Until the 1970s, the presence of lead in gasoline and paint caused many problems for Americans, most notably a decline in IQ, which has been documented in many years of research. A new study by an international group of researchers has found that the decline in IQ associated with lead exposure is not a new phenomenon and actually dates back to the time of the ancient Romans.
The study, published Jan. 6 in the Proceedings of the National Academy of Sciences, examined ice samples from Greenland that contained lead particles that arrived from continental Europe during the Pax Romana period, from 27 BC to 180 AD. Exposures in the Roman Empire were about one-third of those in the United States, when leaded gasoline use was at its peak in the 1970s, before the Clean Air Act was enacted.
“Human or industrial activity 2,000 years ago was already having a continent-wide impact on human health,” study lead author Joe McConnell told NBC News. “Lead pollution in Roman times is the earliest clear example of human impact on the environment.”
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It all has to do with how the Romans created their currency. Smelting silver for coins releases lead that attaches to dust particles in the atmosphere, some of which ended up in Greenland.
“For every ounce of silver produced, 10,000 ounces of lead can be produced,” McConnell explained. “Along with producing silver, the Romans were also smelting and mining silver for coinage and economy, introducing large amounts of lead into the atmosphere.”
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The study found that lead exposure was so severe that it likely lowered the average person’s IQ by 2.5 to 3 points. This is consistent with other studies that have found a link between lead exposure and lower IQ, including a 2022 study that found Americans exposed to lead in childhood had an average 2.6 point lower IQ. . Overall, ancient Romans were exposed to lead levels roughly twice as high as American children today.
If you’re concerned about lead in your home, consider purchasing a lead detector kit to test all your items.