According to FDA study, potato may contain up to 8 mg solanine with the interior having less than the exterior. This normal level is less likely to cause poisoning but the chances increases with the increasing level. The toxic dose is 20 to 25 milligrams. There are reports of solanine poisoning were victims consume green peelings in consecutive fashion.
On the bright side, solanine is a natural defense of the commodity against insect pests. Farmers don’t have to apply fertilizers too much. However, its production may increased to a lethal level if exposed to sun and warm temperature.
Chances of encountering greened potato is rare. Every time I do, slicing off the green part usually suffice. Peeling is always done anyway so it never really matter whether it has green portion or not. However, the story is different when a potato is almost covered with green color. Who knows how much poisonous substance it has. It might not be enough to get myself killed but might be too much for my safety.
I threw it to trash bin!