Silver fueled the rise of the Roman Empire. But the ancient process of mining and extracting silver was also making the air thick with lead, scientists found.

Using modern evidence of lead pollution and its health effects, the international team calculates that lead exposure in the Roman golden age could have caused a population-wide drop in IQ of about 2.5 to 3 points per person. And that goes for most of the Roman Empire, including its provinces of Gaul, northwestern Africa, Iberia, and Britannia.

Lead pollution in ancient Rome likely dropped the average IQ, a study found. The research is based on an analysis of ice cores extracted from Greenland.

The new research adds context to a long-standing debate about the role lead pollution and poisoning may have played in the collapse of the Roman Empire. Some historians have argued that Roman elites and emperors who purportedly displayed odd,

Did lead poisoning contribute to the fall of the Roman Empire? It’s a question historians have long debated, since the Romans sweetened their wine with lead acetate and sipped tap water that flowed through lead pipes.

A new study turned to Arctic ice core records between 500 BCE through 600 CE to find a link between lead pollution and widespread health decline in the Ancient Roman Empire, which most likely lowered the IQs of 80 million people.

Researchers examined three ice core records to identify lead pollution levels in the Arctic between 500 BC to 600 AD.