Lead exposure could be causing six times more deaths from cardiovascular disease than previously thought, a new global study has found.
The research showed that low and middle-income countries (LMICs) suffered the greatest impacts of lead exposure, with the metal also leading to significant IQ loss in young children, as well as causing learning difficulties and chronic kidney disease in adults.
The World Bank analysis indicated that exposure to lead might 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. Up to 95% of the effects were in LMICs, with children in these countries losing an average of 5.9 IQ points during their first five years of life.
The findings suggest that the global health effects of lead exposure could be similar to the impact of fine particulate matter (known as PM2.5) from all outdoor and household air pollution combined, and three times greater than the effects of unsafe drinking water, sanitation and handwashing.
Dr Angie Brown, consultant cardiologist and medical director at the Irish Heart Foundation, described the paper as ‘an important reminder’ of the dangers of lead exposure.
“Lead toxicity is not something that we would generally consider as a risk factor for CVD in Ireland like high blood pressure, diabetes, smoking, high cholesterol etc., as the risk of toxicity has dropped significantly since the removal of lead paint and lead petrol,” she told IMT.
“However, it is important that we raise awareness of this issue as it is still found in old lead pipes that haven’t been replaced, or during renovations while removing old lead paint, and in some recycled material, fertilizers, etc. as chronic low levels of exposure can be an issue.”
The analysis, published in The Lancet Planetary Health journal, estimates the global economic cost of lead exposure to have been US$6 trillion (€5.58 trillion) in 2019, with 23 per cent of this loss due to the lower IQs caused by lead exposure reducing a child’s lifetime total income by as much as 12 per cent.
The economic cost is equivalent to 10 per cent of GPD in LMICs, but just 5 per cent of GPD in higher-income countries.
“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,” the study’s lead author Bjorn Larsen said.
“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. Efforts to address the impacts of lead exposure must reflect that these are as significant as those posed by PM2.5 outdoor ambient and household air pollution.”
The authors of the study used average blood lead level (BLL) estimates from 183 countries, accounting for 99.9% of the world’s population. The average BLL in LMICs was 4.6 μg/dL, compared with 1.3 μg/dL in HICs. People in North America, 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.
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.
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, fertilizers and cultured fish feed.
The presence of each of these sources varies greatly across countries, and the article contends that each source’s contribution to population blood lead levels (BLLs) needs to be better understood in most LMICs in order to develop effective exposure mitigation plans.