The Case for Scaling Fingerprick Blood Lead Testing

Lead is the world’s most damaging chemical pollutant. In 2019 alone, lead was responsible for an estimated 5.5 million adult cardiovascular deaths and an average IQ loss of nearly 5.9 points per child in low- and middle-income countries.

Yet nearly all low- and middle-income countries lack routine blood lead level (BLL) monitoring. Without knowing the extent of exposure or who is affected, governments can’t effectively target interventions. The value of blood tests extends well beyond the individual person tested: elevated results provide clues about sources and patterns of exposure that enable action benefiting entire communities. Because individuals do not capture these broader benefits, testing will be substantially underprovided without deliberate public action.

We should scale up blood lead testing now. Fast, easy-to-use fingerprick tests are already widely used in surveillance programs in the US and other high-income countries. These tests cost less than other BLL testing methods and are well suited to representative surveys. Expanding such surveys would help governments characterize the burden of lead exposure and help motivate policy action.

The technical limitations of these tests should not preclude substantially more population screening. The immediate obstacle to scaling fingerprick testing is not technical feasibility or test performance, but cost. Market shaping could bring these costs down further.

Scaling up blood testing now would complement innovation in testing by signaling a growing market for tests. We need a more competitive market for tests, alongside cheaper, easier-to-use options suited to low- and middle-income countries. We are excited about CHAI and Renaissance Philanthropy's recent launch of a target product profile for a rapid and low-cost BLL test (William Seitz and Eric Trueswell provided feedback on this exercise).

But a better test is not a prerequisite for substantially more testing today. Existing fingerprick tests can help expand testing now.

Representative surveys

Representative surveys are essential for measuring the extent of a country’s lead exposure, identifying where it is concentrated, and assessing efforts to address lead poisoning. The country of Georgia shows what that information can accomplish. In 2018, a nationally representative survey found that 41 percent of children ages 2–7 years had BLLs at or above 5 µg/dL, with evidence pointing to adulterated spices as a key source of exposure. The government followed up with site visits and action targeting supply-chain sources, including spices, cosmetics, and toys. By 2024, the prevalence of children with BLLs at or above 5 µg/dL had fallen by 60 percent or more in the most severely affected communities. Our colleagues Maria Jose Talayero Schettino and Caroline Mallory discuss the Georgia case and emphasize the importance of starting with the evidence.

Georgia’s experience closely mirrors that of the United States, where, decades earlier, findings from the US National Health and Nutrition Examination Survey prompted the creation of state and local lead-screening programs in 1988 and Medicaid blood-lead screening requirements in 1989, which were followed by a rapid and sustained decline in lead exposure.

Blood lead level testing has repeatedly proven essential. Now, for the first time, low- and middle-income countries are rapidly adopting national childhood BLL surveys. At least 20 national BLL surveys were planned, underway, or completed in 2025, compared to only two completed surveys in low- and middle-income countries before 2023. How these surveys are designed will largely determine their scalability and the value of the evidence they generate.

Two common testing approaches are laboratory-based methods and point-of-care analyzers. Among several available laboratory tests, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is widely regarded as the gold standard. This approach typically requires a venous blood draw. The second common approach is fingerprick-based testing, using a point-of-care device. A portable electronic analyzer allows testers to skip the laboratory step.

The two approaches involve important trade-offs. In clinical practice, ICP-MS is often preferred for its greater precision and wider analytical range. Meanwhile, state-of-the-art capillary tests sacrifice some precision and range but offer significant advantages in logistics, cost, and speed. By avoiding venous blood draws, they can also reduce costs and improve data quality. We discuss each of these trade-offs in turn.

Logistics

Capillary testing is much less logistically burdensome than laboratory-based testing. For standard approaches, obtaining venous samples requires specialist phlebotomists, cold-chain transport of blood samples (potentially over long distances), and reliable laboratory capacity, which is unavailable in many areas. For example, Bhutan’s survey designers cited all three issues as barriers to a conventional venous survey, and instead opted for LeadCare II tests. Survey designers in Mexico reached similar conclusions. Under such constraints, the availability of simple field-compatible tests can determine whether a national survey is feasible at all.

Cost

The most common capillary test used today has a large and direct cost advantage over lab-based tests. Recent government procurement records put consumables at roughly $8.50 per test and the analyzer at around $3,000. Allocating the full analyzer cost across 1,000 tests adds $3 per child, for a combined instrument-and-consumables cost of about $11.50 per test. In contrast, a lab test in Nairobi is reported at about $35. Thus, even before accounting for the additional phlebotomy supplies, staff, and cold-chain transport required for venous testing, the cost of capillary tests is already roughly one-third the laboratory-analysis price, although costs vary substantially between countries.

But an even greater cost advantage from capillary testing comes from better survey participation. Respondents are far more likely to agree to a capillary test than to a venous blood draw. For instance, in a contaminated area of Australia, testing participation increased from 39 percent to 75 percent after switching to capillary screening, while the share of children screened by 24 months increased from 63 percent to 98 percent.

The Georgia and Bangladesh MICS surveys used venous sampling and had noncompletion rates of 42 percent and 35 percent, respectively, with most noncompletion being driven by refusal from either the caregiver or child. Meanwhile, Indonesia’s recent national survey relied on capillary tests, and fewer than 1 percent of selected participants refused. Bhutan, Mexico, and Kyrgyzstan also reported very high participation. These high participation rates are consistent with experience from other survey platforms. For instance, across publicly available Demographic and Health Surveys using fingerprick-based tests, 94 percent of selected respondents participated in anemia testing, 95 percent participated for malaria, and 91 percent for HIV.

The participation advantage of capillary testing has cost implications, not least because physically reaching selected respondents accounts for a large portion of any household survey's costs. If a survey must compensate for nonparticipation by traveling to additional households and locations, survey costs can rise much more than the per-test costs would suggest.

In Georgia, a hypothetical fingerprick approach with the same number of successfully completed measurements would require an initial sample of about 770 fewer households than the lab-based approach. However, this advantage is partially offset by the need for more capillary tests to achieve the same statistical precision ICP-MS tests provide. Using a conservative $75 estimate for the cost of an additional sampled household, and applying the LeadCare II manufacturer’s reported precision to the blood lead distributions of surveys completed in Georgia, Bhutan, Bangladesh, and Mexico City, we estimate that capillary-test surveys are on average about 20 percent less expensive—even before accounting for the additional staffing and logistics costs of laboratory-based testing.

Data quality

Using capillary tests reduces the risk of generating false or misleading results. In Georgia, the usable-result rate varied widely—participation was 43 percent in the capital, Tbilisi, rising to 78 percent in Guria, and from 46 percent among children in the richest wealth quintile to 68 percent in the poorest. Regional participation also varied systematically with measured exposure, making the result bias especially difficult to correct. Participation rates matter enormously for the quality of survey results because nonresponse can introduce bias when the people who agree to participate in the survey differ from those who refuse.

Common practice is to use statistical adjustments to re-weight the observed sample to account for differences in participation. But this can only correct bias captured or proxied by the observed characteristics of participants compared to nonparticipants. If participation is affected by factors that are not measured (such as a fear of needles or trust in the healthcare system), significant bias will remain. In the Georgia case, simulating an approach that adjusts survey weights using the wealth index leaves two-thirds of simulated bias uncorrected.

Capillary testing is often preferred even where venous testing is feasible. Fingerprick tests are cheaper, easier to deploy, and less burdensome for families, lowering the cost of each successful test and increasing the share of eligible children who actually produce a usable result. Higher completion rates also improve the effective sample size and representativeness of the survey. At a minimum, where surveyors choose to use venous testing, fingerprick testing should be available as a fallback option for those who would otherwise refuse the venous draw.

From surveys to screening

Representative surveys identify the scale and geographic distribution of lead exposure. Once governments use that information to identify and address the most obvious sources, screening becomes more valuable because it can identify which children and communities remain most exposed. Routine blood lead monitoring and screening already exist in countries including Canada, Germany, and South Korea. In the United States, all children on Medicaid are tested at 12 and 24 months, and 22 states impose broader screening requirements.

Measurement error matters more for screening than for surveys. In a survey, random errors average out. In the case of screening, each result is compared to an action threshold, so small errors can affect whether the child is flagged for follow-up. However, there is no biological cliff at any given cutoff; a child with a true BLL of 4.9 µg/dL and another with 5.1 µg/dL are essentially just as poisoned, but only one result mobilizes action with a 5 µg/dL action threshold. Countries have to draw a line somewhere to optimize resources, and so any given threshold is nothing more than a triage rule. With near-zero systematic bias, LeadCare II’s measurement error centers around the cutoff, meaning most false positives and false negatives would involve children whose true BLLs are close to the action threshold and who are therefore similarly exposed. If policymakers are concerned about children around the threshold and have the resources to address more cases, they can lower the threshold or retest children with borderline results.

In high-prevalence, low-resource settings, screening is particularly valuable for discovering clusters of elevated results. Such clusters can point investigators toward intense shared exposures such as smelters, battery recyclers, and contaminated food products. In Georgia, lead-isotope analysis linked children’s blood lead levels to spices in 72 percent of the 36 children investigated. What matters most, then, is whether a test can reliably identify the most highly exposed children. In simulations calibrated to Mexico City’s blood lead distributions, testing detects 93 percent of true cases above 5 µg/dL. In a Georgia-like scenario, it detects 98 percent. The residual classification errors are overwhelmingly borderline cases; the most severely exposed children are essentially never classified below 5 µg/dL.

The opportunity for market shaping

While fingerprick testing is already cheaper than venous testing, it could be cheaper still. LeadCare II is the only FDA-cleared point-of-care blood lead testing system with a CLIA waiver, which allows it to be used in simple clinical settings instead of a full laboratory. LeadCare II was used for 2.5 million tests a year, more than half of all US blood lead tests.

This combination of a dominant supplier and underdeveloped global demand creates an opportunity for market shaping. We can draw from the volume guarantee approach used by organizations such as MedAccess and CHAI to scale existing technologies. Governments in middle-income countries should commit to purchasing large quantities of fingerpick tests in return for a discount on prices. Such deals can be win-win for suppliers and customers—the expansion into new and underserved markets and predictable multi-year demand can compensate for the cut in margins. Such deals could be made with Meridian, the manufacturer of LeadCare II, and could also help incentivize new entrants to overcome regulatory barriers and enter the market.

The growth in demand will be driven by screening rather than surveys. A nationally representative survey may use only a few thousand tests. At $9 a cartridge, 3,000 tests cost $27,000—a small share of the total cost of fielding a national survey. In contrast, testing one million children costs $9 million in cartridges alone annually. Lowering the price from $9 to $6 saves only $9,000 on a 3,000-test survey but saves $3 million every year in a million-test annual screening program.

The path forward

Fingerprick tests are underrated. At current prices, they can already make representative surveys cheaper, easier to deploy, and less burdensome for families. They can also be used to scale up screening. Negotiating better prices for a bulk purchase could enable a large expansion of screening programs in low- and middle-income countries.

These efforts would complement investments in testing innovation. Coordinated demand that brings prices down could make screening worthwhile in more middle-income countries, allowing programs to identify more exposed children and sources now while creating a demand base that makes investment more attractive to the next generation of better tests.

We thank Emily Schabacker, Leah Rosenzweig, Akhil Bansal, Georgia Bradley, Lee Crawfurd, and Rachel Bonnifield for comments on earlier drafts.