What we eat keeps us alive, but an exhibition at the Cleveland Museum of Natural History shows that even ordinary foods can be killers.
In today’s Quick Bite, WKSU’s Vivian Goodman explores “The Power of Poison.”
The American Museum of Natural History in New York designed “The Power of Poison” exhibition to share with museums across the country. The exhibition looks at poison as a force of nature as well as at its role in human history. And a lot of it concerns food.
“Foods that are poisonous if you don’t treat them properly, and environmental contaminants that affect the health of our food," explains Nicole Burt, a post-doctoral fellow of human health and evolutionary medicine at Cleveland Museum of Natural History.
Toxicology made intentional poisoning less common
The exhibition notes that poison was so popular among murderers that kings and queens used to have food tasters.
“It was at least common enough that people felt warranted to try to protect themselves against it.”
Burt says, with the advent of the science of toxicology, deliberate poisoning fell out of fashion. Spanish chemist Mathieu Orfila wrote the first book on the topic in 1815, cataloguing poisons favored by criminals.
Displays about humans poisoning other humans are among the key attractions of “The Power of Poison.” So are huge spiders, spiny caterpillars and a brightly colored poisonous dart frog.
Pretty and poisonous
The frog’s golden, iridescent skin is pretty to look at and poisonous to predators.
“Their coloring actually does signal that they’re poisonous,” says Burt. "That’s true of animals ... but also if you’re in the wild, toxic berries, things like that often are red or brightly-colored, which signals , ‘I could be dangerous.’”
We’re in a museum, but it hardly feels like it in the dark, mysterious, somewhat scary first gallery of the exhibition.
“We’re in actually a reconstruction of the Columbian rain forest, which has a lot of diversity. And because of that, it encompasses a lot of poisonous creatures and plants. So it’s a good starting-off point.”
Common ingredient deadly if unprocessed
The real Choco Forest is between the Andes Mountains and the Pacific coast. One of the plants that grows there is cassava, also known as manioc or yucca.
“Probably the most important food stuff around the world,” says Burt. “It’s as big as corn and wheat globally.”
For centuries the nutty, sweet, chewy cassava root, has been a staple food source for indigenous peoples of South America, Africa and Asia. The starchy root vegetable is favored for its resistance to both drought and insects.
One of the reasons bugs leave it alone is that it’s so poisonous.
But cassava is safe for human consumption after it’s processed to remove the cyanide. On display in the exhibition are primitive tools still used to do that in the Brazilian rain forest.
“You can just soak it for really long periods of time, and then press it. You can allow it to ferment. You can do other sorts of chemical processing to strip out the poisons.”
Suicide by cassava
Burt says modern processing methods have made cassava a key ingredient in commercial food production worldwide.
“Probably everyone’s eaten some cassava and they just haven’t realized it. If you’ve been to Central or South America or anywhere in Southeast Asia, you’ve almost certainly eaten it. If you’ve ever had tapioca, you’ve definitely had cassava root.”
Too much tapioca won’t kill you because it’s been processed. But even a little uncooked cassava root can be lethal. Burt says when the oppression of Spanish conquistadors forced them to it, suicidal Taino Indians of Brazil would eat cassava "intentionally untreated to kill themselves, because if it’s eaten completely raw it is dangerous enough that it would kill you very quickly.”
Low-protein diets in Third World nations increase susceptibility to the cyanide in cassava root. That’s what caused many deaths in famine-stricken Biafra in 1968. The Bill and Melinda Gates Foundation funds a
project that’s been trying since 2011 to cultivate cassavas fortified with protein and with less cyanide, but it’s been fruitless so far.
Environmental hazards to food
Another concern about cassava is that industrial production of cassava flour, widely used in South America and the Caribbean, can generate enough cyanide in effluents to poison the environment.
Another danger in food, mercury, can be avoided by pregnant women and those with other choices, but not in coastal communities in the Third World that depend on fish and shellfish.
Burt notes mercury occurs naturally, but human activities like burning coal gets too much of it into the atmosphere and the oceans, and into big fish like tuna and swordfish.
“The little photo plankton suck up the mercury, and then they go up and up the food chain till you get to these big predators and you’re getting more mercury for each bite.”
Killer within an apple
Being cautious about consumption of tuna or swordfish makes sense, but should we worry about apples?
Burt takes us to the part of the exhibition where Sleeping Beauty, the fairy tale maiden, lies motionless, paralyzed by the apple the wicked witch gave her.
The display shows there’s a compound in apple seeds that’s lethal when combined with digestive enzymes.
“But you’d have to eat well over 200 apple seeds and really like grind them up, and really get at it to have that happen. So it’s not as dangerous as something like cassava, but it’s possible.”
Other seemingly innocuous foods are deadly if left untreated. Ever wonder why you can’t buy cashews in the shell like peanuts?
“The outer casing of the nut and the fruit actually are really high in urushial which is the same chemical that’s in poison ivy," says Burt. "So if you don’t treat it, you would get contact blisters and things like that.”
Poison alert
She says pain will usually protect us from toxic foods. “It’ll actually make your mouth kind of tingle, or hurt. You might get blisters if you’re either very, very sensitive to the toxins in it, or if it hasn’t been treated properly.”
"The Power of Poison" continues at the Cleveland Museum of Natural History through July 24
When there’s danger in processed foods, we hope to be alerted by recalls, "which is a poisoning issue: listeria outbreaks, botulism outbreaks. But it can also happen if you’re buying canned
foods that are dented or have been compromised. You’ll get botulism. It produces a really foul smell. It’s pretty obvious to stay away from it once it’s really taken off.”
Other hazards may be less obvious. Burt says carnivores also need to be aware of what animals are feeding on.
Secondary poisoning
A display shows the similarity in appearance of cow parsnip and giant hogweed, also known as snake root. Even humans can eat the stalks of cow parsnip. It tastes a little like celery.
“If your cows are eating cow parsnip. They’ll be fine. If they’re eating nothing but snake root, which we have pulled out of most of our fields, that’s actually poisonous enough that if it gets into the milk it can poison humans.”
She says we had to learn that lesson the hard way. “It’s actually called milk sickness, and they had a few unexpected deaths in the Midwest.” Back in 1818 it was milk sickness that killed Abraham Lincoln's mother, Nancy.
Family fun
Museum visitor Marty Russo and his 10-year-old daughter Maria enjoy one of the “Power of Poison” computer-aided interactive displays. It’s about protecting pets from poisons in the environment.
“I thought it was cool that I got to help the little doggie,” says Maria.
“We were able actually to try to determine why it was sick, what it may have gotten into,” adds her father, "through the interaction of the computers here, which actually is really neat.”