# **1 Introduction**

Poor health stands out as a common feature of life in less developed countries (LDCs). Several factors contribute to the persistence of the problem, including poor availability and high cost of good quality health care, insufficient investment in prevention, and the frequent reliance on ineffective and sometimes unnecessarily expensive treatments (see Dupas 2012, Dupas and Miguel 2017, and Tarozzi 2016 for recent reviews). Information campaigns on health risks are sometimes seen as an appealing tool in environmental and health policy. This is because they can be relatively inexpensive to run when compared to other options such as investments in infrastructure or public health measures needed to eliminate the risk at its root. Some health conditions are in fact preventable if appropriate risk-mitigating behavior is adopted. However, governments in LDCs may lack the resources or the political will to carry out even simple information campaigns (let alone campaigns that provide reports specific to each household), and information alone is often not sufficient to promote positive changes in behavior.

This paper describes the results of a randomized controlled trial (RCT) carried out in Sonargaon sub-district of Bangladesh, to examine the impact of different ways of selling a contaminant test on risk-avoiding behavior. Households were offered tests that measure tube well water contamination with arsenic, a common occurrence in the area. The primary objective was to determine whether a novel mode of test delivery, leveraging within-village solidarity networks, could increase health-protective behavioral responses relative to the standard delivery of private information to well users. In a first group of 49 randomly selected villages, field tests were offered at a (subsidized) price of BDT45 (about USD0.60 at current nominal exchange rates, close to the price of one kg of rice in Dhaka), an amount estimated to be just enough to cover for the salary of the surveyors hired for the project.<sup>1</sup> In an additional subset of 48 villages, surveyors received incentives to offer tests—at the same price of BDT45—to _groups_ of buyers: group members were asked to sign an informal agreement according to which those with safe wells would share their well with others in the group whose well water was found to be unsafe. The agreement was not binding legally, but the prior was that it would increase rates of switching from unsafe sources through two mechanisms: first, by making sharing more likely through a form of soft-commitment and, second, by facilitating the spread of information about the safety of wells, thereby facilitating the identification of safe options within the village. While a large literature documents the importance of village networks to cope with shocks, including health shocks (see Fafchamps 2011 for a review), we are not aware of other work studying how informal networks can help in creating opportunities to reduce environmental health risk.<sup>2</sup> The study also examines the impact of a second mode of information delivery, in the form of metal placards attached to the well spout to convey test results. Budget limitations, however, only allowed the inclusion of 15 villages in this experimental arm, reducing statistical power. In these villages,

> 1Throughout the paper, Bangladesh Takas (BDT) are converted into United States Dollars (USD) using a nominal exchange rate of 80BDT/USD, and a PPP exchange rate of 23.145, as indicated in World Bank (2015, Table 2.1).

> 2In broadly related work, Goldberg et al. (2018) show that peer networks can be leveraged to improve screening for tuberculosis in Indian urban areas.

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