Britain’s medieval lead industry had restarted by the mid-600s:
According to a charter summary attributed to the year 835, a nobleman named Humberht paid the rent on an estate in Derbyshire in lead bars, having to organize its transport all the way to Canterbury.
A new study has found an older record of the Peak District’s medieval lead industry, in the teeth of the people who worked it.
Lead in their tooth enamel shows that production had restarted by the middle of the seventh century and that, by about AD 750, children around the mines at Castleton were growing up in heavily polluted homes.
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Roman and medieval lead waste was re-smelted again and again between the 16th and 19th centuries, which erased many of the traces archaeologists would normally use, according to the University of Nottingham.
“Enamel does not remodel after its initial formation, so these samples provide a closed record of lead concentrations during childhood, between the ages of approximately four and 12 years,” the authors write.
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The researchers sampled 17 people: ten from two Castleton cemeteries, Joule Yard (seventh to eleventh centuries) and Spital Field (twelfth to fifteenth), five from a seventh-century cemetery at Wigber Low, and two from the Iron Age site of Eldon Hole.
Lead in teeth is measured in parts per million (ppm), and according to the study values below 0.5 ppm reflect natural background levels, while anything above 0.6 to 0.7 ppm points to human activity.
“All but one of the medieval individuals had lead concentrations of more than 10ppm,” the authors write, “indicating substantial anthropogenic lead exposure in childhood.” Four of the 15 medieval people had levels above 40 ppm.
Even in the seventh century, the team says, the most exposed children in these Derbyshire mining communities carried as much lead as people in industrial cities of about 1750 to 1850, or more.
At Wigber Low, the pattern seemed to follow rank. A man buried in the seventh century with a sixth-century sword, probably an heirloom, had just 2 ppm, about what people in Iron Age and Roman cemeteries outside lead regions carried.
A young woman from the same cemetery, who died at about 17, had 69.1 ppm. A man in an unfurnished grave, who may have grown up in western Britain, had 29.5 ppm.