Authorities in China have launched an investigation into reports of formaldehyde being used to keep cabbages fresh for human consumption.
Evidence gathered from Hebei province shows cabbages dipped in a formaldehyde solution before they were loaded onto trucks.
The footage was first released by an environmental blogger last week. Formaldehyde, a colourless chemical used to preserve biological specimens and known to cause cancer, is strictly prohibited for use in food.
China is the world's largest cabbage producer, with more than 30 million tonnes produced each year, and the crop is exported to neighbours such as Vietnam, South Korea and Russia.
Police have taken action against those involved, and officials are carrying out spot checks on markets nationwide to prevent panic and restore confidence.
The state media says investigators will determine how widespread the practice is and track affected produce through the supply chain.
Kangbao county in Hebei said it would strictly enforce the law and protect the vegetable supply.
Xinfadi market in Beijing, a major source of fresh produce, reported that it had investigated its supply chain and found no affected cabbages in its sales.
The incident attracted intensive media coverage. An editorial in the People's Daily criticized wholesalers for prioritising profit over consumer safety and described their actions as crossing legal and moral lines.
Experts note that while high levels of formaldehyde exposure in the workplace can lead to certain cancers, the impact of low-level exposure remains less clear.
