Poor sanitation presents a public health problem in underdeveloped parts of the world, where it is common practice to relieve oneself without utilizing a latrine. This practice contributes to disease and mortality in these areas, but it has not been clear how to increase sanitation coverage.

To investigate the effects of alternative strategies to increase the use of latrines, researchers from Yale University and the University of Maryland examined the effects of different latrine-marketing strategies in rural Bangladesh communities.

The researchers used a cluster-randomized trial in 380 rural communities within the Tanore district of northwestern Bangladesh. This region was selected because it has low sanitation coverage compared to other parts of rural Bangladesh. When the researchers began their study, only half the participating households had regular access to a hygienic latrine.

The 380 communities were randomly assigned to one of several sanitation programs. The first option, called the Latrine Promotion Program, was a community motivation and health information campaign. The second approach involved subsidy vouchers for the purchase of latrines, along with the Latrine Promotion Program. The third option was a supply-side market access intervention that connected villagers with latrine suppliers and provided information on latrine quality and availability. The final condition was a control group, which received no interventions.

The researchers found that communities that received only the Latrine Promotion Program ended up with similar levels of access to latrines as the control group. The supply-side intervention did not lead to a statistically significant increase in access to hygienic latrines either. In contrast to this, the researchers found that communities that received the subsidy in addition to the Latrine Promotion Program were 14.3 percent more likely to have access to a hygienic latrine, a statistically significant finding. For communities like these in rural Bangladesh, subsidies in combination with a consciousness-raising program may be effective for increasing access to hygienic latrines.

In addition to examining access to hygienic latrines, the researchers also studied utilization of these sanitation facilities. Similar to findings regarding access, the data on utilization showed that the combination of the Latrine Promotion Program and the subsidy was the most effective way to reduce defecation in the environment. They found that this combined program yielded a 22 percent reduction in adults’ non-latrine evacuation when compared to the control group.

In economics, a social multiplier effect occurs when the social climate affects an individual’s behaviors. The researchers conducting this study were curious about possible social multiplier effects in latrine usage. To probe this, the communities receiving subsidies were further broken down by neighborhood, with each neighborhood either receiving a low, medium, or high density of latrine subsidy vouchers. They found that individual households were more likely to utilize their latrine subsidy voucher if neighboring households also received subsidy vouchers. This finding was only significant when low-density areas were compared to high-density areas.

This social multiplier effect also held true for latrine use. The researchers found that individuals living in high-density subsidy areas were more likely to use latrines compared to those from the low-density subsidy areas.

The investigators say that their findings are consistent with literature showing the importance of price as a barrier to adoption of health products. Their findings also show the importance of social influence, as the multiplier effect suggests that as more individuals engage in the practice of latrine usage, it will become more normalized and widespread in the community at large.

The authors note several limitations of their study, including generalizability to other populations, examination of only one level of subsidy, and use of household self-reporting. Of the limitations they acknowledge, the most compelling is the lack of a measure for health outcomes related to latrine usage. It’s a slight disconnect that occurs in this study: though the researchers present latrine use as a public health issue, they examine it as an economic issue.

While examining sanitation utilization from an economic standpoint may be a valid paradigm, it is not necessarily consistent with the goals that the researchers lay out in their abstract. For this reason, the policy prospect of increasing latrine use via a concerted subsidy and awareness-raising campaign should also be examined in terms of health outcomes.

Science, 2015. DOI: 10.1126/science.aaa0491 (About DOIs).