When I first spoke to Richard Fuller in 2007, I was just beginning my work as the climate change correspondent for Time magazine. I thought I knew what the most important neglected environmental problem in the world was: climate change.

But Fuller wanted to tell me about something else. Climate change was incredibly important, no doubt, but under the radar. Millions of children in some of the poorest countries in the world were being poisoned each day by lead, mercury, and other environmental toxins that rich countries had mostly eliminated. And no one was paying attention.

Fuller — an Australian who had started a business sustainability company before diving into the world of nonprofits — was convincing, so much so that he launched me on a three-week reporting trip visiting some of Russia’s most forgotten and most toxic sites. But then he has to be. Since founding the nonprofit Blacksmith Institute in 1999 (which became Pure Earth in 2015), Fuller has focused on alleviating the toll that conventional pollution — especially from lead poisoning — takes on many of the poorest people in the world. It’s a subject that doesn’t tend to attract huge amounts of funding or celebrity do-gooders, but the damage it does to human health is huge.

How huge? According to a March 2021 study that Pure Earth researchers collaborated on, an estimated 632 million children in low- and middle-income countries have elevated blood lead levels suggestive of lead poisoning. Too much lead can cause a host of health problems, from heart disease to premature death, and for children, it is particularly toxic, leading to lifelong cognitive damage.

And as Vox’s Dylan Matthews wrote this year, the study suggested that children in poorer countries were 10 times likelier to have high blood levels than even the children of Flint, Michigan, during the height of that city’s lead contamination crisis. One estimate calculates that the economic cost of lead poisoning in low- and middle-income countries was nearly $1 trillion in 2011, or 1.2 percent of global GDP.

Lead poisoning is as relatively straightforward to fix as its consequences are severe. Lead contamination can come from the informal recycling of lead-acid batteries — an area of particular focus for Pure Earth — or from exposure to lead-tainted cookware and spices. Beyond simply gathering data about the scale of pollution, Pure Earth works to identify common sources of lead in the marketplace, promote safer lead battery recycling practices, and raise awareness among governments and doctors in affected countries about the problem of lead contamination.

It won’t be easy, but virtually eliminating lead exposure would be far simpler than the kind of economy-wide shifts that are needed to truly fight climate change — and the effects would be that much more immediate.

Yet comparatively little money is going to the fight against lead. According to a report by the effective altruist research group Rethink Priorities, Pure Earth is by far the biggest player in the space, yet it can budget just $4-$5 million a year on lead contamination, which makes up perhaps half of global philanthropic spending on the problem. An additional dollar dedicated to lead poisoning can go further than it would for most other environmental threats.

That’s why Fuller’s crusade to bring awareness to what is being done to millions of children around the world is so important and why he remains so passionate after more than 20 years in the field. I once spoke to him from New Orleans, where I was covering the 2010 BP oil spill in the Gulf of Mexico. I thought I was reporting on the most important environmental disaster in the world, but there was Fuller on the phone with his Australian accent, urging me to look into a story about hundreds of children in rural Nigeria who were dying because of lead released during gold mining. “This,” he said, “is true environmental disaster.”