Organic things can carry coded messages about their home environments. Tree rings can tell scientists what the atmosphere was like when the tree was young. Lichens can reveal local air pollution levels. Now, scientists in Canada report that honey carries a message, too.

A survey of urban beehives around Vancouver , which was published last week in Nature Sustainability, showed that the hives’ honey contained minute levels of lead, especially downtown and near the city’s port. The readings suggest that honey can be a sensitive indicator of air quality. And with urban hives growing in number and already more numerous than many people realize, tracking their pollutant levels may offer an inexpensive way to monitor what’s in the air all over the world, said Dominique Weis, a professor of geochemistry at University of British Columbia and a co-author of the paper.

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The project began when Hives for Humanity, a nonprofit that manages community beehives around the city, asked Dr. Weis to check the honey for lead and other substances. Bees are known to pick up trace amounts of metals, which settle on leaves and flowers from the air, as they forage for pollen.

The results showed very small levels of lead, along with traces of iron, zinc and other substances. A person would have to eat more than a pound of the honey a day to reach the U.S. Food and Drug Administration’s provisional tolerable lead intake level for an adult, Dr. Weis said. The Hives for Humanity honey compares favorably with honey elsewhere; its lead levels are below the worldwide average.