Lead pollution may have caused the fall of the Roman empire

Have you ever wondered how lead pollution has impacted society over thousands of years? Imagine if we could take a snapshot of the past and use it to understand the current state of human health and the environment.

Now, a study from the DRI (Desert Research Institute) transforms this tantalizing concept into reality, providing a fascinating glimpse into past environmental pollution and its effect on human health.

Dirty facts from the cleanest places

The Arctic, an untouched frozen wilderness, surprisingly holds long-forgotten records of human activity in its icy depths.

In recent decades, DRI scientists have climbed the highest peaks and drilled deep into the Arctic ice, to extract precious ice cores.

Embedded throughout these ice cores are tiny bubbles of air, meticulously preserved, that contain microscopic clues about the earth’s atmosphere at the time that layer of ice was created.

These bubbles are like natural time capsules, and contain a treasure trove of information that allows scientists to track the levels of atmospheric lead pollution over centuries.

For the past 20 years, researchers at the McConnell Ice Core Laboratory at DRI have been cracking open these icy time capsules.

Their objective? They hope to race the pollution record of the distant past and understand how it continues to impact us.

Arctic ice reveals ancient lead pollution

Through these ice cores, DRI researchers have been able to travel in time, back to the era of the Roman Empire, specifically to the Pax Romana – a 200-year period of relative peace and stability.

During this time, Roman civilization saw a significant increase in mining and smelting operations across Europe.

The unfortunate byproduct of this prosperity was lead pollution.

“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,” enthused Joe McConnell, the study’s lead author.

“The idea that we can do this for 2,000 years ago is pretty novel and exciting.”

Smelting process in ancient Rome

During the Roman Empire, smelting was a crucial process that allowed Romans to extract valuable metals like iron, copper, and lead from their ores.

They set up large furnaces called bloomeries for iron and furnaces for other metals, where they would heat the ore with charcoal in the presence of a strong airflow.

This intense heat caused the metal to separate from the rocky ore, melting and collecting at the bottom of the furnace.

Skilled workers, known as metallurgists, carefully managed the temperature and airflow to ensure the metals melted correctly without wasting fuel or damaging the furnace.

Once the metal was extracted, the Romans used it to create everything from weapons and tools to intricate artworks and building materials.

For example, iron was essential for making swords and armor for their armies, while copper and tin were combined to produce bronze, used in statues and coins.

Lead was used extensively in plumbing and construction, showcasing the Romans’ advanced engineering skills.

Mapping the course of lead pollution

By analyzing the lead isotopes in the ice cores, the researchers tracked the rise and fall of lead pollution levels between 500 BCE and 600 CE.

They found that lead pollution first began to surge during the Iron Age, and peaked during the late 2nd century BCE during the height of the Roman Republic.

After a sharp decline during the 1st-century crisis, it rose once more around 15 BCE, following the rise of the Roman Empire.

The researchers estimate that during the height of the Roman Empire, over 500 kilotons of lead were discharged into the atmosphere, primarily as a byproduct of silver mining.

The silver lining of this cloud of lead pollution is that it helped to link lead pollution records to historical events and socio-economic changes.

Legacy of lead pollution

Despite the initial decline of lead pollution following the fall of the Roman Empire, it wasn’t until the early 2nd millennium CE that lead pollution in the Arctic began to dwarf even the high levels seen during the Roman era.

This chronic exposure to lead pollution has left a lasting legacy in the form of continuous negative health impacts.

“Lead is known to have a wide range of human health impacts, but we chose to focus on cognitive decline because it’s something we can put a number on,” explained the study coauthor, Nathan Chellman, who is assistant research professor of snow and ice hydrology at DRI.

“An IQ reduction of 2 to 3 points doesn’t sound like much, but when you apply that to essentially the entire European population, it’s kind of a big deal.”

As the researchers investigate more deeply into past pollution records and connect them to present-day health, it is becoming increasingly evident how much our activities from thousands of years ago can impact our health today.

The full study was published in the journal Proceedings of the National Academy of Sciences.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–