It's been over a year since a fire destroyed Notre-Dame's iconic spire in April 2019, and we still haven't determined the blaze's full effect on the environment. As Smithsonian reports, evidence of pollution from the incident has been found in an unusual place: Paris's beehives.

A new study published in the journal Environmental Science & Technology Letters explains that hives located downwind from the Notre-Dame fire contained honey with high concentrations of lead. As the cathedral's roof and spire burned, 450 tons of lead melted in the extreme heat, releasing hazardous particles into the air. While lead had clearly settled into the structure itself—making it unsafe to reopen to the public even after it was renovated—the question remains of how far the toxic materials spread beyond the site.

The study shows that at least some lead managed to travel a few miles away from the church. Honey sampled three months after the blaze from hives downwind from the Notre-Dame fire contained four times as much lead as honey from the Parisian suburbs, and 3.5 times as much as Parisian honey collected before April 2019.

This doesn't mean that honey from certain Paris neighborhoods is unsafe to eat. The sample with the highest numbers, taken from a hive 3 miles west of the cathedral, contained 0.08 micrograms of lead per 1 gram of honey. The European Union allows honey to be sold with lead concentrations up to 0.10 micrograms per gram.

“The highest levels of lead that we detected were the equivalent of 80 drops of water in an Olympic sized swimming pool,” study co-author Dominique Weis, director of the University of British Columbia's Pacific Centre for Isotopic and Geochemical Research, said in a statement. But what the findings mean for homes and businesses in Notre-Dame's surrounding area-where environmental lead samples have exceeded the safety guidelines 20 times over in some spots—is still unclear.

[h/t Smithsonian]