The frequency used by the earbuds is as safe as Wi-Fi to humans. This means that since they emit a low frequency they aren't harmful to you. Just like any other gadget an excessive amount of anything can be harmful to a human. The same way the electromagnetic fields (EMFs), which is the energy and radiations emitted can cause harm. But the makers have kept the EMF in control so the use of it will not harm you in any way. But excessive use can. So, you can keep your usage to the minimal and when necessary and not as an accessory.