Supermarket chain Kroger and drugstore chain Walgreens say they will no longer sell e-cigarettes in the U.S. amid mounting health questions surrounding vaping.

The two major retailers announced Monday they would discontinue sales of e-cigarettes at their stores nationwide, citing an uncertain regulatory environment.

The vaping industry has come under scrutiny after hundreds of people have fallen ill and at least eight have died after using vaping devices.

Walmart announced last month it would stop selling e-cigarettes at its stores nationwide.

Kroger said it would stop selling e-cigarettes as soon at its current inventory runs out at its more than 2,700 stores and 1,500 fuel centers. The Cincinnati-based company operates the Ralphs, Harris Teeter and other stores.

Walgreens, based in Deerfield, Illinois, operates more than 9,500 stores in the U.S.