Health impact assessment of marine emissions in Pearl River Delta region.

Global marine vessels emissions are adversely affecting human health particularly in southeast Asia. But health burdens from both ocean- and river-going vessels in Pearl River Delta (PRD) regions are not quantified. We estimated the potential health impacts using pooled relative risks of mortality and hospital admissions in China, and the model derived concentrations of sulfur dioxide (SO2), particulate matter (PM10), nitrogen dioxide (NO2) and ozone (O3) due to vessels emissions. SO2 concentrations due to marine emissions in Hong Kong were 13.6 µg m⁻³ compared with 0.7 µg m⁻³ in PRD regions that were far from the marine vessels. In PRD regions, the estimated annual numbers (per million people) of excess deaths from all natural causes and hospital admissions from cardiorespiratory causes attributable to SO2, NO2, O3 and PM10 combined from marine emissions were 45 and 265 respectively. Marine emission control measures could contribute a large reduction in mortality and hospital admissions in PRD regions especially in Hong Kong.

Effect of influenza on cardiorespiratory and all-cause mortality in Hong Kong, Singapore and Guangzhou.

1. Using a common modelling approach, mortality attributable to influenza was higher in the two subtropical cities Guangzhou and Hong Kong than in the tropical city Singapore. 2. The virus activity appeared more synchronised in subtropical cities, whereas seasonality of influenza tended to be less marked in the tropical city. 3. High temperature was associated with increased mortality after influenza infection in Hong Kong, whereas relative humidity was an effect modifier for influenza in Guangzhou. No effect modification was found for Singapore. 4. Seasonal and environmental factors probably play a more important role than socioeconomic factors in regulating seasonality and disease burden of influenza. Further studies are needed in identifying the mechanism behind the regulatory role of environmental factors.

Residues of persistent organic pollutants (POPs) in human milk in Hong Kong.

Data on pesticide body load in the south China region are scarce. Here, we report the concentrations of 24 persistent organic pollutants (POPs), in 10 pools of human milk samples, collected at 2-6weeks postpartum from 238 primiparous women living in Hong Kong and south China, who participated in the 2002-2003 WHO exposure study. Residues were determined by gas chromatography with electron capture detector and confirmed by gas chromatography with mass spectrometry. The mean levels of alpha-HCH (mean 0.6ngg(-1) fat), beta-HCH (940ngg(-1) fat), gamma-HCH (1.8ngg(-1) fat), dieldrin (1.0ngg(-1) fat) and HCB (21.8ngg(-1) fat) were much lower than the 1985 estimates. Mean levels of alpha-HCH, gamma-HCH, dieldrin, cis-heptachlor-epoxide (0.7ngg(-1) fat), sum-chlordane (6.1ngg(-1) fat), trans-nonachlor (12.0ngg(-1) fat), BDE 47 (1.9ngg(-1) fat) and sum PBDE (3.4ngg(-1) fat) were comparable to the international median levels of the 15 other countries participating in the 2002-03 WHO exposure study. Hong Kong had the highest level of beta-HCH, possibly a residual effect of previous high exposures in the 1970s. Body loads of beta-HCH and chlordane were lower among mothers with younger age while mothers born in mainland China had lower levels of beta-HCH, cis-heptachlor-epoxide, oxy-chlordane and trans-nonachlor. Levels of toxaphene, endrin, endosulfan, bromcyclene and nitrofen were not detected in all or almost all of the milk pools. Continuous monitoring of POPs in human milk, especially beta-HCH, is needed for surveillance and interpretation of time trends, and for linkage to strict enforcement of agricultural regulations.

Part 5. Public health and air pollution in Asia (PAPA): a combined analysis of four studies of air pollution and mortality.

BACKGROUND: In recent years, Asia has experienced rapid economic growth and a deteriorating environment caused by the increasing use of fossil fuels. Although the deleterious effects of air pollution from fossil-fuel combustion have been demonstrated in many Western nations, few comparable studies have been conducted in Asia. Time-series studies of daily mortality in Asian cities can contribute important new information to the existing body of knowledge about air pollution and health. Not only can these studies verify important health effects of air pollution in local regions in Asia, they can also help determine the relevance of existing air pollution studies to mortality and morbidity for policymaking and environmental controls. In addition, the studies can help identify factors that might modify associations between air pollution and health effects in various populations and environmental conditions. Collaborative multicity studies in Asia-especially when designed, conducted, and analyzed using a common protocol-will provide more robust air pollution effect estimates for the region as well as relevant, supportable estimates of local adverse health effects needed by environmental and public-health policymakers. SPECIFIC OBJECTIVES: The Public Health and Air Pollution in Asia (PAPA*) project, sponsored by the Health Effects Institute, consisted of four studies designed to assess the effects of air pollution on mortality in four large Asian cities, namely Bangkok, in Thailand, and Hong Kong, Shanghai, and Wuhan, in China. In the PAPA project, a Common Protocol was developed based on methods developed and tested in NMMAPS, APHEA, and time-series studies in the literature to help ensure that the four studies could be compared with each other and with previous studies by following an established protocol. The Common Protocol (found at the end of this volume) is a set of prescriptive instructions developed for the studies and used by the investigators in each city. It is flexible enough to allow for adjustments in methods to optimize the fit of health-effects models to each city's data set. It provides the basis for generating reproducible results in each city and for meta-estimates from combined data. By establishing a common methodology, factors that might influence the differences in results from previous studies can more easily be explored. Administrative support was provided to ensure that the highest quality data were used in the analysis. It is anticipated that the PAPA results will contribute to the international scientific discussion of how to conduct and interpret time-series studies of air pollution and will stimulate the development of high-quality routine systems for recording daily deaths and hospital admissions for time-series analysis. METHODS: Mortality data were retrieved from routine databases with underlying causes of death coded using the World Health Organization (WHO) International Classification of Diseases, 9th revision or 10th revision (ICD-9, ICD-10). Air quality measurements included nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with aerodynamic diameter < or = 10 microm (PM10), and ozone (O3) and were obtained from several fixed-site air monitoring stations that were located throughout the metropolitan areas of the four cities and that met the standards of procedures for quality assurance and quality control carried out by local government units in each city. Using the Common Protocol, an optimized core model was established for each city to assess the effects of each of the four air pollutants on daily mortality using generalized linear modeling with adjustments for time trend, seasonality, and other time-varying covariates by means of a natural-spline smoothing function. The models were adjusted to suit local situations by correcting for influenza activity, autocorrelation, and special weather conditions. Researchers in Hong Kong, for example, used influenza activity based on frequency of respiratory mortality; researchers in Hong Kong and Shanghai used autoregressive terms for daily outcomes at lag days; and researchers in Wuhan used additional smoothing for periods with extreme weather conditions. RESULTS AND DISCUSSION: For mortality due to all natural (nonaccidental) causes at all ages, the effects of air pollutants per 10-microg/m3 increase in concentration was found to be higher in Bangkok than in the three Chinese cities, with the exception of the effect of NO2 in Wuhan. The magnitude of the effects for cardiovascular and respiratory mortality were generally higher than for all natural mortality at all ages. In addition, the effects associated with PM10 and O3 in all natural, cardiovascular; and respiratory mortality were found to be higher in Bangkok than in the three Chinese cities. The explanation for these three findings might be related to consistently higher daily mean temperatures in Bangkok, variations in average time spent outdoors by the susceptible populations, and the fact that less air conditioning is available and used in Bangkok than in the other cities. However, when pollutant concentrations were incorporated into the excess risk estimates through the use of interquartile range (IQR), the excess risk was more comparable across the four cities. We found that the increases in effects among older age groups were greater in Bangkok than in the other three cities. After excluding data on extremely high concentrations of PM10 in Bangkok, the effect estimate associated with PM10 concentrations decreased in Bangkok (suggesting a convex relationship between risk and PM10, where risk levels off at high concentrations) instead of increasing, as it did in the other cities. This leveling off of effect estimates at high concentrations might be related to differences in vulnerability and exposure of the population to air pollution as well as to the sources of the air pollutant. IMPLICATIONS OF THE STUDY: The PAPA project is the first coordinated Asian multicity air pollution study ever published; this signifies the beginning of an era of cooperation and collaboration in Asia, with the development of a common protocol for coordination, data management, and analysis. The results of the study demonstrated that air pollution in Asia is a significant public health burden, especially given the high concentrations of pollutants and high-density populations in major cities. When compared with the effect estimates reported in the research literature of North America and Western Europe, the study's effect estimates for PM10 were generally similar and the effect estimates for gaseous pollutants were relatively higher. In Bangkok, however, a tropical city where total exposures to outdoor pollution might be higher than in most other cities, the observed effects were greater than those reported in the previous (i.e., Western) studies. In general, the results suggested that, even though social and environmental conditions across Asia might vary, it is still generally appropriate to apply to Asia the effect estimates for other health outcomes from previous studies in the West. The results also strongly support the adoption of the global air quality guidelines recently announced by WHO.

Epidemiology of SARS in the 2003 Hong Kong epidemic.

1. The temporal and spatial evolution of the SARS epidemic in Hong Kong is described. 2. Estimates of key epidemiological distributions and their stability over the course of the epidemic are derived. 3. The characteristics of those who contracted the disease are determined including factors associated with the likelihood of mortality as a result of SARS coronavirus infection.

Spatial clustering of SARS in Hong Kong.

1. Geographic information system (GIS) can be applied during an acute infectious disease outbreak to reveal new geospatial information in addition to standard field epidemiological analyses. 2. When applied in real time during the onset and evolution of an epidemic, GIS can monitor and enhance understanding of the transmission dynamics of an infectious agent, thereby facilitating the design, implementation and evaluation of potential intervention strategies.

Prevalence of SARS-CoV antibody in all Hong Kong patient contacts.

The near absence of transmission (seroprevalence=0.19%) resulting in asymptomatic infection in this representative high-risk group of close contacts indicates that the prevailing SARS-CoV strains in Hong Kong almost always led to clinically apparent disease.

Community psycho-behavioural surveillance and related impact on outbreak control in Hong Kong and Singapore during the SARS epidemic.

1. The promotion of personal protective health practices must take into account background perceptions of risk and psychological responses in the community-at-large. 2. Population psycho-behavioural factors in Hong Kong and Singapore are shown to be an important potential vector for the transmission of an infectious agent. 3. Comparative psycho-behavioural surveillance and analysis can yield important insights into generic versus population-specific issues that could be used to inform, design and benchmark public health infection control measures.

Influenza-associated hospitalisation.

The disease burden associated with influenza includes not only acute respiratory diseases but also cerebrovascular disease, ischaemic heart disease and diabetes mellitus.

DDT levels in human milk in Hong Kong, 2001-02.

High levels of p,p'-DDT were detected in Hong Kong breast milk sampled in 1976 and 1985. Monitoring DDT levels in human breast milk in this region is important to identify trends in exposure. As part of the 2002-03 WHO/EURO coordinated exposure study, the concentrations of DDT and its metabolites were determined in 10 pooled milk samples classified by geographic origin and dietary history, comprising milk samples from 238 primiparous mothers giving birth in Hong Kong. Analysis was performed by Gas Chromatography (GC) with electron capture detector and confirmed by GC/Mass Spectrometry. The sum-DDT concentration (range: 0.92-2.05 mg/kg fat) was age-dependent and indicated a decreasing trend since the 1970s. Mothers who recently came from mainland China had higher p,p'-DDT to p,p'-DDE ratios, suggesting a more recent exposure compared to women mainly residing in Hong Kong. The average Hong Kong sum-DDT level (1.50 mg/kg fat) was among the highest of the contemporary levels (range: 0.12-1.97 mg/kg fat; median: 0.40 mg/kg fat) in the 16 countries/regions participating in the 2002-03 WHO/EURO exposure study. This is probably due to the previous extensive DDT exposure and continuing use of DDT in agriculture in mainland China. Despite the apparent decrease of DDT body load over 30 years, the environmental health hazard from DDT contamination in the Pearl River Delta region remains a concern. Measures to eradicate illegal use of DDT in mainland China and regular food monitoring programs are needed in the region. Despite the presence of DDT and other persistent organic pollutants in human breast milk, breastfeeding should continue to be strongly supported for its life-long benefits to infants.

Agreement between breast milk dioxin levels by CALUX bioassay and chemical analysis in a population survey in Hong Kong.

Chemically-activated luciferase gene expression (CALUX) bioassay and gas chromatography/mass spectrometry (GC/MS) are used to determine dioxin levels in food and humans. Valid measures of the agreement between the two methods would improve interpretation of bioassay results. Paired breast milk samples from 250 mothers, as 11 pooled samples, were analysed by GC/MS for total WHO-TEQ (7 polychlorinated dibenzo-para-dioxins, 10 polychlorinated dibenzofurans and 12 dioxin-like polychlorinated biphenyls) and as individual samples by CALUX. Mean difference between total WHO-TEQ (weighted by TEF system derived in 1997) and mean CALUX-TEQ in each pool was 1.6 pg/g fat (95% CI: 0.7, 2.4), indicating a statistically significant overestimation of CALUX-TEQ compared to WHO-TEQ, probably due to the presence of Ah-receptor agonists. CALUX estimated toxicity of 13 pg/g fat was greater than the WHO-TEQ by 0.9, 3.1 and 0.3 pg/g fat for mothers from Hong Kong, mainland China and overseas territories, respectively. When the 2005 TEF system was applied, a reduction of 14-26% in the WHO-TEQ and a larger but less disperse discrepancy between WHO-TEQ and CALUX-TEQ (3.9 pg/g fat, 95% CI: 3.5, 4.4) were observed. Our study suggested that the mothers' place of residence explained the discrepancy between CALUX-TEQ and WHO-TEQ and should be considered in inter-country comparisons for CALUX-TEQ. For regulatory purposes bioassays for detecting quantitative dioxin contents in any setting must be combined with adequate extraction, clean-up and validation with WHO-TEQs. The larger difference between the two measurements after using the new TEF system warrants further investigation.

Cost of tobacco-related diseases, including passive smoking, in Hong Kong.

BACKGROUND: Costs of tobacco-related disease can be useful evidence to support tobacco control. In Hong Kong we now have locally derived data on the risks of smoking, including passive smoking. AIM: To estimate the health-related costs of tobacco from both active and passive smoking. METHODS: Using local data, we estimated active and passive smoking-attributable mortality, hospital admissions, outpatient, emergency and general practitioner visits for adults and children, use of nursing homes and domestic help, time lost from work due to illness and premature mortality in the productive years. Morbidity risk data were used where possible but otherwise estimates based on mortality risks were used. Utilisation was valued at unit costs or from survey data. Work time lost was valued at the median wage and an additional costing included a value of USD 1.3 million for a life lost. RESULTS: In the Hong Kong population of 6.5 million in 1998, the annual value of direct medical costs, long term care and productivity loss was USD 532 million for active smoking and USD 156 million for passive smoking; passive smoking accounted for 23% of the total costs. Adding the value of attributable lives lost brought the annual cost to USD 9.4 billion. CONCLUSION: The health costs of tobacco use are high and represent a net loss to society. Passive smoking increases these costs by at least a quarter. This quantification of the costs of tobacco provides strong motivation for legislative action on smoke-free areas in the Asia Pacific Region and elsewhere.

Demographic and lifestyle factors associated with dioxin-like activity (CALUX-TEQ) in human breast milk in Hong Kong.

Maternal exposure to dioxins and related compounds before conception may affect the health of the fetus. To identify factors affecting dioxin body load in Hong Kong, in 2002, total dioxin-like activity was estimated in 250 individual milk samples at 2-6 weeks postpartum, from a representative group of primiparous mothers, aged 18-42 years (mean 29 +/- 5 years), by a chemically activated luciferase expression (CALUX) bioassay. Associations between the CALUX-TEQ and 20 socio-demographic and dietary variables were examined separately in mothers younger than 30 years (n = 114) and 30 years or older (n = 119), by multiple linear regression analysis. CALUX-TEQ (mean 14.5 +/- 5.8 pg/g fat) significantly increased by 0.4-0.5 pg/g fat for every year of the mother's age. Mothers born in Guangdong province of China had a significantly higher CALUX-TEQ. Higher seafood consumption (older mothers; p = 0.07) and having a female baby (younger mothers; p = 0.002) were associated with a higher maternal CALUX-TEQ level. Age was the strongest factor affecting human dioxin levels in Hong Kong. Birthplace and residence are important indicators of variations in exposure to environmental pollution in the Asia Pacific region. Temporal trends in body loads of dioxins remain to be established and continuous monitoring of dioxins in humans and foods is necessary as a precautionary approach to guide environmental control measures and prevent exposure to infants.

Seroprevalence of IgG antibodies to SARS-coronavirus in asymptomatic or subclinical population groups.

We systematically reviewed the current understanding of human population immunity against SARS-CoV in different groups, settings and geography. Our meta-analysis, which included all identified studies except those on wild animal handlers, yielded an overall seroprevalence of 0.10% [95% confidence interval (CI) 0.02-0.18]. Health-care workers and others who had close contact with SARS patients had a slightly higher degree of seroconversion (0.23%, 95% CI 0.02-0.45) compared to healthy blood donors, others from the general community or non-SARS patients recruited from the health-care setting (0.16%, 95% CI 0-0.37). When analysed by the two broad classes of testing procedures, it is clear that serial confirmatory test protocols resulted in a much lower estimate (0.050%, 95% CI 0-0.15) than single test protocols (0.20%, 95% CI 0.06-0.34). Potential epidemiological and laboratory pitfalls are also discussed as they may give rise to false or inconsistent results in measuring the seroprevalence of IgG antibodies to SARS-CoV.