The crisis in the car industry has led to a global shortage of a chemical solvent used for everything from checking the mould level in a chocolate bar to making sure a tablet of aspirin is safe.

The solvent, acetonitrile, is a by-product of the process used to make acrylic carpets and plastic parts for the car industry, and as demand for cars has plunged in the global financial crisis, so have supplies of acetonitrile.

That is alarming, say some observers, because the substance is used to break down products such as food or pharmaceuticals into their component parts to check their safety or efficacy, a process known as chromotography. “This is very serious,” said the head of procurement at a large European pharmaceuticals group. “If you cannot test products you cannot sell them.” And, “in many cases, you cannot even make them”.