Researchers: Oldest Evidence of Lead Pollution Found in Greece

01Ancient Greece produced the earliest records of democracy and, scientists now say, lead pollution.

02That is the finding of a study that recently appeared in Communications Earth and Environment.

03The researchers studied sediment cores removed from mainland Greece and below the Aegean Sea.

04They found in the cores the oldest known evidence of lead pollution in the environment dating back around 5,200 years.

05That is 1,200 years older than the former oldest evidence of lead pollution.

06That evidence was discovered in Serbia.

07In ancient times, lead was released into the atmosphere as a product of copper and silver production.

08The toxic or poisonous metal turned to dust over time and settled onto the soil.

09Joseph Maron of Heidelberg University was a co-writer of the new study.

10Silver was used for jewelry, for special objects.

11But it wasn't found in a pure state.

12It was mined in ore combined with lead, Maron said.

13The place with the earliest signs of lead is in northeastern Greece, near the island of Thassos.

14Past evidence suggests Thassos was one of the area's most important places for silver mining and metalwork, said Maron.

15Yale historian Joseph Manning, who was not involved in the study, said lead released from smelting is the world's first form of toxic or industrial pollution.

16The researchers found that levels of lead contamination remained fairly low in ancient Greece.

17The levels remained low throughout the Bronze Age, the Classical Period, and the Hellenistic Period.

18The Classical Period is famous for Athenian democracy and the thinkers Socrates and Plato.

19And the Hellenistic Period saw Greek cultural influence reach its height across the Mediterranean.

20But the new study shows that around 2,150 years ago, a very strong and abrupt increase in lead releases caused by human activities took place across Greece, said co-writer Andreas Koutsodendris of Heidelberg University.

21Around that time, the Roman army won control of the Greek Peninsula, completely changing the area's society and economy.

22As Roman trade, colonies, and shipping grew across the Mediterranean Sea and Black Sea, demand for silver coins also grew.

23As a result, more smelting was required, Co-writer, said.

24Later, the Roman Empire used lead to make tools for eating and building, including pipes.

25Past research, including a study of ice cores from Greenland, had detected high levels of lead across much of the Northern Hemisphere during Roman times.

26But the new study adds a more exact and local picture to how lead levels changed, said Nathan Chelman.

27Chelman, an environmental scientist at the University of Nevada, Reno, was not involved in the research.

28I'm John Russell.