Exposure to lead may have caused 5.5 million adult deaths from cardiovascular disease and the loss of 765 million IQ points in children under the age of five worldwide in 2019, according to a study published in The Lancet Planetary Health journal.

Up to 95 per cent of the effects were in low and middle-income countries (LMICs), with children there losing an average of 5.9 IQ, or intelligence quotient, points during their first five years of life, the researchers said.

The findings indicate the global health effects of lead exposure could be similar to the estimated health effects of small particle pollution, PM2.5, and household air pollution combined, and three times greater than the health effects of unsafe drinking water, sanitation, and handwashing, they said.

IQ loss in LMICs due to lead exposure is nearly 80 per cent higher than a previous estimate, while deaths from cardiovascular disease are six times higher, the researchers said.

The global cost of lead exposure in 2019 was estimated to be USD 6 trillion, equivalent to 7 per cent of global GDP. In LMICs, it was equivalent to more than 10 per cent of GDP, or twice as high as in High-Income Countries (HICs), they said.

Exposure to lead can seriously harm young children's health, including damage to the brain, slowed development, and learning difficulties. In adults, lead exposure can increase people's risk of cardiovascular disease – which accounts for almost 95 per cent of deaths linked to lead exposure – as well as chronic kidney disease and learning disabilities.

Despite the fact that lead-containing petrol has been phased out around the world, exposure to the toxic metal still poses major global health risks, especially in LMICs, the researchers said.

Key sources of exposure include lead acid battery recycling, metal mining, food, soil and dust, leaded paint, cookware from recycled materials, lead-glazed pottery and ceramics, spices, toys, cosmetics, electronic waste, fertilisers and cultured fish feed, they said.

"We know that lead exposure has continued to cause huge impacts on human health, despite most countries banning the use of leaded petrol more than 20 years ago," said study lead author Bjorn Larsen from The World Bank, Washington, US.

"What is concerning about our study is that it indicates these damaging health effects are much greater than we previously thought and that they come at a very high economic cost, especially in low- and middle-income countries," Larsen said.

The authors of the study used blood lead levels (BLL) estimates from the Global Burden of Disease (GBD) 2019 study to estimate the global health impacts and costs of lead exposure.

The average BLL in LMICs was 4.6 microgrammes per decilitre (μg/dL), compared with 1.3 μg/dL in HICs.

People in North America and in Europe and Central Asia had the lowest average BLLs, with the highest among people in South Asia, the Middle East and North Africa, and Sub-Saharan Africa, the researchers said.

The analysis estimates that lead exposure contributed to 5.5 million deaths from cardiovascular disease globally in 2019, or 30 per cent of all cardiovascular disease deaths.

This is more than six times higher than the GBD 2019 estimate of 850,000 CVD deaths from lead exposure. Of the 5.5 million deaths from lead exposure, 90 per cent were in LMICs, they said.

The analysis also suggests that lead exposure caused the loss of 765 million IQ points in children under five years old in 2019, with 95 per cent of the losses among children in LMICs, according to the researchers.

During their first five years of life, children in LMICs on average each lose 5.9 IQ points from lead exposure. The authors estimate this can reduce these children's total lifetime income by as much as 12 per cent, they said.

The authors acknowledge some limitations to their study. These mainly revolve around the accuracy of global estimates of BLLs, as nationwide measurements are not available for many countries, particularly LMICs.

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