Lead is significantly more harmful to the health of children and adults across the world than previously thought, suggests a modelling study presented to the World Bank.
The study, by Norwegian development economist Bjorn Larsen and the Colombian environmental specialist for lead Ernesto Sánchez-Triana, PhD, also showed the considerably negative impact on the intelligence of children, particularly in low- and middle-income countries (LMICs).
Their work, published in The Lancet Planetary Health, noted that the economic consequences of increased exposure to lead are already immense, especially in LMICs.
The study was financed by the Korea Green Growth Trust Fund and the World Bank’s Pollution Management and Environmental Health Programme.
“It is a very important publication that affects all of us,” German paediatrician Dr Stephan Böse-O’Reilly, of the Institute and Polyclinic for Occupational, Social and Environmental Health of the Ludwig Maximilian University Hospital in Munich, Germany, told Medscape Medical News.
“The study, the results of which I think are very reliable, shows that elevated levels of lead in the blood have a much more drastic effect on children’s intelligence than we previously thought.”
It is well known that lead affects the antenatal and postnatal cognitive development of children, he said. But the extent of this effect has quite clearly been underestimated before now.
Larsen and Sánchez-Triana’s work could also prove that lead may trigger more cardiovascular diseases in adulthood.
“We already knew that increased exposure to lead increased the risk of high blood pressure and, as a result, mortality,” said Böse-O’Reilly.
“This study now very clearly shows that the risk of arteriosclerosis, for example, also increases through lead exposure.”
IQ loss
“For the first time, to our knowledge, we aimed to estimate the global burden and cost of IQ loss and cardiovascular disease mortality from lead exposure,” wrote Larsen and Sánchez-Triana.
For their calculations, the scientists used blood lead level estimates from the Global Burden of Diseases, Injuries and Risk Factors Study (GBD) 2019.
They estimated IQ loss in children under five using the internationally recognised blood lead level–IQ loss function. They subsequently estimated the cost of this IQ loss based on the loss in lifetime income, presented as cost in US dollars and percentage of gross domestic product (GDP).
Larsen and Sánchez-Triana estimated cardiovascular deaths due to lead exposure in adults aged 25 or older using a model that captures the effects of lead exposure on cardiovascular disease mortality that is mediated through mechanisms other than hypertension.
Finally, they used the statistical life expectancy to estimate the welfare cost of premature mortality, also presented as cost in US dollars and percentage of GDP.
All estimates were calculated according to the World Bank income classification for 2019.
Millions of deaths
They reported that children younger than five-years-old lost an estimated 765m IQ points worldwide due to lead exposure in this period.
In 2019, 5 545 000 adults died from cardiovascular diseases caused by lead exposure. The scientists recorded 729m of the IQ points lost (95.3%) and 5 004 000 (90.2%) of the deaths as occurring in LMICs.
The IQ loss here was nearly 80% higher than a previous estimate, wrote Larsen and Sánchez-Triana. The number of cardiovascular disease deaths they determined was six times higher than the GBD 2019 estimate.
“These are results with which the expert societies, especially the German Society of Paediatrics and Adolescent Medicine and the German Cardiac Society, and the corresponding professional associations, need to concern themselves,” said Böse-O’Reilly.
Although blood lead concentrations have declined substantially since the phase-out of leaded gasoline, especially in Western countries, lead still represents a major health issue, even in Germany, because it stays in the bones for decades.
European situation moderate
“We need a broad discussion on questions such as whether lead levels should be included in prophylactic assessments in certain age groups, what blood level is even tolerable, and in what situation medicinal therapy with chelating agents would possibly be appropriate,” said Böse-O’Reilly.
“Of course, we cannot answer these questions on the basis of one individual study,” he added.
“However, the work in question definitely illustrates how dangerous lead can be and that we need further research into the actual burden and the best preventive measures.”
In this respect, the situation in Europe is still comparatively moderate.
“Globally, lead exposure has risen in recent years,” said Böse-O’Reilly.
According to an investigation by the Planet Earth Foundation, outside the European Union, lead can increasingly be found in toys, spices and cooking utensils, for example.
“Especially in lower-income countries, there is a lack of consumer protection or a good monitoring programme as we have here in the EU,” Böse-O’Reilly added.
In these countries, lead is sometimes added to spices by unscrupulous retailers to make the colour more intense or to simply add to its weight to gain more profit.
Recycling lead-acid batteries or other electrical waste, often transferred to poorer countries, constitutes a large problem.
“In general, children in Germany have a blood lead level of less than 1 μg/dL,” he said. “In some regions of Indonesia, where these recycling factories are located, more than 50% of children have levels of more than 20 μg/dL.”
Particulate matter
According to Larsen and Sánchez-Triana, the global cost of increased lead exposure was around $6trn in 2019, which was equivalent to 6.9% of global GDP.
About 77% of the cost ($4.62trn) comprised the welfare costs of cardiovascular disease mortality, and 23% ($1.38trn) comprised the present value of future income losses due to IQ loss in children.
“Our findings suggest that global lead exposure has health and economic costs on par with PM2.5 air pollution,” wrote the authors.
This places lead as an environmental risk factor on par with particulate matter and above that, of air pollution from solid fuels, ahead of unsafe drinking water, unhygienic sanitation, or insufficient hand-washing.
“This finding is in contrast to that of GBD 2019, which ranked lead exposure as a distant fourth environmental risk factor, due to not accounting for IQ loss in children – other than idiopathic developmental intellectual disability in a small subset of children – and reporting a substantially lower estimate of adult cardiovascular disease mortality,” wrote Larsen and Sánchez-Triana.
“A central implication for future research and policy is that LMICs bear an extraordinarily large share of the health and cost burden of lead exposure. Consequently, improved quality of blood lead level measurements and identification of sources containing lead are urgently needed there.”
Improved recycling methods
Böse-O’Reilly would like an increased focus on children.
“If children’s cognitive skills are lost, this, of course, has a long-term effect on a country’s economic position," he said. “Precisely that which LMICs actually need for their development is being stripped from them.
“We should think long and hard about whether we really need to send so much of our electrical waste and so many old cars to poorer countries, where they are incorrectly recycled.
“We should at least give the LMICs the support necessary for them to be able to process lead-containing products in the future so that less lead makes it into the environment.”
Study details
Global health burden and cost of lead exposure in children and adults: a health impact and economic modelling analysis
Bjorn Larsen, Ernesto Sánchez-Triana.
Published in The Lancet Planetary Health on 11 September 2023
Summary
Background
Lead exposure is a worldwide health risk despite substantial declines in blood lead levels following the leaded gasoline phase-out. For the first time, to our knowledge, we aimed to estimate the global burden and cost of intelligence quotient (IQ) loss and cardiovascular disease mortality from lead exposure.
Methods
In this modelling study, we used country blood lead level estimates from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. We estimated IQ loss (presented as estimated loss in IQ points with 95% CIs) in the global population of children younger than 5 years using the blood lead level–IQ loss function from an international pooled analysis. We estimated the cost of IQ loss, which was calculated only for the proportion of children expected to enter the labour force, as the present value of loss in lifetime income from the IQ loss (presented as cost in US dollars and percentage of gross domestic product with a range). We estimated cardiovascular deaths (with 95% CIs) due to lead exposure among people aged 25 years or older using a health impact model that captures the effect of lead exposure on cardiovascular disease mortality that is mediated through mechanisms other than hypertension. Finally, we used values of statistical life to estimate the welfare cost of premature mortality (presented as cost in US dollars and percentage of GDP). All estimates were calculated by World Bank income classification and region (for low-income and middle-income countries [LMICs] only) for 2019.
Findings
We estimated that children younger than 5 years lost 765 million (95% CI 443–1098) IQ points and that 5 545 000 (2 305 000–8 271 000) adults died from cardiovascular disease in 2019 due to lead exposure. 729 million of the IQ points lost (95·3% of the total global IQ loss) and 5 004 000 (90·2% of total) cardiovascular disease deaths due to lead exposure occurred in LMICs. IQ loss in LMICs was nearly 80% higher than a previous estimate. Cardiovascular disease deaths were six times higher than the GBD 2019 estimate. The global cost of lead exposure was US$6·0 trillion (range 2·6–9·0) in 2019, which was equivalent to 6·9% (3·1–10·4) of the global gross domestic product. 77% (range 70–78) of the cost was the welfare cost of cardiovascular disease mortality, and 23% (22–30) was the present value of future income losses from IQ loss.
Interpretation
Our findings suggest that global lead exposure has health and economic costs at par with PM2·5 air pollution. However, much work remains to improve the quality of blood lead level measurement data, especially in LMICs.
Medscape article – Lead Pollutants as Harmful to Health as Particulate Matter (Open access)
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