Environmental Hazards and Intervention CMED 6912
Foodwaste and Landfills in Hong Kong
By Pauline Leong
Problems of Foodwaste in Hong Kong
In 2011, there was about 3,200 tonnes foodwaste produced daily in Hong Kong while around 2,995 tonnes of food waste (94% of foodwaste) are disposed at landfills everyday (See Figure 1) and (See Figure 2) .
This biodegradable waste gives great pressure to waste disposal and also leads to rapid depletion of the limited landfill void space.
Landfills in Hong Kong
Solid waste could be handled by incineration, landfills and recycling. However, there is only one incinerator commissioned now. Landfills are the major way to manage solid waste in Hong Kong (See Figure 3) . There are about 13,458 tonnes of solid waste disposal at landfills in 2011, of which 8,996 tonnes (about 67%) are municipal solid waste (See Figure 4) . Most of the municipal solid waste in Hong Kong is composited by putrescible (See Figure 5) .
Figure3: Recovery of municipal solid waste in 2011 of Hong Kong
Figure 4: Disposal of solid waste in landfills in 2011
Figure 5: Composition of Municipal Solid Waste (MSW) of Hong Kong in 2011
There were 16 landfill sites which were closed and with their current use as recreational use. Currently, there are about 3 strategic landfills and all are operated in New Terrorities namely West New Terrorities Landfill, North East New Terrorities Landfill, South East New Terrorities Landfill (See Figure 6)  which commenced its operation from 1993-1995. The capacity of landfills will reach its maximum capacity in 2013 (See Figure 7)  as projected while there is call for extension of landfills causing great protest and controversy especially on the environmental and health hazards brought to the community.
Landfills have its pros and cons to be employed for waste disposal. Firstly, it is quite a cheap disposal method. Secondly, the waste was used to fill the quarries prior toreclamation. Thirdly, the landfill gas contributes to renewable energy supply. However, there are a number of drawbacks incurred. Firstly, the production of carbon dioxide, methane, sulphur, nitrogen as well as volatile organic compounds from anaerobic decomposition of organic matters causes air pollution. Secondly, the leachate and run
off causes water pollution. Thirdly, some proven or suspected carcinogens or teratogens such as benezene, dioxins, arsenic, nickel, vinyl chloride, chromium, polycyclic aromatic hydrocarbon etc. would emit from the sites. Last, landfill sites will attract animal vectors (seagulls, flies, rats) for some communicable disease and with problems of odour, dust, road traffic problems to the communities near-by .
Potentials Effect on Health Outcomes
Apart from the health hazards of waste management workers by occupational exposure, the health hazards of long term environmental exposure to people living next to landfill sites are under major concern. The potential health effects of landfills including air, water and soil contamination is summarized by Figure 8 . It includes cancer risk, cardiovascular disease, respiratory disease, headache, gastroenteritis,nausea, fatigue, as well as skill irritation . Relationship on cancer and birth defects by living near landfills are under extensive research in the UK and US in the 1980s [10,11].
Figure 8: Potentials Health Impacts of pollution by landfills
Scientific Evidence on Health Impacts
Figure 9: Potential Cancer Risks by Emission Toxin at Landfills
In 1995, Goldberg et. al conducted a study about the cancer risk of the people living in communities next to the Miron Quarry municipal solid waste landfill in Montreal, Quebec, Canada from 1981-1988 indicating a higher risk for lung, liver, stomach, prostate cancers in male, and cervical, uterine, and stomach cancer in female (See Figure 9). However, there is an absence of measurement of exposure which hampers the credibility of evidence . Moreover, a detailed UK study does not indicate that the occurrence of cancer is associated with living close to the landfill sites [12,13]. Similarly, there are a lot of literature about potential negative health effects on populations living next to a landfill but there is an absence of evidence in supporting the emission of toxic substance highlighted would cause cancer at environmental levels as much of the research based on occupational or accidental exposure at high levels or the experiment of the carcinogenicity of those substance from animal studies . Thus, the evidence for causal relationship between emission of toxic substance and cancer is inconclusive.
2) Birth defect and reproductive disorders
The association of reproductive defeats and landfills has been extensively researched mainly covering the lower birth weight (< 2500 g), spontaneous abortion, fetal and infant mortality as well as the occurrence of birth defects (Figure 10) . Case studies of Love Canal site (1965 to 1978) and Lipari Landfill in New Jersey (1971-75) indicated that the low birth rate is highly related with time and volume of dumping at a large waste disposal site . A study conducted in California also supported the neonatal deathsand low birth weight were found to associate with time and volume of waste disposal in landfills. However, two large scale multiple site case-control studies in the USA found there was no association with birth weight and landfills .
Figure 10: Risk of adverse birth outcomes in populations living near landfill sites
A large geographical study of study landfill sites has further supported that the association between residence near
by a landfill site and the prevalence of birth defects in Great Britain from 1982 to 1997 with large samples [13,14]. There was a small increase in the risk level of birth defects of families with newborns living within 2 km away from landfill sites. However, the study was not able to indicate whether the association are causal, or whether they might be others confounding factors that could not be addressed fully. The UK study further supports significantly heightened risk for a number of birth defects, including hypospadias, abdominal wall defects,neural tube defects, epispadias, as well as surgical correction of gastroschisis and expohalos.
Knowledge Gap on Scientific Evidence
Several studies have proven excess risk of about two to three times for certain congenital anomalies and low birth weight of families living near landfill sites. However, it is difficult to draw conclusions on the causality with the problems of small sample size, exposure misclassification, the existence of confounders and reporting bias from the participants. Most importantly, no comprehensive and longterm landfill and health impact studies has been done in Hong Kong while the excess risks of congenital anomalies and low birth weight living near landfill sites was not big enough to support further policy intervention. Further research effort is essential to identify effects of potential data artefacts and confounding on the associations with landfills. Most of the research mainly focuses on the emission to air. However, more future research into other emission such as land, water and other waste management facilities could be helpful.
Local Case Study: Nuisance of Bad odors from Landfill of Tseung Kwan O
Although there is no available evidence on the health hazards from landfills in Hong Kong, people in communities near landfills are often disturbed by the bad odors and its immediate negative health impacts. For example, the residents of Lohas Park hold frequent complaints the bad odors from the landfill site of Tsuen Kwan O in Hong Kong (See Figure 11) . Landfill gas odors are created by bacterial or chemical processes. The potential sources of landfill odors include sulfides, ammonia. Many people are affected by the offensive odors emitted from a landfill with the problem of nausea or headaches. Some even claimed being awakened in the midnight and disturb their sleep .
Figure 11: Distance between Lohas Park and Tseung Kwan O landfill site
Effects on environment
Despite the health problems, the emission of greenhouse gases from landfill such as methane and carbon dioxide, those contributing to global warming and climate change e.g. heat wave . Besides, the noise pollution and traffic problem generate by the heavy-duty vehicles moving in and out in the landfill area.
Interventions to reduce the hazards
In concern of the potential hazards on human living nearby landfills, possible interventions to reduce the hazard would be mainly lying on 1) reduction of food waste and 2) promotion of waste recycling.
1) Reduce production of food waste
The pilot study of urban metabolism of Hong Kong shown that the per capita food, water and materials consumption have risen starting from 1970s by 20%, 40% and 149% respectively(See Figure 12).
Figure 12: Trends in resource consumption in Hong Kong from 1971-1997
Different forms of pollution have escalated with this increasing affluence, materialism, total air emissions, carbon dioxide outputs, municipal solid wastes and sewage discharges have raised by 30%, 250%, 245% and 153% respectively (See Figure 13) .
Figure 12: Growth of pollution in Hong Kong from 1971-1997
Education and awareness campaigns on consumerism and environmental hazards could be promoted to help people in building more sustainable environments by reducing waste disposal on avoidable food consumption. Avoiding dissipate of food by banquets, institutes (school canteens or hostel) and domestic use could be promoted by incentives, such as requesing “Less Rice Please” in participating restaurants can enjoy $1 incentive which promoted by Greeners Action . Likewise, choice for different portion size, such as BIJAS vegetarian in theCentennial Campus of The University of Hong Kong , which provides buffet style services and charges by weight, in order, reduces the generation of foodwaste. Moreover, the unconsumed foodwaste by markets, supermarkets and restaurants could be reused in serving dishes in feeding the deprived populations through Food Bank and Food Canteens of Non-Government Organization, such as People’s Food Bank of St. James’ Settlement .
2) Promotion foodwaste recycling
As foodwaste may not be totally avoidable in both production and consumption, foodwaste recycling could be promoted to reduce the putrescible in landfills. Negative impacts of “foodwaste” can be turned into positive benefits which is useful to the environment. Nitrogen, potassium and phosphorus fertilizers are essential to agricultural production and the prices of these materials have double increased within the past decade. Foodwaste contains phosphorus that is a valuable resources and essential plant nutrient . Other valuable resources, including energy, can be recovered from foodwaste via aerobically or anaerobically composting or incinerated energy generation .
1) Reuse, recycling and reducing the wastes (see figure 14) 
The implementations of waste recycling policies in Hong Kong still have much room for improvements. Here are some recommendations which could be implemented by governments:
Ø Implementation of high landfills charging scheme
Ø Setting up a centralized center for recycling solid waste
Ø Provide easily accessible drop-off recyclable material points near residential area
Ø Promoting innovative demolition methods
Ø Reusing the reusable waste as donations to NGOs
2) Implementation of health assessments and nuisance caused by landfills sites
The information from the landfills study done by Environmental Protection Department of Hong Kong in 2001 was outdated for reference. Besides, the study mainly focuses on ecological impact which health impact on long term exposure has been ignored. A collaboration between the academy, Environmental Protection Department and Health Authorities is recommended in conducting large scale survey in providing local evidence on the relationship between landfills, short-term health effects including nuisance and psychological discomfort. Currently, electronic nose was installed by EPD at residential area near-by the landfills to assess the level of air pollution. However, the perception and influence of odor are quite subjective and could not be evaluated through the machine.
3) Hazards of Long term Exposure and psychological discomfort
Current evidence could not provide convincing information to support health hazards caused by long term exposure at low risk. For example, cancer may develop after quite a long term exposure with its latency period. With the high density of population and limited living area in Hong Kong, much of the population is exposed to the hazards of landfill sites. e.g. Lohas Park near-by Tsueng Kwan O Landfill site. Long term longitudinal studies are essential to follow up health conditions of residents living next to landfills.
In conclusion, the problems of foodwaste and hazards of landfills have to be resolved by a multi-prolonged approach through collaborations of government departments, NGOs, concern groups and the academy through continuous surveillance on health hazards, research, polices and education with government dedication. The public should not overuse and misuse the natural resources especially in food to prevent the hazards to their health.
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