Food safety is an essential public health issue for all countries. Foodborne diseases due to microbial pathogens, biotoxins, and chemical contaminants in food represent serious threats to the health of thousands of millions of people. Serious outbreaks of foodborne disease have been documented on every continent in the past decades, illustrating both the public health and social significance of these diseases. Consumers everywhere view foodborne disease outbreaks with ever-increasing concern. Outbreaks are likely, however, to be only the most visible aspect of a much broader, more persistent problem. Foodborne diseases not only significantly affect people's health and well-being, but they also have economic consequences for individuals, families, communities, businesses and countries. These diseases impose a substantial burden on health-care systems and markedly reduce economic productivity. Poor people tend to live from day to day, and loss of income due to foodborne illness perpetuates the cycle of poverty.
The integration and consolidation of food industries and the globalization of the food trade are changing the patterns of food production and distribution. Food and feed are distributed over far greater distances than before, creating the conditions necessary for widespread outbreaks of foodborne illness. In a recent crisis, more than 1500 farms in Europe received dioxin-contaminated feed from a single source over a two-week period. Food produced from animals given this contaminated fodder found its way onto every continent within weeks. The international spread of meat and bonemeal prepared from cattle affected by bovine spongiform encephalitis (BSE) needs no further description. The full economic consequences of such incidents and the anxiety raised among consumers are still being assessed.
Other factors account for the emergence of food safety as a public health issue. Increasing urbanization leads to greater requirements for transport, storage and preparation of food. In developing countries, food is often prepared by street vendors. In developed countries, up to 50% of the food budget may be spent on food prepared outside the home. All these changes lead to situations in which a single source of contamination can have widespread, even global consequences.
The globalization of the food trade offers many benefits to consumers, as it results in a wider variety of high-quality foods that are accessible, affordable and safe, meeting consumer demand. The global food trade provides opportunities for food-exporting countries to earn foreign exchange, which is indispensable for the economic development of many countries. However, these changes also present new challenges to safe food production and distribution and have been shown to have widespread repercussions on health.
Food safety programmes are increasingly focusing on a farm-to-table approach as an effective means of reducing foodborne hazards. This holistic approach to the control of food-related risks involves consideration of every step in the chain, from raw material to food consumption. Hazards can enter the food chain on the farm and can continue to be introduced or exacerbated at any point in the chain.
Although significant progress has been made in many countries in making food safer, thousands of millions of people become ill each year from eating contaminated food. The emergence of increased antimicrobial resistance in bacteria causing disease is aggravating this picture. The public is increasingly aware of the risks posed by pathogenic microorganisms and chemical substances in the food supply. The introduction of new technologies, including genetic engineering and irradiation, in this climate of concern about food safety is posing a special challenge. Some new technologies will increase agricultural production and make food safer, but their usefulness and safety must be demonstrated if they are to be accepted by consumers. Furthermore, the evaluation must be participatory, transparent and conducted using internationally agreed methods.
Until recently, most systems for regulating food safety were based on legal definitions of unsafe food, enforcement programmes for the removal of unsafe food from the market and sanctions for the responsible parties after the fact. These traditional systems cannot respond to existing and emerging challenges to food safety because they do not provide or stimulate a preventive approach. During the past decade, there was a transition to risk analysis based on better scientific knowledge of foodborne illness and its causes. This provides a preventive basis for regulatory measures for food safety at both national and international levels. The risk-based approach must be backed by information on the most appropriate and effective means to control foodborne hazards.
The dangers of foodborne pathogenic microorganisms have been known for decades. The risk of milk-borne transmission of tuberculosis and salmonellosis was recognized early in the twentieth century, and control by pasteurization was an early intervention. Similarly, problems with botulism were managed by controlling the application of heat to low acid foods in hermetically sealed containers. Despite remarkable advances in food science and technology, foodborne illness is a rising cause of morbidity in all countries and the list of potential foodborne microbial pathogens keeps increasing. Furthermore, foodborne illness is a major cause of preventable death and economic burden in most countries. Unfortunately, most countries have limited data on foodborne disease and its impact on public health.
It is only recently that the burden of food contamination and foodborne disease have been systematically assessed and quantified. Studies on foodborne disease outbreaks in the USA, Australia, Germany, and India have confirmed the enormity of the problem with millions being affected or dying from foodborne diseases. The data indicates that up to 30% of the population in industrialized countries may be affected by foodborne illness each year. The global incidence of foodborne disease is difficult to estimate, but in 1998 it was estimated that 2.2 million people, including 1.8 million children, died from diarrhoeal diseases.
The economic cost associated with foodborne diseases caused by microorganisms has only recently been estimated. In the US, the costs of human illness due to seven specific pathogens have been estimated to range between US $6.5 billion to $34.9 billion. The medical costs and value of lives lost from five foodborne infections in England and Wales were estimated at UK £300-700 million annually in 1996. The cost of an estimated 11,500 cases of food poisoning per day in Australia was calculated at AUD $2.6 billion annually. Yet on the basis of per capita income, the economic burden on people in India affected by an outbreak of Staphylococcus aureus food poisoning was found to be higher than in case of a similar outbreak in the US.
Major outbreaks involving E.coli and Salmonella have highlighted problems with food safety and increased public anxiety that modern farming systems, food processing and marketing may not provide adequate safeguards for public health. While our understanding of the ecology of food poisoning organisms and the environment in which they may grow and survive has increased, our ability to control some of these organisms has declined. This may be due in part to modified production practices, lack of control of hazards at the farm level, industry difficulties in controlling hazards during production, growing demand for fresh foods, the trend towards minimal processing of foodstuffs and longer shelf-life for many foodstuffs. For example, Salmonella persists as a major cause of food poisoning and its incidence is on the rise. Salmonella Typhimurium DT 104 is widely distributed in cattle herds and is resistant to several antibiotics. The incidence of this organism is on the increase, as is the number of antibiotic resistant isolates. More than one third of people infected by this organism require hospitalization with approximately three percent of cases being fatal.
Enterohaemorrhagic Escherichia coli O157:H7 has emerged as a significant foodborne pathogen, and has been highly publicised through major outbreaks of disease. E.coli O157:H7 was first recognized as a pathogen in 1982, but progress to identify reservoirs and sources of the organism was initially hampered by a lack of sufficiently sensitive detection methods. Other strains of enterohaemorrhagic E.coli (EHECs) pose a particular problem in that they are impossible to differentiate culturally from other flora in the gut. Identification requires advanced techniques.
E.coli O157:H7 serves as an example of the limitation of the present knowledge and understanding of many pathogens and how they contaminate food. In the past few decades a range of microorganisms have emerged as potential causes of foodborne disease. Several relatively unknown bacteria have been identified as major causes of foodborne illness e.g. Campylobacter jejuni, Vibrio parahaemolyticus, and Yersinia enterocolitica may cause foodborne illness. As microorganisms have the ability to adapt, modified modes of food production, preservation and packaging have resulted in altered food safety hazards. For example, organisms such as Listeria monocytogenes, and to a lesser extent Clostridium botulinum, have emerged and re-emerged because of changes in the way high-risk foods are packaged and processed.
A range of protozoa and viruses may also infect food e.g. Cryptosporidium parvum, Toxoplasma gondii, Clonorchis sinensis, Norwalk virus, and hepatitis A. The effective prevention and control of these organisms requires widespread education and possibly new initiatives such as HACCP being introduced at primary production level.
Chemical hazards are also a significant source of foodborne illness, although the effect is often difficult to link to a particular food and may occur long after consumption. In particular, there have been long-standing concerns about the chemical safety of food due to misuse of pesticides during food production and storage, resulting in the occurrence of undesirable residues. Similarly, heavy metal contaminants can enter food through soil or water or food contact material, as can other environmental contaminants such as PCBs. All can lead to acute or chronic illness.
More recently, contamination from dioxins entering the animal feed supply has highlighted both the importance of controlling the whole food chain and the international concerns about food safety systems. Misuse and illegal use of food additives create their own food safety problems. Phthalates in infant formulae, substances in food with oestrogenic activity, and veterinary drug residues, etc have also heightened public concern.
These problems are not confined to food produced on land. They also include algal toxins in fish and the widespread use of chemicals in fish farming. Mycotoxins are another group of highly toxic or carcinogenic chemical contaminants of biological origin produced by certain species of fungi. Five important mycotoxins are aflatoxins, ochratoxins, fumonisins, zearalenone, and trichothecenes. Crops such as peanuts, corn, pistachio, walnuts, copra are susceptible to mycotoxin contamination. Aflatoxins are among the most studied mycotoxins, and the relationship between aflatoxin ingestion and primary liver cancer is well established. Almost all plant products can serve as substrates for fungal growth, and subsequently mycotoxin contamination of human food and animal feed. Animal feed contaminated with mycotoxins can result in the carry-over of toxins through milk and meat to consumers.
While the importance of chemicals hazards is well recognized, our understanding of the effect of chemicals in food intolerances and allergies, endocrine system disruption, immunotoxicity, and certain forms of cancer are incomplete. Further research is necessary to determine the role of chemicals in foods in the etiology of these diseases. In developing countries, little reliable information is available on the exposure of the population to chemicals in food.
Consumers, particularly in developing countries, are often exposed to wilful adulteration of their food supply. This can lead to health hazards and to financial losses for the consumer. Adulteration of milk and milk products, honey, spices, edible oils, and the use of colours to mask product quality to cheat the consumer are quite common. Although risks associated with adulteration are usually low, such episodes invoke public outrage and anger as it violates public trust in the integrity of the food supply. With 60-70% of the income of middle class families in developing countries being spent on food, food adulteration can impact heavily on both the family budget and the health status of the family members.
Genetically Modified Organisms (GMO) and Novel Foods
Modern biotechnology, also referred to as genetic engineering or genetic manipulation, involves transfer of hereditary material (DNA, RNA) from one organism to another in a way that cannot be achieved naturally i.e. through mating or cross breeding. Genetic engineering can now transfer the hereditary material across species boundaries. This can broaden the range of genetic changes that can be made to food and can expand the spectrum of possible food sources.
The accelerating pace of developments in modern biotechnology has opened a new era in food production and this may have a tremendous impact on world food supply systems. However, there are considerable differences of opinion among scientists about the safety, nutritional value and environmental effects of such foods.
Overall, it is argued that the consequences of some gene transfer methods are less predictable when compared to those of traditional plant breeding methods and considerable scientific evidence will be needed to clear these foods from points of view of nutrition, food safety and impact on the environment. The revolutionary nature of modern biotechnology and its likely impact on world food resources has created worldwide interest and debate among scientists, consumers and industry as well as among policy makers at national and international levels.
Urbanization, Nutrition and Food Security
In 2020, the world population is projected to reach 7.6 billion, an increase of 31% over the mid-1996 population of 5.8 billion. Approximately 98% of the population growth occurring during this period will take place in developing countries. While urbanization is a global phenomenon, it has been estimated that between the years 1995 and 2020 the developing world's urban population will double, reaching 3.4 billion. Such population growth poses great challenges to world food security and food systems. Further extension of improved agriculture and animal husbandry practices; use of measures to prevent and control pre- and post-harvest losses; more efficient food processing and distribution systems; introduction of new technologies including the application of biotechnology, and others will have to be exploited to increase food availability to meet the needs of growing populations.
Growing urbanization and associated changes in the way food is produced and marketed have led to a lengthening of the food chain and potential for introducing or exacerbating foodborne hazards.
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