Researchers studying sediment cores recovered from mainland Greece and the Aegean Sea have discovered the oldest known evidence of lead pollution, dating back to around 5,200 years ago. This shocking find, which predates previous instances of recorded lead pollution by 1,200 years, sheds light on the environmental impacts of ancient industrial activities. Previously, the earliest record was found in a peat bog in Serbia.
Lead was emitted as a byproduct during the smelting of ore to extract copper and silver. Upon smelting, this toxic metal condensed as dust and settled on the ground. Joseph Maran, an archaeologist at Heidelberg University and co-author of the new study published in Communications Earth and Environment, stated, “Silver was used for jewelry, for special objects — but it wasn’t found in a pure state,” highlighting how it was mined from ore which contained lead.
The site with these earliest indications of lead contamination is located near the island of Thasos, which played a significant role as one of the main hubs for silver mining and metalwork. Maran noted the historical importance of Thasos, as archaeological evidence suggests its substantial contributions to the ancient economy.
Historian Joseph Manning from Yale, who was not involved in the study, remarked, “Lead released from smelting is the world’s first form of toxic or industrial pollution.” This assertion underlines the long-standing impact of human industrial activity on the environment, dating back to antiquity.
Interestingly, the researchers observed low and localized levels of lead contamination across ancient Greece during significant periods including the Bronze Age, the Classical period, and the Hellenistic period. The Classical period is iconic for its contributions to democratic ideals and philosophical thought, with figures like Socrates and Plato, whereas the Hellenistic period marked the apex of Greek culture across the Mediterranean.
Detrimental changes emerged around 2,150 years ago, with the researchers identifying “a very strong and abrupt increase” in lead emissions, prompted by intensified human activities across Greece. Andreas Koutsodendris, co-author and researcher at Heidelberg University, indicated this increase coincided with the Roman army’s conquest of the Greek peninsula around 146 B.C., which significantly reshaped societal and economic structures.
During the expansion of Roman trade, colonies, and shipping, the demand for silver coins surged, necessitating more extensive smelting operations which led to heightened lead emissions. Koutsodendris explained how this shift marked a dramatic transition, as the Roman Empire later employed lead not only for currency but also as material for construction, including pipes and tableware.
Previous research, including analyses of Greenland ice cores, has pointed to high levels of lead pollution during Roman times throughout the Northern Hemisphere. This recent study narrows down the timeline, as Nathan Chellman, an environmental scientist at the University of Nevada, Reno, articulated, saying, “This adds a more specific and local picture to how lead levels changed.”
Overall, the findings of this study underline the long-standing challenge posed by industrial pollution, tracing its roots back to ancient practices and their ramifications on environmental health. This historical perspective invites reflection on contemporary issues related to industrialization and its environmental costs, reminding us how past behaviors can resonate through time.
The evidence of lead pollution found off the coast of Greece brings to light how our ancestors significantly altered their environment, setting the stage for the complex relationships humans have with nature and industry. Such discoveries are pivotal, not only for our historical knowledge but also for the lessons they impart on sustainability and environmental stewardship moving forward.