Some substances are more toxic than others. The toxicity of a substance is described by the types of effects it causes and its potency. 1  Types of Effects: Different chemicals cause different effects.
I think I remember reading that injured means bruises and lascerations, seriously injured meant hospital but not life threatening, critically injured meant hospital ICU time and fatally injured meant injuries leading to dying sometime later.
1 A hemorrhagic stroke describes brain tissue that is damaged because of bleeding, most often because of uncontrolled high blood pressure.  A stroke is a medical emergency. The patient or family needs to call 9-1-1 (activate EMS) to access emergency care.