The clip runs for a few seconds and needs no explanation: people dip cabbage heads into a solution, then load them onto trucks. An environmental blogger posted it last week, and the authorities in the northeastern province of Hebei confirmed it is genuine. The solution, according to the report, contained formaldehyde - a chemical that is strictly banned in China for preserving food and is classified as a possible carcinogen.

Police have taken measures against those involved, state media said. The local government in Kangbao county issued a sentence that is almost universal for situations like this: "Strict legal measures will be taken against all illegal or non-compliant activities in order to ensure the safety of vegetable supply." Extraordinary inspections are being carried out across the country in parallel, and the investigation is meant to establish how widespread the practice is and to withdraw the contaminated batches.

The problem does not stop at the border

This is not local news. China produces over 30 million tonnes of cabbage a year - roughly half of global output - and exports significant quantities to neighbouring Asian countries, among them Vietnam, South Korea and Russia. The Xinfadi market in Beijing announced it had checked the origin of its cabbage and that no contaminated batches had reached it.

Note the structure of the response: first a blogger's video, then confirmation from the authorities, then an attempt to prevent panic. The institutions did not discover the problem - they discovered it after someone filmed it. That is a pattern that is no Chinese speciality.

The question that remains for the reader here is more specific. Imported vegetables go through inspection - the Food and Veterinary Agency is the body that takes samples and publishes the results. How many samples have been taken this year, what were they tested for and where were the findings published? That is data that does not need a blogger with a mobile phone to come to light, only an institution doing the job it was set up to do.