A good place to start

http://museum.gov.ns.ca/poison/pptoxin.htm

http://vm.cfsan.fda.gov/~djw/pltx.cgi?QUERY=squash

No 8 (as an example)
AUTHOR(S): Kirschman, J. C.; Suber, R. L.
TITLE: "Recent food poisonings from cucurbitacin in traditionally bred
squash."
YEAR: 1989 CITATION: Food Chem Toxicol, 27 (8), 555-556 [English]
FDA #: F06386 || GRIN: 3164
COMMON NAME: squash || STANDARD COMMON NAME: ---
FAMILY: Cucurbitaceae || LATIN NAME: ---
STANDARD PLANT NAME: Cucurbita genus

http://www.geo-pie.cornell.edu/issues/toxins.html
Some Common Plant Toxins and Antinutrients

Chemical families of naturally-occuring plant-made toxins found at low
levels in many foods that we eat. Effect on humans and animals is based
on laboratory tests using toxin concentrations much higher than the
concentrations normally found in food.

Toxin Family

Examples of Occurrence in Plants

Effect on humans and animals
Cyanogenic glycosides Sweet potatoes, stone fruits, lima beans
Gastrointestinal inflammation; inhibition of cellular respiration
Glulcosinolates Rape (canola), mustard, radish, cabbage, peanut,
soybean, onion Goiter; impaired metabolism; reduced iodine uptake;
decreased protein digestion
Glycoalkaloids Potato, tomato Depressed central nervous system; kidney
inflammation; carcinogenic; birth defects; reduced iron uptake
Gossypol Cottonseed Reduced iron uptake; spermicidal;
carcinogenic
Lectins Most cereals, soybeans, other beans, potatoes Intestinal
inflammation; decreased nutrient uptake/absorption
Oxalate Spinach, rhubarb, tomato Reduces solubility of calcium,
iron, and zinc
Phenols Most fruits and vegetables, cereals, soybean, potato, tea,
coffee Destroys thiamine; raises cholesterol; estrogen-mimic
Coumarins Celery, parsley, parsnips, figs Light-activated
carcinogens; skin irritation

http://www.geo-pie.cornell.edu/issues/convtoxins.html
Plant toxins in Conventionally-Bred Crops












Conventionally-bred crop varieties may actually pose a greater risk from
increased plant toxins than genetically engineered plants. In order to
develop varieties with improved disease resistance, plant breeders
usually begin by crossing the disease-prone conventional variety with a
disease-resistant wild relative of the crop plant. Because the disease
resistance in the wild variety may often be caused by higher levels of
natural pest-killing toxins, the breeder may be unknowingly selecting
varieties with increased levels of a chemical toxic to both the plant
pest and to humans. One variety of potatoes developed in the 1970's to
be resistant to insects was found to have very high concentrations of
glycoalkyloids, a family of chemicals that can cause a potentially
lethal suppression of the central nervous system. This potato was never
marketed-- primarily because it tasted very bitter!

Plant breeders developed a variety of celery that was highly insect-
resistant. Surprisingly, people who handled the variety and then were
exposed to strong sunlight developed rashes and burns. It was later
discovered that the new variety contained almost eight times the normal
quantity of psoralen, a light-activated natural compound known to be
toxic and carcinogenic. This celery variety was on the market for
several years (including long after it was learned to have high toxin
levels).

The FDA does not require any pre-market safety testing of whole-plant
foods derived from plant breeding. Although the FDA has the authority to
remove foods from the market which are determined to contain unsafe
levels of toxins, quantification of those toxins before marketing is a
responsibility left entirely to breeders and producers.


--
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