Researchers have found that lead exposure caused a decrease of up to 3 IQ points in the average individual,
New research suggests that widespread lead contamination during the Roman Empire led to a near two-century long period of cognitive decline across Europe.
The study, published in the Proceedings of the National Academy of Sciences on Monday, indicates that the average Roman citizen likely experienced a 2.5 to 3-point reduction in their intelligence quotient (IQ) due to lead exposure.
Analysis of Greenland ice core chemicals reveals a significant increase in lead pollution during the Roman Empire, beginning after 15 BC and persisting until the end of the Pax Romana in AD 180.
“It’s remarkable that we could quantify European air pollution from nearly 2,000 years ago and assess its potential health effects on the Roman civilization,” commented lead author Joseph McConnell, a climate and environmental scientist at the Desert Research Institute.
These findings are “quite significant” as they show that “industrial activities have caused widespread human health damage for over two millennia,” he added.
The Roman Empire, which at its height encompassed the Mediterranean, Western Europe, and parts of the Middle East, engaged in extensive silver and lead mining and smelting for currency and economic purposes. This resulted in substantial atmospheric lead dispersal, the scientist explained.
“While a 2.5- to 3-point IQ reduction might seem small, its impact across the entire population over the approximately 180 years of the Pax Romana is substantial,” McConnell concluded.
Although the study focused on air pollution, Romans also encountered lead through plumbing and cookware.
The role of widespread lead use in the Roman Empire’s decline has been a subject of ongoing scientific debate.
“I’ll leave it to epidemiologists, historians, and archaeologists to determine if the levels of atmospheric lead pollution and its health consequences we identified… were historically significant,” McConnell stated.