Among the several ongoing conflicts in Nigeria, Western attention has turned especially to fatal clashes between Muslim-majority Fulani herdsmen and Christian-majority farmers. The issue has captivated the White House: President Donald Trump threatened in November that if “the Nigerian Government continues to allow the killing of Christians,” the United States would “go into that now disgraced country, ‘guns-a-blazing,’” then followed through with airstrikes on Islamic State enclaves on Christmas Day.
Less than two months later, 162 people were massacred in Kwara state. Easter weekend brought more attacks, including a Palm Sunday killing of at least 20 in Jos.
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The roots of the conflict are multifold and under dispute, but it comes against a backdrop of persistent, troubling violence in Africa’s largest country. And global leaders who want to turn down the temperature should consider an overlooked lever to calm the violence: the same policy that helped U.S. violent crime rates fall by more than half within a lifetime. Reducing the incredibly high prevalence throughout Nigeria of lead poisoning, which study after study has linked to aggression and violent behavior, could translate into significant reductions in the bloodshed plaguing the region.
Breakout research in the 1990s uncovered the link between lead and violence, beginning in the United States. The U.S. introduced, then eliminated, leaded gasoline in the middle of the 20th century. And the graph tracking lead rates in gasoline between the 1940s and 1980s follows the same shape as the graph of violent crimes committed 20 years later, when Americans exposed to lead as children reached young adulthood. The correlation held across time and place: States that introduced leaded gasoline later experienced a spike in violent crime later, and those living closer to highways showed higher rates of juvenile delinquency.
The eventual reduction in crime came right on schedule, too. Those who remember the peak and fall of violent crime in the mid-1990s observed the coming of age of the children of lead abatement policies in the 1970s.
Researchers debate exactly how much of the 20th-century crime pattern can be explained by lead, but meta-analysis after meta-analysis confirms a causal link between lead and violence. It’s not just America — similar patterns between lead rates and crime were found in New Zealand, West Germany, Italy, and the United Kingdom. MRIs of children with elevated blood lead levels in Cincinnati found reduced gray matter in the brain areas associated with impulsivity and mood regulation; the same study also found that an increase in childhood blood lead levels of 5 micrograms per deciliter predicted a 5-6% rise in arrest rates.
Nigeria, for its part, faces a lead-poisoning crisis. A conservative estimate suggests that about half of all Nigerian children have blood lead levels associated with lifelong cognitive impairment; compare this with Flint, Michigan, at the height of its water crisis, where the numbers were around 1 in 20. There is no research into the connections between lead poisoning and the kind of organized violence that plagues Nigeria. But this poisoning affects 70% of the 112 million children living in Nigeria overall — and an estimated 22 million in the Middle Belt, where violence against Christian farmers is concentrated.
According to the World Bank, the biggest single driver of lead pollution is lead-acid battery recycling, which happens in highly unsafe facilities that blanket surrounding communities in lead dust. A New York Times investigation described clouds of soot and children coughing up black particles in the vicinity of a factory near Lagos; safety standards are likely even lower in the Middle Belt, where conditions favor even more informal recycling practices.
Nigerian lead recyclers have little incentive to switch to safer practices (in fact, when we visited in 2025, the country’s one safe recycling facility sat empty, unable to compete with undercutting dirty recyclers). Unsafe recycling thrives under weak regulatory oversight, propped up by a U.S. market that does not discriminate between responsibly recycled lead and lead from factories that spew their externalities onto children for kilometers around.
We underwrite this devastation every time we get behind the steering wheel because the U.S. market buys between 60% and 85% of Nigerian lead exports for use in car batteries.
But our financial complicity also means that American industry leaders, policymakers, and consumers have meaningful leverage over the crisis. If Nigerian lead recyclers had to meet a safety standard to sell to the U.S. market, they would have a financial incentive to upgrade their operations.
The Office of the U.S. Trade Representative could open a Section 301 investigation into the labor practices of unsafe lead-acid battery recyclers. Congressional leaders have already advocated trade restrictions on Nigerian beef and cattle products, which are raised by Fulani herdsmen; they could add proposals for recycled lead that cannot be traced back to a safe factory. The Commerce Department could impose a countervailing duty on imported recycled lead, which can undercut domestic recyclers because its makers do not shoulder the costs of pollution standards. If that evaded burden became part of the cost of selling lead to the U.S., there would no longer be a financial incentive to offload externalities onto nearby children.
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The simplest solution, though, would be a credible commitment from the companies that make the batteries, as represented by the Battery Council International, to source only from lead recycling facilities certified as meeting minimal safety standards. Lawmakers and advocacy groups have begun to pressure BCI to sign on to such an agreement, which, based on our research, would raise costs just minimally, if at all.
Switching U.S. companies’ recycled lead supplier won’t be a magic bullet to end conflict in Nigeria. But it’s low-hanging fruit that we have every reason to think would be a step in the right direction. American industry leaders and policymakers have a moral obligation to stop underwriting the toxic pollutant that is seemingly intensifying ethno-religious violence.
Yona Sperling-Milner is a senior at Harvard University and a policy fellow at the Coalition for Responsible Lead Sourcing, which works to find U.S. market solutions to global lead poisoning.
