🌅 Today’s stat: -3 points

SOURCE

McConnell et al. (2025)

WHAT TO KNOW

• Researchers used ice core records to analyze airborne lead levels from the rise of the Roman Republic to the fall of the Roman Empire (roughly 500 BCE to 600 CE), finding lead pollution began during the Iron Age and peaked in the 2nd century BCE, at the height of the Roman Republic, before decreasing sharply and then rising again around 15 BCE, with the rise of the Roman Empire. Using modern data on the impact of lead exposure on childhood brain development, the researchers found airborne lead in ancient Rome enhanced childhood blood lead levels enough to cause “widespread cognitive decline” throughout the Roman Empire.

WHY IT MATTERS

• The team focused on childhood blood lead levels because children are particularly vulnerable to lead exposure; even low levels can permanently affect brain development, leading to reduced IQ, behavioral challenges, and lower academic performance. The present study adds to the long-running academic debate surrounding lead’s connection to the downfall of Rome, as ancient Romans also ate food cooked in lead vessels and drank water delivered to homes through a vast network of lead pipes (the airborne lead came from mining and smelting large amounts of silver).

CONNECT THE DOTS

• Airborne lead in the 1970s—before leaded gasoline and leaded paints were phased out—was up to 40 times higher than the levels found in ancient Rome. American children in the 1970s also had blood lead levels roughly five times higher than children in ancient Rome, corresponding to an average IQ decline of about 9 points.