Toshifumi Mannami

Cigarette smoking and risk of coronary heart disease incidence among middle-aged Japanese men and women: the JPHC Study Cohort I.

Background Few data have been available on the sex-specific magnitude of the smoking effect on the risk of coronary heart disease (CHD) in Asia. Design and methods A population-based prospective cohort study of 19 782 men and 21 500 women aged 40–59 years between 1990–1992 and 2001 was conducted to examine the relationship between smoking status and the risk of CHD. Results A total of 260 incidences of CHD were confirmed among men, including 174 myocardial infarctions (MI). The numbers among women were 66 and 43, respectively. The multivariate relative risk [95% confidence interval (CI)] for current smokers versus never-smokers in men after adjustment for cardiovascular risk factors, several life style factors and public health centre was 2.85 (1.98, 4.12) for total CHD and 3.64 (2.27, 5.83) for MI. These respective risks in women were 3.07 (1.48, 6.40) and 2.90 (1.18, 7.18). Among men, a dose-dependent relationship was observed between the number of cigarettes and the risk of MI. The population-attributable risk per cent (95% CI) of CHD was 46% (34, 55) in men and 9% (0, 18) in women. Smoking cessation, however, led to a rapid decline in the CHD risk within 2 years. Conclusion Smoking raises the risk of CHD significantly in both sexes of middle-aged Japanese, with large public health significance especially in men. Smoking cessation would have an immediate effect on risk reduction.

Impact of metabolic syndrome on brachial- ankle pulse wave velocity in Japanese

The aim of this study was to determine the effect of metabolic syndrome on brachial-ankle pulse wave velocity (baPWV) by using the new guidelines for diagnosis of this syndrome in Japan. We examined 525 men and women without a history of cardiovascular disease or cancer, and an ankle-brachial index<0.9. The baPWV was measured using a device (Form PWV/ABI) that simultaneously monitored bilateral brachial and ankle pressure wave forms. Metabolic syndrome was defined as a waist circumference ≥85 (90) cm in men (women) and two or more of the following risk factors: hypertension, dyslipidemia, and glucose intolerance diagnosed by a 75 g oral glucose tolerance test. The baPWV showed a significant linear relationship with waist circumference, waist-to-hip ratio, body fat, systolic and diastolic blood pressure, triglycerides, fasting glucose, 2-h-postload glucose, fasting insulin, and glycosylated hemoglobin-A1c, after adjusting for sex and age. These factors were also strongly related to fasting insulin levels. When subjects were classified into six groups based on waist circumference and the number of risk factors for metabolic syndrome (0, 1, and ≥2), we found that more risk factors clearly increased the odds ratios for an elevated baPWV in those subjects in the highest quartile of the baPWV distribution in multivariate logistic models. An increase in odds ratio was observed despite a normal waist circumference and may well have been due to increased fasting insulin and blood pressure levels. An increase in the number of risk factors for metabolic syndrome was highly correlated with an increased baPWV, probably due to insulin resistance.

A Method for On-Site Analysis of Urinary Benzene by Means of a Portable Gas-Chromatograph

Benzene is one of the toxic air pollutants released from automobile fuel, exhaust, tobacco smoke etc., and is commonly found in both indoor and outdoor air. Since benzene is a carcinogenic substance classified into group 1 (carcinogenic to humans) by the International Agency for Research on Cancer (IARC), it is important to assess the human health risk posed by exposure to environmental or occupational benzene. The analytical trials were performed to determine blood and urinary unchanged benzene as a specific index for low benzene exposure. But these methods require sophisticated and expensive instruments such as a gas chromatograph-mass spectrometer which can be used only in a laboratory. Moreover, benzene in biological fluids is volatilized so easily that it may cause the loss of samples during collection, transportation and preservation which is the most common cause of uncertainties. Therefore, the development of simple and specific methods to perceive benzene exposure are expected. In this study, we developed a method for on-site analysis of benzene in urine by head space-gas chromatography (HS-GC) employing a field portable GC, since on-site analysis can provide rapid data without time-consuming and loss-inducing processes such as transportation and preservation.

Possible sources of urinary benzene among nonoccupationally exposed Japanese subjects.

Unmetabolized benzene in urine (U-benzene) is known to be the best marker among the indices for the biological monitoring of occupational and environmental exposure to benzene. In this study, we determined the levels of U-benzene among Japanese university students exposed to benzene nonoccupationally and analyzed the relation between U-benzene levels and the possible factors responsible for environmental benzene exposure. In urinalysis, U-benzene concentration among 124 students was detected in the range from 18 (minimum detection limit) to 249 ng/l. The frequency distribution of U-benzene concentration peaked at 0–19 ng/l. Mean and median values of 40 and 20 ng/l for U-benzene concentration in nonoccupationally exposed subjects were lower than those in a previous study. Stepwise multiple linear regression analysis was performed to assess the potential sources of exposure to environmental benzene by analyzing the relation between U-benzene and personal, behavioral, and environmental factors. The results showed that only smoking habit (P < 0.01) and residential house age (P < 0.05) were independent determinants of U-benzene levels. In addition, U-benzene levels in relation to smoking and house age suggested that these factors could be associated with the synergistic elevation of U-benzene. The present study showed U-benzene levels among non-occupationally exposed Japanese subjects and revealed that the major exposure sources to benzene in the general environment were tobacco smoking and indoor air contamination.