Children with extreme exposure to lead are at risk of lifelong physical and mental disability. The most practical treatment for this kind of exposure is oral chelation therapy—and we estimate there are millions of children who need this treatment. This includes roughly:
- one million children in India
- two hundred thousand children in China
- one hundred thousand children in Nigeria
Figure 1. Number of children who need oral chelation therapy
Note: Based on Ericson et al. (2021), who report the mean and standard deviation of blood lead levels and note that blood lead is log-normally distributed. We used this to estimate the percentage of children with 45µg/dL < BLL < 70µg/dL, then we scaled by child population. This is a simplified approach; World Health Organization guidelines recommend different treatments depending on both the level of exposure and whether the child shows symptoms. For example, symptomatic children with very high BLLs (above 70µg/dL) may require inpatient parenteral chelation, while asymptomatic teenage children above 45µg/dL may not receive medication at all.
These numbers come from some simple modelling. We use country-specific blood lead parameters from Ericson et al. (2021) and apply them to a log-normal distribution, allowing us to predict the percentage of children who have a blood lead level (BLL) between 45µg/dL and 70µg/dL (the World Health Organization [WHO] threshold at which oral chelation therapy is recommended). We then checked these estimates against the few nationally (or regionally) representative surveys with available data:
- India (1999, N = 626): our model predicted 0.28 percent; the survey found 0.16 percent.
- Mexico (2023, N = 627): this survey only reported whether BLL exceeded 30µg/dL. For comparison, our model predicted 0.12 percent of children above 30µg/dL, while the survey found 0.81 percent.
These surveys have small sample sizes that are unlikely to capture the extreme tail of exposure. Nevertheless, the broad conclusion holds: a relatively small percentage of children need this medicine. This amounts to millions worldwide—and hundreds of thousands in several of the more populous, low- and middle-income countries (LMICs).
In about half of countries, there is an oral chelation drug available, d-penicillamine, but it has very serious side effects—enough so that it is often not recommended for use with children. And non-oral chelation medicines—while extremely useful for rarer cases where blood lead levels are above 75mcg/dl or for children who have been vomiting—require health equipment and professionals to administer the drugs, making them considerably more expensive.
The other main oral chelation drug, succimer, would be the best option for most severe lead poisoning cases in LMICs if it were affordable. It has far fewer side effects than d-penicillamine and is much more effective. Succimer induces about a 15–40 percent drop in BLL from a treatment course of two weeks. If the individual is removed from the source of exposure, the effect size doubles and lasts forever. In one outbreak, succimer chelation was associated with a “large reduction in the death rate” among affected children. It’s for these reasons that we focus on succimer in this blog.
Why do off-patent chelation drugs still cost $1,000?
Scott Matafwali from the Lead Exposure Elimination Project (LEEP) recently pointed out that a single course of succimer can cost $500–$1,000 to buy in low-income countries like Zambia, where hospitals import the American-made product. Some Indian pharmaceutical companies also appear to import the medicine from the same Western manufacturer. Yet access remains limited. In India, for example, district hospitals don’t have it on hand, and treatment would likely be delayed or impossible unless a patient’s family is able to pay for and navigate private imports.
There are some promising indications about how cheaply succimer could be produced at scale. The drug is off-patent and made from common chemicals; a generic version is already manufactured in India and sold online for around $150 per 1800mg course. In Europe, it is even marketed as an unlicensed nutritional supplement for as little as $8.
The biggest issue is demand. Countries have low awareness about the issue, doctors don’t test for lead, and patients and their caregivers don’t know to ask for succimer treatment. Succimer is included on the WHO’s Essential Medicines List, but in 2019, only eight of the world’s emerging and developing economies followed suit within national Essential Medicines Lists (nEMLs), making hospitals legally unable to procure it in most cases. India, China, and Nigeria still exclude succimer from their nEMLs, as does Zambia, despite a decades-long mining pollution crisis via which half of children in certain districts require chelation.
Is demand coming?
So far, succimer has been an orphan drug—but that might be changing soon as the global movement to end childhood lead poisoning ramps up.
Countries are beginning to take notice, national lead testing is coming, and a greater commitment to lead abatement is likely to follow across a wide range of countries. This may be a longer-term process—but acute crises can also prompt sudden upsurges of demand. For example, in 2010, Zamfara, Nigeria, saw an outbreak of severe lead poisoning associated with gold mining in the region. Over the next two years, Médecins Sans Frontières used more than 15,000 courses of succimer to treat affected children, which would tally to a total cost of $7.5 million, assuming $500 per course procurement prices. In contrast, use of the Indian generic ($150 per course) would have cost just $2.25 million—saving $5.25 million.
With new data and demand at the country level, countries should first consider adding succimer to their nEMLs. But to see a real impact, we also need to make succimer affordable.
We need a quality-assured generic to close the affordability gap
Despite potentially cheaper prices for the Indian generic, most international buyers will still opt for the American-made, FDA-approved succimer brand because it is the only option approved by a national drug regulatory authority recognised as a WHO-Listed Authority (WLA). This is for good reason: approval from a WLA basically guarantees that the drugs are appropriately labeled and high-quality, which is a real concern here. To this point, the Indian company that makes the generic has recently been involved in a fake drugs scandal.
To break the monopoly, we need a cheap generic with an international stamp of approval—either from a WLA or through WHO prequalification. WHO could expand its prequalification program to include chelation drugs, enabling international buyers to purchase prequalified generics. Donors, meanwhile, could signal to manufacturing companies that they would be willing to finance the ~$600,000 upfront cost of getting a new generic prequalified—perhaps in exchange for an even cheaper purchase price in future years.
Demand for lead poisoning medicine is growing fast. It's time to make the treatment available and affordable.
We are grateful to Lesley Onyon, Eric Trueswell, and Lee Crawfurd for helpful comments on an earlier draft.
