Students at an elementary school and a middle school in Montgomery County may have been exposed Wednesday to mercury after a student brought a vial of it onto a bus.

Montgomery County Fire and Rescue officials said that about 9 a.m., a student brought a vial of mercury onto a bus and showed it to other students. The bus drops off kids at Francis Scott Key Middle and Charles Drew Elementary schools. Both schools are in Silver Spring.

At first, Montgomery fire officials said they “didn’t believe anyone was exposed” to the mercury vial. But they later confirmed that they “had detected a spill on the bus.”

Authorities said at mid-morning that they had isolated and were evaluating 25 students at the middle school and another 10 students at the elementary school, according to Pete Piringer, a fire department spokesman.

“Everything is isolated and under control,” he said. “There are no immediate health risks.”

“No one is sick, but we do have some kids who were potentially exposed to the mercury.”

He said the bus is “being placed out of service,” and other buses will be brought in.

According to the Environmental Protection Agency Web site, health effects of exposure to elemental (metallic) mercury range from tremors, emotional changes and insomnia at lower levels to kidney effects, respiratory failure and death at higher levels. The EPA urges those concerned about exposure to consult a physician.

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