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DRUG smugglers beware: police can now find out where a shipment of cocaine
comes from. James Ehleringer of the University of Utah and his colleagues have
shown that they can match samples of cocaine to their country of origin with
over 90 per cent accuracy. They look at the carbon and nitrogen isotope ratios,
which are determined by the environment in which the coca plants were grown
(Nature, vol 408, p 311). The US Drug Enforcement Administration plans
to use the technique in its labs.