This is the summary of the report. Click the button above to read the pdf of the full report (47 pages).

Lead is a heavy metal that is toxic to humans, especially children (WHO, 2021). There are about 815 million children in the world with levels of exposure that are considered harmful (Pure Earth & UNICEF, 2020). This represents a potentially enormous loss of wellbeing in the world. Lead exposure can come from a range of – sometimes surprising – sources such as paint, spices, cosmetics, battery recycling sites, ceramic and aluminium cookware, etc., and it can permanently impair physical, mental, and emotional health.

In this report we conduct our own shallow evaluation of a new lead project targeting leaded cosmetics applied to children in Ghana being carried out by Pure Earth. Pure Earth is a non-profit environmental health organisation which focuses on protecting people and the environment from the harms of toxic pollution. Their current focus is on reducing lead and mercury poisoning in low- and middle-income countries.

This forms part of our broader work to assess the cost-effectiveness of interventions and charities based on their impact on subjective wellbeing, measured in terms of wellbeing-adjusted life years (WELLBYs). One WELLBY is equivalent to a 1-point increase on a 0-10 wellbeing scale for one person over one year. We focus on subjective wellbeing because it is what ultimately matters in determining if someone’s life is going well. By using wellbeing as a common outcome, it allows to make apples-to-apples comparisons between very different interventions.

We estimate that funding Pure Earth’s project to target cosmetics in Ghana will be highly cost-effective and produce 108 WELLBY per $1,000 donated to the organisation (‘WBp1k’), or, conversely, it would cost $9.23 to produce one WELLBY via this project.

For context, this is 14 times more cost-effective than GiveDirectly for which we estimated the cost-effectiveness at 7.55 WBp1k (i.e., $132 per WELLBY; McGuire et al., 2022a). GiveDirectly is an NGO which provides cash transfers to very poor households. We take cash transfers as a useful benchmark because they are a straightforward, plausibly cost-effective intervention with a solid evidence base. (For more detailed and updated charity comparisons, see our charity evaluations page.)

In the rest of this summary we describe the cosmetics project in more detail, discuss the funding landscape in the anti-lead-exposure space, and the strength and limitations of our analysis.

The cosmetics project

In a survey of 3,227 children in Ghana, Pure Earth found that 93% from the Northern part of Ghana used Chilo (often known as ‘Kohl’), a type of eyeliner applied to both girls and boys, even at a very young age. This sort of eyeliner has regularly been found to have elevated levels of lead. The lead would be orally ingested through hand to mouth contact or absorbed through the skin and cause adverse effects on the children’s development and wellbeing. Chilo is not the only cosmetic which might contain lead in Ghana, but Pure Earth believes it is the primary source, and our modelling throughout reflects this.

Pure Earth’s programme will be in two parts. The first part will involve advocacy to the government and data collection to help them target and neutralise the source of the lead in cosmetics with regulations and enforcement. They expect this to take ~2 years. The second part will involve technical assistance to ensure new regulations are followed and enforced. This part will be carried out over ~3 years. To our knowledge this is the first evaluation of a program targeting lead in cosmetics.

Funding to reduce lead exposure

Lead exposure is associated with a similar health burden as HIV/AIDS and malaria (measured in DALYs; IHME, 2021). Despite that, in 2021, lead exposure programmes received only around $10 million in funding compared to the $2.4 billion malaria received (240x lead funding), and the $9.9 billion HIV/AIDS (990x lead funding) received (Pure Earth Annual Report 2022/23). Malaria and HIV/AIDS are themselves often considered neglected; hence, lead exposure would qualify as potentially very neglected.

Reducing lead exposure also appears tractable (i.e., feasible to address effectively). It seems policies to reduce lead in products, reduces the lead in people. For example, in the US blood lead levels (BLLs) dropped by 94% between the late 1970s and 2017 due to regulation on petrol and paints (Dignam et al, 2019). On top of that, it also seems like conducting advocacy and providing technical assistance is effective at getting governments to take action. For instance, between 2019 to 2021, Pure Earth’s and Stanford University’s advocacy and technical assistance in Bangladesh resulted in the lead chromate added to turmeric decreasing from 30% to 0% (Forsyth et al., 2023). Intuitively, we think this is because lead is not a politicised issue, and its neglectedness by governments is more due to a simple lack of knowledge than anything else. Thus, when governments are made aware of the issue, and offered the technical assistance to solve it, they gladly and quickly accept.

Hence, attention and funding for combatting lead exposure is growing. The grantmaking organisation Open Philanthropy recently launched the Lead Exposure Action Fund (LEAF) to support charities working on reducing lead exposure. This is their biggest collaboration to date, with over $104 million already committed. While this is good news, does this new fund mean the good funding opportunities have already been filled?

At the time of writing, we know that the Lead Exposure Elimination Project (LEEP) and Pure Earth’s spice programmes are currently funded. Nevertheless, Pure Earth has more projects they can tackle with extra funding, this cosmetic project being one of them which they think will be successful and impactful. Pure Earth still needs to secure funding of $1.8 million over 5 years for the Ghana cosmetics project which involves advocacy and follow-up work to ensure enforcement. The timeliness of this project is key to make use of the current momentum in Ghana for lead regulations.

Strengths and limitations of our analysis

Ideally, we would base our analysis on causal studies that show the long-term impact on wellbeing from Pure Earth intervening in an area. This evidence does not exist, so instead we estimate this effect by combining three sources of less certain evidence:

• information about lead levels due to cosmetics in Ghana
• a prediction of how much Pure Earth will reduce this exposure (based on advocacy, which is generally more uncertain to model)
• a general link between blood lead levels and wellbeing

Overall, we assess the quality of evidence is ‘low’. The depth of our evaluation is relatively shallow, meaning we have completed only some (10-60%) of the analyses we think are needed. Therefore, our evaluation is speculative.

Throughout our analysis we decide to use conservative assumptions in order to account for this uncertainty. If we relaxed some of these assumptions, we find that the cost-effectiveness could reasonably rise from 108 → 1,359 WBp1k. This is despite some steep discounts for poor evidence quality, still not being relaxed.

We model the benefits of reducing lead exposure as removing the exposure in childhood which results in a reduction in wellbeing harm over the whole lifespan. We know lead exposure in adulthood can still do harm to the adult, but childhood exposure to adult outcomes is the most prevalent and best researched pathway.

Despite this being the best researched pathway, one core concern is causal identification of the link between lead exposure in childhood and later harms, especially the impact on wellbeing. In total we found only three papers in our brief search which employ a causal identification strategy to identify the impact of lead on long-term outcomes. However, none of these long-term outcomes analysed in these papers are subjective wellbeing or mental health outcomes. Instead, to understand the impact on wellbeing, we must rely on the meta-analytic effect from three correlational studies (n = 1,157). Thus, we suggest that while the cost-effectiveness of lead looks very promising, we would place great value on research using causal identification strategies to study the impact of childhood lead exposure on adult subjective wellbeing or mental health.

We are concerned about the similarities we see in the philanthropic world’s approach to lead exposure and to deworming. When deworming was first put forward as a cost-effective funding opportunity, people got very excited. But these analyses were based on uncertain estimates of long-term benefits, held up by the very low price per person. More recent evaluations of deworming have been more tempered. While we think the evidence for the badness of lead exposure is stronger, lead is in a similar place in that there are few causal estimates and the cost-per-person affected is very low which drives the high cost-effectiveness (as opposed to a high per-person effect which is easier to observe and measure).

We think there are lots of reasons to believe that more research would definitively prove lead is a very harmful substance for long-term wellbeing. Most importantly, we have seen some preliminary causal results which suggest a far greater effect than our meta-analysis, and use a considerably larger number of observations. Unfortunately these results are still preliminary so we are unable to share them. Additionally, there has been some causal data relating childhood lead to adult outcomes (such as income, crime and cognitive functioning) which are related to wellbeing, and implies we would expect wellbeing to also be harmed by childhood lead exposure.

We suggest some ways which we think academics could help strengthen the evidence base on the link between lead and wellbeing in Appendix E. Funding and gathering more causal evidence should be of the highest priority. With stronger causal evidence, we would be much more confident in recommending charities and interventions tackling lead exposure.

Conclusions

In conclusion, we find that this intervention has the highest cost-effectiveness of any opportunity we have reviewed so far. This somewhat offsets our concerns about evidence quality, because we have used conservative figures throughout and so this high cost-effectiveness is still a lower bound figure. Nonetheless, we suggest treating lead with a healthy amount of caution until we have stronger evidence lest the mistakes made in the past with deworming are repeated. It is also worth noting that this intervention has the possibility of succeeding, failing, or something in between. Our estimate captures the expected impact of the intervention, taking the likelihood of success into account. This means that, if the intervention is successful, the impact of the intervention will be greater than our estimate. But on the other hand, if the intervention fails, the impact could be small. Thus, this giving opportunity is particularly well-suited for donors who are comfortable with some uncertainty about the impact of their donation.

Notes and acknowledgements

Updates note: In 2022 we performed a shallow exploration of reducing lead exposure as a cause area (McGuire et al., 2023b). We rely heavily on this for this report.

Summary spreadsheet note: There is a summary spreadsheet available. But note that some of our analysis is conducted in R and explained in the report.

Author note: Ben Stewart, Samuel Dupret, Joel McGuire, and Ryan Dwyer contributed to the conceptualization, investigation, analysis, data curation, and writing of the project. Michael Plant contributed to the conceptualization, supervision, and writing.

The views expressed in this document do not necessarily reflect the perspectives of employees of the evaluated charities.

Charity information note: We thank Kate Porterfield, Drew McCartor, and Carol Sumkin for providing information about Pure Earth.