Toxic

adjective

1. Having a chemical nature that is harmful to health or lethal if consumed or otherwise entering into the body in sufficient quantities.

   "Tobacco smoke contains many toxic substances."

2. Appearing grossly unwell; characterised by serious, potentially life-threatening compromise in the respiratory, circulatory or other body systems.

   "The child appeared toxic on arrival at the hospital."

3. Severely negative or harmful.

   "a toxic environment that promoted bullying"

4. (of a person) Hateful or strongly antipathetic.

   "It is not good to be around toxic people."