Analytical chemists won't run out of work any time soon. The world is reassuringly full of unknowns. Perhaps less reassuring is the nature of some of these unknowns. Koni Grob at the Kantonales Laboratory in Zurich, which he calls 'a nano FDA', has been looking at the compounds that food packages shed into the food we eat. His most recent focus has been on the plastic gaskets found inside jar lids. He finds that when oil–like that in tomato sauce, for example-touches these gaskets, all sorts of known and unknown things leach out into the food.

'Many people want to have bio or organic food, but I think that they are not aware that by far the highest source of contamination is food packaging.' Many compounds, like epoxidized soybean oil and Bisphenol-A diglycidyl ether are present in oily jarred foods in levels far exceeding the maximums for contamination at the plant. And there are hundreds or thousands of other things in there that he has found with gas chromatography but not yet identified.

However, there is no need to ditch all your tasty oily foods in a panic. Grob is clear that this is a challenge for analysts, not a worry for consumers. In fact, he's ambivalent about getting media coverage of his project. 'Our philosophy is to inform those really involved and not the consumers, he says. 'It is the authorities that have to do a lot more about this.'