If leaches take too much of your blood, it is harmful.
no.
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.
They are harmful because they react with water too make acid rain
yes; kerosene is harmful because it pollutes the environment and people might be sick or die and also is harmful for animals too.
yes yes
Too much salt.
yes it can hurt you if it is too bright
weak
As with many things salt can be harmful in excessive amounts but it is also essential to life too.