COSMOS MAGAZINE

Roman Empire IQ decline blamed on lead pollution 

By Imma Perfetto

Air pollution from large-scale mining and smelting at the height of the Roman Empire would have caused widespread cognitive declines, new research has found.

The study examined measurements of lead pollution in 3 Arctic ice cores dating from 500 BCE to 600 CE, an era spanning the rise of the Roman Republic through to the fall of the Roman Empire.

Longitudinal ice core samples. Credit: Jessi LeMay

This is the first study to take a pollution record from an ice core and invert it to get atmospheric concentrations of pollution and then assess human impacts.

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Lead author, Joe McConnell of Desert Research Institute

Based on modern epidemiological understanding of the effects of childhood blood lead levels, they suggest there would likely have been reductions in IQ levels of at least 2 to 3 points during the Pax Romana – the 200-year height of the Empire.

In the past 150 years, humans have been exposed to atmospheric lead largely from the burning of fossil fuels, and from leaded petroleum especially since the 1920s.

“As lead pollution has declined during the last 30 years, it has become more and more apparent to epidemiologists and medical experts just how bad lead is for human development,” says McConnell.

It is now understood that any level of lead exposure is damaging to human health. This is especially the case for children, for which low-level exposure is linked to reduced intelligence quotient (IQ), concentration, and academic abilities.

According to the study, human exposure to lead arose through many potential routes during antiquity, including water pipes, utensils and pottery, toys, ornaments, cosmetics, and even intentional ingestion. It was also in the air.

cosmosmagazine.com 

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