The Romans made incredible inventions like concrete, aqueducts, and the modern calendar. However, a study suggests their achievements might have been even greater if they hadn’t been affected by lead poisoning.
Researchers from the University of Oxford found that lead pollution reduced the average IQ of Europeans by 2–3 points during Roman times. While this drop might seem small, it’s significant when applied to an entire population, according to Nathan Chellman, a co-author of the study. Lead exposure is known to harm health in many ways, including affecting brain development.
To understand how much lead was in the environment during the Roman era, scientists studied ice cores from the Arctic. These ice layers contained evidence of lead pollution from 500 BC to 600 AD, covering the rise and fall of the Roman Empire. The research focused on the “Pax Romana,” a period of peace and prosperity from 27 BC to 180 AD.
The team analyzed lead isotopes to trace the source of the pollution, which mainly came from mining and smelting. During silver mining, a lead-rich mineral called galena was melted to extract silver. This process released huge amounts of lead into the air. For every ounce of silver, thousands of ounces of lead were produced.
Lead pollution first increased during the Iron Age and peaked in the late 2nd century BC, at the height of the Roman Republic. It dropped during the 1st century BC, a time of political crisis, but rose again around 15 BC with the rise of the Roman Empire. High pollution levels lasted until the Antonine Plague (165–180 AD), which weakened the Roman Empire. Researchers estimate that over 500 kilotons of lead were released into the atmosphere during the peak of the Roman Empire.
While lead pollution during Roman times was significant, the study found that it was much lower compared to the peak of lead pollution in the early 1970s, which was 40 times higher. However, the study highlights how human activities have been harming health for thousands of years.
Dr. Joe McConnell, the study’s lead author, called the research groundbreaking. It’s the first time pollution data from an ice core has been used to estimate ancient atmospheric pollution levels and their effects on humans. “The fact that we can do this for events from 2,000 years ago is exciting and unique,” he said.
