Unintended consequences of development - bednets edition

Scholars supporting Randomized Control Trials (RCTs) have long advocated the use of bed-nets to keep out mosquitoes as a cost-effective way to fight malaria. They have invoked meta-studies on the use of bed-nets and its effectiveness in different environments to claim sufficient external validity to scale up the intervention.

In this context, the New York Times has an interesting story about the unexpected use to which anti-malaria bed-nets are being put in parts of Africa. It writes,

Nets... are widely considered a magic bullet against malaria — one of the cheapest and most effective ways to stop a disease that kills at least half a million Africans each year. But Mr. Ndefi and countless others are not using their mosquito nets as global health experts have intended. Nobody in his hut, including his seven children, sleeps under a net at night. Instead, Mr. Ndefi has taken his family’s supply of anti-malaria nets and sewn them together into a gigantic sieve that he uses to drag the bottom of the swamp ponds, sweeping up all sorts of life: baby catfish, banded tilapia, tiny mouthbrooders, orange fish eggs, water bugs and the occasional green frog... 

Across Africa, from the mud flats of Nigeria to the coral reefs off Mozambique, mosquito-net fishing is a growing problem, an unintended consequence of one of the biggest and most celebrated public health campaigns in recent years. The nets have helped save millions of lives, but scientists worry about the collateral damage: Africa’s fish. Part of the concern is the scale. Mosquito nets are now a billion-dollar industry, with hundreds of millions of insecticide-treated nets passed out in recent years, and many more on their way. They arrive by the truckload in poor, waterside communities where people have been trying to scrape by with substandard fishing gear for as long as anyone can remember. All of a sudden, there are light, soft, surprisingly strong nets — for free. Many people said it would be foolish not to use them for fishing...

The people don't use the mosquito nets for mosquitoes. They use them to fish... But the unsparing mesh, with holes smaller than mosquitoes, traps much more life than traditional fishing nets do. Scientists say that could imperil already stressed fish populations, a critical food source for millions of the world’s poorest people... Many of these insecticide-treated nets are dragged through the same lakes and rivers people drink from, raising concerns about toxins.

None of this is to down-play the undoubted utility of bed-nets in combating malaria. In fact, this was well-known to health experts for long and did not need to be established by spending millions of dollars on expensive and time-consuming field experiments. The more substantive benefit of RCTs and related research on bed-nets (and others like de-worming) may have been not so much on establishing its benefits but in drawing billions of dollars from philanthropic foundations and non-profits into financing bed-net campaigns. The RCTs have provided the objective basis for donors searching for cheap and high-impact development interventions, of which there are very few, to funnel their resources.

But the example from Africa illustrates the complex challenges associated with all such interventions. The unintended consequences of development interventions, and there are always some with any intervention, are revealed only when it is scaled up and over time. No amount of field studies, regression controls, and validation can help us prepare for such "unknown unknowns" of development. So before we advocate the use of bednets or deworming or toilets or multi-grade teaching to the level or safe water storage or mobile phone-based reminders or something else as superior to their competing alternatives, we would be well-advised to pause and be cautioned about its unintended consequences.