The Underestimated Toll: Heart Disease Deaths and IQ Decline from Lead Exposure

In 2019, around 5.5 million global adults succumbed to heart disease, while children under five experienced a collective IQ reduction of 765 million points due to lead contamination, as reported in a recent study from the Lancet Planetary Health journal.

Research indicates that metals like lead disrupt the way human cells function, leading to issues such as oxidative stress and lasting inflammation. These problems can precipitate conditions like hypertension, elevated cholesterol, and alterations in the heart’s contracting ability. Such changes make a person more susceptible to medical complications including ischemic heart disease, strokes, heart enlargement, heart failure, and diseases of peripheral arteries. Beyond affecting IQ, lead also hampers brain growth in young children. A study from 2022 revealed that this can cause behavioral challenges, like reduced attention spans, increased tendencies towards antisocial behavior, and learning problems. Another study in 2023 established that the negative effects of lead exposure persisted into adulthood, manifesting as poorer results on standardized exams.

“The discovery that 5.5 million deaths in 2019 resulted from lead exposure was unexpected,” says Bjorn Larsen, an author of the study and an environmental economist affiliated with the World Bank.. Larsen explained that their mortality estimate was significantly higher because their study considered a comprehensive range of cardiovascular effects from lead exposure, unlike the 2019 Global Burden Disease (GBD) study. Even though both studies utilized the same dataset, Larsen’s estimate was sixfold higher. The GBD research primarily evaluated lead’s impact on blood pressure, while the recent study also assessed other cardiac effects, like artery hardening leading to strokes.

Ernesto Sánchez-Triana, the study’s co-author and the global head of pollution management and circular economy at the World Bank, commented about the grave implications of the study. He stressed the substantial global health risk from lead exposure, emphasizing, “There is no safe threshold for lead exposure.”

The Unequal Impact and Global Implications

The study uncovered a lopsided distribution of IQ losses, with more than 95% taking place in developing nations—a figure nearly 80% above previous estimates. Data also showed that people in low and middle-income countries bear a disproportionate brunt of the health and economic consequences of lead exposure. These countries exhibit blood lead levels markedly higher than those observed in affluent nations.