HOW DOES SANITATION AND WATER SUPPLY INFRASTRUCTURE AFFECT CHILD MORTALITY?

Responsible researcher: Bruno Benevit

Original title: Watersheds in Child Mortality: The Role of Effective Water and Sewerage Infrastructure, 1880 to 1920

Authors: Marcella Alsan and Claudia Goldin

Intervention Location: United States

Sample Size: 2440 municipalities-years

Sector: Healthcare

Variable of Main Interest: Infant Mortality Rate

Type of Intervention: Basic sanitation

Methodology: Difference in differences

Summary

Infant mortality rates have reduced significantly over the last 150 years. This improvement is often attributed to technological advances in terms of health and health services, as well as the implementation of public policies. The objective of this article was to analyze the impact of the creation of a sanitation and water supply district in the Boston region on the infant mortality rate between 1880 and 1920. Using difference-in-differences methodology across several specifications, the authors identified that the joint implementation of both types of infrastructure was fundamental for the reduction in the infant mortality rate observed in the period.

1. Policy Problem

Infant mortality was the main cause of low life expectancy at birth in the United States and much of Europe. In the US state of Massachusetts, infant deaths accounted for 20.4% of all deaths in 1880, while births accounted for just 2.5% of the total population at the time (Alsan and Goldin, 2019). However, between 1870 to 1930, infant mortality plummeted from about 1 in 5 to 1 in 16 white babies in the United States—in Massachusetts, deaths of children under five declined sevenfold.

The period coincides with the implementation of public water and sanitation systems. Sanitation reduces fecal-oral transmission of pathogens by removing excrement from drinking water sources, decreasing human contact with feces, and limiting exposure to fly-borne gastrointestinal diseases. Clean water interventions remove impurities, making water safe for consumption and hygiene. These interventions were considered by several authors as fundamental to explaining the downward trend in child morbidity observed, highlighting the importance of this type of public policy.

2. Policy Implementation Context

At the end of the 19th century, the Boston metropolitan area was facing a major health crisis. Rapid population growth and unbridled industrialization have resulted in unsanitary conditions in the region's cities and municipalities. Sewer systems were primitive and often dumped untreated waste directly into rivers and Boston Harbor. This not only polluted water sources but also contributed to outbreaks of waterborne diseases such as cholera and typhoid fever. Furthermore, limited access to clean water exacerbates public health problems, as many communities relied on contaminated water sources.

However, the situation began to change with the implementation of proactive public policies. The creation of the Metropolitan Sanitation District (DSM) and the construction of sewage treatment and water supply systems were crucial steps in improving sanitary conditions. The DSM enabled efficient coordination between various municipalities to address the sewage problem, while water treatment systems made drinking water safe for consumption. Over the following years, child morbidity showed a significant reduction, indicating the importance of investing in sanitation infrastructure and clean water as vital components of public health and well-being in urban communities.

3. Assessment Details

The data used in this study was composed of a set of information bases related to water and sanitation interventions in the Boston metropolitan area. Primary data sources include annual reports from the State Board of Health, the Metropolitan Sanitation Commission, the Metropolitan Water District, and the Metropolitan Water and Sanitation Board. These reports detail the dates on which water and sanitation interventions were completed in different municipalities in the region, providing records on the implementation of public health services over time. Additionally, the data encompass county-level demographic and vitality information collected from the Massachusetts Secretary of State's annual vital statistics reports.

The main sample comprised a panel of 60 municipalities between the period 1880 and 1920, consisting of 2440 municipal-years. This sample included all municipalities within the immediate area of ​​the Boston Harbor basin, in addition to municipalities outside the immediate area of ​​Boston that were incorporated cities until 1895. Additionally, two coastal municipalities (Ipswich and Weymouth) and five with the largest 1880 populations (Attleboro, Clinton, Milford, Natick, and Peabody).

4. Method

To assess the impact of sanitation policies on health, outcome variables related to infant mortality were considered. The main variable of interest was the infant mortality rate (logarithmic), as well as mortality rates for other ages: under one, under two and over five years old. Therefore, the differences in the characteristics observed between the treated and control municipalities were initially evaluated.

As the main empirical strategy, the Difference in Differences (DID) method was used, assuming the condition of parallel trends in the trajectory of health outcome variables between the treated and control groups in case of non-occurrence of intervention by health infrastructure policies. water supply and sanitation. Several model specifications were presented, considering different sets of variables, fixed effects (of time and municipality) and temporal trends, in addition to count and linear models at the (non-logarithmic) level. Standard errors were clustered at the county level throughout the analysis.

As a robustness strategy, the authors analyzed possible concomitant effects. Analyzes were conducted to examine possible effects on population composition resulting from improved infrastructure, which could abruptly affect infant mortality rates from the immigration of wealthier individuals. Furthermore, heterogeneous effects were verified considering the period of the year (spring-summer and autumn-winter), population composition (municipal population growth rate, proportion of British foreigners, and proportion of Irish foreigners). The effects of interventions by category of disease causing death and on the non-infant mortality rate were also estimated. Finally, the study presents results with samples considering different groups of treated and control municipalities.

5. Main Results

Initial results demonstrated similarity in most characteristics between municipalities in both treated and control groups. In general, few changes were observed in mortality rates in the municipalities over the 9 years preceding the intervention.

The results of the main analysis indicated that the joint introduction of water supply and sewage systems caused a significant reduction of 33.6% in the infant mortality rate in the municipalities that underwent the intervention over the 41 years observed. When analyzed separately, the results indicated significant effects of lesser magnitude resulting from the implementation of sewage systems, while the water supply system did not show statistical significance. These results were consistent considering various model specifications.

Regarding the analyzes of heterogeneous effects, the results indicated that, as there was a significant reduction in infant mortality from gastrointestinal diseases (associated with improvements in basic sanitation), a less significant effect was identified in reducing deaths from respiratory diseases and non-significant effects on child mortality from tuberculosis and the non-infant mortality rate. The infant mortality rate showed significant effects when considering the period from April to September (spring-summer), and non-significant effects between October and March (autumn-winter), results consistent with the greater vulnerability of children to gastrointestinal diseases, more common in warmer periods.

In terms of relative gains related to socioeconomic conditions, the results indicate that municipalities with a greater share of Irish foreigners (at the time, more vulnerable) saw more significant reductions in the infant mortality rate compared to those with a greater share of British people. Additionally, municipalities with lower population growth showed significant effects of reducing the infant mortality rate, unlike half of the municipalities with higher population growth rates. The results remained significant considering different compositions of municipalities in the sample, indicating the robustness of the results.

6. Public Policy Lessons

This article conducted an analysis of the importance of basic sanitation infrastructure, focusing on water and sewage interventions, for reducing infant mortality in the Boston metropolitan area between the years 1880 and 1920. The results revealed that the implementation of systems Clean water and effective sanitation has played a key role in improving child health, accounting for around a third of the reduction in child mortality over 41 years.

The results of this study have significant implications for the formulation of public policies related to child health and basic sanitation infrastructure. They highlight the importance of investments in clean water and sanitation systems as effective measures to reduce child mortality. Furthermore, they highlight the need for comprehensive and coordinated approaches in the planning and implementation of sanitation infrastructure, especially in urban regions. These findings can guide future policy decisions and investment strategies that aim to improve children's health in urban contexts, both in the United States and in other parts of the world, where similar challenges persist.

References

ALSAN, M.; GOLDIN, C. Watersheds in Child Mortality: The Role of Effective Water and Sewerage Infrastructure, 1880–1920. Journal of Political Economy , vol. 127, no. 2, p. 586–638, apr. 2019.