The chemical makeup of ice in polar regions, like the ice in Greenland, can provide valuable insights into past environments. As snow accumulates and transforms into ice layers, the chemicals trapped within serve as a historical record. By drilling and analyzing long ice cores, scientists can study various qualities, such as past atmospheric carbon dioxide levels or, in this case, lead concentrations.
Researchers examined three ice cores and discovered fluctuations in lead concentrations over approximately a thousand years that aligned with significant events in Rome’s economic history. Lead levels increased, for instance, when Rome extended control over areas like present-day Spain and intensified silver production in the region.
Lead emissions from Roman activities, particularly silver mining and smelting, became embedded in Greenland’s ice through atmospheric deposition. By estimating the amount of lead in Greenland’s ice, researchers used climate models to determine the extent of Roman lead emissions needed to contaminate Greenland to the observed level.
The study also delved into the health implications of lead exposure during the Pax Romana era, a period of peace in the Roman Empire from 27 B.C.E. to A.D. 180. The average lead exposure during this time was found to be significantly lower than lead exposure in the late 1970s United States but approximately double the current exposure levels for American children.
The research highlights that individuals living near silver mines in Iberia likely had heightened lead exposure. While the study primarily focused on atmospheric lead, experts suggest that the actual lead exposure in ancient Rome was likely underestimated, considering other sources like lead-lined vessels, plumbing, and drinking goblets.
Although the study’s conclusions may not fully capture the extent of lead’s impact on ancient Rome, they contribute to the ongoing discourse on the role of lead in the empire’s decline. Historians and health experts have debated for years whether lead contributed to Rome’s downfall, and this research provides additional evidence of its potential influence.
Erratic behavior was attributed to the consumption of significant amounts of lead-laced wine. “I’m quite convinced lead was one of the factors that contributed to the decline of the Roman Empire, but it was only one factor. It’s never just one thing,” Lanphear said. Joe Manning, a history professor at Yale University, noted that most researchers believe Rome’s fall was due to a combination of factors such as plagues, economic issues, and climate changes. Manning emphasized the harsh conditions of ancient Rome, where life expectancy was only around 25 to 30 years. “You do not want to go into a city in the ancient world under any circumstances. It’d be the last place you’d want to visit. They’re so dirty, disease-ridden, dysentery everywhere,” Manning said. “The lead is on top of really horrible sanitary conditions.”
