How Many UK Children Have Elevated Levels of Lead in Their Blood?

Lead exposure in childhood is associated with adverse effects on neurodevelopment, cognition and behaviour at blood lead concentrations previously regarded as low. No threshold has been identified below which adverse effects can be excluded. In July 2021, England therefore reduced the public-health intervention concentration for children from 10 µg/dL to 5 µg/dL, bringing a substantially larger group of children within the scope of public-health investigation and case management.

The effect on surveillance was immediate. Cases reported through the Lead Exposure in Children Surveillance System (LEICSS) increased sharply following the change. In 2022, the first complete calendar year under the new definition, 191 children were reported, of whom 119 (62%) had blood lead concentrations between 5 and <10 µg/dL and would therefore have fallen below the former intervention concentration. More recent surveillance shows that detections at ≥10 µg/dL have also increased, indicating that the rise cannot be explained by the lower intervention concentration alone; increased clinical awareness and testing are also contributing to case ascertainment.

LEICSS, however, is a passive surveillance system rather than a population survey. It records children who are tested, identified and reported; it cannot determine the prevalence of elevated blood lead concentrations among children in England. UKHSA consequently states that there are no contemporary comprehensive survey data establishing how many children in England have blood lead concentrations ≥5 µg/dL. In the absence of such data, estimates vary substantially. UKHSA has illustrated the possible scale by applying recent US prevalence data to English children aged 1–5, producing an estimate of approximately 34,541, while Institute for Health Metrics and Evaluation modelling estimated that 213,702 people aged 0–19 in the UK had concentrations ≥5 µg/dL in 2019. These estimates differ in population, methodology and reference period and should not be interpreted as equivalent measurements of UK prevalence.

This article examines what is known about elevated blood lead concentrations in UK children, what changed when the intervention concentration was lowered, and why surveillance cannot answer the underlying prevalence question. It considers the UK approach to childhood lead screening, the distinction between clinical screening and representative population biomonitoring, and the evidence required to determine how many UK children currently have elevated levels of lead in their blood.

Lead exposure in children has declined substantially in the United Kingdom over recent decades, following measures including the removal of lead from petrol and restrictions on its use in paint and other products. That success can create the impression that childhood lead exposure has become principally a historical problem. It has not disappeared. Lead remains in the built environment, in contaminated soil and dust, in some consumer products and imported materials, and in legacy drinking-water plumbing. Children continue to be identified with blood lead concentrations sufficiently elevated to trigger clinical and public-health investigation.

The difficulty is establishing how many.

England has a defined public-health intervention concentration for childhood lead exposure. It has laboratory testing, clinical guidance and a national surveillance system for identified cases. Yet it does not currently have a nationally representative biomonitoring programme capable of measuring the distribution of blood lead concentrations across the child population. UKHSA states explicitly that there are no recent comprehensive survey data establishing how many children in England are exposed above the current intervention concentration.

This distinction between cases detected and children exposed is fundamental.

The Lead Exposure in Children Surveillance System is designed to identify children resident in England with elevated blood lead concentrations and initiate public-health action. It is a passive surveillance system. A child must first be tested and an elevated blood lead concentration detected before that child can enter the surveillance pathway. LEICSS can therefore describe the children who are being identified; it cannot provide a denominator from which the prevalence of elevated blood lead concentrations in the general child population can be calculated.

The importance of that distinction increased substantially in 2021.

Until 5 July 2021, the LEICSS surveillance definition required a blood lead concentration of at least 10 µg/dL (0.48 µmol/L). Following a review of evidence on the health effects of lower-level exposure, England halved the public-health intervention concentration to 5 µg/dL (0.24 µmol/L) for children under 16 and pregnant women. UKHSA describes 5 µg/dL as an intervention concentration: a concentration at which the finding is unlikely to represent background exposure and warrants investigation for an identifiable source.^[1] It is not a biological boundary separating harmful from harmless exposure. UKHSA states that there is no defined safe threshold for the harmful effects of lead in children and recognises adverse neurobehavioural effects at concentrations of 5 µg/dL and below.

Lowering the intervention concentration changed the population of children captured by surveillance. In 2022, the first complete year operating at ≥5 µg/dL, LEICSS recorded 191 cases. Of these, 119 children (62%) had concentrations between 5 and <10 µg/dL, while 72 (38%) were at or above the former 10 µg/dL intervention concentration. The majority of children identified that year would therefore not have met the previous surveillance definition.

But the subsequent data reveal something more complicated than a simple threshold effect. By 2024, UKHSA reported that 159 cases (58%) were between 5 and <10 µg/dL, while 88 children were still being detected at ≥10 µg/dL. The latter number was unchanged from 2023 and higher than the 72 recorded in 2022. UKHSA considers this evidence that factors other than lowering the intervention concentration — including increased clinical awareness — have contributed to the increase in detected cases.

This raises a larger epidemiological problem. If the number of cases identified depends partly upon whether clinicians suspect lead exposure and request a blood test, then changes in reported cases cannot by themselves establish changes in underlying population exposure. A surveillance system can become better at finding a problem without the problem itself becoming more common.

In the absence of representative contemporary UK measurements, estimates of the underlying number are consequently very different from the number appearing in LEICSS. UKHSA’s 2025 report applied a US prevalence estimate of 1.1% among children aged 1–5 to the corresponding population in England and calculated that approximately 34,541 children might have blood lead concentrations ≥5 µg/dL. Separately, modelling by the Institute for Health Metrics and Evaluation estimated 213,702 UK children and young people aged 0–19 at or above 5 µg/dL in 2019, with an uncertainty interval of 186,117 to 281,542.

Neither figure is a measured contemporary prevalence count for UK children. Nor can either legitimately be compared directly with annual LEICSS case numbers: they concern different populations, age ranges, periods and epidemiological quantities.

That leaves a deceptively simple question without a direct empirical answer:

How many UK children currently have elevated levels of lead in their blood?

Answering it requires separating four things that are easily conflated: the concentration at which public-health intervention occurs; the number of children detected through surveillance; estimates of the underlying population prevalence; and the way in which the UK chooses to look for elevated blood lead in children in the first place.

The starting point is therefore the concentration itself: why England moved from 10 to 5 µg/dL, what that figure represents, and what it does not.

The Lead Exposure in Children Surveillance System is England’s national surveillance system for children with elevated blood lead concentrations. It was established to improve the identification and public-health management of childhood lead exposure and to provide a national picture of cases detected through clinical and laboratory pathways. It is operated by the UK Health Security Agency, having previously been administered by Public Health England.

Formal surveillance of childhood lead exposure in England began in 2010 with the Surveillance of elevated blood Lead in Children study, a collaborative project involving the British Paediatric Surveillance Unit and the Health Protection Agency. Its authors recommended establishing a laboratory-based surveillance system to enable timely public-health management of cases. A pilot, the Lead Poisoning in Children surveillance system, was instigated in 2014 and, following evaluation, permanently implemented as LEICSS in 2016.

A note on the annual reports is necessary before the figures are presented. UKHSA titles each LEICSS annual report by its year of publication, while the report covers the preceding calendar year. The annual report for 2025 therefore presents surveillance data for 2024; the 2024 report presents data for 2023; the 2023 report presents data for 2022; and the 2022 report presents data for 2021. References throughout this article follow that convention and state the data year.

LEICSS does not routinely test children itself. Cases enter the system after a child has had a blood lead test through clinical care or investigation and the result reaches the surveillance system. In 2024, 223 of the 247 confirmed cases — around 90% — were identified through direct laboratory reporting, with the remainder reaching surveillance through other routes.^[2]

The pathway into LEICSS therefore begins before surveillance itself. A child may have symptoms, developmental or behavioural concerns, pica, a recognised environmental exposure or another risk factor that prompts a clinician to consider lead. A blood sample must then be requested and successfully obtained, lead must be measured, the result must be reported, and the child must meet the surveillance case definition. In simplified form:

possible exposure, symptom or risk factor → clinical recognition → decision to test → blood sample → laboratory result → reporting → case-definition assessment → LEICSS case

Each stage matters. A child with an elevated blood lead concentration who is never tested cannot appear in LEICSS.

This is why LEICSS is described as a passive surveillance system, rather than a screening or population biomonitoring programme. Its annual figures measure the number of qualifying children who were identified and reported through the surveillance pathway. They do not measure the number of children in the general population with elevated blood lead concentrations.

The current harmonised UKHSA series provides comparable annual case totals from 2015. During the six complete years before the intervention concentration was lowered, annual numbers were relatively small, ranging from 33 to 49 cases. The surveillance definition during this period required a blood lead concentration of at least 10 µg/dL.

The series contains 1,016 recorded cases between 2015 and 2024, but that total should not be interpreted as a single epidemiologically consistent decade of surveillance. The case definition changed substantially midway through the period.

Between 2015 and 2020, LEICSS recorded 231 cases, an average of 38.5 per year. In 2021, the transition year, the total increased to 121. The annual report for that year records 31 cases notified before the case definition changed on 5 July and 90 afterwards.^[3]

The increase continued during the first three complete years under the ≥5 µg/dL definition: 191 cases in 2022, 226 in 2023 and 247 in 2024. Together, those three years produced 664 confirmed cases, an average of 221.3 per year, compared with 38.5 per year during 2015–20. The annual number of children detected was therefore approximately 5.75 times higher in the first three complete years under the new definition.

That comparison needs careful interpretation. It does not show that childhood lead exposure in England increased nearly sixfold. Part of the discontinuity is built into the surveillance system itself: from July 2021, children with blood lead concentrations between 5 and <10 µg/dL became eligible for inclusion when previously they had not been.

There is also a technical reason to use the current UKHSA series rather than assembling figures from successive archived annual reports. LEICSS is a live surveillance system, and historical records have undergone small retrospective revisions as cases were reconciled and de-duplicated. All four recent annual reports carry the same last-updated date, and the collection page records subsequent corrections and additions. The current harmonised series is therefore the more appropriate basis for comparing annual totals.

The latest data also illustrate the difference between reports received and confirmed LEICSS cases. In 2024, UKHSA received 275 reports, of which 247 met the surveillance definition. The national case-detection rate was 23 cases per million children aged 0–15 years.

Again, that is a detection rate, not an estimate of prevalence. The denominator describes the population from which detected cases arose, but the numerator depends upon which children were tested and reported. LEICSS is therefore well suited to monitoring identified cases, supporting public-health investigation and observing changes in case detection. It cannot, by itself, establish how many children in England have blood lead concentrations above the intervention concentration.

The change in case definition nevertheless created an opportunity to examine something more specific. From 2022 onwards, the published blood lead distributions allow children between 5 and <10 µg/dL to be separated from those who would still have met the former ≥10 µg/dL definition. That comparison shows much more clearly what happened when England lowered its intervention concentration.

If LEICSS cannot measure population prevalence, the obvious question is whether other evidence can tell us how many UK children have blood lead concentrations at or above 5 µg/dL.

Several numbers are available, but they differ substantially.

At first sight, these figures appear irreconcilable. They are not. They are estimates or observations of different epidemiological quantities, in different populations, produced by different methods. The three figures cannot be placed on a single scale and treated as alternative measurements of the same population.

The most concrete number is the smallest. In 2024, 247 children aged under 16 in England met the LEICSS case definition. The national detection rate was 23 cases per million children. Of the 247 cases, 223 were reported directly through participating laboratories and 24 through other routes.

These are real, identified children with blood lead concentrations at or above the intervention concentration. But the figure of 247 answers a narrow question: how many qualifying children were detected and reported to LEICSS during 2024?

It does not answer: how many children in England had a blood lead concentration ≥5 µg/dL during 2024?

UKHSA makes this distinction explicitly. Its report states that surveillance of clinically reported cases is likely to underestimate the number of affected children because lower blood lead concentrations often produce no overt clinical symptoms. It also states directly that there are no data available regarding the number of children in England exposed to lead above this threshold.

The LEICSS figure should therefore be regarded as an annual flow of newly detected cases, not a population prevalence estimate.

Because England lacks contemporary representative prevalence data, UKHSA has examined surveys from comparable high-income countries to illustrate the possible scale of childhood exposure.

Its 2025 report cites a US estimate that 1.1% of children aged 1–5 years had blood lead concentrations ≥5 µg/dL. Applying that proportion to the corresponding population of children in England, using ONS mid-2023 population estimates, produced an estimate of approximately 34,541 children above the intervention concentration.

This number is very different from 247, but it is also a fundamentally different type of number. Those 34,541 children have not been identified through blood testing in England. UKHSA has taken a prevalence measured in another country and applied it to the English population as an illustration of what the underlying number might look like if English children had a similar prevalence. UKHSA itself qualifies the calculation by noting that population differences must be considered when using international survey data in this way.

There is a useful demonstration of this uncertainty in UKHSA’s own successive reports. The report published in 2024 used an earlier US estimate of 2.6% and applied it to English children aged 1–4, producing an estimate of approximately 64,780 children above 5 µg/dL.^[5] The following year’s report used the more recent US estimate of 1.1% among children aged 1–5 and produced approximately 34,541.

The English population did not suddenly halve its childhood lead prevalence between those publications. The comparator changed.

That illustrates both the usefulness and the limitation of international extrapolation. It can demonstrate that the number expected from population studies may be substantially greater than the number detected through passive surveillance. It cannot substitute for measuring the English population itself.

The largest and most frequently cited UK estimate comes from IHME modelling associated with the Global Burden of Disease 2019 study and published in UNICEF and Pure Earth’s The Toxic Truth ^[6].

For the United Kingdom, the model estimated that in 2019, 213,702 children and young people aged 0–19 had blood lead concentrations ≥5 µg/dL, with an uncertainty interval of 186,117 to 281,542 ^[7]. At the former 10 µg/dL intervention concentration, the corresponding estimate was 29,036, with an uncertainty interval of 25,099 to 42,470.

The difference between those two estimates is important. Within the IHME model, lowering the concentration of interest from 10 to 5 µg/dL increases the estimated population above it by more than sevenfold. It reinforces why the lower end of the blood lead distribution matters when considering the number of children potentially affected.

But 213,702 is not a count of British children who received blood tests. The UNICEF and Pure Earth report states that its country-level blood lead calculations were supplied by IHME using GBD 2019 modelling. The estimate therefore depends on the empirical data available to the model and statistical estimation where direct country data are incomplete. This is particularly important in the UK because, as already established, contemporary nationally representative childhood blood lead measurements are absent.

The uncertainty interval also makes clear that 213,702 should not be interpreted as a precise headcount.

The temptation is obvious. If IHME estimated 213,702 UK children above 5 µg/dL and LEICSS identified 247 cases in 2024, it might appear possible to divide one by the other and estimate what proportion of affected children the surveillance system detects.

That calculation would be epidemiologically invalid.

The numerator and denominator do not describe the same population. 247 is one year’s flow of newly detected cases among children aged 0–15 in England. 213,702 is a modelled estimate of the population aged 0–19 above a specified blood lead concentration across the United Kingdom in 2019. One is an annual surveillance count; the other is an estimated population stock. The age ranges, geography, time periods and methods all differ.

It would therefore be incorrect to say that LEICSS detects approximately 0.1% of lead-exposed children. Nor can 247 be subtracted from 213,702 to produce a figure for the number of “undiagnosed” children.

The same problem applies to the UKHSA extrapolation of 34,541. It concerns children aged 1–5 in England and is derived by transferring a US prevalence estimate to the English population. It is not a measured pool of children from which the year’s 247 LEICSS cases can simply be deducted.

The estimates nevertheless contain useful information when their limitations are respected.

LEICSS establishes that children with blood lead concentrations ≥5 µg/dL continue to be detected in England and that the number being identified has risen substantially.

International population surveys demonstrate that representative sampling generally finds elevated blood lead at a prevalence far greater than would be inferred from clinically detected cases alone. UKHSA itself concludes from these surveys that the number reported through LEICSS is significantly lower than the likely number of affected children in England.

The IHME model goes further by attempting to estimate the UK population burden despite the absence of contemporary representative national measurements. Its estimate suggests a potentially substantial population above 5 µg/dL, but its precision is constrained by exactly the evidence gap this article is examining.

The three figures should therefore be read together, but not equated. 247 tells us how many children England found in one year. 34,541 illustrates what the number might look like among young English children if a recent US prevalence applied here. 213,702 is a modelled estimate of the number of UK 0–19-year-olds above 5 µg/dL in 2019.

None is a contemporary, directly measured estimate of the prevalence of elevated blood lead across UK children.

That is why the apparently straightforward question in the title remains unresolved. The UK has observed cases, international extrapolations and modelled estimates. What it does not have is a contemporary representative measurement of its own child population.

Identifying a child with an elevated blood lead concentration is only the beginning of a public-health investigation. The concentration establishes that lead has entered the child’s body; it does not identify where the lead came from. A child may encounter lead from several environmental and household sources, and more than one source may be present at the same time.

This distinction is particularly important when interpreting LEICSS. The surveillance system records confirmed elevated blood lead concentrations, while its Enhanced Surveillance Questionnaire gathers information about possible sources and circumstances of exposure. These data provide valuable evidence about the environments in which identified cases occur, but they are not a population source-apportionment study.

In 2024, UKHSA received completed questionnaires for 101 cases whose investigations had concluded. Among these, the most frequently recorded potential exposures were soil (24%), paint (17%), drinking water and/or lead pipes (12%), and parental or guardian occupational exposure (6%). Other potential sources included imported utensils, ceramics and pewter (4%), imported spices and food (2%) and traditional medicines (1%). Individual children could have more than one potential exposure recorded.

Those percentages need to be interpreted carefully, and four qualifications apply.

First, they do not mean that 24% of childhood lead exposure in England is caused by soil, 17% by paint or 12% by drinking water and lead pipes. The data concern a selected subset of children already identified with elevated blood lead, and the categories describe potential exposures identified during investigation.

Second, only 101 of the 247 confirmed cases in 2024 had concluded questionnaires included in this analysis, and case management requires a questionnaire only where blood lead is at or above 10 µg/dL. That subset is therefore weighted towards the more heavily exposed cases rather than drawn at random.

Third, exposures can overlap, so the figures do not sum to 100.

Fourth, and most important for interpreting change over time, the comparison between years is unstable. UKHSA reports that drinking water and lead pipes doubled from 6% to 12%. Its narrative describes the 6% as the previous year, but the table it draws on gives 6% as the pooled figure across the 236 questionnaires completed between 2021 and 2023. Across that same comparison, soil fell from 67% to 24% and paint from 44% to 17%. Falls of that magnitude in a single step are unlikely to describe a real change in where children are encountering lead, and are more likely to reflect a change in how questionnaires were completed or coded. Workplace exposure also rose, from 3% to 6%. The apparent rise in drinking water sits inside that same shift and should be read with the same caution.

Lead-based paint remains an important potential source in older housing. Although its use was progressively restricted from the 1960s and eventually banned from sale in 1992, lead paint may remain beneath later decorative layers. When intact and undisturbed it presents a different exposure potential from paint that is deteriorating, flaking, sanded or disturbed during renovation.

For young children, the pathway is frequently indirect. Lead-containing paint and other materials contribute lead to household dust, which can settle on floors, toys and other surfaces. Normal hand-to-mouth behaviour then provides a route of ingestion. Pica can substantially increase exposure where a child deliberately ingests paint flakes, soil or other non-food materials.

Soil can contain lead from several historical sources, including former industrial activity, deposition from leaded petrol, exterior paint and other urban contamination. Again, the presence of lead in soil does not by itself establish that it caused an individual child’s elevated blood lead. Exposure depends on concentration, accessibility, behaviour and the extent to which contaminated soil or dust is ingested.

Lead used or disturbed in the workplace can also reach children indirectly. Workers in occupations involving lead may carry contaminated dust home on clothing, footwear, tools, vehicles or personal belongings. A child may therefore be exposed without ever entering the workplace itself.

Potentially relevant activities can include metalworking, construction and renovation, demolition, recycling and waste processing, work involving batteries, shooting and other activities where lead-containing materials or dust are encountered.

The presence of an occupational exposure in the household is again a potential pathway, not automatic proof of causation.

Some sources of childhood exposure are not fixed features of the UK built environment. UKHSA investigations recognise a range of consumer and household products as potential sources, including imported ceramics and cookware, traditional medicines and cosmetics, and some foods or spices. Lead-containing glazes or pigments can contaminate food, while lead may also be introduced into spices and other products during production, processing or through adulteration.

These pathways are important because they are easily missed if an investigation focuses only on the child’s home or on conventional UK environmental sources.

Drinking water represents a different type of potential exposure because lead is not normally present in significant quantities in water when it leaves the treatment works. Where lead occurs at the tap, it is principally associated with contact between water and lead-containing plumbing materials.

In the UK, this is particularly relevant to older properties. Lead communication pipes, private supply pipes and internal lead plumbing may remain in service, while lead can also be released from some fittings, solder and other plumbing components. PHE’s 2021 review summarises the regulatory position as follows: the use of lead water pipes was phased out by the end of the 1960s and the use of lead solders by the late 1980s, and under the Water Supply (Water Fittings) Regulations 1999 lead pipe, fittings and solder are prohibited for use in new installations. The same review records a regulatory limit of 10 µg/L for lead in drinking water under the Water Supply (Water Quality) Regulations 2016 and the Private Water Supplies (England) Regulations 2016.

Lead can dissolve into water during contact with lead-containing materials, and particulate lead may also be released from corrosion scales or disturbed deposits. The resulting concentration at the tap is not fixed. It can vary with water chemistry, the length and configuration of lead pipework, stagnation time, previous water use, flow conditions and particulate mobilisation.

This makes source attribution particularly demanding. The presence of a lead pipe establishes a potential source; it does not establish how much that source contributed to a child’s blood lead concentration. Conversely, a single low water sample does not necessarily exclude drinking water as a contributor, because the concentration measured depends upon the sampling conditions and the section of plumbing represented by the sample. What a single result can and cannot establish is set out in our review of sampling protocols and what a lead result actually means.

There is, however, one place where the contribution of drinking water has been measured rather than inferred. France’s national biomonitoring survey, Saturn-Inf, was accompanied by a nested environmental study, Plomb-Habitat, which visited the homes of 484 of the participating children and measured lead in tap water, soils, household settled dusts, paints, traditional cosmetics and craft ceramics.^[8] Because blood and environmental measurements were collected from the same children, the study could identify which household characteristics were associated with higher blood lead across the population rather than only among children already suspected of exposure.

The environmental factors significantly associated with blood lead concentration were the consumption of tap water in homes with lead service connections, peeling paint or recent renovation in old housing, hand-to-mouth behaviour, passive smoking, and having a mother born in a country where lead is often used ^[4].

Tap water drawn through a lead service connection therefore appears in that list alongside deteriorating paint, and it does so in a study designed to represent a national child population rather than a set of investigated cases. That is a stronger form of evidence about drinking water’s contribution than English surveillance can currently produce, because England has no equivalent study. It is also evidence about French housing, French water chemistry and French plumbing, and should not be read as a quantification of the contribution in the United Kingdom.

The category recorded in English surveillance — “drinking water and/or lead pipes” — also does not establish that elevated lead was analytically demonstrated in the household’s drinking water in every case. Potential exposure, environmental confirmation and causal attribution are different evidential stages.

Attempting to assign every elevated blood lead concentration to one source can itself be misleading.

A child living in an older urban property might simultaneously encounter legacy paint, contaminated household dust, lead in garden soil and lead plumbing. Another child might have both an environmental source at home and exposure associated with a parent’s occupation. Imported products may add another pathway.

Blood lead concentration integrates lead absorbed from these sources. It does not carry a signature identifying the proportion contributed by each one.

This is why environmental investigation is central to case management. The practical objective is not necessarily to prove that one source accounts for the entirety of a child’s blood lead before action can be taken. It is to identify credible continuing sources and reduce or eliminate exposure wherever reasonably possible.

The distinction also matters at population level. LEICSS can show which potential exposures repeatedly arise among detected cases, but it cannot establish what proportion of blood lead across the entire UK child population comes from paint, soil, drinking water, imported products or any other source.

Answering that larger question would require a different study design: representative biological measurements combined with systematically collected environmental, housing, behavioural and socioeconomic information. France has done it. England has not.

For the present, the evidence supports a narrower conclusion. Childhood lead exposure in the UK is not a single-source problem. The children identified through surveillance may encounter lead in the fabric of older housing, soil and dust, household products, food and ceramics, occupationally transported contamination and drinking water supplied through legacy lead plumbing.

A child can only enter LEICSS after a chain of events: exposure must exist, the possibility of lead must be recognised, a test must be requested, a sample obtained, an elevated result identified, and the case reported. Children can be lost at every stage. That is why the system measures annual case detection and not population prevalence, and why no denominator can be derived from it.

The same limitation applies to clinically requested testing in Wales, and no contemporary nationally representative childhood biomonitoring programme was identified in Scotland or Northern Ireland. The last representative English population data date from the 1990s.

Without a representative sample, the UK cannot determine with confidence:

• the proportion of children with blood lead concentrations at or above 5 µg/dL, or above other concentrations such as 3.5 or 10 µg/dL;
• how exposure varies by age, or how strongly it is patterned by deprivation, housing age, geography or ethnicity;
• whether average and upper-tail concentrations are continuing to fall;
• or how much of the national burden is associated with particular sources, including legacy lead plumbing.

That distinction matters for policy, and it is not the same argument as universal screening. Population screening, targeted testing and representative biomonitoring are different tools. A nationally representative biomonitoring study could establish prevalence and distribution without routine clinical testing of every child, and those data would then inform the separate question of whether universal, targeted or risk-stratified screening is worthwhile. How the current screening review and the ECLIPS study bear on that question is set out in How the UK Counts Childhood Lead.

The missing denominator is not a minor technical limitation. It determines how confidently the scale of the problem can be described, how effectively resources can be targeted, and how future prevention policy can be evaluated.

So, how many UK children have elevated levels of lead in their blood?

The most accurate answer is that we do not currently know.

We know how many children are being identified through surveillance in England. In 2024, LEICSS recorded 247 confirmed cases with blood lead concentrations at or above the 5 µg/dL public-health intervention concentration. We also know that case detection has increased substantially since England lowered that concentration from 10 to 5 µg/dL in July 2021.

The change has had a measurable effect. During the first three complete years under the lower intervention concentration, 664 children were identified through LEICSS. Of these, 416 had blood lead concentrations between 5 and <10 µg/dL. They represented almost two-thirds of confirmed cases and would not have met the former ≥10 µg/dL surveillance definition.

Lowering the intervention concentration has therefore brought a substantial group of children within public-health surveillance who previously fell below the level at which formal intervention was triggered.

But it has also exposed the limitations of the surveillance data.

The number of children detected at ≥10 µg/dL has risen as well. England identified 72 such children in 2022 and 88 in both 2023 and 2024, compared with an average of 38.5 total cases per year during 2015–20, when ≥10 µg/dL was the LEICSS case definition. The Leeds experience provides further evidence that increased clinical awareness and blood lead testing can substantially increase case detection.

LEICSS is therefore telling us something important, but it is not measuring prevalence. It records children whose elevated blood lead concentrations have been detected. Children who are not tested are not represented.

That distinction explains the enormous difference between the numbers encountered throughout this article. 247 children were detected through LEICSS in England in 2024. UKHSA has estimated that approximately 34,541 children aged 1–5 in England might have blood lead concentrations ≥5 µg/dL if a recent US prevalence estimate were applicable to the English population. IHME modelling estimated that 213,702 children and young people aged 0–19 across the UK had blood lead concentrations ≥5 µg/dL in 2019.

These figures should not be used to calculate how many children LEICSS is “missing”. They describe different populations, age groups, years and epidemiological quantities. But their disparity illustrates the central problem: England can count the children it finds, but the UK does not have the contemporary representative blood lead measurements required to count — or reliably estimate from its own empirical data — the population from which those cases arise.

That is not inevitable.

The United States, Canada, Germany and France demonstrate that representative population biomonitoring can establish childhood blood lead distributions without universally screening every child. A properly designed sample can estimate the proportion above 5 µg/dL, describe the lower and upper parts of the distribution, identify inequalities in exposure and determine whether concentrations are continuing to decline. France’s Plomb-Habitat study went further still, identifying tap water drawn through lead service connections among the household factors significantly associated with children’s blood lead — the kind of finding England cannot currently produce.

The UK does not have an equivalent contemporary national dataset.

ECLIPS may represent the beginning of a response to that evidence gap. Its work in Leeds is testing whether home finger-prick sampling and household recruitment can make larger-scale childhood blood lead measurement practical. But a study in one city cannot establish UK prevalence. A national answer would ultimately require representative measurement across a population sufficiently broad to capture geographical, demographic, socioeconomic and housing differences.

The renewed UK National Screening Committee review may also reconsider how children at elevated risk should be identified. But screening is a separate question from population measurement. The UK does not need to decide that every child should receive a blood lead test before it can establish how much lead is present in children’s blood at population level.

More than three decades after the last representative English childhood blood lead data, the fundamental evidence gap therefore remains.

We know that childhood blood lead concentrations fell dramatically during the late twentieth century. We know that lead exposure has not disappeared. We know that adverse effects occur at concentrations below the former 10 µg/dL intervention level. We know that lowering the intervention concentration to 5 µg/dL has brought hundreds of additional children within public-health surveillance. And we know that when clinicians test more children, more cases are found.

What we still do not know is how many UK children currently have blood lead concentrations at or above 5 µg/dL.

Until blood lead is measured in a contemporary representative sample of UK children, the answer will continue to depend on surveillance counts, international comparisons and statistical models rather than direct national measurement.

For a country that has already decided that 5 µg/dL warrants public-health intervention, that is a significant gap in the evidence.

1. UK Health Security Agency. Lead: environmental and public health intervention. London: UKHSA; 2025.
2. UK Health Security Agency. Lead Exposure in Children Surveillance System (LEICSS) annual report, 2025. Health Protection Report 19(12). London: UKHSA; 2025. [Surveillance data for 2024.]
3. UK Health Security Agency. Lead Exposure in Children Surveillance System (LEICSS) annual report, 2022. London: UKHSA; 2022. [Surveillance data for 2021.]
4. Etchevers A, Bretin P, Lecoffre C, Bidondo M-L, Le Strat Y, Glorennec P, et al. Blood lead levels and risk factors in young children in France, 2008–2009. Int J Hyg Environ Health. 2014;217(4–5):528–37.
5. UK Health Security Agency. Lead Exposure in Children Surveillance System (LEICSS) annual report, 2024. Health Protection Report 18(10). London: UKHSA; 2024. [Surveillance data for 2023.]
6. UNICEF, Pure Earth. The toxic truth: children’s exposure to lead pollution undermines a generation of future potential. 2nd ed. New York: UNICEF and Pure Earth; 2020.
7. Institute for Health Metrics and Evaluation. Global Burden of Disease Study 2019: blood lead estimates. Seattle, WA: IHME; 2020. UK country estimates reproduced in UNICEF and Pure Earth (2020), Annex A.
8. Lucas J-P, Le Bot B, Glorennec P, Etchevers A, Bretin P, Douay F, et al. Lead contamination in French children’s homes and environment. Environ Res. 2012;116:58–65.