RESUMEN
OBJECTIVES: The aim of this study was to investigate the effect of shift working on the risk of developing impaired glucose tolerance (IGT). METHODS: This study comprised 6413 male employees (5608 daytime workers, 512 3-shift workers and 293 2-shift workers) whose work schedules remained constant during the follow-up period (mean follow-up period 9.9 years). IGT was defined as Hemoglobin A1c ≥ 5.9%. The Cox proportional hazards model was used to estimate the risk of developing IGT, after making adjustments for age, smoking, alcohol consumption, leisure-time physical activity, body mass index (BMI) and Hemoglobin A1c (HbA1c) at baseline. Analysis was additionally performed for a sub-cohort of 1625 workers with BMI of 20.0-25.0 kg/m² that did not change by >2.0 kg/m² during the follow up period. RESULTS: The risk of developing IGT was significantly elevated among both 3-shift workers [hazard ratio (HR) 1.78, 95% confidence interval (95% CI) 1.49- 2.14] and 2-shift workers (HR 2.62, 95% CI 2.17-3.17). Significant elevations of the risk were still observed at the additional analysis on the sub-cohort (3-shift work: HR 3.55, 95% CI 2.02-6.25; 2-shift work: HR 4.86, 95% CI 2.62-9.01). CONCLUSIONS: Both 2- and 3-shift workers were associated with a high risk factor of developing IGT compared to day workers. Moreover, 2-shift workers had a higher risk than 3-shift workers. The risk was observed even among workers whose body mass remained within the normal range.
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Prueba de Tolerancia a la Glucosa , Tolerancia al Trabajo Programado , Índice de Masa Corporal , Hemoglobina Glucada/análisis , Humanos , Masculino , Modelos de Riesgos Proporcionales , Estudios RetrospectivosRESUMEN
OBJECTIVES: The authors investigated the effect of shift working on the risk of obesity using data from the Industry-based Shift Workers' Health (IbSH) study, a retrospective cohort study based on a health care database system belonging to a manufacturing corporation in Japan. METHODS: The study database contains data on annual health check-ups and work schedules for every worker in the corporation in Japan since 1981. Study subjects consisted of 9912 male employees (8892 daytime workers and 920 rotating three-shift workers; mean age at first check-up was 23.7 years) whose work schedules were consistent during the follow-up period. Obesity was defined as a body mass index ≥ 25.0. RESULTS: 3319 cases of obesity were recorded over the 27.5 years of retrospective follow-up. Kaplan-Meier survival analysis visually demonstrated an increased risk of obesity among shift workers. The risk becomes particularly obvious after 10 years of follow-up. Cox proportional-hazards model analysis revealed a significantly increased risk among shift workers (RR 1.14, 95% CI 1.01 to 1.28). CONCLUSION: The risk of obesity among male shift workers was visually and statistically demonstrated.
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Obesidad/etiología , Enfermedades Profesionales/etiología , Tolerancia al Trabajo Programado , Adulto , Métodos Epidemiológicos , Humanos , Japón/epidemiología , Estilo de Vida , Masculino , Actividad Motora/fisiología , Obesidad/epidemiología , Obesidad/fisiopatología , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/fisiopatología , Adulto JovenRESUMEN
In 1999, the Japanese Law on Equal Employment Opportunity and Conditions was amended and the previous prohibition of the assignment of female workers to night work was abolished. Subsequently, the number of female shift workers has been increasing in Japan, necessitating greater attention to the health care of this population. The aim of the current study is to evaluate the relationship between anxiety expressed about starting three-shift work and background characteristics among female workers who were being assigned to three-shift work for the first time. The subjects were 38 middle-aged female workers (age range: 44 to 59 years) who were working at a chemical plant. The women completed a self-administered questionnaire before starting three-shift work. Levels of anxiety about starting three-shift work were assessed by the question 'Do you feel anxious about starting three-shift work?' The available responses were: 'Very agree', 'Considerably agree', 'Rather agree', 'Slightly agree' and 'Not agree at all', and 63% of the subjects gave one of the first two answers, which were defined as indicating anxiety. We also acquired information regarding lifestyle and occupation for each subject, including the following factors: frequency of breakfast consumption, subjective sleep insufficiency, previous experience of similar work before beginning shift work, previous experience of two-shift work, and responsibility for household duties. In the study, we found a marginally statistically significant trend association between frequent breakfast consumption and anxiety about starting three-shift work (P(trend) = 0.09). Anxiety was also high among subjects with sleep disorders, especially those suffering from subjective sleep insufficiency (P = 0.08). Due to the small study population, these results should be interpreted with caution and confirmed by future studies.
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Ansiedad , Salud Laboral , Encuestas y Cuestionarios , Salud de la Mujer , Tolerancia al Trabajo Programado/psicología , Adulto , Femenino , Humanos , Estilo de Vida , Persona de Mediana Edad , Admisión y Programación de Personal , Trastornos del Sueño del Ritmo Circadiano/psicología , Factores SocioeconómicosRESUMEN
PURPOSE: To examine the relation of green tea consumption with oral carcinogenesis, we prospectively analyzed data from a nationwide large-scale cohort study in Japan. METHODS: A total of 20,550 men and 29,671 women aged 40-79 years, without any history of oral and pharyngeal cancer at baseline survey, were included in the present study. During a mean follow-up period of 10.3 years, 37 oral cancer cases were identified. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for oral cancer according to green tea consumption by sex, while adjusting for age, smoking, alcohol drinking, and other dietary factors. RESULTS: For women, the HRs of oral cancer for green tea consumption of 1-2, 3-4, and 5 or more cups per day were 0.51 (95% CI: 0.10-2.68), 0.60 (95% CI: 0.17-2.10), and 0.31 (95% CI: 0.09-1.07), respectively, compared with those who drank less than one cup per day (p for trend, 0.08). For men, no such trends were observed. CONCLUSIONS: Our findings did not suggest a prominent inverse association of green tea consumption with oral cancer, although there was a tendency for a reduced risk in women.
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Neoplasias de la Boca/epidemiología , Té , Adulto , Anciano , Estudios de Cohortes , Femenino , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Factores de Riesgo , Té/efectos adversosRESUMEN
We conducted this study to estimate the association and population attributable risk (PAR) of smoking with all-cause and cause-specific mortality based on a general prospective cohort study in Japan. A total of 8,129 subjects (3,996 males and 4,133 females) aged 40 or over were analyzed. The follow-up period was from 1986 to 2003. Smoking habit was classified into three categories of never smoker, former smoker, and current smoker. The Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). We also estimated the PAR of smoking, and calculated the 95% CI of PAR based on the bootstrap procedure. A total of 112,151 person-years were counted for 8,129 subjects over an average of 13.7 years of follow-up. The results showed that smoking increased the risk of dying from all cancers, cardiovascular, and respiratory diseases in both sexes. For all causes of death, smokers had a HR of 1.30 (95% CI: 1.09, 1.54), PAR of 13.1% (95% CI: 7.6, 22.3) in males, and HR of 1.81 (95% CI: 1.43, 2.29), and PAR of 6.1% (95% CI: 3.1, 9.3) in females compared to never smokers. These results confirm an increased risk of mortality from all causes, as well as from all cancers, cardiovascular disease, and respiratory disease in relation to smoking habit. Smoking is responsible for a considerable proportion of deaths due to all causes as well as cause-specific deaths. Population-based antismoking programs should be implemented to reduce such avoidable deaths.
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Fumar/mortalidad , Adulto , Anciano , Causas de Muerte/tendencias , Estudios de Cohortes , Femenino , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Estudios ProspectivosRESUMEN
OBJECTIVE: To estimate stroke mortality and evaluate risk factors for total stroke deaths and its two principal subtypes in a cohort study in Japan. METHODS: A total of 9651 subjects aged 40 or over and free of stroke were analyzed in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 2003. Mortality rate per 100,000 person-years of stroke was estimated. The Cox proportional hazards model was used to estimate the hazard ratios and 95% confidence interval. RESULTS: A total of 226 stroke deaths were recorded during 132,972 years of follow-up. Among these, 47 were intracerebral hemorrhage and 109 were cerebral infarction. Stroke mortality rates were 209.4 per 100,000 person-years in males, and 140.5 in females. The results showed that advanced age, male gender, low body mass index (BMI), history of diabetes, hypertension, and transfusion were associated with an increased risk of mortality from total stroke. CONCLUSION: We confirmed that advanced age, male gender, low BMI, history of diabetes, history of hypertension and history of transfusion were associated with an increased risk of total stroke mortality. In addition, the magnitude of these associations differed between the two principal stroke subtypes.
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Hemorragia Cerebral/etiología , Hemorragia Cerebral/mortalidad , Infarto Cerebral/etiología , Infarto Cerebral/mortalidad , Accidente Cerebrovascular/etiología , Accidente Cerebrovascular/mortalidad , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Consumo de Bebidas Alcohólicas/efectos adversos , Índice de Masa Corporal , Causas de Muerte , Complicaciones de la Diabetes/complicaciones , Conducta Alimentaria , Femenino , Estudios de Seguimiento , Encuestas Epidemiológicas , Humanos , Hipertensión/complicaciones , Japón/epidemiología , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Modelos de Riesgos Proporcionales , Medición de Riesgo , Factores de Riesgo , Distribución por Sexo , Fumar/efectos adversos , Accidente Cerebrovascular/clasificación , Encuestas y Cuestionarios , Reacción a la TransfusiónRESUMEN
BACKGROUND: It remains unclear whether chronic ingestion of arsenic in drinking water affects the peripheral nervous system. We examined the effects of arsenic exposure on nerve conduction velocity using electromyography. METHODS: A cross-sectional study was conducted of a population living in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 (93.7%) of 143 inhabitants took part in the study, and 36 (76.6%) of 47 inhabitants in a low-arsenic exposed village were recruited as a control group. Of the participants, 109 inhabitants in the arsenic-affected village and 32 in the low-arsenic exposed village aged > or =18 years were used for the analyses. An expert physician performed skin examinations, and median nerve conduction velocity was examined by electromyography. Arsenic levels in tube-well water and urine were measured. A mean level of arsenic in tube-well water in the arsenic-affected village was 158.3 microg/L, while that in the low-arsenic exposed village was 5.3 microg/L. RESULTS: No significant differences in the means of the motor nerve conduction velocity (MCV) and sensory nerve conduction velocity (SCV) were observed in relation to arsenic levels in tube wells, urine, and the duration of tube-well use. Further, no differences in mean MCV or SCV were found between the subjects with and without arsenic dermatosis, with mean SCV of 52.8 m/s (SD 6.3) in those without and 54.6 m/s (5.2) in subjects with arsenic dermatosis (p=0.206). CONCLUSION: These findings suggest that chronic arsenic poisoning from drinking water is unlikely to affect nerve conduction velocity, at least within the range of arsenic in drinking water examined in the present study.
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Arsénico/efectos adversos , Agua Dulce/química , Conducción Nerviosa/efectos de los fármacos , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Contaminantes Químicos del Agua/efectos adversos , Adolescente , Adulto , Arsénico/orina , China/epidemiología , Estudios Transversales , Ingestión de Líquidos , Electromiografía , Exposición a Riesgos Ambientales/efectos adversos , Femenino , Humanos , Masculino , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Contaminantes Químicos del Agua/orinaRESUMEN
We examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: "once per week or less," "2-4 times per week" and "daily intake." The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person-years of follow-up. The "once per week or less" group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33-1.14) and 0.25 (95% CI: 0.11-0.59) in the "2-4 times per week" and "daily intake" groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13-1.51) and 0.51 (95% CI: 0.16-1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27-1.09) and 0.36 (95% CI: 0.16-0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22-1.56) and 0.37 (95% CI: 0.13-1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer.
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Conducta Alimentaria , Neoplasias Hepáticas/mortalidad , Neoplasias Hepáticas/prevención & control , Verduras , Adulto , Anciano , Femenino , Estudios de Seguimiento , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Análisis Multivariante , Oportunidad Relativa , Estudios Prospectivos , Distribución por SexoRESUMEN
The present study investigated the association between visual display terminal (VDT) work and sick building syndrome (SBS) and the role of psychosocial factors in the relationship. Subjects were 2,161 Japanese office workers who responded to a cross-sectional anonymous self-administered questionnaire survey. Questions included were derived from the Miljömedicin 040, a validated questionnaire on SBS symptoms. After exclusion of data with missing information, data for 1,881 subjects were used for analysis. Multivariate logistic regression was used to estimate the odds ratio for SBS with adjustment for potential confounding factors, including psychosocial work stress. In multivariate analysis, the odds ratio for SBS was significantly elevated for men engaged in VDT work for 4 or more hours a day (OR=2.5, 95%CI: 1.0, 5.9) compared with less than 1 hour a day, showing a significant trend association (P for trend=0.04). In women, although the odds ratio for SBS with VDT use of 4 or more hours a day was somewhat elevated with adjustment for non-psychosocial factors (OR=1.5, 95%CI: 0.5, 4.3), the increase was greatly attenuated after adjustment for psychosocial work distress (OR=1.1). In conclusion, our study suggests that extended hours of VDT use might be related to increased SBS symptoms. Moreover, psychosocial distress related to VDT work might mediate the relationship between VDT use and SBS symptoms in women.
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Terminales de Computador , Síndrome del Edificio Enfermo/psicología , Interfaz Usuario-Computador , Adulto , Estudios Transversales , Femenino , Humanos , Japón , Masculino , Encuestas y CuestionariosRESUMEN
OBJECTIVE: Recent studies have shown that generation of reactive oxidants during arsenic metabolism can play an important role in arsenic-induced injury. The purpose of this study was to examine the relationship between arsenic in drinking water and oxidative stress in humans by measuring 8-Hydroxy-2'-deoxyguanosine (8-OHdG). METHODS: We performed a cross-sectional study in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 of the 143 inhabitants (93.7%) of the village participated in the study. The levels of 8-OHdG, arsenic and its metabolites were measured in urine collected from the participants. Regression analyses were performed to investigate the relationship between arsenic species and 8-OHdG levels in urine. RESULTS: In the polluted village, monomethylarsenic was significantly higher in subjects with arsenic dermatosis than those without dermatosis despite no difference in mean levels of arsenic in well water between both types of subject. For subjects with arsenic dermatosis, arsenic species and metabolites in urine are significantly associated with 8-OHdG, while there was no statistically significant relationship for subjects without arsenic dermatosis. For all residents of the polluted village, the levels of dimethylarsenic and 8-OHdG were significantly higher for those who had been exposed to well water for more than 12 years. CONCLUSIONS: These results provide evidence of a link between exposure to arsenic from drinking water and oxidative stress, which may play an important role in arsenic-involved injuries.