Researchers examined records from three ice cores to determine levels of lead pollution in the Arctic from 500 BC to 600 AD. The presence of lead isotopes allowed the authors to identify mining and smelting operations across Europe as possible sources of contamination during this period. Advanced computer modeling of atmospheric movement was then used to map atmospheric lead pollution levels across Europe. Combined with studies linking lead exposure to cognitive decline, scientists also saw a 2.5 to 3 point drop in intelligence quotient across the Roman Empire.
A 4th century AD bronze and silver coin found in Lod, central Israel. Image credit: Israel Antiquities Authority.
“This is the first study to take pollution records from ice cores and calculate them backwards to get pollution concentrations in the air and assess the impact on humans,” said Desert Research Institute researcher Dr. Joe McConnell. said.
“The idea that we could do this 2,000 years ago is very novel and exciting.”
Dr Andrew Wilson, a historian at the University of Oxford, said: 'Our research uncovers precise links between records of lead pollution and historical events such as population declines associated with periodic epidemics and pandemics. , which changed our understanding of the Roman period.”
Ancient lead pollution was primarily caused by silver mining, where the lead-rich mineral galena was melted down to extract the silver.
This process produced thousands of ounces of lead for every ounce of silver, much of which was released into the atmosphere.
In adults, high levels of lead exposure have been linked to infertility, anemia, memory loss, cardiovascular disease, cancer, and decreased immune responses, among others.
In children, even low levels of exposure are associated with lower IQ, poorer concentration, and poorer academic performance.
Meanwhile, the US CDC I will consider There is no risk-free lead exposure level, as a blood lead level of 3.5 μg/dl is the point for medical intervention in children.
Dr Nathan Chellman, a researcher at the Desert Research Institute I decided to focus on that.”
“A two to three point drop in IQ doesn't seem like a big deal, but when you apply this to basically the entire European population, it becomes quite significant.”
The researchers found that atmospheric lead pollution began in the Iron Age and peaked during the height of the Roman Republic in the late 2nd century BC.
It then declined sharply in the 1st century BC during the crisis of the Roman Republic, but increased around 15 BC with the rise of the Roman Empire.
Lead contamination remained at high levels from 165 AD until the Antonine Plague of the 180s, which seriously affected the Roman Empire.
It was not until the High Middle Ages, at the beginning of the second millennium AD, that lead pollution in the Arctic exceeded the persistently high levels of the Roman Empire.
Research shows that during the height of the Roman Empire, which spanned nearly 200 years, more than 500,000 tons of lead were released into the atmosphere.
“Ice core records show that lead pollution in the Arctic was up to 40 times higher at its historic peak in the early 1970s, but the insights gained from this study show that lead pollution in the Arctic was up to 40 times higher at its historic peak in the early 1970s, but It shows how it has impacted health,” Dr. McConnell said.
of study Published in Proceedings of the National Academy of Sciences.
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Joseph R. McConnell others. 2025. Roman mining and smelting led to atmospheric lead pollution across Europe, increased blood lead levels, and decreased cognitive function. PNAS 122 (3): e2419630121;doi: 10.1073/pnas.2419630121
Source: www.sci.news
