 gasoline tanker truck drivers. With regard to ETBE airborne concentrations, the GM was 4.12 ppm (0.93-8.71 ppm) at the handles of hanging pumps but dropped to less than 0.01 ppm (less than 0.01-0.01 ppm) at the side of a public road. Conclusion: The diffusive sampling method can be used for the measurement of occupational ETBE exposure. The threshold limit of TLV-TWA 5 ppm recommended by the ACGIH was not exceeded in any of the workers in this study. Source

Namera A.,Hiroshima University | Takeuchi A.,Osaka Occupational Health Service Center | Saito T.,Tokai University | Miyazaki S.,GL Sciences Inc. | And 3 more authors.
Journal of Separation Science

A sequential analytical method was developed for the detection of arsenite, arsenate, and methylarsenate in human urine by gas chromatography-mass spectrometry (GC-MS). The combination of a derivatization of trivalent arsenic compounds by 2,3-dithio-1-propanol (British antilewisite; BAL) and a reduction of pentavalent arsenic compounds (arsenate and methylarsenate) were accomplished to carry out the analysis of arsenic compounds in urine. The arsenic derivatives obtained using BAL were extracted in a stepwise manner using a monolithic spin column and analyzed by GC-MS. A linear curve was observed for concentrations of arsenic compounds of 2.0 to 200 ng/mL, where the correlation coefficients of calibration curves were greater than 0.996 (for a signal-to-noise (S/N) ratio >10). The detection limits were 1 ng/mL (S/N > 3). Recoveries of the targets in urine were in the range 91.9-106.5%, and RSDs of the intra- and interday assay for urine samples containing 5, 50, and 150 ng/mL of arsenic compounds varied between 2.95 and 13.4%. The results from real samples obtained from a patient suspected of having ingested As containing medications using this proposed method were in good agreement with those obtained using high-performance liquid chromatography with inductively coupled plasma mass spectrometry. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kawai T.,Osaka Occupational Health Service Center | Takeuchi A.,Osaka Occupational Health Service Center
Journal of Occupational Health

Comparison of the exposure-excretion relationship between men and women exposed to organic solvents: Toshio KAWAI, et al. Osaka Occupational Health Service Center-Objectives: The present study was initiated to examine if application of the same biological occupational exposure limits (BOELs) for organic solvents is applicable across the sexes. Methods: A survey was conducted in 69 micro-scale enterprises in a furniture-producing industrial park. In practice, 211 men and 52 women participated in the survey. They worked in a series of production process, and were exposed to solvent vapor mixtures. The exposure intensities were monitored with two types of diffusive samplers, one with carbon cloth (for solvents in general) and the other with water (for methyl alcohol) as adsorbents. Solvents in the adsorbents and head-space air from urine samples were analyzed with capillary FID-GC. The measured values were subjected to linear regression analysis followed by statistical evaluation for possible sex-related differences in slopes. Results: Essentially no significant difference was detected between men and women in regression line parameters including slopes. Possible differences in the cases of acetone and toluene were discussed and excluded. Conclusions: With the exceptions for acetone and toluene, the present study did not detect any clear differences between men and women. In examinations of past reports, no support for the observed differences was found. The present findings deserve further study so that a solid conclusion can be formed. Source

Kawai T.,Osaka Occupational Health Service Center | Sakurai H.,Occupational Health Research and Development Center
Journal of Occupational Health

Objectives: For several organic solvents (solvents in short), biological occupational exposure limits (BOELs) have been established for un-metabolized solvents in urine, based on the solvent exposure-urinary excretion relationship. This study was initiated to investigate the possibiliy of estimating a BOEL from the Pow (the partition coefficient between n-octyl alcohol and water), a physico-chemical parameter. Methods: Data were available in the literatures for exposure-excretion relationship with regard to 10 solvents for men and 7 solvents for women. Results: Statistical analysis revealed that the slopes (after correction for molecular weights and logarithmic conversion) of the exposure-excretion regression lines linearly correlated (p<0.01) with the log Pow values the respective solvents. No significant difference (p>0.05) was observed between men and women, and it was acceptable to combine the data for the two sexes. Thus the log Pow-log slope relation was represented by a single equation for both sexes. Based on the observations, procedures were established to estimate BOEL values from Pow. Successful estimations of BOELs for styrene, tetrahydrofuran and m-xylene (a representative of xylene isomers) were calculated as examples. Conclusions: The present study proposed promising procedures for estimation of a BOEL from the Pow. Source

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