Some pesticides are based on nerve toxins that can be deadly to people and animals as well. It is estimated that some 2.5 million tons of them are applied annually worldwide. They are used on banana plantations to kill nematode worms that destroy the banana plants. But these chemicals pose a threat to the health of the people who work on the plantations.
In a field trial in Costa Rica, biodegradable poisons - or biopesticides - are being tested. Some say they could become an alternative to highly toxic, more conventional pesticides.