Public health wonder or unwitting vector of disease: the challenge of delivering safe supplies

Abstract

The stark contrast captured in the title for this article is an accurate reflection of the range of possibilities that come with taking responsibility for supplying drinking water to the public. Provision of safe drinking water is widely and justifiably accepted as one of the most important technological and public health achievements of the past 150 years. Yet, drinking water that is distributed widely to the public provides a notoriously effective vehicle for the spread of a variety of microbial diseases. Evidence for both extremes is compelling. Throughout the affluent world, waterborne bacterial diseases like cholera and typhoid, which were leading causes of death during the industrial revolution of the 1800s and early 1900s, had been virtually eliminated by the 1950s. Yet, in the rest of the world, the World Health Organization estimates that: ‘1.8 million people die every year from diarrhoeal diseases (including cholera); 90% are children under five, mostly in developing countries and 88% of diarrhoeal disease is attributed to unsafe water supply, inadequate sanitation and hygiene’ (World Health Organization 2004). Even in affluent nations, drinking water outbreaks have occurred more often, with more disastrous consequences than many water professionals appreciate (Hrudey and Hrudey 2004). In 1993, an outbreak of cryptosporidiosis in Milwaukee, USA spread through the drinking water supply was estimated to have infected over 400,000 consumers, hospitalized approximately 4,400 consumers (Corso et al. 2003) and resulted in approximately 50 deaths over the following 2 years among immune-compromised patients who became infected (Hoxie et al. 1997). In 2000, an outbreak of enterohemorrhagic Escherichia coli (E. coli O157:H7) and Campylobacter spp. made over 2000 ill, 65 were hospitalized and seven consumers were killed by the contaminated drinking water of Walkerton, Canada, a town of approximately 5,000 residents (O’Connor 2002a). These and a surprising number of other serious drinking water disease outbreaks have been caused by microbial pathogens. Although exposure to high levels of a few chemicals via drinking water has caused serious health effects in specific circumstances, microbial pathogens remain the most direct, tangible and pervasive risk to human health via drinking water exposure. Among the limited number of chemicals that are well-documented to cause human illness by S. Hrudey (&) University of Alberta, Edmonton, AB, Canada e-mail: steve.hrudey@ualberta.ca