Remember the Flint, Michigan, water crisis? The public health disaster that, at its peak, poisoned nearly 5 percent of the city’s children with dangerously high levels of lead in their water? It was perhaps one of the few public health crises in the US that rose to the prominence of a national scandal, sparking outrage and dominating headlines for years.

The fallout led to lawsuits, local and federal investigations, firings of top officials, and a settlement north of $600 million.

But as scandalous as the Flint crisis was, it represents just the tip of a global iceberg.

Around the world, an estimated one in three children — about 800 million kids — has lead levels in their blood as high, or higher, than the kids in Flint did. That should be a huge cause of concern because lead is a potent neurotoxin that leads to impaired IQ in children, premature deaths in the elderly, and a host of negative effects that last a lifetime. And as far as we know, there are no safe levels of lead exposure.

Starting in the 1970s, the US and many European countries began eliminating lead from paint and gasoline as the health dangers became undeniable. Algeria, the last country to do so, phased out leaded gasoline in 2021, but lead paint still remains legal in many low- and middle-income countries.

But increasingly, researchers are pointing to lead-acid batteries — which are used everywhere, in both developing and wealthy nations, to start nearly every gas car and to provide backup power in hospitals and data centers — as one of the leading yet most neglected sources of lead exposure worldwide.

The batteries themselves aren’t dangerous. The problem arises once they’re dead and need to be recycled. A typical car battery holds about 15–20 pounds of lead, which is worth about $15 based on the global price of lead. That makes these batteries valuable, not trash. And in a lot of low- and middle-income countries, that value is extracted in small mom-and-pop shops, tin-roof sheds, or shoddy recycling operations — about 10,000 to 30,000 of them globally.

Here’s how a typical informal operation works in much of the Global South: Workers buy old batteries, crack them open, drain the acid on the ground, then melt down the lead plates in makeshift furnaces. The melted lead is poured into molds, and the resulting ingots are then sold to make new batteries or other products.

Doing this is much cheaper and more profitable than running a proper facility, but far more dangerous. The process releases lead-filled dust that drifts into nearby homes, soil, and water. The toxic leftovers from melting down plates — called slag — often end up dumped in nearby fields and streams.

Even when work moves into formal factories, the danger doesn’t necessarily go away. In Nigeria, for example, licensed plants often operate with poor dust control, careless slag disposal, and little protection for workers. And the problem isn’t confined to poorer nations. A 2023 investigation from the New York Times revealed that........

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