The average IQ of a citizen of the Roman Empire likely declined by 2.5 to 3 points from 27 BC to 180 AD just from the presence of lead in the atmosphere alone, NBC News reports citing a new paper published in the journal Proceedings of the National Academy of Sciences on Monday.

The estimate was calculated based on the presence of lead particles extracted from an ice core sample in Greenland, concentrations that saw a dramatic increase in the level of the metal corresponding to a time when silver mining rapidly increased in the Iberian Peninsula with the lead a byproduct of smelting the silver to mint coinage. This was very far from the only source of lead poisoning for Romans however, as people were exposed via water pipes, cups, and wine vessels.

Meaning that 2.5 to 3 point drop was just what could be measured from the smelting and almost certainly lowballs the damage. “Their estimates are likely to be an underestimate,” said Canadian lead expert and public health professor Dr Bruce Lanphear after having read the study.

“Virtually nobody escaped. Human or industrial activities 2,000 years ago were already having continental-scale impacts on human health,” said Joe McConnell, one of the head authors of the paper and a climate scientist at the Reno-based Desert Research Institute. “Roman-era lead pollution is the earliest unambiguous example of human impacts on the environment.”

Research back in the 1980s suggested Roman elites steadily lost their shit because of lead in the wine they drank, accelerating the empire’s eventual collapse. “I’m quite convinced lead was one of the factors that contributed to the decline of the Roman Empire, but it was only one factor. It’s never just one thing,” said Lamphear. Nowhere in NBC’s article is any sort of “DURRR HERE’S A LESSON FROM HISTORY THAT’S RELEVANT CUZ AMERICA IS LIKE TEH ROMAN EMPIRE NOW.”