Lead Pollution May Track the Rise and Fall of Medieval Kings

Scientists analyze cores taken from glaciers to see what was happening in the atmosphere when that ice formed. One thing they can measure is lead pollution, which spiked during the Industrial Revolution because of so many factories built, and during the 1970s, due to leaded gasoline. But lead pollution goes back much further. The villages of Castelton in the UK is surrounded by medieval castles, and was once a hub of lead mining.

Here, farmers mined and smelted so much lead that it left toxic traces in their bodies—and winds blew lead dust onto a glacier 1500 kilometers away in the Swiss Alps. Loveluck and his colleagues say the glacier preserves a detailed record of medieval lead production, especially when analyzed with a new method that can track deposition over a few weeks or even days.

Lead tracks silver production because it is often found in the same ore, and the team found that the far-flung lead pollution was a sensitive barometer of the medieval English economy. As they report in a study published this week in Antiquity, lead spiked when kings took power, minted silver coins, and built cathedrals and castles. Levels plunged when plagues, wars, or other crises slowed mining and the air cleared. “This is extraordinary—lead levels correlate with the transition of kings,” says historian Joanna Story of the University of Leicester, who was not part of the study.

Most people associate lead pollution with the Industrial Revolution, when lead became widely used in paints, pipes, and ceramics. But researchers have long known that the Romans also absorbed high levels of lead as they smelted silver and other ores. Recently, scientists have identified startling spikes of lead deposited in medieval times in Arctic ice cores and in lake sediments in Europe. A study last year suggested most of the pollution came from mines in Germany.

The new study, however, points to England.

Lead spikes in the Alpine glacial cores correspond to an amazing degree with the recorded history of Britain's rulers. Read the record of pollution at Science magazine. -via Damn Interesting

(Image credit: Mango salsa)