Green Potatoes should never be offered for sale. If you find them in the pack, even partially green, either bring them back to the shop or bin them.
The reason for this is the green advertises the presence of SOLANINE.
Solanine is a substance that can cause upset tummies, and more, in humans.
The green, itself, is Chlorophyll and is not harmful. Potatoes produce Chlorophyll, when exposed to light. For potatoes, turning green is useful as a defence against predators, such as birds and pests. These predators are attracted by the white or pink skin of the potato. While growing in the fields, potatoes are attacked by birds and pests, if they peep through the surface of the ground. The exposed parts of the potato will, quickly, turn green in sunlight and this makes them less appealing to predators.
As an extra defence, when they turn green, potato tubers produce Solanine. This is a natural poison that is a pest killer. Humans, who consume even small amounts of Solanine, can develop severe stomach aches and sometimes vomiting and diarrhea. Children and babies are very susceptible, and symptoms can persist for 7 to 10 days.. Cooking will not eliminate the Solanine in potatoes.
The green can also occur when potatoes are exposed to artificial light. This means that retailers must store potatoes in a suitable environment to prevent this happening.
Unwashed potatoes fare better. The clay, attached to unwashed potatoes, acts as a protector, just like sun screen on human faces. For this reason, companies that process potatoes, such as crisp and chip makers, demand, that their potatoes are not washed, before delivery.
At home, washed, or even unwashed, potatoes should be stored in a dark press or paper bags. Storing in a fridge is not necessary.
So, before you buy, take a closer look at what is being offered.