Sunday, February 26, 2012

Lead Poisoning and the Fall of Rome

That lead poisoning somehow caused the fall of Rome is an old idea that still circulates among cynical adolescents. The Romans certainly did use lead for many purposes, including curse tablets, jewelry, and water pipes (illustrated above) as well as cosmetics, cooking pots, and defrutum, wine that was sweetened by boiling it down in lead pots.

In recent decades we have acquired some data on lead poisoning in history, from studies of bones. They do show high levels of lead; some Roman skeletons have 30 mg of lead per kg of bone, 30 times the level that the WHO considers unsafe. On the other hand, you can see from the graph above that the Roman levels were nothing unusual in history. The average level of lead in late medieval skeletons from Britain is higher than the level of skeletons from Rome (that's the floating point), and much higher than the level in Roman Britain. That line kept going up into the early nineteenth century; Europeans in their period of dynamic expansion and world dominance had higher levels of lead than the Romans, which makes it unlikely that lead poisoning was much of a threat to Roman power.

These graphs also provide another way of measuring the collapse of Roman civilization in the fifth to 7th centuries. If you consider lead contamination as a proxy for industrial production, it looks like industrial production in Britain fell by at least 60% after the Romans withdrew.

No comments: