What share of global lead poisoning is battery recycling?
Nobody really knows, but probably a lot.
Lead poisoning is a massive global health issue, and used-lead acid batteries (ULABs) are suspected to be one of the leading causes.
But, remarkably, there is almost no research on the share of lead poisoning caused by ULABs.
Lead acid batteries are used in essentially all cars on the road today (including EVs), as well as many other types of vehicles, but only last ~500 cycles and then have to be recycled.
The batteries have on on average 15-20 pounds of lead in them, and this lead trades on the global market for around $2,000 per metric ton.
Because lead is valuable, there is a large industry, especially in the developing world, of recycling the lead from these used lead-acid batteries (ULABs), generally to go back into lead-acid batteries.
Researchers agree that ULAB recycling is one of the largest global causes of lead poisoning — even if they aren’t sure what share of poisoning it is relative to other sources, notably lead paint:
“Substandard recycling of lead-acid batteries is a leading contributor to lead poisoning in children.” - The United Nations & Pure Earth’s “The Toxic Truth” report
“The sources of ongoing lead exposure vary within and across LMICs, but include battery recycling, spice adulteration, ceramic and aluminum cookware, cosmetics, paint, environmental contamination, and traditional medicines, among others. The relative contribution of these different sources is not yet well characterized.” CGDEV
“There is little research on quantitatively assessing the relative importance of exposure pathways … our impression from conversations and the gray literature is that lead paint and unsafe recycling of lead acid batteries are the largest sources of exposure in LMICs.” - Rethink Priorities’s excellent primer on the issue
“Unsafe battery recycling is a major contributor to childhood lead poisoning.” Chowdhury et al. (2021)
“For many of the major identified sources of lead poisoning, such as lead paint, used lead acid batteries, spices, and cookware…” (G7 workshop on lead)
“This enormous burden of lead poisoning in LMICs is preventable. It results from a combination of sources of exposure, some of the most important being:
Lead that is intentionally added to paint, spices, cookware, and cosmetics.
Lead that contaminates the environment from unsafe lead-acid battery and e-waste recycling practices.” (Federation of American Scientists, here)
But despite all of these statements, no one seems to know exactly how bad it is.
Formal and informal recycling
There are two kinds of ULAB recycling: formal (in centralized and generally licensed factory settings) and informal (unlicensed individuals and firms recycling batteries themselves).
Formal recycling can be dangerous, especially in low and middle-income countries (LMICs). The New York Times reported last year that even in relatively richer countries like Mexico, formal lead recycling plants can poison the areas around them. A study of increased formal ULAB recycling in Mexico found negative effects on infant birth rates, and two working papers have found negative effects using education data in Mexico and Kenya.
But informal recycling is likely far worse, particularly when considering the per-battery impact. Much of the safety in formal ULAB recycling comes from using large machines and protective equipment.
Informal recycling rarely, if ever, has this specialized equipment or serious safety precautions. It’s small-scale and distributed, and more likely to be in urban and residential areas. Additionally, informal recyclers generally process fewer batteries, so a higher share of informal recycling leads to a higher number of poisonous sites.
The nature of informal recycling also makes it more likely that those not doing the recycling are seriously exposed compared to formal plants. Individuals often remove the lead from batteries with their hands, and then heat it to melt it into lead ingots that are then sold back into the market.
The relative formal-informal appears to vary from country to country. Bangladesh and India are considered to be on the higher end, and I’ve come across estimates of around 80% and 90% informal recycling respectively. But I’ve talked with experts who were less comfortable with these numbers, and given the broader lack of research on the issue, I’m not convinced of their accuracy.
The best (and only) attempt I could find to get a number on informal ULAB recycling is Bret Ericson’s “The Global Burden of Lead Toxicity Attributable to Informal Used Lead-Acid Battery Sites” (2016). He estimated that informal ULAB recycling in LMICs was responsible for 127,248 to 1,612,476 Disability-Adjusted Life Years (DALYs) in 2013.
The logic that both the UN/Pure Earth report, which doesn’t try to get a number, and Ericson et al. use is basically: 1) a vast majority (~85%) of lead use in the world goes towards lead acid batteries, 2) most of these batteries are getting recycled, 3) some share of this recycling is being conducted haphazardly by poor people in places without effective laws against it, and 4) this is dangerous and causes a lot of local lead poisoning.
(Ericson et al. also attempt to do this in a bottom-up way by using a study of toxic site prevalence in Ghana — we’ll do a post diving deeper into the paper’s methodologies soon.)
There are good concerns around using the Ericson number as a baseline. Among these, it's an order-of-magnitude range and more than 10 years old. But it’s by far the best estimate we have, and he is conservative in his approach.
The generally accepted number for total global lead DALYs is an estimate of 21.7 million in 2019 from the Global Burden of Disease study.
If you divide out these numbers, informal ULAB recycling would appear to be responsible for roughly between 0.59% and 7.4% of global lead poisoning.
I couldn’t find an Ericson-style attempt to calculate the formal recycling burden. It’s certainly not zero, but it seems hard to say at scale beyond that.
It’s probably better than informal recycling — among other things, it centralizes recycling in factories often outside populated areas — but clearly has a real level of emissions and consequent negative effects.
Given the current state of the research on this, it might make the most sense to assume that whatever the informal recycling burden is, the total burden that includes formal recyclers is higher.
However, eliminating informal recycling must come before an increased focus on formal recyclers. By centralizing recycling, it is then possible to improve safety precautions at scale. Otherwise, it seems reasonable to me that additional regulation on formal recyclers would increase their costs and shift recycling to the informal sector, potentially have a net-negative impact.
ULABs appear to responsible for a similar level of lead poisoning to lead paint
It makes sense to compare ULABs with other leading causes of exposure — the ones that come up most often are lead paint, spices, and cookware. But, as you may have suspected, there is so little research on this that the comparison is basically impossible given the existing data.
Of the aforementioned causes, I could only find an estimate of global incidence for lead paint.
Rethink Priorities spent some time looking into this, and ended up concluding that lead paint was probably around 7.5% of global burden.
This would be at the same level as the high-end of the conservative Ericson estimate for informal ULAB recycling, but given that Rethink Priorities seems to be more aggressive in their calculations, it seems fair from this to conclude lead paint and informal ULAB recycling are probably at a similar scale.
Another paper by Ericson et al. in 2021 aggregated studies on blood lead levels (BLLs) in LMICs. Of the 478 studies that identified probable exposure sources, 118 were primarily traced to ULABs (although this includes both recycling and manufacturing), while only 8 were attributed to lead paint.
On its face, this might suggest that ULABs are of much greater concern than lead paint, but because this suffers from core issues around selection bias as well as an impulse towards the most acute cases, I think there’s not much you can extrapolate — just what it says: that a lot of the existing studies on BLLs trace back to ULAB recycling.
The leading group working on lead paint, LEEP, seems to think that the share due to lead paint is substantially higher (at least in Malawi). But the LEEP number seems to be basically a guess, discounted from US lead paint numbers:
This highlights the extent to which all of these numbers are really just best guesses. There is so little research into any of the causes that any attempt at comparison, especially across causes, is basically worthless, beyond using them to argue these are causes worth addressing.
The existing numbers are conservative underestimates
These estimates are almost certainly too low.
There is consensus, both among published papers and experts we’ve talked to, that lead paint and ULABs are among the leading causes of lead poisoning in LMICs.
If you put the largest two causes at 7.5% each, this still leaves 85% of lead poisoning unexplained. If we assume that spices and cookware are each also at the same scale — and I’m not sure that’s a fair assumption — this still leaves 60% unexplained.
This implies that our estimate of the burden of the largest causes is too low, or there are a lot of other poisonous causes out there that researchers are unaware of.
Here, the LEEP impulse to use 20% makes somewhat more sense.
If you accept the premise that what experts consider the major causes probably are the major causes, an ~20% share for each of the four most discussed would explain closer to 80% of poisoning, after which there is a reasonable tail of smaller and less common causes, like certain kinds of cosmetics.
Takeaways
The field is massively understudied.
Lead poisoning is a massive global health issue and significantly reduces global GDP, potentially by up to $6 trillion per year.
People agree that ULABs are probably one of the leading causes. But beyond this, we can’t really say why or how.
This is reflective of how little research there is on ULABs, and lead poisoning more generally.
There’s only been one published attempt to calculate the burden from informal ULAB recycling! It uses data from 2013, is conservative in its approach, and necessitates a confidence interval that ranges from “not an issue” to “leading global cause”.
This might be due to the nature of lead poisoning — it’s possible that we’re never going to have great numbers on the relative sources of poisoning in LMICs. We may have to accept that ULABs are one of the leading causes and never be able to fully prove it.
But there’s simultaneously little research on how to solve the ULAB problem. This kind of research will be crucial for proving tractability and enabling policymakers to effectively get something done.