Ancient Greece produced the earliest records of democracy - and, scientists now say, lead pollution.
That is the finding of a study that recently appeared in Communications Earth and Environment. The researchers studied sediment cores removed from mainland Greece and below the Aegean Sea. They found in the cores the oldest known evidence of lead pollution in the environment dating back around 5,200 years.
That is 1,200 years older than the former oldest evidence of lead pollution. That evidence was discovered in Serbia.
In ancient times, lead was released into the atmosphere as a product of copper and silver production. The toxic, or poisonous, metal turned to dust over time and settled onto the soil.
Joseph Maran of Heidelberg University was a co-writer of the new study.
“Silver was used for jewelry, for special objects — but it wasn't found in a pure state,” it was mined in ore combined with lead, Maran said
The place with the earliest signs of lead is in northeastern Greece, near the island of Thasos. Past evidence suggests Thasos was one of the area’s most important places for silver mining and metalwork, said Maran.
Yale 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.”
The researchers found that levels of lead contamination remained fairly low in ancient Greece. The levels remained low throughout the Bronze Age, the Classical period and the Hellenistic period. The Classical period is famous for Athenian democracy, and the thinkers Socrates and Plato. And the Hellenistic period saw Greek cultural influence reach its height across the Mediterranean.
But 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.
Around that time, the Roman army won control of the Greek peninsula, completely changing the area’s society and economy. As Roman trade, colonies and shipping grew across the Mediterranean Sea and Black Sea, demand for silver coins also grew. As a result, more smelting was required, Koutsodendris said.
Later the Roman Empire used lead to make tools for eating and building, including pipes.
Past research – including a study of ice cores from Greenland – had detected high levels of lead across much of the Northern Hemisphere during Roman times.
But the new study adds a more exact “and local picture to how lead levels changed,” said Nathan Chellman. Chellman, an environmental scientist at the University of Nevada, Reno, was not involved in the research.
I'm John Russell.
Christina Larson reported on this story for the Associated Press. John Russell adapted it for VOA Learning English.
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Words in This Story
sediment core – n. a sample of circular layers of the Earth's ground that gives information about surface conditions over time
smelt – v. to melt or fuse a substance to separate the metals
abrupt – adj. sudden and unexpected
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