能川 和浩

OBJECTIVES: The increasing number of working elderly people has enhanced the importance of workplace health promotion activities. We investigated the association between the health status of workers approximately 60 years of age and the risk of all-cause mortality after compulsory retirement in Japan. METHODS: The 2026 participants (1299 males and 727 females) had retired from a metal-products factory at ≥60 years of age. Baseline health examinations were conducted at 60 years of age and included questions about medical history and lifestyle factors; the participants also underwent a physical examination. The participants were followed up annually by mail for an average of 7.4 years. The association between health status at age 60 years and the risk of all-cause mortality was assessed by Cox proportional hazards regression analysis. RESULTS: During the study, 71 deaths were reported. The age- and sex-adjusted hazard ratio (HR [95% confidence interval]) for all-cause mortality was higher for males (HR, 3.41 [1.73-6.69]) compared with females, participants with a low body mass index (<18.5 kg/m2 ; HR 3.84 [1.91-7.73]) compared with normal body weight, smokers (HR, 2.63 [1.51-4.58]) compared with nonsmokers, and those with three or more of four metabolic abnormalities (obesity, high blood pressure, dyslipidemia, and glucose intolerance) (HR 2.29 [1.04-5.02]) compared with no metabolic abnormalities. The associations were unaffected by adjustment for these factors. CONCLUSION: Maintenance of an appropriate body weight, smoking cessation, and elimination of metabolic syndrome are required for older workers to prevent early death after retirement.

Background: Exposure to cadmium (Cd) via food is supposed to affect life prognosis of inhabitants of Cd-polluted area in Japan. However, there have been few reports demonstrating a significant relationship between the amount of Cd intake and mortality. We aimed to investigate the relationship between mortality and individual lifetime Cd intake (LCd) in inhabitants of the polluted Jinzu River basin, Toyama, Japan. Methods: We conducted a 26-year follow-up survey in 2407 inhabitants (1208 men and 1199 women) who participated in health examinations for screening of renal dysfunction from 1979 to 1984. The calculation of LCd in each inhabitant was based on the formula of Nogawa (Nogawa et al., 1989): (mean Cd concentration in rice of the present hamlet × 333.5 g/day + 34 μg/day) × 365 days/year × number of years of residence in the present hamlet + 50 μg/day × 365 days/year × number of years living in Cd non-polluted regions. In this formula, 333.5 g/day is the 1970 average daily intake of rice in this area, 34 µg/day is the Cd intake from foods other than rice in this area, and 50 μg/day is the average intake of Cd in non-polluted areas in Japan. Mortality risk ratios of LCd for all and specific causes were estimated after adjustments for age at baseline, smoking status, and history of hypertension using a Cox hazard model or Fine and Gray competing risks regression model. Results: The mortality risk ratios of LCd (+ 1 g) for all causes in women were significantly dose-dependently increased (risk ratio: 1.08). Relative risk of LCd for kidney and urinal tract disease, renal diseases, renal failure and toxic effects of cadmium were significantly higher in women. Conclusions: The present study documents that individual LCd dose-dependently decreased life prognosis over long-term observation in women. LCd was significantly related to the increased mortality for renal disease and toxic effect of Cd in women. The result provides clear evidence that life prognosis was adversely affected by Cd-exposure, especially in women.

The aim of this study was to investigate the relationship between mortality and rice cadmium (Cd) concentration in inhabitants of a polluted area in Japan. The target subjects were inhabitants of the Jinzu River basin who participated in health examinations for screening of renal dysfunction from 1979 to 1984. The mean rice Cd concentration in each hamlet was used as an index of the Cd exposure. We conducted a 26 year follow-up survey in 3281 inhabitants (1544 men and 1737 women) whose data regarding the rice Cd concentration were available. Mortality risk ratios for all and specific causes were estimated after adjustments for age at baseline, smoking status and history of hypertension using a Cox hazard model or Fine and Gray competing risks regression model. The mortality risk ratios of rice Cd concentration (+0.1 ppm) for all causes in women were significantly increased (risk ratio: 1.04). Furthermore, the relative risks of rice Cd concentration for kidney and urinary tract disease, renal diseases, renal failure and toxic effects of cadmium were significantly increased in both sexes. These findings indicated that increased rice Cd concentration decreased the prognosis for life over a long-term observation in women. This result provides important information for determining the worldwide standard for allowable rice Cd concentration.