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Frequently (and not so frequently) Asked Questions

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BRIEF: What kind of a poisonous bean could you put in a soup?


QUESTION:
I'm researching a mystery novel and I was wondering if you could help me. If someone cooked rosary peas, would they still be poisonous? Is there any kind of poisonous bean that could go in say... soup? If you can help me, please let me know. I'll make sure to include your name in the acknowledgments page. Like I said, it is a weird question. But, I need the answer so I can write chapter 29.

ANSWER:

Rosary peas (Abrus precatorius) contain abrin, which is a special kind of protein called a lectin. Abrin and it is, microgram for microgram, about the most toxic natural substance known. I have never tested this on animals with abrin, nor do I know of anyone else who has, but theoretically, moist heat (such as that found in boiling soup) should denature the protein and render the abrin harmless. Given the unbelievably toxic nature of abrin, I would not eat rosary pea soup for at least two reasons: 1. I do not know for sure that moist heat irreversibly denatures abrin and 2. If the dried peas are not presoaked or cooked long enough, then water may not penetrate all the way to the center of the pea and all of the protein may not be denatured properly, leaving enough intact abrin to kill. There are a couple of thermostable (not destroyed by heat) toxins present in fava beans, but they only affect the 100-200 million people in the world who are glucose-6-phosphate dehydrogenase deficient. Ingesting fava beans causes these people to to develop hemolytic anemia and it can be fatal. Can your fictional victim be G6PD deficient? Most peas and beans are rendered less toxic by boiling in soup. That is why they are prepared that way! There is an aweful poisoning that is caused by eating uncooked pulses (another word for legume seeds like beans and peas and lentils) and that is the neurolathyrsm caused by eating Lathyrus sativa seeds. In India, laborers used to get paid in these pulses instead of money. The seeds would be made into an uncooked paste or dough ball and eaten raw or semi-raw. After eating this for a few months, the men suddenly suffered rigidity, paralysis and often dropped dead. It is thought that hard work or exercise or perhaps malnutrition were contributing factors. Maybe your victim could be a an anorectic workkout-obsessed person with an eating disorder that includes scarfing raw dough (I have actually known a person like that.) Could he or she have the dough adulterated with Lathyrus by the murderer? It would take a while, but who would suspect (except your heroine/hero detective)? Perhaps this is why authors often put mushrooms rather than beans into their literary stews! Or add unexpected spices that cause the victim to uncritically quaff a liquid that has been poisoned, etc.