https://phys.org/news/2025-01-pollution-widespread-iq-declines-ancient.html [phys.org]
Lead exposure is responsible for a range of human health impacts, with even relatively low levels impacting the cognitive development of children. DRI scientists have previously used atmospheric pollution records preserved in Arctic ice cores to identify periods of lead pollution throughout the Roman Empire, and now new research expands on this finding to identify how this pollution may have affected the European population.
The study, published Jan. 6 in Proceedings of the National Academy of Sciences, examined three ice core records to identify lead pollution levels in the Arctic between 500 BCE through 600 CE. This era spans the rise of the Roman Republic through the fall of the Roman Empire, with the study focusing on the approximately 200-year height of the Empire called the Pax Romana.
Lead isotopes allowed the research team to identify mining and smelting operations throughout Europe as the likely source of pollution during this period. Advanced computer modeling of atmospheric movement then produced maps of atmospheric lead pollution levels across Europe. Combined with research linking lead exposure to cognitive decline, the research team also identified likely reductions in IQ levels of at least 2 to 3 points among the European population.
"This is the first study to take a pollution record from an ice core and invert it to get atmospheric concentrations of pollution and then assess human impacts," says Joe McConnell, research professor of hydrology at DRI and lead author of the study. "The idea that we can do this for 2,000 years ago is pretty novel and exciting."