Recent developments and trends

Although we often speak of ‘the’ environmental problem, what we in fact have is a large family of problems affecting the geophysical system, ecosystems and human health and varying enormously in magnitude, nature and temporal and spatial scale. There is a similar diversity in how these problems are framed conceptually by individual societies, under the influence of myriad historical, cultural and social factors. It is therefore instructive to start out by considering a few historical examples of the way in which perceptions of environmental issues have changed over time.
In 19th-century Western Europe the main focus of what we today term environmental hygiene was on the agents of infectious disease. The classic anecdote concerns the London doctor John Snow, who in 1849 suspected that the prevalence of cholera in the vicinity of Broad Street was related to a mixing of sewerage and drinking water. His advice, correctly, was to take the handle off the Broad Street water pump. Since then there has been a thorough-going separation of sewerage and drinking water supply systems in industrial countries, where the incidence of (drinking) water-borne infections has consequently plummeted. Measured in so-called disability-adjusted lost years the burden of disease associated with drinking water, sanitary facilities and poor personal hygiene is now about 0.1% of what it once was. Indeed, in industrialised countries infectious diseases associated with drinking water now scarcely feature on the environmental agenda. The situation in the developing world is quite different, though. Here substandard drinking water and sewerage systems and poor standards of personal hygiene are responsible for 7.6% of the burden of disease (Murray and Lopez 1997; Prüss and Havelaar 2001).