Gerry writes:

Lead pollution in ancient Rome was so high that it dropped the population's IQ by around 3 points, if not more.

Elites were exposed to lead through water pipes, cooking pots, bath tubs, cosmetics and the syrups that sweetened their wine. But the most widespread exposure for Romans came from industrial pollution caused by the mining and smelting of metals used to make money.

Romans melted down galena, a lead-rich ore, to extract the silver needed for coins, and lead was a major byproduct of the process.

"For every ounce of silver you produce, you might produce thousands of ounces of lead," said Joseph McConnell, a climate and environmental scientist at the Desert Research Institute in Reno, Nev. "Nobody could escape it."

McConnell and his colleagues estimated the Romans' lead exposure and reported the drop in IQ that epidemiologists have associated with that level of exposure.

They examined airborne lead that drifted north from ancient Rome and was preserved in ice cores extracted from Greenland and the Russian Arctic. The samples dated between 2,500 and 1,400 years ago-an era that included the rise and fall of the empire.

The researchers matched the chemical fingerprint of the lead found in the cores to lead sources in the empire, according to McConnell.

The findings, published last month in the Proceedings of the National Academy of Sciences, revealed that lead pollution peaked during a prosperous period known as the Pax Romana, when ancient Rome spanned portions of the Middle East, Europe and North Africa.

The researchers' models showed 3,300 tons to 4,600 tons of lead were emitted annually at the time, suggesting that ancient Romans had lead levels between 2 micrograms and 5 micrograms per deciliter of blood. Other research links that amount to a decline of around 3 IQ points.

To read the complete article (subscription required), see:
Ancient Rome Was So Polluted With Lead That IQs Dropped(https://www.wsj.com/science/environment/ancient-rome-lead-pollution-health-iq-058a3235)