BLAME for Europe’s lead pollution lies as much with medieval metalworkers as
with 20th-century polluters, a study of Swedish lake sediments has revealed.
Ingemar Renber and his colleagues at Umeå University in Sweden identified
periods of heavy lead pollution by measuring relative amounts of lead-206 and
lead-207 in mud from four Swedish lakes. The ratio of these two isotopes has
steadily declined over the years, enabling the researchers to date the deposits.
The heaviest pollution tallied with the heyday of smelting in the Middle Ages,
beginning about AD 960 and peaking at 1530.
Renber and his colleagues conclude that half…
