Our recent paper in Environmental Pollution estimates that lead battery recycling might account for a third of global lead exposure, significantly larger than previous estimates (open access CGD working paper version here).
Last month, we received a critical comment on that paper from three scientists. Two are consultants for the International Lead Association (the industry body representing lead producers globally), and the third works there directly. Their comment, and our response, are now both online at the journal.
This is a familiar pattern in health science, in which industry-funded consultants push back on estimates of harm from products their clients sell. It's worth reading the comment with that context in mind, but also judging the substantive points on their own merits. We think they don't hold up.
In case you don’t have access to the journal, we reproduce our response here.
Schoof et al. make two criticisms of our paper. First, they claim that we do not provide sufficient evidence that harms from used lead-acid battery sites can extend up to 5km away. They discuss one piece of evidence we provide—from Pure Earth's Toxic Site Identification Program (TSIP). Only 927 of the 5,182 soil lead measurements in the TSIP database are measured more than 165 metres away from a polluted site, making the pollution decay model we created uncertain at long distances. But they neglect to discuss the additional evidence we cite from Berkhout et al. (2025), Ipapa (2023), Litzow et al. (2024), Kundu et al. (2024), and Tanaka et al. (2022), in which quasi-experimental causal effects on test scores and health outcomes from recycling sites are found between one and ten kilometres away.
Second, whilst Schoof et al. say that they accept that “no safe level of lead exposure has been demonstrated,” they go on to claim the opposite—that low levels of exposure do not cause harm. They present weak evidence for this claim. They discuss one recent study that fails to find statistically significant effects of low-level exposure on IQ, but that study is under-powered to detect small effects, with a sample of only 262 children (Vester et al., 2026). They also discuss another study that fails to find statistically significant effects of low-level exposure on cardiovascular mortality, but again is under-powered to do so. The authors of that study themselves state “too few deaths precluded robust analyses of cardio-vascular and cardiac mortality from 2009 to 2010 onwards” (An et al., 2024). Uncontrolled confounding of the relationship between blood lead and health outcomes is a legitimate concern, but several studies explicitly address this concern using quasi-experimental designs, and do show effects even at low levels of exposure, such as Aizer et al. (2023) and Reyes (2015).
Finally, we dispute the logic behind the concern that our analysis might “detract from the hard work that needs to be done to address the most significant sources.” Whether exposure from lead-acid battery recyclers extends for metres or kilometres, the source is the same. Our analysis strengthens the case for addressing this source of exposure.
Lead is a valuable commodity. It shouldn’t be in almost any consumer products, and for most sources of lead exposure, the best solution is an enforced ban. Batteries are the exception. Despite the rise of electric vehicles with lithium or sodium batteries, we’re still going to need lead for car batteries, probably for decades. So it needs to be recycled safely. The International Lead Association (the trade body funding the authors of this comment) says it wants exactly the same thing—safe battery recycling. That's a goal we share. Which is why we'd rather see the industry's scientific resources aimed at fixing unsafe recycling than at disputing how far its harms spread. We welcome scientific debate and criticism. We might be wrong. But in this case we think these specific criticisms are misplaced.
