Pure Earth – Comprehensive Summary

Last updated: November, 2024

Problem

In low and middle-income countries (LMICs) where most of the world’s population lives, Ericson et al. (2021) estimate that of the 632 million children in LMICs 48.5% have blood lead levels higher than the CDC’s former¹The CDC states “This level is based on the 97.5th percentile of the blood lead values among U.S. children ages 1-5 years from 2015-2016 and 2017-2018 National Health and Nutrition Examination Survey (NHANES) cycles.” (CDC, 2021). They have since lowered that level to 3.5 μg/dL based on new data that BLLs continue to decrease in the USA. reference level of 5 μg/dL. We say “reference level” because it used to be the level at which higher blood lead levels were considered unsafe – it’s now commonly understood that there is no safe level.

According to Pure Earth and UNICEF (2020), there are nearly a billion children (815 million) in the world with clearly unsafe levels of lead in their blood (BLLs above 5 μg/dL) and 176 million with high lead levels (above 10 μg/dL).

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.

Compare this to the $2.4 billion malaria received, or the $9.9 billion HIV/AIDS (Pure Earth Annual Report 2022/23). That means that despite having a similar burden to health other (still very neglected) disease receive between  240x and 990x more funding than reducing lead exposure.

Solver

Pure Earth was founded in 1999 and aims to address lead and mercury poisoning and pollution. Since their inception they have worked at around 3,000 locations in about 50 countries, primarily focussing on low- and middle-income countries (LMICs).

Intervention

Pure Earth has demonstrated they can reduce lead exposure at scale. Most notably, in recent years they’ve performed two successful campaigns to remove lead from spices.

In Bangladesh: From 2019 to 2021 they found that lead in market samples reduced from 47% (211 samples) to 0% (87 samples) and the percent of mills with direct evidence of lead chromate adulteration (pigment on-site) decreased from 30% (of 33 mills) to 0% (of 21 mills) (Forsyth et al., 2023).

Georgia: From 2020 to 2022 the percentage of spices with lead levels above the reference level reduced by 86% (Forsyth et al., 2024).

Evaluation

Methods

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

Impact

To estimate the wellbeing effects of reducing lead exposure, we focused on the long-term effects of reducing exposure in childhood on later in life.

• We build a model of the effect of a 1 unit decrease in lead exposure (1 BLL, or  μg/dL) based on correlational longitudinal evidence from Australia and New Zealand (n = 947).

• Using this we estimate that the effect per decrease in 1 BLL across childhood (the first 10 years of life) is 1.61 WELLBYs over the child’s lifetime.

• We then estimate the how much lead exposure in Ghana cosmetics contribute to (0.40 μg/dL).

• We then guess that the technical assistance Pure Earth provides will decrease lead from cosmetics by 38%, so 0.40 * 38% = 0.15 (or decrease BLLs from 4 to 3.76 μg/dL).

• This 0.15 BLL decrease will effectively “last” for 4 years in our model due to our guess at what the counterfactual is²It is worth noting that moving the date lead is removed from cosmetics forward by 4 years, technically does not mean that everyone under 10 experiences exactly 4 years less lead exposure. For example, due to the way we have modelled this we assume that beyond the age of 10, further exposure to lead causes no further harm. Therefore, even if the counterfactual is 4 years, a 9 year old would only benefit from 1 less year of exposure. On the other hand, a child born one year after the lead is removed, would have counterfactually experienced lead exposure from cosmetics for the first 3 years of their life. The difference between modelling this way and simply just using the number of children under 10 currently alive and assuming they experience 4 years less of exposure is relatively small due to the former modelling choice having counteracting forces of a larger population being affected, but for a shorter average period. We used both models for a range of counterfactual years and found the differences were marginal. For simplicity we therefore just assume everyone under 10 experiences exactly 4 years less lead exposure..

• This effectively implies a 1.61 WELLBY * (4 years/10 years) * (0.15 BLL) = 0.098 WELLBY increase per child affected by the policy in Ghana.

• We then apply several adjustments (0.75 for non-causal data, 0.51 for replicability, and 0.50 for generalisability) to arrive at a per person effect of 0.019 WELLBYs.

• This then increases to 0.025 when we add some guesses about household spillovers.

We then estimate the overall wellbeing effect of the whole project by multiplying the adjusted per person effect by the total population of those in Ghana under 10: 9,162,721 (UNDP). Therefore total WELLBYs produced is 0.025 WELLBYs * 9,162,721 = 226,702 WELLBYs.

Cost

Pure Earth has told us that the technical support portion of this project will cost a total of $1.8 million. This is $300k for two years of advocacy and support to bring in regulations and collect the data necessary to format a strategy, and then a further 3 years of monitoring at $400k per year to ensure the regulations are successfully enforced.

This does not include the overhead costs (administration and fundraising) included in the running of Pure Earth though. To account for this we inflate this cost by the percentage of total costs ($8,089,140) made up by non-programme costs ($1,317,788) in their 2023 audited financial statement. After this 1.16 adjustment, total costs are $2,093,235.

Cost-effectiveness

Now that we have the total WELLBYs generated and the cost to generate them, we can estimate the cost-effectiveness of this project. We calculate the cost-effectiveness to be 1000 * 226,702 WELLBYs / $2,093,235 = 108 WELLBYs per $1,000 (WBp1k), or $9.23 to produce a WELLBY.

Quality of evidence

Overall, we assess the quality of evidence is ‘low’, making our evaluation speculative.

The largest source of uncertainty in this report is the effect of lead exposure on children on adult mental health and wellbeing. Currently we rely on three correlational studies, of which two (both looking at the Port Pirie data) find non-significant results. The huge attrition rates in the Port Pirie studies means we think their results are low quality, and so their insignificant results concern us less.

To account for some of our data concerns we have applied three adjustments (0.75 for non-causal data, 0.51 for replicability, and 0.50 for generalisability) to attempt to remain conservative. However, no amount of discounts will ever be sufficient if lead has no causal effect on adult mental health. This is why we strongly encourage future research on lead to not only place an emphasis on ‘where is there lots of lead?’, but also ‘how much harm is it doing?’ and employ causal identification strategies, rather than rely on simple associations.

Depth of our analysis

We think this is a ‘low (or shallow)’ depth report. Namely, we have only reviewed some of the relevant available evidence on the topic, and we have completed only some (10-60%) of the analyses we think are useful.

Funding need

Pure Earth still needs to secure funding of $1.8mil over 5 years for the Ghana cosmetics project which involves advocacy and follow-up work to ensure enforcement.

Conclusion

In this shallow evaluation of Pure Earth’s campaign to remove lead from cosmetics in Ghana, we have demonstrated both the significant potential and considerable uncertainty surrounding the intervention’s impact. While the predicted cost-effectiveness of reducing blood lead levels (BLLs) through Pure Earth’s efforts is highly promising, estimated at 108 WBp1k, this analysis is largely speculative, relying on limited evidence and assumptions. Nonetheless, the intervention offers an exciting opportunity to improve the wellbeing of Ghanaian children by reducing exposure to a dangerous neurotoxin.

Given our uncertainty, we also need for more research into both the harms of lead exposure and the effectiveness of advocacy interventions in accelerating regulatory action in general, and particularly for reducing lead exposure. This project may represent one of the most cost-effective opportunities available to donors today, but it’s also highly uncertain, presenting a potential “high risk, high return” opportunity for philanthropic funding.  

Our reports so far

In 2022 we performed a shallow exploration of reducing lead exposure as a cause area (McGuire et al., 2023b). We concluded that something in the area would probably hold cost-effective opportunities for improving wellbeing.

In November 2024, we published an analysis of Pure Earth and their cosmetic programme in Ghana [link to come]. This is where we determine the cost-effectiveness of Pure Earth.