The figure is “enormous”, recognizes Bjorn Larsen of the World Bank. According to a study published in the scientific journal The Lancet Planetary Health this Tuesday, September 12, lead pollution was the cause of 5.5 million deaths from cardiovascular diseases worldwide in 2019.
This cause represents 30% of all deaths linked to cardiovascular pathologies. This level is six times higher than current estimates, namely 850,000 deaths attributable to lead according to the study on the Global Burden of Disease for 2019, this immense research program which serves as the basis for numerous studies. Low- and middle-income countries (90%) are mainly affected.
According to the conclusions of this study led by the World Bank, the role of lead in cardiovascular diseases would therefore be greater than that of smoking or cholesterol, underlines to AFP Bjorn Larsen, one of the authors of the study. Lead poisoning would represent a problem as serious as air pollution.
An impact on children’s brains
To reach these conclusions, the authors of the study, led by two economists from the World Bank, evaluated the level of lead poisoning in the population of numerous countries (183) based on estimates from blood tests. These had been modeled in the Global Burden of Disease. They then cross-referenced this data with the expected health consequences of lead poisoning.
Unlike previous research, remember The world, this new study does not only take into account the effect of lead on blood pressure (hypertension). It includes other parameters such as atherosclerosis (the thickening of the arteries leading to cardiac arrest and stroke) or the reduction in heart rate variability, which leads to long-term cardiovascular problems.
Lead poisoning is the cause of numerous pathologies, particularly in children under five years old. Lead exposure particularly impacts children’s brain development. Thus, based on data concerning the year 2019, it would have led to a loss of intelligence quotient (IQ) of around 765 million points among children under 5 years old worldwide. This figure exceeds previous estimates by 80%.
A staggering economic cost
Exposure also has an immense economic cost. The study led by the World Bank estimates it at $6,000 billion for the year 2019, the equivalent of 7% of global GDP.
There are multiple sources of lead exposure: food, soil, dust, water, paint, toys, cosmetics, metal mining, electronic waste, fertilizers, etc.
“The use of lead in fuels, for many years, has caused its dispersion in all compartments of the environment, but lead does not degrade and will not disappear,” recalls the World Philippe Grandjean, one of the best specialists in the links between neurodevelopment and environmental exposures, who did not participate in this work.
Questionable choices of methodology
The results of the study led by the World Bank were, however, greeted with caution by researchers who consider certain methodological choices questionable. It’s “interesting work but subject to many uncertainties,” Roy Harrison told AFP.
This air pollution expert at the University of Birmingham emphasizes in particular that it is difficult to reliably assess the degree of lead poisoning among populations in developing countries.
Another doubt concerns the exact degree to which lead poisoning contributes to cardiovascular disease. However, the impressive results of the study depend a lot on the choice of a high risk factor, based on a study only carried out in the United States. “If they are confirmed, (these results) will be major in terms of public health. But as they stand, they only constitute an interesting hypothesis,” believes Roy Harrison.