About 30 per cent of children under 14 in Yunnan are suffering from some degree of lead poisoning, an official survey has found. The survey was conducted by Yunnan's Children Lead Prevention and Cure Office, the only official institute of its kind on the mainland. Office director Liu Dakun said yesterday that the centre had checked more than 10,000 children and found 30 per cent were suffering from excessive lead levels. 'In some cities, such as Gejiu, Lanping and Dongchuan, the [figure] could be 50 to 60 per cent.' Besides Beijing, Shanxi and Henan, Yunnan, which is rich in minerals, has been known for years as one of the worst provinces for lead poisoning. Mr Liu said that in some villages in mining areas, all children checked were affected because villagers stored ore in their houses. 'These children play with the ores and some of them have a very high level of lead in their blood,' he said. Some big villages in Lanping close to lead mines had never produced any college students because lead poisoning had severely affected children's brain development. The lead mines had polluted all the water and crops of these villages. The problem was not only found in the countryside. According to a survey conducted in 2003, about half the children in Kunming , the capital of Yunnan, had lead poisoning, local media reported. Deng Fusheng, a chemical engineer with the office, said cities' problems were mainly caused by vehicle fumes. Food was another factor, he said. 'Food like popcorn and preserved eggs all contain high level of lead and I suggest that it is better for children under 14 not to take them.' Toxic chemicals have been a hot issue in the past month. Pollution cases affecting villagers, especially children, have been widely reported, causing nationwide concern. Some officials in charge of environmental protection in Liuyang , Hunan, were suspended after cadmium poisoning killed at least five people and made hundreds more ill. In Fengxiang, Shaanxi province, more than 850 children have been poisoned by lead spewed out from nearby factories. Mr Liu said that since 2004 the office had conducted annual surveys focusing on lead poisoning. The surveys usually involved at least 2,000 children and another one will be conducted next month. 'We mainly check children between the age of two and six who are in kindergarten,' he said. 'We hope to identify and treat the poisoned children at an early age, as the older they get, the harder the treatment.'