Ancient Greece, known for pioneering democracy and Western philosophy, also holds the distinction of being the earliest source of lead pollution, according to new research.
Scientists studying sediment cores from mainland Greece and the Aegean Sea have uncovered the oldest known evidence of lead contamination, dating back around 5,200 years. This discovery is 1,200 years older than the previous record, which was found in a peatbog in Serbia.
In ancient times, lead was released into the air as a byproduct of smelting ore for copper and silver. The toxic metal would then condense as dust and settle on the soil.
Joseph Maran, a Heidelberg University archaeologist and co-author of a new study published in Communications Earth and Environment, explained that silver was often used for jewelry and special objects, but it was rarely found in its pure form. Instead, it was mined as ore combined with lead.
The earliest signs of lead contamination have been found in northeastern Greece, near the island of Thasos. Previous archaeological findings indicate that Thasos was a major hub for silver mining and metalworking in the region, according to Maran.
Yale historian Joseph Manning, who was not involved in the study, pointed out that lead released from smelting represents the world’s first form of toxic or industrial pollution.
The researchers found that lead contamination levels remained relatively low and concentrated in ancient Greece, which is often regarded as the birthplace of European civilization, throughout the Bronze Age, Classical period, and Hellenistic period. The Classical period is notable for figures like Socrates and Plato and for the rise of Athenian democracy, while the Hellenistic period marked the peak of Greek cultural influence across the Mediterranean.
However, around 2,150 years ago, the researchers noted a significant and sudden rise in lead emissions linked to human activities across Greece, according to co-author Andreas Koutsodendris from Heidelberg University.
Around 146 B.C., when the Roman army conquered the Greek peninsula, the region’s society and economy underwent significant changes. As Roman trade, colonies, and shipping expanded throughout the Mediterranean and Black Seas, there was a growing demand for silver coins, which led to increased smelting that released lead, according to Koutsodendris.
Later, the Roman Empire used lead in various ways, including for tableware and construction materials such as pipes.
Previous research, including studies of ice cores from Greenland, had already shown high levels of lead across much of the Northern Hemisphere during Roman times. However, this new study provides a more detailed and localized understanding of how lead levels changed, said Nathan Chellman, an environmental scientist at the University of Nevada, Reno, who was not part of the research.