In a paper published in this month's Nature Medicine, Ole Isacson, James Schumacher and their colleagues at Harvard Medical School have made a start.

ECONOMIST: Something new in mind

"Coca production was not going to be reduced just because fumigation flights spray some fields, as long as these farmers don't have any other economic options, except to cut down forests to grow coca somewhere else, " said Adam Isacson of the Washington-based Center for International Policy.

BBC: NEWS | Americas | Coca-growing spreads in Colombia