For the last 10 years, the health service in Sri Lanka has been overwhelmed with cases of young people attempting suicide. The method they use is to poison themselves with the seeds of the yellow oleander tree, a plant that grows widely across the island.
The reasons they give often seem trivial - scolding by their parents, or disappointment in love. British doctor Michael Eddleston talks to Jolyon Jenkins about his research in Sri Lanka, which tries to understand the reasons behind the suicide epidemic.
India's snakes are the most deadly in the world, killing 50,000 people every year. One of the world's top experts in snake bites is Ian Simpson, a retired British economist, who loves snakes so much that he has emigrated to India to be near them and help look after their victims.
is a poison produced by mould that grows on damp crops. It hit the headlines when it was named as one of Saddam Hussein's biological weapons of mass destruction.
Professor Stanley Feldman has spent 50 years studying curare - the plant poison used by Amazonian Indians on the tips of their blow darts. He's injected himself with it and even once had an accidental overdose.
has been a popular method of poisoning people since the Middle Ages, but there are some life forms which thrive on it. Biologist Ron Oremland has discovered microbes living in lakes in America that use arsenic in the same way that we use oxygen.