Olfactory and taste dysfunctions caused by COVID-19: a nationwide study

BACKGROUND

Olfactory dysfunctions (OD) and taste dysfunctions (TD) are widely recognized as characteristic symptoms of COVID-19; however, the frequency and mode of occurrence has varied depending on the viral mutation. The prevalence and characteristics of OD/TD in Japan have not been definitively investigated. The purpose of this study is to assess the prevalence of OD/TD in Japan during the Alpha variant epidemic, and measure symptom prolongation at 6 months and 1 year later following initial infection.

METHODS

Patients treated for COVID-19 between February to May 2021 were evaluated for OD/TD symptoms and provided with a QOL questionnaire. Olfactory tests and taste tests were performed using Open Essence and Taste Strips, respectively.

RESULTS

Among the 251 COVID-19 patients who participated, 119 underwent both olfactory and taste tests. Prevalence of subjective OD and TD at the time of survey was 57.8% and 40.2%, respectively. After 12 months, the prevalence fell to 5.8% for OD and 3.5% for TD. Among the OD/TD patients, 36.6% experienced parosmia, and 55.4% experienced parageusia. Prevalence of parosmia and parageusia was higher at 6 and 12 months than at the time of survey. Patients with long-lasting disease reported qualitative dysfunctions and scored significantly higher in food-related QOL problems. Most patients who were aware of their hyposmia had low scores on the olfactory test (83.1%). In contrast, only 26.7% of patients who were aware of their hypogeusia had low scores on the taste test.

CONCLUSIONS

The prevalence of COVID-19-related OD and TD at the time of survey was 57.8% and 40.2%, respectively. Subjective symptoms of OD and TD persisted for one year in 5.8% and 3.5% of patients, respectively. More than half of the patients with OD or TD complained of qualitative dysfunction and a decrease in their QOL related to eating and drinking. Most patients with TD did not have true TD, but rather developed flavour disorders associated with OD. This conclusion is supported by the finding that patients with subjective OD had low scores on the olfactory test, whereas most patients with subjective TD had normal scores on the taste test.

2,3,7,8-Tetrachlorodibenzo-p-dioxin in breast milk increases autistic traits of 3-year-old children in Vietnam

Dioxin levels in the breast milk of mothers residing near a contaminated former airbase in Vietnam remain much higher than in unsprayed areas, suggesting high perinatal dioxin exposure for their infants. The present study investigated the association of perinatal dioxin exposure with autistic traits in 153 3-year-old children living in a contaminated area in Vietnam. The children were followed up from birth using the neurodevelopmental battery Bayley-III. The high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposed groups (⩾3.5 pg per g fat) showed significantly higher Autism Spectrum Rating Scale (ASRS) scores for both boys and girls than the mild-TCDD exposed groups, without differences in neurodevelopmental scores. In contrast, the high total dioxin-exposed group, indicated by polychlorinated dibenzo-p-dioxins/furans (PCDDs/Fs)--the toxic equivalents (TEQ) levels⩾17.9 pg-TEQ per g fat, had significantly lower neurodevelopmental scores than the mild-exposed group in boys, but there was no difference in the ASRS scores. The present study demonstrates a specific impact of perinatal TCDD on autistic traits in childhood, which is different from the neurotoxicity of total dioxins (PCDDs/Fs).

Causes of death and renal tubular dysfunction in residents exposed to cadmium in the environment

OBJECTIVES

To clarify the causes of death of residents with renal tubular dysfunction induced by cadmium (Cd) in the environment.

METHODS

A 15 year follow up study was performed with the inhabitants living in the Cd polluted Kakehashi River basin in Japan. Standardised mortality ratios (SMRs) for causes of death, classified by ICD-9, were computed using the person-years method to investigate the excess mortality of subjects with urinary beta2-MG (microglobulin) > or =1000 microg/gCr. Mortality risk analysis was performed using Cox's proportional model to compare mortality between subjects with urinary beta2-MG > or =1000 and <1000 microg/gCr, and to investigate the relationship between the degree of urinary beta2-MG and mortality.

RESULTS

Excess mortality due to heart failure and cerebral infarction in both sexes, and nephritis and nephrosis in men, was observed among subjects with urinary beta2-MG > or =1000 microg/gCr. Significant increases in mortality risk for cerebral infarction in men and for malignant neoplasms in women with urinary beta2-MG > or =1000 microg/gCr were observed during the first five year observation period. For nephritis and nephrosis, the mortality risks for men and women with urinary beta2-MG > or =1000 microg/gCr significantly increased over the 15 year observation period. The mortality risks for heart failure and cerebral infarction increased in proportion to the increased urinary beta2-MG in both sexes. Increased mortality risks for nephritis and nephrosis were identified in the subjects with urinary beta2-MG > or =10000 microg/gCr in both sexes.

CONCLUSION

Renal tubular dysfunction induced by Cd affected the causes of death, and mortality for heart failure, cerebral infarction, and nephritis and nephrosis was increased among inhabitants living in a Cd polluted area in Japan. In women, cancer mortality may have been increased while Cd pollution was ongoing.

Exercise blood pressure in young adults as a predictor of future blood pressure: a 12-year follow-up of medical school graduates

It has not been fully clarified whether exercise blood pressure (BP) in young adult men and women is useful to predict future BP, especially in Asian people. A long-term prospective study was conducted in graduates of a medical school in Japan; 138 men and 76 women whose mean age was 19.8 and 19.2, respectively, at baseline. A 5-min exercise tolerance test was performed at baseline, and BP immediately after exercise was measured. BP at 50% intensity exercise was also calculated. Multiple regression analysis was carried out to clarify the relationship of exercise BP at baseline to follow-up BP after an average of 12 years. In multivariate-adjusted models, the relationship of systolic blood pressure (SBP) at follow-up was stronger to SBP immediately after exercise (F=7.7, P=0.006) than to resting SBP (F=3.7, P=0.055) in men. The models in men showed that SBP immediately after exercise was a stronger predictor of follow-up SBP than SBP at 50% intensity exercise, and the results were similar for diastolic blood pressure (DBP) in men. For SBP in women, resting SBP was the strongest predictor of follow-up SBP (F=14.3, P<0.001), and exercise SBP was not significant predictor. For DBP in women, any DBP at rest or after exercise was not significantly related to DBP at follow-up. In young adult men, SBP and DBP immediately after exercise would be a stronger predictor of future SBP and DBP rather than BP at rest. However, in young adult women, resting SBP rather than exercise SBP would be better to predict future SBP.

Influence of years engaged in agriculture and number of pregnancies and deliveries on mortality of inhabitants of the Jinzu River basin area, Japan

BACKGROUND

The occurrence of itai-itai disease is thought to be affected by such factors as pregnancy, lactation, hormonal disorders, aging, and calcium deficiency.

AIMS

To study the influence of years engaged in agriculture and number of pregnancies and deliveries on the mortality of inhabitants of the Jinzu River basin area, which has been an endemic region for itai-itai disease.

METHODS

From 6,667 participants (3,181 men, 3,486 women; participation rate 93.4%) in the 1967 health survey, 3,639 subjects (1,591 men, 2,048 women) whose years engaged in agriculture were established, and 2,559 women/2,410 women with a known number of pregnancies/deliveries were selected as the target population. These data were confirmed on the basis of self reported replies confirmed afterwards by interview. The survival survey was conducted for 6,127 days from 1 August 1967 to 10 May 1984. Subjects were divided according to three water systems: the Jinzu River, non-Jinzu River, and mixed water system; the influence on mortality of the years engaged in agriculture and the number of pregnancies/deliveries was analysed using a Cox's proportional hazards model according to the water systems.

RESULTS

The mean years engaged in agriculture and mean number of pregnancies/deliveries were not different among the three water systems. Cox's hazard ratios of these parameters to mortality were not statistically significant in the any of the water systems.

CONCLUSIONS

Neither the years engaged in agriculture nor the number of pregnancies/deliveries influenced mortality in subjects living not only in the non-Jinzu River basin but also in the Jinzu River basin using a Cox's proportional hazards model.

[[Comparison of mortality rates of elderly people in China and Japan]]

"The mortality rates and causes of death among elderly people aged sixty five and over were compared between China and Japan. The data used for comparison was China's 1990 and Japan's 1990 vital statistics. It appears that the mortality rate in China was higher than Japan. Comparing the causes of death, it was found that the death rates involving cerebrovascular diseases, malignant neoplasms and heart diseases in urban districts of China [were] higher than those in Japan. Also the death rate of people with bronchitis in rural districts was significantly higher in China.... The differences in the medical systems and life styles in China and Japan were suspected as the reasons for the differences of death rates and causes of death...." (SUMMARY IN ENG)

Effects of maternal exposure to cadmium on pregnancy outcome and breast milk

OBJECTIVE

The effects of cadmium (Cd) on birth weight have been discussed in the scientific literature. However, investigations on the effects of maternal body burden of Cd on the next generation during pregnancy and lactation have been limited. The relation between maternal exposure to Cd and pregnancy outcome or Cd in breast milk in Japanese mothers was investigated.

METHODS

Cd concentrations in urine and colostrum milk samples of 57 mothers were measured by atomic absorption spectrophotometery. The relations between maternal urinary Cd and infant growth, gestational age at birth, and Cd in breast milk were investigated.

RESULTS

The rate of perterm deliveries of mothers with higher urinary Cd (> or =2 nmol/mmol creatinine (Cr)) was higher than that of mothers with lower urinary Cd (<2 nmol/mmol Cr). The gestational age was significantly correlated with urinary Cd even after adjustment for maternal age. The height and weight of newborn infants of mothers with higher urinary Cd were significantly lower than those of the newborn infants of mothers with lower urinary Cd, but these decreases were ascribed to early delivery induced by Cd. The Cd in breast milk of mothers with higher urinary Cd was significantly higher than that of mothers with lower urinary Cd. A significant positive correlation was found between maternal urinary Cd and Cd in breast milk.

CONCLUSION

Maternal exposure to Cd seems to increase early delivery, which leads to a lower birth weight. Also, the Cd is transferred in part to the next generation through breast milk after birth.

Birth weight, childhood growth, and cardiovascular disease risk factors in Japanese aged 20 years

To determine whether birth weight and childhood growth, especially rate of height increase, are independently related to major cardiovascular disease risk factors in adult life, the authors conducted a 20-year follow-up study in a Japanese population, using the record-linkage method. From medical checkup data for babies and for residents aged 20 years in Ishikawa, Japan, the authors obtained 20-year follow-up data (1985-1994) on 4,626 participants (2,198 men and 2,428 women) born in 1965-1974. Using multiple linear regression analysis, the authors estimated that a 1-standard-deviation higher birth weight was significantly associated with systolic blood pressure that was lower by 1.6 mmHg in men and by 1.0 mmHg in women, and with a serum cholesterol level that was lower by 0.07 mmol/liter in men and by 0.04 mmol/liter in women, after adjustment for current weight and rate of height increase. Moreover, after adjustment for birth weight and current weight, a 1-standard-deviation higher rate of height increase from age 3 years to age 20 years was significantly associated with systolic blood pressure that was lower by 0.7 mmHg in men and by 0.5 mmHg in women, and with serum cholesterol that was lower by 0.09 mmol/liter in men and by 0.05 mmol/liter in women. The results suggest that lower birth weight and lower rate of height increase during childhood are independently associated with increases in blood pressure and serum cholesterol in adult life.

Dust exposure and lung cancer mortality in tunnel workers

The eastern part of the Toyama Prefecture in Japan is one of the high-incidence areas of silicosis due to tunnel construction. In 1977 and 1978, we conducted a questionnaire survey primarily concerning the occupational history of all male inhabitants over 30 years of age living in five villages in this area and found 603 tunnel workers and inhabitants without dust history. These workers have been followed up to 1994 for about 17 to 18 years to clarify the relationship between tunnel work and lung cancer mortality. The SMR's of workers with dust exposure for all causes and for lung cancer was 120 and 188, respectively, which was significantly higher than those of the Japanese general population. After adjustment for age and smoking habits using Cox's proportional hazard model, tunnel work showed a significant relationship to mortality. Mortality risk ratio of tunnel workers was 2.15 compared with that of inhabitants without dust exposure history.

Trends in stroke incidence and acute case fatality in a Japanese rural area : the Oyabe study

BACKGROUND AND PURPOSE

Stroke mortality in Japan has significantly declined during recent decades. To determine the cause of this decrease, we studied the trends in stroke incidence and case fatality within 28 days after stroke in a rural area in Japan.

METHODS

We used a population-based registry during 1977-1991 in Oyabe, a rural area in the central part of Japan. The average population aged 25 years and older numbered 32 859 persons. Changes in age-standardized stroke incidence rate were calculated and compared between the 3 periods 1977-1981, 1982-1986, and 1987-1991. The 28-day case fatality rate was evaluated and also compared between the 3 periods by onset year.

RESULTS

The total number of strokes was 2068. The age-standardized incidence rate of all strokes decreased during the 15-year period, from 605 to 417 per 100 000 in men and from 476 to 329 per 100 000 in women. A marked decline was found during 1977-1986 but was not apparent during 1987-1991. Moreover, there was an increase in the group aged 75 years and older. The 28-day case fatality rates for all strokes improved from 18.0% to 14.2% in men and from 26.8% to 19.1% in women during the observation period.

CONCLUSIONS

These data indicate that declines in the stroke incidence and the 28- day case fatality have been associated with a marked decrease in stroke-related mortality in Japan.

Relationship between urinary cadmium and mortality among inhabitants living in a cadmium polluted area in Japan

A 15 year follow-up study of 3119 inhabitants living in a cadmium polluted area was conducted to investigate the influence of environmental cadmium exposure on the mortality. The cumulative survival curves of the subjects with urinary cadmium concentration > or = 10 microg/g creatinine was lower than that of the subjects with < 10 microg/g creatinine in the men aged 50-59 and 60-69 years and in the women aged 60-69 and 70-79 years. In the men aged 50-69 years and the all aged women, the cumulative survival curves became lower in proportion to the increase of urinary cadmium concentration, when the subjects were divided into four groups according to the amount of urinary cadmium concentration (< 5, 5-9.9, 10.1-19.9, > or = 20 microg/g creatinine). These results suggested a dose response relationship between cadmium exposure and mortality.

Relationship between shift work and onset of hypertension in a cohort of manual workers

OBJECTIVES

This study investigated the possibility of a relationship between blood pressure level and rotating 3-shift work in a prospective follow-up of workers in a zipper and aluminum sash factory in Japan.

METHODS

Altogether 1551 men aged 18-49 years were followed prospectively for 5 years, and the cumulative incidence of hypertension among 3-shift workers was compared with that of day workers. A multiple logistic analysis was used for adjusting for base-line characteristics such as age, body mass index, blood pressure, and drinking habit.

RESULTS

In the younger age group, the relative risk of the rotating 3-shift workers during the observational period was increased compared with that of day workers after adjustment for the confounding factors. In the older group, the cumulative incidence of hypertension was not higher for workers who had continued shift work. However, a relatively high risk of hypertension was found for workers who converted from 3-shift work to day work when compared with those who remained on shift work and day work.

CONCLUSIONS

It is suggested that there is an association between 3-shift work and blood pressure.

Microalbuminuria and hypertension in nondiabetic Japanese men

To investigate the relationship between microalbuminuria and hypertension in nondiabetic subjects, we selected 245 Japanese men aged 35 to 69 years on the basis of the results of a 75 g oral glucose tolerance test. Prevalence of hypertension (blood pressure levels > or =140/90 mm Hg or treatment of hypertension) in microalbuminuria-positive (0.03 to 0.3 g/d) subjects was significantly higher than that in microalbuminuria-negative (<0.03 g/day) subjects. Also, the significant increase of levels of triglycerides, serum uric acid, and area of plasma insulin were recognized in microalbuminuria-positive subjects. Urinary albumin was significantly related to both systolic and diastolic blood pressure in a manner independent of these relevant factors, including area of insulin. With regard to renal functions, creatinine clearance of microalbuminuria positive subjects was significantly increased and fractional excretion of sodium of microalbuminuria-positive subjects was significantly decreased as compared with those of microalbuminuria-negative subjects. In normotensive subjects, serum uric acid, which is known to be related to sodium handling at renal tubules of microalbuminuria-positive subjects, was significantly higher than those of microalbuminuria negative subjects as well as triglycerides and area of insulin, without the differences of the levels of blood pressure and BMI. Therefore, it is suspected that microalbuminuria is a renal facet of insulin resistance, and a predictor value of hypertension.

[The development of the Japanese version of the Maslach Burnout Inventory and the examination of the factor structure]

This article presents an evaluation of the factor structures of the Japanese version of the Maslach Burnout Inventory (MBI). The MBI is a widely used psychometric instrument for measuring 'burnout' developed by Maslach and her co-workers. The MBI consists of four subscales: Emotional Exhaustion, Personal Accomplishment, Depersonalization, and Involvement. The MBI was translated into Japanese along with a back-translation and was administered to a sample of 267 nurses. Various psychometric analyses showed that the Japanese version of the MBI has high reliability for the 22 items scored for the frequency dimension. The factor analysis using principal factoring with an oblique rotation resulted in three factor structures that had different implications from the MBI: Emotional Exhaustion/Depersonalization, Personal Accomplishment, and Physical Exhaustion. The correlationship between the MBI and the General Health Questionnaire (GHQ), measures of depression, showed that burnout was a unique phenomenon.

Ischaemic heart disease deaths in a Japanese rural area evaluated by clinical records

A community-based survey to examine the actual number of ischaemic heart disease (IHD) deaths was undertaken in the western area of Toyama, a rural area with a population of 209,000. IHD deaths (International Classification of Diseases [ICD], ninth revision, codes 410-414) and heart failure (HF) deaths (ICD code 428) according to the death certificate aged 15 to 74 in 1987 to 1990 were reevaluated from medical records using the criteria of the multinational monitoring of trends and determinants in cardiovascular disease (MONICA). Of 97 subjects with IHD and of 170 subjects with HF according to the death certificate, 85 cases (87.6%) and 143 cases (84.1%) could be examined, respectively. Using the MONICA criteria, of 85 subjects with IHD, 18 (21.2%) were reevaluated as "definite acute myocardial infarction (AMI)" and 30 (35.3%) as "possible AMI". On the other hand, of 143 subjects with HF, 1 (0.7%) were reevaluated as "definite AMI" and 12 (8.4%) as "possible AMI". From these results, the number of deaths as reevaluated IHD was estimated 104.5 in the study period, and it was 7.7% increase at least compared with the number of deaths judged from the death certificate.

Ten-year follow-up study on the relation between the development of non-insulin-dependent diabetes mellitus and occupation

To investigate the relation between occupation and the development of non-insulin-dependent diabetes mellitus (NIDDM), we undertook a 10-year follow-up survey of male employees of a zipper and aluminum sash factory in Japan. Of 1,218 employees we followed 1,087 subjects. We classified the subjects into five occupations: managers, technical workers, clerical workers, workers in transport, and laborers. NIDDM incidence was 3.1% for 10 years. The age-adjusted incidence of the workers in transport was the highest and that in laborers was the lowest. We used a multiple logistic analysis for adjustment with baseline characteristics such as age, BMI, fasting plasma glucose, and family history of diabetes mellitus. Adjusted relative risk of the workers in transport compared with the laborers was significantly high (3.95). Our work suggests that occupation is related to the development of NIDDM.

Ultrasonic assessment of calcaneus in inhabitants in a cadmium-polluted area

We used ultrasound (US) transmission to evaluate the speed of sound (SOS) and broadband ultrasonic attenuation (BUA) in the calcaneus in 17 male and 18 female inhabitants of a Cd-polluted area and 23 men and 45 women living in a nonpolluted area. Significant decreases in SOS and stiffness (Stiff), which was an index empirically derived from SOS and BUA, were found in Cd-exposed women. To evaluate the usefulness of the US measurements for detecting bone abnormality in Cd-exposed people, we examined the associations with the bone measurements of metacarpus by the previously used microdensitometry (MD) method and the grade of renal tubular damage due to Cd exposure. Bone density estimated by MD, sigmaGS/D, was significantly correlated with BUA, SOS, and Stiff in the Cd-exposed men and with BUA and Stiff in the Cd-exposed women. Further, in the Cd-exposed women, the decreases in BUA and Stiff correlated significantly with the increases in urinary beta 2-microglobulin, while sigmaGS/D by the MD method did not. These results suggest that the measurement of the calcaneus using US is not only radiation free but also can be used as a tool for population surveys aiming to evaluate bone damage in people, especially women, showing renal tubular damage due to environmental Cd exposure.

Blood pressure and urinary C-peptide excretion in subjects with varying degrees of glucose tolerance

To determine whether blood pressure is associated with 24-h urinary C-peptide excretion in subjects with varying degrees of glucose tolerance, we studied 247 Japanese men aged 30-69 who had never been treated with antihypertensive medications or with insulin. Plasma glucose and insulin responses during a 75-g oral glucose tolerance test, blood pressure and body mass index were obtained and urinary C-peptide excretion, in total and per kg body weight, were examined by 24-h urine collection. In monovariate analyses, urinary C-peptide excretion per kg body weight increased significantly as the blood pressure level rose (p < 0.05). After adjustment for age and body mass index by analysis of covariance, this relationship remained significant (p < 0.05), where adjusted mean values (+/- SEM) of urinary C-peptide per kg body weight were 1.56 +/- 0.05 microgram/24h/kg in the normotensive group and 2.04 +/- 0.17 microgram/24h/kg in the hypertensive (stage 2-4) group. When stratified simultaneously by glucose tolerance status and blood pressure level, adjusted mean values of urinary C-peptide per kg body weight were significantly higher in diabetic hypertensives than in diabetic normotensives. These results suggest that increase in 24-h urinary C-peptide excretion, i.e. 24-h insulin secretion, might contribute to an elevation of blood pressure both in normal and diabetic individuals.

Significance of elevated urinary human intestinal alkaline phosphatase in Japanese people exposed to environmental cadmium

Urinary human intestinal alkaline phosphatase (IAP), beta 2-microglobulin (beta 2-MG) and N-acetyl-beta-D-glucosaminidase (NAG) were analyzed in 40 Japanese environmental-cadmium (Cd)-exposed and 40 non-exposed subjects to evaluate early biological markers for Cd-induced renal damage. All urinary indicators were significantly higher in the Cd-exposed subjects than non-exposed subjects. A fourth-order function was fitted for the relationship between beta 2-MG and IAP or NAG. The beta 2-MG concentration corresponding to the inflexion point for IAP was smaller than that for NAG. This result may support the contention that the cells containing IAP are damaged earlier than those containing NAG, and that IAP is a useful marker for detecting renal tubular dysfunction in people moderately exposed to Cd. However, in the stage of severe renal damage, the combination of IAP and beta 2-MG is considered to be more useful.

Plasma insulin and blood pressure in normotensive Japanese men with normal glucose tolerance

OBJECTIVE

To determine whether blood pressure within the normal range is associated with plasma insulin concentration in a Japanese population with normal glucose tolerance.

METHODS

We studied 491 normotensive Japanese men with normal glucose tolerance, who had never been treated with antihypertensive medications. Plasma glucose and insulin response during a 75-g oral glucose-tolerance test, blood pressure, body mass index, serum lipids, alcohol consumption and smoking status were obtained. The subjects were divided into quartiles according to mean blood pressure level (< 79, 79-84, 85-91 and > or = 92 mmHg). To eliminate possible confounding factors, analysis of covariance was also performed.

RESULTS

In univariate analyses the plasma insulin response after an oral glucose load, especially after 60 min, was significantly related to blood pressure level. Plasma glucose was related to blood pressure level only at fasting. When adjusted for age, body mass index, plasma glucose response and alcohol consumption, plasma insulin concentrations after 30 and 60 min in the highest quartile were significantly higher than those in the lowest quartile.

CONCLUSIONS

Blood pressure was significantly and independently related to plasma insulin level after an oral glucose load in normotensive Japanese men with normal glucose tolerance. The results suggest that the relationship between blood pressure and insulin resistance already exists in a prehypertensive state even in a lean Asian population.

Mortality of inhabitants in an area polluted by cadmium: 15 year follow up

OBJECTIVE

To assess the influence of environmental exposure to cadmium (Cd) on long term outcome of inhabitants living in an area polluted by Cd.

METHODS

A follow up study for 15 years (from 1974-5 to 1991) was carried out on 2408 inhabitants (amounting to 95% of the target population, 1079 men and 1329 women) of the Kakehashi River basin in Ishikawa Prefecture, Japan. These inhabitants had been the subjects of the health impact survey in 1974-5 to evaluate (by measurement of urinary retinol binding protein (RBP)) renal dysfunction induced by Cd. Analysis of mortality was performed by dividing subjects into a urinary RBP positive (> or = 4 mg/l) group and RBP negative (< 4 mg/l) group.

RESULTS

After adjustment for age with Cox's proportional hazard model, RBP > or = 4 mg/l showed a significant relation to mortality in both sexes. At this time, the mortality risk ratio of the RBP positive to negative group was 1.71 in the men and 1.42 in the women. When the SMRs according to causes of deaths in the RBP positive group were compared with those of the RBP negative group or the overall Japanese population increases of SMR for cardiovascular diseases, especially heart failure, and renal diseases were found in both sexes.

CONCLUSION

These results suggest that the prognosis of the exposed inhabitants with renal tubular dysfunction is unfavourable, and these increases of mortality are due to heart failure and renal diseases.

Comparative study on mortality patterns in Japan and China

On the basis of the 1990 Chinese death notice data and 1990 Japanese populations vital statistical materials, the mortality patterns and proportions of individual causes of death in the two countries were compared. In both sexes, the mortality rates were the highest in almost all age groups in Chinese rural areas followed by urban areas and Japan. In Japan and in Chinese urban areas, malignant neoplasms cardiovascular diseases and cerebrovascular diseases were the major causes of death, with these three making up about 60% of the total. In Chinese rural areas, these three conditions were responsible for 43% of all deaths, a considerably lower figure as compared to those in the other two areas, and the mortality rates for infectious diseases and accident/suicide were higher than those in the other two areas. Of the three major adult diseases, cerebrovascular diseases were found to be especially frequent in both Chinese urban and rural areas. On the other hand, ischemic heart disease was found at comparable levels in Japan and China and the rate was lower than in other developed countries. Site-specific mortality rates for malignant neoplasms were characterized by high rates for lung, liver and esophageal cancers in China. The mortality rates for bronchitis in both Chinese urban and rural areas were markedly higher than those in Japan These differences in mortality rates and proportions of individual causes of death between China and Japan are thought to be attributable to the differences in medical services and the level of risk factors for each disease.

[A study of thyroid hormone levels of inhabitants of the cadmium-polluted Kakehashi River basin]

We compared thyroid hormone levels of inhabitants (19 men and 16 women) of the cadmium (Cd)-polluted Kakehashi River basin in Ishikawa Prefecture, with those of subjects (23 men and 47 women) living in a non-polluted area. In addition, we investigated the relationships between the thyroid hormone levels and indices of renal dysfunction induced by Cd exposure. The following results were obtained: 1) The free T4 level of females was significantly lower than that of controls. 2) The T3 level of inhabitants of both sexes was significantly higher than that of controls. 3) The level of free T4 among females became lower with the increases of urinary beta 2-microglobulin (beta 2-MG), urinary protein, urinary sugar, urinary amino acids and serum creatinine (Cr) levels, and with decreases of creatinine-clearance (CCr) and %TRP. 4) We could not find any relationship between the increase of T3 and the indices of renal dysfunction induced by Cd exposure in either sex.

Potassium/energy and phosphorus/calcium ratios reflect the quality of nutrition

A nutritional survey and questionnaire regarding dietary habits were administered to 649 men ranging in age from 35 to 64 years receiving a one-day health screening examination. First, comparisons of nutrient intake based on the nutrient rate of the Recommended Dietary Allowances for Japanese (RDA), and the total score on the questionnaire regarding dietary habits according to the RDA rates of total energy and calcium (Ca) were investigated. Then, the comparisons of intake of food groups, intake of nutrients and the total score on the questionnaire regarding dietary habits according to potassium/energy (K/E) ratio and phosphorus/calcium (P/Ca) ratio were determined. Last, differences between comparisons with the nutrient rates of RDA and comparisons with K/E ratio and P/Ca ratio were investigated. The following results were obtained: 1. Even in the group with RDA rates of total energy or Ca of > or = 90% and < or = 110% the RDA rates of some other nutrients were out-side the appropriate range. 2. In the group with high K/E ratios, as compared to the group with low ratios, the intake of potatoes, pulses, fruits, green/yellow vegetables, other vegetables, soy sauce, other beverages, fish/shellfish, and milk products showed high values, while cereals and fats/oils showed low values. For this reason, in the former group as compared to the latter, the intake and RDA total energy rate showed low values whereas the intake and RDA rates of nutrients such as Ca, Fe, and vitamin A were low. 3. In the group with high P/Ca ratios, as compared to the group with low ratios, the intake of beer and meats showed high values while that of pulses, green/yellow vegetables, and milk products showed low values. For this reason, in the former group as compared to the other groups, despite the fact that the intake and RDA total energy rate tended to be higher, the intake of nutrients such as Ca, P, K, and vitamin A showed lower values. 4. The RDA rates of all of the nutrients of group with a high K/E ratio and the group with a low P/Ca ratio generally showed largely appropriate values. 5. These results suggest that indices reflecting the balance of minerals such as the K/E and P/Ca ratios more objectively reflect the quality of nutrition than comparisons based on the RDA rates of total energy and specific-nutrient.

Prognostic factors of renal dysfunction induced by environmental cadmium pollution

To assess the influence of environmental cadmium (Cd) exposure on long-term outcome, a follow-up study was conducted from 1981-1982 to March 1991 on 3178 inhabitants living in the Cd-polluted Kakehashi River basin. The standardized mortality ratios of the urinary beta 2-microglobulin (beta 2-MG)-, protein-, and amino acid-positive subjects of both sexes and the urinary glucose-positive female subjects were higher than those of the subjects with urinary-negative findings or the general Japanese population during the observation period. After adjusting for age using Cox's proportional hazards model, significant associations were found between mortality and urinary indices. In multiple comparisons using all of the indices, urinary protein and beta 2-MG in the women and urinary protein in the men were the factors most contributing to the mortality rates. In the urinary protein-negative female group as well, a significant association was found between urinary beta 2-MG and mortality. These results suggest that the prognosis of subjects with Cd-induced renal dysfunction is unfavorable, with the mortality rate increasing even in the early stage of proximal tubular dysfunction. Urinary protein and urinary beta 2-MG are important prognostic factors, with the latter, in particular, considered to be useful as an early index predictive of premature mortality.

Urinary beta 2-microglobulin concentration and mortality in a cadmium-polluted area

A 9-y follow-up study of 3,178 persons who lived in a cadmium-polluted area was conducted to assess the influence of environmental cadmium exposure on long-term outcome. The standardized mortality ratios of the urinary beta 2-microglobulin-positive subjects (> 1,000 micrograms/g creatinine) of both sexes were higher than those of the general Japanese population, whereas the cumulative survival curves were lower than those of the urinary beta 2-microglobulin-negative group. A significant association was also found between urinary beta 2-microglobulin and mortality, using a Cox's proportional hazards model. Moreover, mortality rates increased in proportion to increases in the amount of urinary beta 2-microglobulin excreted. These results suggest that the prognosis for cadmium-exposed subjects with proximal tubular dysfunction is unfavorable. The mortality rate tended to become higher as the severity of renal dysfunction progressed.

[Study of an outbreak of itai-itai disease]

We studied an outbreak of itai-itai disease in the Jinzu River basin, in Toyama, Japan. One hundred and fifty females recognized as itai-itai disease patients till by 1990 were studied for the ages and years of onset and residence in the cadmium-polluted area. 1. Cases were recognized from as early as 1929, increased gradually to the peak of 1955-1959 and rapidly decreased up to the 1970s. 2. It was found that the later the patients was born, the younger the age of onset, though there was no difference of ages of onset between the cases born in the 1910s and the cases born from 1920. 3. The onset of itai-itai disease was most frequently seen at 50-59 years of residence in the cadmium-polluted area. It was found that the later a person started to inhabit the cadmium-polluted area, the shorter the period of residence in the cadmium-polluted area up to onset of itai-itai disease. 4. Comparing the patients who inhabited the cadmium-polluted area from birth and those who had moved there from non-polluted areas, the age of onset was higher in the latter, but there were no significant differences in the period of residence up to onset. From these findings, it appeared that itai-itai disease was not caused by aging, but by cadmium exposure starting from the 1910s.

Urinary trehalase activity as an indicator of kidney injury due to environmental cadmium exposure

One hundred and seventy-eight subjects, patients with Itai-itai disease and their family members, aged 12-87 years living in a cadmium (Cd)-polluted area in the Jinzu River basin (Cd-exposed group) and 176 controls (control group) were examined. In the Cd-exposed group urinary trehalase increased with increasing age, urinary beta 2-microglobulin (beta 2-m) and retinol-binding protein. Although urinary cadmium was higher in the Cd-exposed group, no particular correlation was found between urinary trehalase and urinary cadmium. Seventeen men and 11 women showed raised urinary trehalase activities despite normal values of urinary beta 2-m (less than 300 micrograms/g.creatinine), suggesting that urinary trehalase increases earlier than urinary beta 2-m. In 19 patients with Itai-itai disease included in the Cd-exposed group, urinary trehalase decreased with decreasing reciprocal of serum creatinine, suggesting that urinary trehalase decreases in the most advanced cases of chronic cadmium nephropathy due to reduced tubular cell mass.