BOSTON (AP) — The wildly popular fidget spinners that seem to be in the hands of the half the children in the U.S. are also potentially dangerous, a consumer watchdog group warned Wednesday.

The small plastic and metal spinners, already banned in many schools because they distract students, can fall apart, and the small pieces can create a choking hazard, Boston-based World Against Toys Causing Harm said in its summer safety report , released on the first day of summer.

Children in Texas and Oregon have been taken to hospitals recently after choking on fidget spinner pieces, W.A.T.C.H. said. O...