More than 200 children are being treated in hospital with lead poisoning in north-west China after school chefs used inedible paint to decorate their food.
Eight people have been arrested after tests showed the food samples from a kindergarten in Tianshui City in Gansu province had lead levels that were 2,000 times over the national safety limit.
In total, 233 children from Peixin Kindergarten had high levels of lead in their blood after eating steamed red date cake and sausage corn bun.
The school principal asked the kitchen staff to buy the paint online, according to a police statement.
But after the children fell ill, officers had to search for the supplies which had been hidden.
The paint was clearly marked as inedible, the statement said.
One parent told the BBC that he was worried about the long-term effects of lead poisoning on his son’s liver and digestive system.
Mr Liu took his child to hospital in Xi’an for testing last week after other parents raised the alarm. His son now needs 10 days of treatment and medication.
Chinese state media aired footage which it said was from CCTV cameras in the kitchen which showed staff adding paint pigment to the food.
Investigators found that the red date cake and the corn sausage rolls had lead levels of 1052mg/kg and 1340mg/kg respectively which both exceed the national food safety standard limit of 0.5mg/kg.
The principal of the privately-run kindergarten and seven others, including its main investor, will now be investigated on suspicion of producing toxic and harmful food.
It is not known how long the paint has been used in the food, but several parents told Chinese state media that their children have been complaining of stomach and leg pain and a lack of appetite since March.
An investigation was launched after they raised their concerns with the local authorities.
The mayor of Tianshui, Liu Lijiang, said the incident exposed shortcomings and loopholes in public food safety supervision and the city would draw lessons from the event.