Researchers from Heidelberg University have uncovered the oldest known evidence of lead pollution in the environment, dating back approximately 5,200 years, according to Ekathimerini.
In ancient times, lead was released into the atmosphere as a byproduct of copper and silver ore smelting, later condensing as dust and accumulating in the soil.
Joseph Maran, an archaeologist at Heidelberg University, noted, "Silver was used for jewelry and special items, but it was not found in pure form; it was mined in ore combined with lead."
The Filippi wetland, located in northeastern Greece near the island of Thasos, is where the earliest traces of lead contamination were discovered. Previous archaeological evidence has shown that Thasos was one of the region's most significant sites for silver mining and metal processing, according to Maran.
The researchers found that lead contamination levels remained relatively low and localized in ancient Greece, considered the cradle of European civilization, during the Bronze Age, Classical period, and Hellenistic period.
The Classical period is recognized for Athenian democracy and figures like Socrates and Plato, while the Hellenistic period saw Greek cultural influence peak across the Mediterranean.
However, around 2,150 years ago, the researchers identified a "very strong and sudden increase" in lead emissions attributed to human activities throughout Greece, remarked Andreas Koutodendris from Heidelberg University.
Approximately during this time, in 146 BC, the Roman army conquered the Greek peninsula, transforming the region's society and economy, which increased the demand for silver coins and, consequently, pollution.
Previous studies, including ice core analysis from Greenland, revealed high levels of lead across much of the Northern Hemisphere during the Roman era. Nevertheless, the new research provides a "more specific and localized picture of how lead levels changed," stated Nathan Chelman, an environmental scientist at the University of Nevada, who was not involved in the study.