by Daniel Gallardo Albarrán (Wageningen University)
Lack of access to clean water and sanitation facilities are still common across the globe. Simultaneously, infectious, water-transmitted illnesses are an important cause of death in these regions. Similarly, industrializing economies during the late 19th century exhibited extraordinarily high death rates from waterborne diseases. However, unlike contemporary developing countries, the former experienced a large decrease in mortality in subsequent decades which meant that deaths from waterborne diseases were totally eradicated.
What explains this unprecedented improvement? The provision of safe drinking water is often considered a key factor. However, the prevalence of waterborne ailments transmitted through faecal-oral mechanisms is also determined by water contamination and/or the inadequate storage and disposal of human waste. Consequently, doubts remain about efficacy of clean water per se to reduce mortality; this necessitates an integrative analysis considering both waterworks and sewerage systems.
My research adopts this approach by considering the case of Germany between 1877 and 1913 when both utilities were adopted nationally and crude death rates (CDR) and infant mortality rates (IMR) declined by almost 50 per cent. A quick glance at trends in mortality and the timing of sanitary infrastructures in Figure 1 suggests that improvements in water supply and sewage disposal are associated with better health outcomes. However, this evidence is only suggestive: Figure 1 only presents the experience of two cities and, importantly, factors outside public health investments — for example, better nutrition, improved infant care — may account for changes in mortality To study the link between sanitary improvements and mortality more systematically, I examine two new datasets containing information on various measures of mortality at city level (overall deaths, infant mortality and cause-specific deaths) and the timing when municipalities began improving water supply and sewage disposal.
The first set of results show that piped water reduced mortality, although its effects were limited given the absence of efficient systems of waste removal. Both sanitary interventions account for (at least) a fifth of the decrease in crude death rates between 1877 and 1913. If we consider the fall in infant deaths instead, I find that sewers were equally important in providing effective protection against waterborne illnesses, since improvements in water supply and sewage disposal explain a quarter of the fall in infant mortality rates.
I interpret these findings causally because both interventions had a persistent short-term impact on mortality instantaneously following their implementation, not before. As Figure 2 shows, CDR and IMR immediately decline following the construction of both waterworks and sewerage, and mortality exhibits no statistically significant trends in the years preceding the sanitary interventions (the reference point for these comparisons is one year prior to their construction). Furthermore, using cause-specific deaths I find that sanitary infrastructures are strongly associated with enteric-related illnesses, and deaths from a very different set of causes — homicides, suicides or accidents — are not.
The second set of results relates to the heterogeneous effects of sanitary interventions along different dimensions. I find that their impact on mortality are less universal than hitherto thought, since their effectiveness largely depended on local characteristics such as income inequality or the availability of female employment.
In sum, my research shows that the mere provision of safe water, is not sufficient to explain a significant fraction of the mortality decline in Germany at the turn of the 20th century. Investments in proper waste removal were needed to realize the full potential of piped water. Most importantly, the unequal mortality-reducing effect of sanitation calls for a deeper understanding of how local factors interact with public health policies. This is especially relevant today, as international initiatives, for example, the Water, Sanitation and Hygiene programmes led by UNICEF, aims to of promote universal access to sanitary services in markedly different local contexts.
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