Managing chemical hazards

Historically, concerns about water quality have been driven by the need to reduce risks of exposure to waterborne pathogens. Indeed, microbiologically unsafe drinking water still poses major risks in many parts of the world. For example, the World Health Organization (WHO) estimates that 9 percent of the 6.3 million deaths of children under age five globally are caused by diarrhea, much of it attributable to waterborne pathogens.1, 2 However, in their efforts to reduce this infectious disease burden, well-intentioned donor organizations have sometimes inadvertently introduced new risks into communities by failing to account for potential chemical contamination. An example is programs initiated by the United National Children’s Fund in the 1970s to reduce childhood diarrheal mortality rates by replacing local surface water supplies with groundwater extracted from shallow tube wells. The wells were not tested for arsenic, but many were highly contaminated, leading to what one author called “the largest poisoning of a population in history”.3 Thus, even though eliminating or decreasing exposure to pathogens remains the foremost goal of many water supply programs, attention to potential chemical exposures also is critical.