Potato-Solanum tuberosum L.-Poisonous plant

Potato

General poisoning notes:

Potato (Solanum tuberosum) is a common introduced garden plant cultivated for its edible tubers. The entire plant contains toxic glycoalkaloids but usually in harmless quantities in the edible tubers. However, in the presence of light, the tubers photosynthesize and coincidentally increase the amount of toxins. The skin, eyes, and sprouts of the tubers can develop toxic amounts. Even the flesh of the tuber can develop toxic quantities of the glycoalkaloids. Cattle, sheep, and swine as well as humans were poisoned and died after ingesting parts of potato plant. Other animals were also been poisoned experimentally. A dog became comatose after ingesting green potato tubers. The aboveground plant portion can also be toxic. The berries produced by the plant can contain 10-20 times more glycoalkaloids than the tubers (Cooper and Johnson 1984). The glycoalkaloids solanine and chaconine are not destroyed by normal cooking. Alkaloidal levels above 20 mg/100 g are considered unsafe for human consumption. Some cultivars have naturally high concentrations of alkaloids and have been rejected for use. Care should be taken to store potatoes in light-proof paper bags. If any green-colored potatoes are found, they should be discarded. Potato peelings and sprouts destined for a compost heap should be buried and kept from dogs or other animals. Sharma and Salunkhe (1989) provide an excellent review of potatoes and toxins and their effects on animals.

Nomenclature:

Scientific Name: Solanum tuberosum L.

Vernacular name(s): potato

Scientific family name: Solanaceae

Vernacular family name: nightshade

Geographic Information

Plant or plant parts used in or around the home.

Notes on Poisonous plant parts:

Potato tubers can develop toxic levels of glycoalkaloids if they are exposed to sunlight. The development of the toxins coincides with the production of chlorophyll in the presence of light. The toxins are highest in the skin, eyes, and sprouts. In a test on rats fed 10% sprouts from early pregnancy, 55% of litters died because of failure to lactate. Potato cultivars, such as ''Lenape'' have been developed with natural toxic levels of alkaloids in the tubers; these cultivars have not been released for use. The leaves, stems, and berries of potato also contain toxic substances. The concentration of alkaloids in the berries may be 10-20 times that of the tubers (Butterworth and Pelling 1980, Cooper and Johnson 1984, Cheeke and Schull 1985, Salunkhe 1989).

Toxic parts:

Immature fruit, leaves, stems, tubers.

Notes on Toxic plant chemicals:

Two glycoalkaloids, alpha-solanine and alpha-chaconine, are the major alkaloids in potatoes. The major effects are gastrointestinal tract irritation and nervous system impairment. Exposing the potato tubers to light may increase the concentration of glycoalkaloids to 0.05% in the tuber instead of the usual 0.008%. Potatoes are now screened for toxin levels, which must be below 20 mg/100 g. Levels above 14 mg/100 g are bitter. One variety developed in the 1960s, ''Lenape'', had levels over 30 mg/100 g and was rejected. Berries of potatoes have also been tested and an LD-50 of 677 g/kg was found in mice. It has been estimated that ingesting 400 g of potato berries would be required to induce symptoms in humans (Butterworth and Pelling 1980, Filadelfi 1982; Cooper and Johnson 1984, Sharma and Salunkhe 1989).

Toxic plant chemicals:

Chaconine

Solanine

Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada. 

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

Anemia, anorexia, convulsions, death, diarrhea, restlessness.

Notes on poisoning:

Cattle were poisoning after they were given access to green, decayed, or sprouting potatoes. In Europe, feeding large quantities of stored potatoes to young cattle over long periods is recognised as causing severe anemia (Cooper and Johnson 1984).

Dogs

General symptoms of poisoning:

Breathing, labored, coma, pupil dilation.

Humans

General symptoms of poisoning:

Abdominal pains, confusion, death, drowsiness, gastroenteritis, hallucination, headache, trembling, vomiting.

Notes on poisoning:

Ingesting potatoes with green flesh, skin, or tubers causes sickness and, in some cases, human fatalities. Symptoms of ingestion include those common to gastrointestinal problems and nervous disorders. Clinical signs include headache, vomiting, diarrhea and abdominal pain. Neurological symptoms include apathy, restlessness, drowsiness, stupor, confusion, hallucinations, dizziness, trembling, and visual impairment. In severe cases, fatalities occur. Certain birth defects are believed to result from ingesting potatoes infected with potato blight (Phytophthora infestans). However, no definitive proof has been found yet (McMillan and Thompson 1979, Sharma and Salunkhe 1989).

Rodents

General symptoms of poisoning:

Craniofacial problems, gastroenteritis.

Notes on poisoning:

Pregnant hamsters were gavaged with potato sprout material. Some dams died as a result of experimentally ingesting sprout material. Fetal craniofacial malformations occurred in 24% of cases (Keeler et al. 1990).

Sheep

General symptoms of poisoning:

Death, incoordination, weakness.

Swine

General symptoms of poisoning:

Anorexia, coma, convulsions, diarrhea, incoordination, pupil dilation, restlessness, salivation, vomiting, weakness.

Notes on poisoning:

In Europe, swine that ingested potatoes were poisoned and subsequently died. Some animals died suddenly, whereas others showed signs of incoordination, convulsions, and appeared dazed. Additional symptoms included anorexia, excess salivation, vomiting, diarrhea or constipation, and circulatory failure. Some cases required amputation, resulting from necrosis of the feet (Cooper and Johnson 1984).