But,many of the harmful effects of smoking ARE reversible.

VOA: special.2010.03.09

But too much stress can be harmful.

VOA: special.2009.03.24

But some doctors say the CT scan exposes patients unnecessarily to harmful radiation, as much radiation as a patient might receive from 400 chest x-rays.

VOA: standard.2010.04.07

Iron is a vital nutrient, but too much iron can be harmful.

VOA: standard.2010.08.05