CURWOOD: Coming up, it's high noon at the World Trade Organization talks, as the Americans and Europeans face off over food policies. First, this Environmental Health Note from Diane Toomey.

TOOMEY: Cassava is one of the most important foods in tropical countries, providing many people with a key source of carbohydrates. But if the plant is not properly prepared, it can trigger the production of cyanide. That's because cassava contains linamarin, a substance that discourages insects and animals from eating the plant. But if humans eat improperly prepared cassava, the linamarin breaks down and releases cyanide into the body. This release of cyanide also happens during the processing of the plant, as it's heated, crushed and dried. So women and children who most often prepare cassava can be poisoned with cyanide gas. Chronic low-level cyanide exposure can lead to neuropathy, a nerve damaging disorder. And severe cyanide poisoning is associated with an irreversible paralytic disorder that can lead to death.

But at Ohio State, there's a cyanide-free cassava plant. Researchers there genetically modified the plant, blocking the operation of the genes responsible for linamarin production, reducing its content by up to 99 percent. Preliminary studies also show that linamarin may be important in the transport of nitrogen from cassava leaves to its roots. So, researchers say field trials will be necessary to determine if the inhibition of linamarin will affect plant yields.

That's this week's Health Note, I'm Diane Toomey.

CURWOOD: And you're listening to Living on Earth.