A school district in Nebraska will start randomly testing students who take part in extracurricular activities for nicotine, after educators noticed a sharp rise in the use of e-cigarettes, a school official said Monday.

The new policy at Fairbury Public Schools reflected the growing recognition nationwide of the public health threat of e-cigarettes. Their soaring use among teenagers has worried health experts, parents and school administrators who point to nicotine’s highly addictive qualities and the ways it can interrupt adolescent brain development.

[The price of cool: A teenager, a Juul and nicotine addiction.]

“It has been something that has been on our mind for a while because we have seen a drastic increase in students that are vaping,” Stephen Grizzle, the district’s superintendent, said in an interview. “Smoking in general, but vaping seems to be the craze right now.”

Mr. Grizzle said that for more than a year, educators had noticed more signs of vaping in classrooms, restrooms and other places at Fairbury Junior-Senior High School, an institution of about 400 students in grades 7 through 12.