A recent study published in the Proceedings of the National Academy of Sciences reveals that lead pollution in ancient Rome may have contributed to a reduction in average IQ by up to three points across Europe. The research indicates that lead exposure, prevalent from 27 BC to 180 AD, was linked to mining and smelting activities, particularly in silver extraction.
Researchers analyzed ice core samples from Greenland, correlating lead isotopes with historical mining operations. They found that for every ounce of silver produced, thousands of ounces of lead were released into the atmosphere, affecting the health of the Roman population.
During the peak of the Roman Empire, lead levels in children’s blood reached 2.4 micrograms per deciliter (µg/dl), compared to 1 µg/dl during the Neolithic period. This exposure has been associated with cognitive decline, particularly in children, as noted by co-author Nathan Chellman from the Desert Research Institute (DRI).
Joe McConnell, another co-author, emphasized the significance of this pollution as the earliest documented example of human impact on the environment. The study highlights how ancient industrial activities had far-reaching effects on human health and cognition.
Lead pollution began during the Iron Age and peaked in the late 2nd century BC, coinciding with the height of the Roman Republic. It persisted until the Antonine Plague, releasing over 500 kilotons of lead into the atmosphere during the empire's reign.