If leaches take too much of your blood, it is harmful.
Yes. Too much of ANYTHING can be harmful. The entire universe runs on the Goldilocks principle; too much, not enough, or just right.
Not too harmful but will give you heart burn
Yes, too salty.
yes yes
Too much salt.
yes it can hurt you if it is too bright
weak
yes; kerosene is harmful because it pollutes the environment and people might be sick or die and also is harmful for animals too.
As with many things salt can be harmful in excessive amounts but it is also essential to life too.
Vapor cigarettes are too new to be aware of any harmful effects that they may have on people.
death