Relationship between morningness-eveningness typology and cumulative fatigue or depression among Japanese male workers.

This study clarified relationships between morningness-eveningness typology and cumulative fatigue or depressive state in Japanese male workers. 959 male chemical factory workers answered a questionnaire that included the MEQ, SDS, CFSI, age, marital status, sleep indexes, life habits, and labor load. Logistic regression analysis was performed with SDS and CFSI as objective variables. We obtained valid responses from 884 subjects, who were classified according to MEQ into definitely morning type (4.1%), moderately morning type (38.6%), intermediate type (55.1%), moderately evening type (2.3%), and definitely evening type (0%). The results of logistic regression analysis show that the odds ratio of a subscale among CFSI, chronic fatigue in the moderately evening type (3.33, p=0.046) was elevated compared with that in the intermediate type (2.07, p=0.004). However, the odds ratio of SDS (1.67, p=0.028) and two subscales among CFSI, decreased vitality (1.67, p=0.021), and depressive feelings (2.02, p=0.001), for which significant relationships were found only in the intermediate type, were higher in the moderately evening type than in the intermediate type. These results suggest that relationships between cumulative fatigue or depressive state and circadian typology exist among workers independent of working hours, sleep indexes, or life habits.

The antioxidant and non-antioxidant contributions of vitamin E in vitamin E blended ultra-high molecular weight polyethylene for total knee replacement.

Vitamin E (VE) blended ultra-high molecular weight polyethylene (UHMWPE) has been developed in Japan as a material for use in total knee replacement (TKR). Various results have demonstrated that VE blended UHMWPE reduces the incidence of delamination failure and lowers the amount of wear produced during knee simulator testing. It was also found that wear particles from VE blended UHMWPE elicited a reduced biological response compared to conventional UHMWPE. A great deal of research concerning vitamin E (VE) stabilized ultrahigh molecular weight polyethylene (UHMWPE) has focused on VE's effects as an antioxidant and its ability to prevent the oxidative degradation of UHMWPE chains. However, other chemical and mechanical changes have been observed in VE blended UHMWPE that are unrelated to the oxidative protection that VE provides. This paper provides a general review of VE blended UHMWPE, with a particular focus on the non-antioxidant effects of VE. The potential application of VE blended UHMWPE in total hip replacement (THR), along with the differences in loading conditions between the knee and the hip are also discussed.

[Qualitative research of contexts of occupational physician's advice].

OBJECTIVES: No consistent procedure has been established for advice given by occupational physicians concerning scope of disease, criteria of diagnosis and laboratory data, and basis of judgment. The aim of this study was to identify practice-based contexts of occupational physician's advice. METHODS: We interviewed 6 occupational physicians, and held focus group discussions (FGD) involving 19 occupational physicians, academic researchers, and clinical doctors. Scripts of the interview and FGD were coded to identify the contexts of occupational physician's advice. Additionally, to assure the generalizability of the proposed contexts of occupational physician's advice, we also conducted a survey to collect cases of advice, for which the fitness of the proposed contexts was confirmed. RESULTS: Four contexts of occupational physician's advice were identified from interviews and FGD, and an additional context was detected through the occupational physician's survey, namely Type 1, work potentially affects a worker's health; Type 2, risk management and prevention of accidents relating to disease; Type 3, recommendation to visit a doctor (referral); Type 4, communication to the head of the department/supervisor; and Type 5, fit for work with appropriate adjustment of work environment and/or conditions. All 48 cases collected could be classified into one or more of these five contexts. DISCUSSION: This study clarified that several contexts exist for occupational physician's advice in practice. The five proposed contexts reveal different responsibilities and judgments between occupational physician, worker, and employer. Understanding the contexts of occupational physician's advice is important for enhancing consensus-building between stakeholders.

Strain-induced crystallization and orientation of vitamin E-blended ultrahigh molecular weight polyethylene.

The effects of vitamin E addition on the strain-induced crystallization and molecular chain orientation of ultrahigh molecular weight polyethylene (UHMWPE) were examined in order to clarify the wear mechanism of vitamin E-blended UHMWPE in knee prostheses. The structure changes of vitamin E-blended UHMWPE before and after tensile strain were analyzed by X-ray diffraction, Raman spectroscopy and image correlation method. The vitamin E-blended UHMWPE exhibited lower strain-induced crystallization than virgin UHMWPE but a higher Ic value in Raman spectroscopic analysis. The vitamin E-blended UHMWPE also exhibited a larger percentage of negative areal dilatation under tensile strain. These results suggest that the addition of vitamin E to UHMWPE decreases the strain-induced crystallization and increases the strain-induced orientation of the molecular chains present in the amorphous phase.

Benchmark duration of work hours for development of fatigue symptoms in Japanese workers with adjustment for job-related stress.

The objective of this study was to calculate benchmark durations and lower 95% confidence limits for benchmark durations of working hours associated with subjective fatigue symptoms by applying the benchmark dose approach while adjusting for job-related stress using multiple logistic regression analyses. A self-administered questionnaire was completed by 3,069 male and 412 female daytime workers (age 18-67 years) in a Japanese steel company. The eight dependent variables in the Cumulative Fatigue Symptoms Index were decreased vitality, general fatigue, physical disorders, irritability, decreased willingness to work, anxiety, depressive feelings, and chronic tiredness. Independent variables were daily working hours, four subscales (job demand, job control, interpersonal relationship, and job suitability) of the Brief Job Stress Questionnaire, and other potential covariates. Using significant parameters for working hours and those for other covariates, the benchmark durations of working hours were calculated for the corresponding Index property. Benchmark response was set at 5% or 10%. Assuming a condition of worst job stress, the benchmark duration/lower 95% confidence limit for benchmark duration of working hours per day with a benchmark response of 5% or 10% were 10.0/9.4 or 11.7/10.7 (irritability) and 9.2/8.9 or 10.4/9.8 (chronic tiredness) in men and 8.9/8.4 or 9.8/8.9 (chronic tiredness) in women. The threshold amounts of working hours for fatigue symptoms under the worst job-related stress were very close to the standard daily working hours in Japan. The results strongly suggest that special attention should be paid to employees whose working hours exceed threshold amounts based on individual levels of job-related stress.

Shift work is a risk factor for increased blood pressure in Japanese men: a 14-year historical cohort study.

To clarify the effect of shift work on blood pressure in Japanese men, a 14-year historical cohort study was conducted in day workers (n=3963) and alternating shift workers (n=2748) who received annual health checkups between 1991 and 2005 in a Japanese steel company. The end points were a >or=10%, >or=15%, >or=20%, >or=25%, or >or=30% increase in systolic blood pressure or diastolic blood pressure from baseline during the period of observation. The association between shift work and an increase in blood pressure was investigated adjusting for age, body mass index, hemoglobin A1c, total serum cholesterol, creatinine, aspartate aminotransferase, gamma-glutamyl transpeptidase, uric acid, drinking habit, smoking habit, and habitual exercise by multivariate pooled logistic regression analyses. Shift work was significantly associated with the various end points. The odds ratios (and 95% CIs) were as follows: >or=10%, 1.15 (1.07 to 1.23); >or=15%, 1.21 (1.12 to 1.31); >or=20%, 1.15 (1.04 to 1.28); >or=25%, 1.20 (1.06 to 1.37); and >or=30%, 1.23 (1.03 to 1.47) for systolic blood pressure and >or=10%, 1.19 (1.11 to 1.28); >or=15%, 1.22 (1.13 to 1.33); >or=20%, 1.24 (1.13 to 1.37); and >or=25%, 1.16 (1.03 to 1.30) for diastolic blood pressure. Our study in male Japanese workers revealed that alternating shift work was a significant independent risk factor for an increase in blood pressure. Moreover, the effect of shift work on blood pressure was more pronounced than other well-established factors, such as age and body mass index.

A longitudinal study on the effect of shift work on weight gain in male Japanese workers.

OBJECTIVE: This study compared the effect of alternating shift work and day work on weight gain in Japanese male workers. METHODS AND PROCEDURES: A longitudinal cohort study was conducted in day workers (n = 4,328) and alternating shift workers (n = 2,926) of a steel company who received annual health checkups over a 14-year period between 1991 and 2005. The association between the type of job schedule and weight gain was investigated using multivariate pooled logistic regression analyses. The endpoints in the study were either a 5, 7.5, or 10% increase in BMI during the period of observation, compared to the BMI at entry. RESULTS: The type of job schedule was significantly associated with all three BMI endpoints (5% increase in BMI; odds ratio (OR) for comparison between alternating shift workers and regular day workers, 1.14; 95% confidence interval (CI), 1.06-1.23): (7.5% increase in BMI; OR, 1.13; 95%CI, 1.03-1.24: 10% increase in BMI; OR, 1.13; 95%CI, 1.00-1.28). BMI at study entry was also positively associated with the 5, 7.5, and 10% increases in BMI during the study. On the other hand, age and drinking habits were negatively associated with 5, 7.5, and 10% increases in BMI. DISCUSSION: Our study revealed that alternating shift work was an independent risk factor for weight gain in male Japanese workers. Efficient health screening and regular checkups, combined with support to control unhealthy lifestyle factors, would be of considerable benefit for maintaining the health of Japanese shift workers.

Estimation of benchmark dose as the threshold amount of alcohol consumption for blood pressure in Japanese workers.

In order to determine the threshold amount of alcohol consumption for blood pressure, we calculated the benchmark dose (BMD) of alcohol consumption and its 95% lower confidence interval (BMDL) in Japanese workers. The subjects consisted of 4,383 males and 387 females in a Japanese steel company. The target variables were systolic, diastolic, and mean arterial pressures. The effects of other potential covariates such as age and body mass index were adjusted by including these covariates in the multiple linear regression models. In male workers, BMD/BMDL for alcohol consumption (g/week) at which the probability of an adverse response was estimated to increase by 5% relative to no alcohol consumption, were 396/315 (systolic blood pressure), 321/265 (diastolic blood pressure), and 326/269 (mean arterial pressures). These values were based on significant regression coefficients of alcohol consumption. In female workers, BMD/BMDL for alcohol consumption based on insignificant regression coefficients were 693/134 (systolic blood pressure), 199/90 (diastolic blood pressure), and 267/77 (mean arterial pressure). Therefore, BMDs/BMDLs in males were more informative than those in females as there was no significant relationship between alcohol and blood pressure in females. The threshold amount of alcohol consumption determined in this study provides valuable information for preventing alcohol-induced hypertension.

Working hours and mental and physical fatigue in Japanese workers.

BACKGROUND: Establishing a threshold number of working hours is very important when making recommendations to protect people from the potentially harmful health effects caused by long working hours. AIM: To clarify the influence of working hours on both mental and physical symptoms of fatigue and use the data obtained to determine permissible working hours. METHODS: Cross-sectional survey of male day-shift workers using the Self-Rating Depression Scale (SDS) and the Cumulative Fatigue Symptoms Index (CFSI). Working hours were subdivided into six groups and odds ratios were calculated for positive outcomes on the SDS and CFSI using logistic regression analysis. RESULTS: A total of 715 workers participated. In the group working 260-279 h/month, the odds ratios for SDS and 'irritability', 'anxiety' and 'chronic tiredness' of the CFSI were significantly increased. In the group working >or=280 h/month, the odds ratios on CFSI for 'general fatigue', 'physical disorders', 'anxiety' and 'chronic tiredness' were likewise significantly increased. CONCLUSIONS: The present results clarified that working hours should be <260 h/month in order to minimize fatigue symptoms in male day workers.

Investigation of renal damage among residents in the cadmium-polluted Jinzu River basin, based on health examinations in 1967 and 1968.

The purpose of this study was to investigate the prevalence of renal disorders in the Jinzu River basin in Toyama Prefecture, Japan where Itai-itai disease was endemic, based on the results of epidemiological studies performed in 1967 and 1968. Furthermore, was there a regional accumulation of the prevalence of abnormal urinary findings in that area? Early morning urine samples were collected from 13 183 subjects (6155 men, 7028 women) who then responded to questionnaires about lifestyle and health. The subject participation rate was 90%. Our findings showed that subjects living in the area of the Jinzu River basin have significantly higher prevalence of abnormal urinary findings compared to subjects living in neighboring river basins and these geographical distributions demonstrated a definite regional accumulation in those areas. The findings of this study verified the regional accumulation of renal disorders in the Jinzu River basin and indicate an association of the occurrence of renal disorders with the water from the Jinzu River.

Estimation of the number of working hours critical for the development of mental and physical fatigue symptoms in Japanese male workers - application of benchmark dose method.

BACKGROUND: To clarify the influence of working hours on subjective fatigue symptoms and obtain the critical dose (number of hours) to determine the number of permissible working hours, we calculated the benchmark dose (BMD) and the 95% lower confidence limit on BMD (BMDL) of working hours for subjective mental and fatigue symptoms using multivariate logistic regression. METHODS: Self-administered questionnaires were distributed to all 843 male daytime workers aged < or = 60 years in a single chemical factory, and 715 provided complete replies. The odds ratios of daily working hours were determined using positive findings of the Self-rating Depression Scale and 8 subscales of the Cumulative Fatigue Symptom Index as dependent variables, and other potential covariates as independent variables. Using significant parameters for the working hours and those for other covariates, the BMD and BMDL (BMD/BMDL) values were calculated for corresponding dependent variables. The benchmark response (BMR) was set at 5% or 10%. RESULTS: The BMDL with a BMR of 5% was shown to be 9.6-11.6 hr per day, which corresponds to 48-58 working hours per week and 36-78 overtime hours per month. CONCLUSIONS: These results suggest that special attention should be paid to the workers whose working hours exceed these BMD/BMDL values.

Health status of workers in small and medium-sized companies as compared to large companies in Japan.

The health status of workers in small companies has been noted to be relatively poor, but no actual comparisons of groups of variously sized companies within the same region based on the same methodology have ever been conducted. We undertook this study to clarify differences in health status according to company size. The subjects comprised workers of a Japanese steel company and various subcontractors who received health checkups in 2003. We obtained answers from 83 companies employing 11,844 workers and analyzed the data for 6,480 men aged 40 yr or more, comparing results of the health checkups, health management practices, and number of occupational health personnel according to company size (number of employees). Mean worker age in the various groups ranged from 49.7 to 54.0 yr. Drinking and smoking habits did not differ between them. There was a significant trend to higher prevalences of diabetes and hypertension, and lower prevalences of renal disease and hypercholesterolemia in smaller companies. Mean body mass index and diastolic blood pressure were significantly higher in companies with 1,000-2,999 workers. Health management practices satisfied the legal requirements of the respective company size. Occupational physicians devoted more time per worker in companies with 1,000-2,999 and 50-299 workers. No consistent differences were apparent between small and large companies in worker health status. Inter-company activities for occupational safety and health were undertaken and labor regulations almost equally adhered to. Endeavors to maintain a certain level of hygiene and health management play an important role in maintaining worker health in small companies.

Long-term longitudinal study on the relationship between alternating shift work and the onset of diabetes mellitus in male Japanese workers.

OBJECTIVE: This study investigated the effect of alternating shift work (ASW) on the onset of diabetes mellitus in Japanese workers compared with onset in day-shift work (DSW). METHODS: A longitudinal study was carried out on a DSW group (n = 3203) and ASW group (n = 2426) of a steel company who received their annual health checkups over a 10-year period between 1991 and 2001. The association between job schedule type and onset of diabetes mellitus (glycated hemoglobin A1c > or =6.0% or medication) was investigated by multivariate pooled logistic regression analyses. RESULTS: The odds ratio (95% confidence interval) for the development of diabetes mellitus in the ASW group compared with the DSW group was 1.35 (1.05-1.75). CONCLUSIONS: Our study revealed that the ASW is an independent risk factor for the onset of diabetes mellitus.

Benchmark dose of working hours in relation to subjective fatigue symptoms in Japanese male workers.

PURPOSE: We used a multiple logistic regression model to calculate benchmark doses (BMDs) and their 95% lower confidence bound (BMDL) of working hours for subjective fatigue symptoms. METHODS: A self-administered questionnaire survey was conducted in 3069 male daytime workers between the ages of 18 and 60 years who worked in a Japanese steel company. Dependent variables were positive findings for eight properties by using the Cumulative Fatigue Symptoms Index (CFSI): decreased vitality, general fatigue, physical disorders, irritability, decreased willingness to work, anxiety, depressive feelings, and chronic tiredness. Independent variables were daily working hours, age, lifestyle factors, working conditions (type of work and number of holidays), marital status, and living arrangements. Using significant parameters for working hours and those for other covariates, BMD/BMDL of working hours was calculated for the corresponding property of the CFSI. Additionally, benchmark response (BMR) was set at 5% or 10%. RESULTS: The BMD/BMDL of working hours per day with a BMR of 5% were 11.8/10.8 (irritability), 11.4/10.2 (anxiety), and 11.2/10.6 (chronic tiredness), and those with a BMR of 10% were 14.2/12.6 (irritability), 14.2/12.1 (anxiety), and 13.1/12.2 (chronic tiredness). CONCLUSIONS: These results strongly suggest that special attention should be given to workers whose working hours exceed these BMD/BMDL values.

A longitudinal study on the relationship between shift work and the progression of hypertension in male Japanese workers.

OBJECTIVE: In this 1991-2001 cohort study of 6495 male workers in a Japanese steel company, we investigated whether shift work affects progression from mild hypertension to severe hypertension. DESIGN: A prospective cohort study. PARTICIPANTS: Participants had mild hypertension at entry into the study with systolic blood pressure of 140-159 mmHg or diastolic blood pressure of 90-99 mmHg or both before treatment. In summary, 2911-2941 workers were included for each endpoint. Pooled logistic regression analysis was performed to adjust for the effect of contributing factors and annual variations. MAIN OUTCOME: Either severe hypertension (systolic blood pressure >or= 160 mmHg and/or diastolic blood pressure >or= 100 mmHg), severe systolic hypertension (systolic blood pressure >or= 160 mmHg) or severe diastolic hypertension (diastolic blood pressure >or= 100 mmHg) was defined as a different endpoint of observation. RESULTS: Job schedule was significantly associated with progression from mild hypertension to severe hypertension and severe diastolic hypertension. The odds ratios of shift workers compared with regular day workers were 1.23 (95% confidence interval: 1.05-1.44) and 1.28 (95% confidence interval: 1.07-1.52) for severe hypertension and severe diastolic hypertension, respectively. Age, body mass index, creatinine, gamma-glutamyl transpeptidase, and glycosylated hemoglobin A1c were also significantly associated with severe hypertension, severe systolic hypertension and severe diastolic hypertension. CONCLUSION: Our study revealed that shift work is a significant and independent risk factor for the progression of hypertension.

Three-shift system increases job-related stress in Japanese workers.

We assessed the relationship between shift work and job stress. The target subjects were 4,962 male workers (3,078 day workers and 1,884 shift workers) aged 18 to 60 yr who work in a Japanese steel company. We used the "Brief Job Stress Questionnaire", which was developed by a research group organized by the Japanese Ministry of Labour. We evaluated the effect of shift work on job stress using logistic regression analysis including age, lifestyle factors, work conditions, marital status, and living arrangements in the model. Job schedule type was significantly associated with job control, with an odds ratio of 2.22 for shift workers compared to day workers. The logistic regression analysis revealed that the odd ratios for having one or more stressor items in an unfavorable condition were significantly higher for shift workers compared to day workers. Increase in the amount of overtime and decrease in the number of holidays led to a significant deterioration in job stress. Our study reveals that the 3-shift system of employment increases work-related stress, and that job control is low among shift workers. To reduce job stress in this occupational population, a reduction in the amount of overtime and an increase in the number of holidays seem to be useful interventions.

Health effects of cadmium exposure in the general environment in Japan with special reference to the lower limit of the benchmark dose as the threshold level of urinary cadmium.

OBJECTIVES: This study investigates renal dysfunction in areas without known environmental cadmium pollution and calculates the threshold level of urinary cadmium. METHODS: Urinary total protein, beta2-microglobulin (beta2-MG), and N-acetyl-beta-D-glucosaminidase (NAG), used as indicators of renal dysfunction, and urinary cadmium concentration, used as an indicator of cadmium exposure, were measured in two sets of 24-hour urine samples from each of 828 participants (410 men, 418 women), aged 40-59 years and living in three areas without any known environmental cadmium pollution. In multiple regression and logistic regression analyses the association between indicators of cadmium exposure and indicators of renal dysfunction were studied. The lower 95% confidence limit of the dose (benchmark dose) corresponding to a 5% (BMDL5) or 10% (BMDL10) level of each indicator of renal dysfunction above the background level) was calculated as the threshold level of urinary cadmium. RESULTS: With all the expressed units [g creatinine(-1) and day(-1)] in the multiple regression analysis, the partial regression coefficients showed a significant association between urinary cadmium concentration and total protein, beta2-MG, and NAG for both genders, except for total protein for women (g creatinine(-1) and day(-1). The same results were obtained for both genders in the logistic regression analysis. The BMDL10 was 0.6-1.2 microg/g creatinine and 0.8-1.6 microg/day for the men and 1.2-3.6 microg/g creatinine, and 0.5-4.7 microg/day for the women. CONCLUSIONS: Cadmium exposure and the levels of the indicators of renal dysfunction were associated among the men and women aged 40-59 years in areas without any known environmental cadmium pollution. The threshold level of urinary cadmium in Japan seems to be almost the same as in Belgium and Sweden.

Association of working conditions and lifestyle with increased serum gamma-glutamyltransferase: a follow-up study.

BACKGROUND: This study investigated the association of working conditions and lifestyle with the development of increased serum gamma-glutamyltransferase (GGT) in Japanese workers. METHODS: A follow-up study was carried out on workers of a telecommunication enterprise who received their first annual health check-up between 1992 and 1996, when they were between 40 and 54 years of age. Workers who had high serum GGT (> or =60 IU/L in males, > or =30 IU/L in females), a past history of disease, or current illness at their first check-up were excluded from the analysis. In total, the study included 15,586 workers. The association between working conditions and lifestyle and development of increased serum GGT (> or =60 IU/L in males, > or =30 IU/L in females) was investigated by pooled logistic regression analyses. RESULTS: In males, body mass index, consumption of alcohol (<2 times/week, 2-5 times/week, >5 times/week), smoking (<20 cigarettes/day, > or =20 cigarettes/day), rarely taking three meals a day, marked preference for salty meals, and little preference for vegetables were positively associated with the development of increased serum GGT. Preferences for fatty meals (marked, moderate) were negatively associated with the development of increased serum GGT. In females, age and BMI were positively associated with the development of increased serum GGT. CONCLUSIONS: Applying a new statistical analysis to this retrospective cohort study of 5 years, we revealed the health influences of alcohol consumption, smoking and eating habits on increased serum GGT. On the other hand, this study indicated that shift work or other working conditions are not significant risk factors for increased serum GGT.

Relationship among prevalence of patients with Itai-itai disease, prevalence of abnormal urinary findings, and cadmium concentrations in rice of individual hamlets in the Jinzu River basin, Toyama prefecture of Japan.

This study investigated the associations among prevalence of patients with Itai-itai disease, and prevalence of abnormal urinary findings and cadmium (Cd) concentrations in rice in individual hamlets of the Jinzu River basin. From the 13,183 participants of the 1967 and 1968 health examinations, we selected 3,094 subjects as the target population who had resided in the current hamlet for a total of 30 years or longer and aged >/=50 years, and in the hamlet both the Cd concentration in rice and prevalence of patients with Itai-itai disease were known. When the inhabitants were divided into four groups according to the Cd concentration in rice or prevalence of abnormal urinary findings, significant relationships among three factors (Cd concentration in rice, prevalence of abnormal urinary findings and prevalence of patients with Itai-itai disease) were demonstrated clearly using the Cochran-Armitage test. Correlation coefficients among the three factors in 55 hamlets showed that the prevalence of the patients with Itai-itai disease increased according to increases in the mean Cd concentration in rice and increasing prevalence of urinary findings. This study demonstrated that Itai-itai disease is induced by exposure to environmental Cd and that renal dysfunction plays an important role in its development.

Lack of association of human G-protein beta 3 subunit variant with hypertension in Japanese workers.

OBJECTIVE: To examine the association between hypertension and the C825T polymorphism in the G-protein beta 3 subunit gene in Japanese workers. METHODS: This study used logistic regression analysis and multiple regression analyses to investigate whether the C825T polymorphism was associated independently with hypertension or blood pressure when factors such as age, body mass index, blood chemistry and lifestyle were taken into consideration. The target subjects were 1452 male and 1169 female workers selected from 3834 male and 2591 female workers in a single company. Hypertension was defined as a systolic blood pressure > or = 140 mmHg and/or diastolic blood pressure > or = 90 mmHg, or taking antihypertensive medication. The power of the study was estimated as 83% for males and 41% for females based on allelic frequencies in Caucasians. RESULTS: Genotype distributions for C825T in hypertensive males (CC = 58, CT = 135, TT = 63) and females (CC = 20, CT = 36, TT = 20) were not significantly different from normotensive males (CC = 300, CT = 614, TT = 282) or females (CC = 274, CT = 602, TT = 217), respectively. Allele distributions were not significantly different in either sex. Multiple logistic regression analysis showed that genotype was not associated significantly with hypertension, whereas there was a significant relationship between hypertension and age, family history of hypertension, body mass index, hematocrit, platelet count, gamma-glutamyl transpeptidase (gamma-GTP) and uric acid. Data analysis using one-way analysis of variance and multiple regression showed that the C825T allele had no significant influence on either systolic, diastolic or mean blood pressure. CONCLUSIONS: This study indicates that the C825T polymorphism is not a significant factor for hypertension or blood pressures in Japanese people. Targeting of this polymorphism is therefore unlikely to be beneficial when attempting to prevent hypertension in the general Japanese population.