A study on the prevalence of hepatitis B surface antigen among Chinese adult males in Singapore.

A study was conducted in Singapore on 8829 Chinese men aged 35 years or more to determine whether the prevalence of hepatitis B surface antigen (HBsAg) positivity is associated with the source from which the subjects were recruited, or with occupation as an indicator of socioeconomic status. The HBsAg prevalence rates were significantly different (p less than 0.0001) among the five source groups: 8.3% in healthy blood donors, 7.8 in other healthy subjects, 9.2 in non-hepatic outpatients, 10.3 in hospital non-hepatic patients who were not gravely ill, and 11.2 in hospital non-hepatic patients who were gravely ill. After statistical adjustment by multiple logistic regression for age and occupation, the odds ratio (using 'other healthy subjects' as the reference group) ranged from 0.98 (95% CL = 0.65-1.47) for healthy blood donors to 1.42 (95% CL = 0.95-2.12) for hospital non-hepatic patients who were gravely ill. The HBsAg prevalence rates were also significantly different (p less than 0.0001) among occupations: 8.5% in professional, technical and administrative personnel, 9.7 in clerical, sales and services personnel, 10.3 in agricultural and factory workers and unskilled labourers, and 10.5 among the unemployed and retired. After statistical adjustment for age and source groups, the odds ratio (using professional, technical and administrative subjects as the reference group) ranged from 1.07 (95% CL = 0.99-1.17) for the unemployed and retired subjects, to 1.19 (95% CL = 0.93-1.53) for agricultural and factory workers and unskilled labourers.

Cardiovascular diseases in Chinese, Malays, and Indians in Singapore. II. Differences in risk factor levels.

STUDY OBJECTIVE: The aim of the study was to examine cardiovascular risk factors to see how these might explain differences in cardiovascular disease mortality among Chinese, Malays, and Indians in the Republic of Singapore. DESIGN: The study was a population based cross sectional survey. Stratified systematic sampling of census districts, reticulated units, and houses was used. The proportions of Malay and Indian households were increased to improve statistical efficiency, since about 75% of the population is Chinese. SETTING: Subjects were recruited from all parts of the Republic of Singapore. SUBJECTS: 2143 subjects aged 18 to 69 years were recruited (representing 60.3% of persons approached). There were no differences in response rate between the sexes and ethnic groups. MEASUREMENTS AND MAIN RESULTS: Data on cardiovascular risk factors were collected by questionnaire. Measurements were made of blood pressure, serum cholesterol, low and high density lipoprotein cholesterol, fasting triglycerides and plasma glucose. In males the age adjusted cigarette smoking rate was higher in Malays (53.3%) than in Chinese (37.4%) or Indians (44.5%). In both sexes, Malays had higher age adjusted mean systolic blood pressure: males 124.6 mm Hg v 121.2 mm Hg (Chinese) and 121.2 mm Hg (Indians); females 122.8 mm Hg v 117.3 mm Hg (Chinese) and 118.4 mm Hg (Indians). Serum cholesterol, low density lipoprotein cholesterol and triglyceride showed no ethnic differences. Mean high density lipoprotein cholesterol in males (age adjusted) was lower in Indians (0.69 mmol/litre) than in Chinese (0.87 mmol/litre) and Malays (0.82 mmol/litre); in females the mean value of 0.95 mmol/litre in Indians was lower than in Chinese (1.05 mmol/litre) and Malays (1.03 mmol/litre). Rank prevalence of diabetes for males was Indians (highest), Malays and then Chinese; for females it was Malays, Indians, Chinese. CONCLUSIONS: The higher mortality from ischaemic heart disease found in Indians in Singapore cannot be explained by the major risk factors of cigarette smoking, blood pressure and serum cholesterol; lower high density lipoprotein cholesterol and higher rates of diabetes may be part of the explanation. The higher systolic blood pressures in Malays may explain their higher hypertensive disease mortality.

Driving experience and the risk of traffic accident among motorcyclists.

In a case-control study on the risk of traffic accidents among motorcyclists in Singapore, we demonstrated an inverse monotonic relationship between accident risk and driving experience. As compared to drivers with less that 1 yr of driving experience, the odds ratios (adjusted for race, age and frequency of riding) for those with driving experience of 1-4, 5-9 and 10 yr or more were 0.60, 0.50 and 0.36, respectively. We propose that intensive in-circuit training of learner motorcyclists should replace the conventional on-the-road training on the basis that the former serves to increase their driving experience without subjecting the learner motorcyclists to the risk of sustaining road accident.

Blood cholinesterase levels among agricultural workers in four Asian countries.

In this study whole blood cholinesterase activities were determined (tintometric method) of agricultural pesticide users exposed to organophosphorus compounds in Indonesia, Malaysia, Sri Lanka and Thailand. Analysis of the data demonstrated a universal relationship between cholinesterase levels and the time between the last exposure to organophosphorus compounds and the day of blood collection for cholinesterase determination. It is suggested that it takes approximately 5 days before whole blood cholinesterase levels revert to their normal values. No relationship between whole blood cholinesterase levels and the sex of pesticide users was demonstrated except in Sri Lanka where female sprayers had lower values. It is suggested that these lower values are associated with the anaemic status of female agricultural workers. No relationship between whole blood cholinesterase level and age was demonstrated. The measurement of pre-exposure cholinesterase values is essential for comparison of values after pesticide application.

Stomach cancer incidence in a cohort of fishermen in Singapore.

A retrospective cohort study of 279 Chinese fishermen in Singapore was undertaken to examine the possibility of an elevated incidence of stomach cancer. The fishermen as a group had a greater than twofold excess in stomach cancer relative to Chinese men of similar age and over the same calendar years in Singapore, but the difference was not statistically significant. On further examination it was revealed that the four stomach cancer cases were observed among the subgroup of divers. The standardized incidence ratio for the divers was 4.3, which was significantly greater than unity. There was no evidence of an increased risk for cancer of any other site (lung, nasopharynx and liver) in this cohort. Dietary factors are suggested as a possible explanation for the observation of an increased risk for stomach cancer among fishermen, but larger studies are required to test this hypothesis.

Mercury in scalp hair of healthy Singapore residents.

Two hundred and twenty-five hair samples (150 Chinese, 44 Malays and 31 Indians) from healthy residents not occupationally exposed to mercury were analyzed by cold vapour atomic absorption spectrophotometry to determine their total, inorganic and organic mercury levels. The arithmetic means of total mercury levels in hair were 6.1, 5.2 and 5.4 ppm for the Chinese, Malays and Indians, respectively. Factors contributing to the amount of mercury in hair, including consumption of fish and marine products, use of traditional ethnic medicines, artificial hair waving, age, sex and ethnicity were analyzed. Fish consumption, sex and ethnicity are factors found to contribute significantly (p less than 0.05) to mercury levels in hair.

Atomic absorption spectrophotometric microdetermination of total mercury in undigested biological samples.

The influence of reaction time upon stannous (II) chloride as a reductant in the cold-vapor atomic absorption spectrophotometric method was investigated. In this comparative study, virtually all operating conditions, including volumes and chemicals used, were made identical except for the redesigning of the reaction vessels. The use of a reaction mixing time of 2 minutes (TR method), rather than immediate bubbling with aspiration (IL method) of total mercury from undigested biological samples, has several advantages. There is an average 4.5-fold increase in sensitivity of peak height readings with virtually no loss of mercury vapor from the reaction vessel by diffusion. Using the TR method also eliminated interaction of mercury with the matrices investigated, viz., undigested blood, undigested saliva, undigested urine, and digested hair samples. The average recovery for the TR method was superior to the IL method, 99.3 +/- 3.2% vs. 84.7 +/- 3.3%, p less than 0.05. In addition, mercury concentrations determined with the TR method were identical using either peak area or peak height readings. It was also found that concentrations determined using either the formulae given by Magos and Clarkson (4) and Farant et al. (5) or an aqueous calibration curve were equivalent. Only 0.2-1.0 mL of biological samples was needed for each analysis in the study.

Changing patterns of community health university research in Singapore during 1970-1979.

PIP: During the last decade, tremendous changes have occurred in health status and patterns of health care in Singapore. These changes have presented great opportunities for the Department of Social Medicine and Public Health to conduct research into a wide variety of topics of vital interest to community health. Subjects studied include health problems of urbanization, especially those related to industrial health, highrise living, and traffic accidents; health consequences of changing lifestyles particularly those related to smoking and alcohol; the changing epidemiology of communicable and noncommunicable diseases, particularly those related to smoking and alcohol; the changing epidemiology of communicable and noncommunicable diseases, particularly those relating to hypertension, cancer, tuberculosis and venereal diseases; new aspects of health care delivery especially those pertaining to the aged; Chinese medicines and primary health care; health education techniques and priorities, with special respect to teachers, mothers, and workers, and road users; and medical problems and social changes, including the erosion of the extended family system and the wider practice of abortion. The enormous coverage of research activities carried out by the department is seen in the publication figures by staff and postgraduate students of our department (1970, 5; 1971, 6; 1972, 7; 1973, 23; 1974, 24; 1975, 29; 1976, 28; 1977, 18; 1978, 14; 1979, 23). It is obvious therefore that in this short paper we can only hope to select some research projects for discussion. Among ongoing major projects which did not receive mention in the text of this paper are the Study of Occupational Health Hazards of Firemen, the Prospective Cohort Study on the relationship of Hepatitis B Carrier Status and the development of Hepatoma, a study of transplacental passage of lead and problems of Child Rearing in Highrise Apartments.^ieng

Blood cadmium levels in Malaysian pregnant women.

Blood cadmium levels in Malaysian pregnant women were determined. There was no significant urban-rural difference in mean blood cadmium levels.

The development of and recent trends in occupational health in Singapore.

Occupational health in Singapore developed largely over the past 10-15 years. The rapid progress in general awareness, personnel, services, education and research, is described. The role of Singapore as a regional centre for education, consultancy service and research is increasing. The development and functions of government agencies, the University, statutory boards and voluntary organizations are discussed. Common occupational diseases include pneumoconiosis, metal poisoning, occupational dermatitis, noise-induced deafness and psychological disturbances. Evidence suggests gross under-reporting of these conditions. About 150 research papers concerning occupational health in Singapore have been published so far. There can be little doubt that the importance of the discipline will gather even greater momentum in Singapore in the future.

Lead exposure patterns and parameters for monitoring lead absorption among workers in Singapore.

A study was carried out among 1414 workers in 14 industries in Singapore to determine the extent of their exposure to lead and their lead absorption. High-level exposure situations found included secondary lead smelting, followed by mixing of lead salt stabilizers and lead storage battery manufacture. Other exposure situations included those relating to lead welding, print shop, wire splicing, leaded paint manufacture, fire-fighting and soldering. Early cases of lead absorption could not be detected by clinical signs alone. Other parameters such as blood lead and delta-aminolaevulinic acid dehydratase had to be used. There was good correlation between a rise in blood lead and a fall in delta-aminolaevulinic acid dehydratase levels.

Influence of age on VDU work.

This study was conducted in a data processing centre with intensive work load. The keying speed and typing errors were monitored daily by the management for performance appraisal. The average keying speed of the operator was about 10,000 key strokes per hour. A survey on the subjective symptoms and feelings of fatigue of 68 experienced data entry operators revealed that there was no significant difference as far as physical health was concerned for the 42 young(18-30 years old) and 26 older operators (31-45 years old). However, there was a higher prevalence of visual strain and musculo-skeletal complaints among the older workers. A follow up study on the performance of 22 operators for 5 years showed that there was a significant reverse correlation between age and keying speed, r = 0.74 (p less than 0.01). A lower but significant correlation was also noted for typing errors and age, r = 0.50, (p less than 0.05). These results suggest that age has a significant influence on speed, accuracy and health of VDU operators. When discussing the ergonomics approach to VDU work, attention must be paid to the effect of this factor.

Effects of ageing on taxi driving.

The effects of ageing on taxi driving were studied on 256 drivers from the largest taxi co-operative in Singapore. 123 of the drivers were below 45 years (28-44 yrs.) while the other 133 were 45 years or older (45-63 yrs.). The older drivers had a significantly higher prevalence of glucosuria (p less than 0.05) and poor visual acuity (p less than 0.01). In addition, 31.6% of the older drivers had elevated blood pressure as compared to 21.9% of the younger drivers. Psychophysiological test scores for mean reaction times (p less than 0.01), psychomotor dexterity and eye-hand co-ordination (p less than 0.01) and reaction discrimination errors (p less than 0.05) were also significantly poorer for the older drivers. In spite of these findings, the working hours, the average mileage driven, and the accident records of the older drivers were comparable to that of the younger drivers, thus suggesting that age does not play a major role in affecting the work capacity or accident liability of the drivers.

Mental status of residents in old people's homes.

As part of an intensive survey of institutionalized elderly in 5 non-government homes for the aged in Singapore, mental health assessment of the residents was carried out systematically. Among 359 respondents, 30.1% often felt sad or cried often. Sleep disturbances affected 47.7% of the total respondents. Females were more prone to both depression and insomnia even after controlling for age difference; about 50% of the females aged 60-74 years and 70% of the females aged 75 years and above had frequently experienced these problems. A review of the literature on mental health and suicidal behaviour among the elderly is also presented.

An epidemiological study of lung functions and hearing acuity in Singapore firemen.

This study was conducted on 506 firemen in Singapore. Interviews, pulmonary function tests and audiometry were conducted. With regard to pulmonary function, the results showed that forced vital capacity (FVC) increased up to the age of 25-30 years for both Chinese and Malays. Both FVC and forced expiratory volume in one second (FEV1.0) increased with standing height over the whole age range studied. The mean values of FVC and FEV1.0 were higher in Chinese. It was also found that the FEV1 of the subjects in the study showed a greater decline in rate with age than other workers studied by the authors previously. The hearing threshold of 83 fire fighters showed a prominent upward shift of 6-8 KHz at ages 20-30. This upward shift was more pronounced in the right ear. The implications of the findings are discussed and a comparison with results of other similar studies in other countries is made.

Electrocardiographic findings in 204 residents of homes for the aged.

Electrocardiograms from 204 subjects aged 60 and above, residing in homes for the aged, were analysed. 13% had evidence of cardiovascular disease. 55% of the electrocardiograms showed at least one abnormality. At least 10% of electrocardiograms showed left atrial hypertrophy, first degree atrioventricular block, right bundle branch block, pathologic Q waves, ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities. Increase of age from 60 to 100 years was associated with prolongation of PR and QT intervals, but shortening of the RR interval.

Transit time analysis of the forced expiratory spirogram of fire-fighters.

Analysis of the forced expiratory spirogram using time as the primary variable had been shown to be a promising method for detecting small airway dysfunction. This paper describes its application on 277 fire-fighters. Spirometry was performed when the fire-fighters were at rest and had not been fighting fires for the previous 24 hours. The best of three spirograms were used to compute the mean transit time (MTT). Through multiple linear regression analysis, age was the only factor that was significantly associated with MTT. The regression coefficients for age of smoking and non-smoking fire-fighters were nearly equal (0.011 and 0.010 seconds per year respectively). When 28 pairs of smoking and non-smoking fire-fighters were matched for age, duration of service, ethnicity and job groups, their average MTT were not significantly different. An increasing age-adjusted mean MTT was seen among the non-smoking fire-fighters with job groups requiring greater exposure to fire-fighting. Normal smokers had been shown to have a much greater regression coefficient for age on MTT when compared to normal nonsmokers. When compared with this study, the regression equation for MTT of non-smoking fire-fighters differed markedly from that of normal non-smokers and approached that of normal smokers. Coupled with the 'dose-response' relationship shown in the non-smoking fire-fighters, this study provides evidence of pulmonary dysfunction in fire-fighters. This pulmonary dysfunction may be localised in the small airways.

Non-fatal injuries among motorcyclists treated as in-patients in a general hospital.

In a study of the injury pattern among 198 motorcyclists who sustained road traffic accidents from 1986-1987, it was found that the following body regions, in decreasing order of frequency, were involved: external region (surface or integumentary lesion of any body region) with 285 injuries, extremities and bony pelvis with 118 injuries, head and face with 94 injuries, chest with 10 injuries, abdomen with 3 injuries, and spine with 2 injuries. Despite the extensive use of crash helmets, head injuries were still a common and severe form of injury resulting from traffic accidents, indicating the need for improvement of safety standards of crash helmets. Lower limb injuries, mostly fractures of bones and dislocation of joints, are also amenable to prevention through design of leg protection devices. Injuries to other body regions are difficult to prevent and other measures such as legal and administrative means, should be fully exploited in accident prevention.

Risk factors for birth defects in Singapore: a case control study.

To explore possible risk factors for birth defects, a matched case-control study was carried out at Kandang Kerbau Hospital in Singapore from January 1986 to December 1988. Cases and controls were selected from livebirths born in that hospital during that period. Cases were babies who were clinically detected as having defects at birth and the diagnosis reconfirmed at 6 weeks post partum. Each case was matched to a control by maternal age, ethnic background of mother, the same class of maternity ward and time of delivery. Five hundred and seventy-two matched pairs were accrued for the study. The parents of both cases and controls were interviewed at 6 weeks post partum. Information on the medical and birth history of both mother and baby was obtained from medical records. Using conditional logistic regression analysis to adjust for potential confounders, the strongest risk factors for birth defects were family history of birth defects (OR 3.3; 95% CI 1.8-6.4) and parents having a previous abnormal baby (OR 2.4; 95% CI 1.1-5.3). Other notable risk factors included drug history during pregnancy (OR 1.2; 95% CI 0.8-2.0), the ingestion of traditional medicine during pregnancy (OR 1.4; 95% CI 1.0-2.0), injuries or accidents during pregnancy (OR 2.2; 95% CI 1.5-3.2) and maternal diabetes mellitus (OR 1.3, 95% CI 0.3-7.1). Mothers in professional occupations (OR 1.4, 95% CI 0.7-2.6) and those in production occupation (OR 1.2, 95% CI 0.9-1.7) had an increased risk for birth defects compared to housewives.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of work injuries in eight Asian countries.

This study is based on a survey conducted in Hong Kong, Indonesia, Korea, Malaysia, the Philippines, Singapore, Sri Lanka and Thailand on occupational injuries during the years 1975-1980. The number of work accidents have risen rapidly during this period in all of the 8 countries studied. In the case of Thailand, the total number of work injuries increased four fold from 1975-1978, whereas, in Singapore it has almost doubled in 6 years. The number of permanent disablement nearly trebled in Korea, and the Philippines for the year 1967-1980. The largest percentage of accidents are lost-time injuries in all of the 8 countries. Thailand had a three fold increase in lost-time injuries whilst in Hong Kong the figure doubled. Six out of the 8 countries indicated that the building construction industry had the largest number of fatal accidents, followed by the manufacturing industry.