Issues over TikTok have been mounting in Tennessee schools for the past year. The app and the social media challenges on it have been accused of encouraging students to steal and vandalize school property and call in fake shooting threats.

But there might be new cause for concern as the state’s attorney general, Herbert H. Slatery III, has announced an investigation into the potential harm on children’s mental health. The social media app has 1 billion active users, and much of its popularity comes from teens and younger children.

It’s part of a nationwide effort to better understand the effects of the app. States like California, Montana and Massachusetts have also launched their own investigations.

The probe comes less than a year after the state started a similar one into Instagram, which a Wall Street Journal investigation found posed greater risk to children’s mental health, especially teenage girls.

On Tuesday, president Joe Biden also noted the issue in his State of the Union address, saying it’s time to strengthen privacy protections for children.