08 June 2010 - Compiling available datasets from developed and developing countries, studies by the Food and Agriculture Organization of the United Nations (FAO) suggest a positive relationship between gross domestic product (GDP) per capita and daily food waste production. This comes as no surprise given that rising incomes allow for higher allocations to purchase food items, including animal proteins. As a next step, these data were coupled to garbage collection figures, again a GDP per capita dependent variable, in order to generate rough estimations of the proportions of urban food waste not collected and thus available to opportunistic feeders or scavengers, including birds, rats, mice, stray/feral dogs and cats, and also wild canidae approaching town areas in search of food items. This scavenging for food waste represents a public health risk of growing importance to mega-cities around the world.
By 2025, for instance, in mega-cities hosting anywhere from 14 to 27 million people, it is estimated that urban food waste available to scavengers will range from 28 to 70 percent of total food waste. This translates-depending on population, incomes, eating habits and other factors-into an estimated 1,400 and 3,100 daily tonnes of urban food wastes (see table). Most of these cities are located in south Asia and Africa.
The successful colonization of urban environments by wildlife (synurbanisation) may have significant implications for disease flare-up. Incidentally, most emerging infectious disease agents are also circulating in wildlife and are zoonotic. It is expected that rising incomes and population growth will continue to fuel urban development in major cities, and in situation where this translates into a piling up of urban food wastes, this may contribute to the emergence of zoonotic diseases.
Apart from the common food and water related disease agents that cause infections in humans (Salmonella, E. coli or Cholera), there are also specific diseases such as rabies and alveolar ecchinococcosis that may be passed by stray dogs to humans, while originating from wild foxes that have encroached urban environments because of the available food waste here and/or because of ecological dynamics forcing animals out of their usual, natural habitats.